Methylmercury blood guidance values for Canada

Review of non-invasive biomarkers as a tool for exposure characterization in human health risk assessments

Blood and urine are historically the most frequent matrices used for measuring chemical levels in human biomonitoring studies. As biomonitoring programs are refreshed, consideration of specific priority substances and specific population targets provide opportunities for inclusion of alternative non- or minimally invasive matrices. This review describes methods used in health risk assessment to characterize exposure and risk based upon biomarkers from noninvasive matrices other than urine or blood, including human milk, hair, fingernails, toenails, exhaled breath, deciduous teeth, sweat, semen, meconium, and feces. Illustrative examples of these methods relevant to chemical management are provided. This review suggests that, although these alternative noninvasive biomarkers are not frequently used in human health risk assessment at present, these biomarkers may prove useful in (1) characterizing exposure and health risk in vulnerable populations, (2) cumulative risk assessments, and (3) community-based risk assessments, depending upon the substance of concern. To incorporate alternative noninvasive biomarkers into human health risk assessments with confidence, more research is needed to improve our knowledge of the relationships between external dose, internal dose, and biologic consequent effects in matrices other than blood and urine.

Methodologies and challenges in Arctic human health risk assessment: case studies and evaluation of current practices

In Arctic populations, a primary route of exposure to contaminants is through the diet. The health risks associated with these exposures can be characterised by conducting human health risk assessments. However, while there is guidance from many international and national organisations, there are limited examples of human health risk assessment in the Arctic. The 2022 AMAP Human Health Assessment Report was the first AMAP report to describe, in one place, the utility of food-based, dietary intake-based and human tissue-based contaminant data in estimating risk. Here, we present available tools, case studies and challenges associated with conducting human health risk assessments in the Arctic. Future efforts in the Arctic should be able to use this information to best interpret human exposure to contaminants in a risk-based context.

Metal exposure in the Greenlandic ACCEPT cohort: follow-up and comparison with other Arctic populations

Humans are exposed to metals through diet and lifestyle e.g. smoking. Some metals are essential for physiologically body functions, while others are non-essential and can be toxic to humans. This study follows up on metal concentrations in the Greenlandic ACCEPT birth-cohort (mothers and fathers) and compares with other Arctic populations. The data from 2019 to 2020 include blood metal concentrations, lifestyle and food frequency questionnaires from 101 mothers and 76 fathers, 24-55 years, living in Nuuk, Sisimiut, and Ilulissat. A high percentage (25-45%) exceeded international guidance values for Hg. For the mothers, the metal concentrations changed significantly from inclusion at pregnancy to this follow-up 3-5 years after birth; some increased and others decreased. Most metals differed significantly between mothers and fathers, while few also differed between residential towns. Several metals correlated significantly with marine food intake and socio-economic factors, but the direction of the correlations varied. Traditional marine food intake was associated positively with Se, As and Hg. To the best of our knowledge, this study provides the most recent data on metal exposure of both men and women in Greenland, elucidating metal exposure sources among Arctic populations, and documents the need for continuing biomonitoring to follow the exceeding of guidance values for Hg. [Figure: see text].

Mercury in saliva, milk, and hair of nursing mothers in southeastern Iranian mothers: levels, distribution and risk assessment

This research is on lactating mothers in the city of Chah Bahar in Iran. This descriptive-analytical and questionnaire study selected a random sample of 80 mothers to examine mercury levels in their hair, milk, and saliva. The average concentration of mercury in milk, hair and saliva of mothers was 1.23 ± 0.48 µg/l, 1.81 ± 0.55 µg/g and 1.10 ± 0.63 µg/l, respectively. There was a significant correlation between mercury levels in mothers saliva and hair. Still, only a weak correlation was found between mercury levels in milk and hair, and milk and saliva, possibly associated with the high lipid content in milk. The number of children and length of the mother's pregnancy were related to the amount of mercury in the mother's milk. The number of teeth filled with amalgam, consumption of fish and marine products, consumption of fruit, and infant's weight at birth were also associated with the amount of mercury in breast milk. Chewing gum, fish consumption, infant's birth weight, weight, and length of pregnancy were among the factors associated with the amount of mercury in mothers' saliva. The mercury concentration in milk exceeded the WHO (1.4-1.7 µg/g) normal level in 8.5% mothers, and hair mercury was found in 12.5% mothers. It should be kept in mind that any amount of mercury can be harmful.

Characterizing visual field loss from past mercury exposure in an Indigenous riverine community (Grassy Narrows First Nation, Canada): a cluster-based approach

BACKGROUND

Between 1962 and 1975, a chlor-alkali plant in Canada discharged approximately 9 metric tons of mercury (Hg) into the Wabigoon River. Over the following decades, biomarkers of Hg exposure of persons from Grassy Narrows First Nation (Asubpeeschoseewagong Anishinabek), located downriver from the discharge, reflected Hg concentrations in fish. Hg exposure is known to target the calcarine fissure, resulting in visual field (VF) loss. Most studies and clinical reports focus solely on peripheral VF loss; little is known about the impact of Hg on the central and paracentral portions. The present study sought to characterize the patterns of VF loss with respect to past and current Hg.

METHODS

A 28-year hair-Hg (HHg) database, created from a 1970-97 government biomonitoring program, served to select study participants with ≥ 4 year-based HHg measurements (n = 81). Blood-Hg was assessed for current exposure. Light sensitivity thresholds across the VF were analyzed monocularly, using a Humphrey Field Analyzer (HFA). Following post-hoc exclusions, based on HFA interpretation indices, 65 participants were retained. Both eyes were combined for analyses (n = 130 eyes). Unsupervised hierarchical clustering of HFA plot data was used to identify patterns of VF loss. A series of mixed effects models (MEM) were performed to test the associations for current Hg exposure with respect to HFA interpretation indices and clusters, as well as for longitudinal past Hg exposure.

RESULTS

The clustering approach decomposed the light sensitivity deficits into 5 concentric clusters, with greatest loss in the peripheral clusters. No relation was observed between any of the cluster scores and current blood-Hg. VF deficits increased with past Hg exposure. Longitudinal MEM showed that HHg was significantly (p < 0.05) associated with all peripheral, paracentral, and central cluster scores, as well as with HFA interpretation indices.

CONCLUSIONS

Past Hg exposure in Grassy Narrows First Nation was associated with present day VF loss. The cluster-based location-specific approach identified patterns of VF loss associated with long-term Hg exposure, in both the peripheral and the central areas. The functional implications of this type of visual loss should be investigated.

The evolution of symptoms of nervous system dysfunction in a First Nation community with a history of mercury exposure: a longitudinal study

BACKGROUND

Since the 1960's, mercury (Hg) contamination of the aquatic environment of Asubpeeschoseewagong Anishinabek (Grassy Narrows First Nation) territories has impacted the community members' traditions, culture, livelihood, diet and health. Despite decreasing Hg exposure over time, a recent study suggested that long-term exposure contributed to later-life symptom clusters of nervous system dysfunction. Here, the objective was to evaluate, 5 years later, the prevalence and progression of these symptoms and examine the contribution of long-term, past Hg exposure.

METHODS

The symptom questionnaire, applied in the 2016/17 Grassy Narrows Community Health Assessment (GN-CHA) (Time 1), was re-administered in the 2021/22 Niibin study (Time 2). A total of 85 adults (median age: 47y; range: 29-75y) responded at both times. Paired statistics were used to test the differences (Time 2 - Time 1) in self-reported symptom frequencies. The symptom clustering algorithm, derived from the entire study group of the GN-CHA (n = 391), which had yielded 6 clusters, was applied at Time 1 and 2. Equivalent hair Hg measurements (HHg) between 1970 and 1997 were used in Longitudinal Mixed Effects Models (LMEM), with a sub-group with ≥ 10 repeated HHg mesurements (age > 40y), to examine its associations with symptom cluster scores and their progression.

RESULTS

For most symptoms, paired analyses (Time 2 - Time 1) showed a significant increase in persons reporting " very often" or "all the time", and in the mean Likert scores for younger and older participants (< and ≥ 50y). The increase in cluster scores was not associated with age or sex, except for sensory impairment where a greater increase in symptom frequency was observed for younger persons. LMEM showed that, for the sub-group, long-term past Hg exposure was associated with most cluster scores at both times, and importantly, for all clusters, with their rate of increase over time (Time 2 - Time 1).

CONCLUSIONS

The persistence of reported symptoms and their increase in frequency over the short 5-year period underline the need for adequate health care services. Results of the sub-group of persons > 40y, whose HHg reflects exposure over the 28-year sampling period, suggest that there may be a progressive impact of Hg on nervous system dysfunction.

Long-Term Environmental Methylmercury Exposure Is Associated with Peripheral Neuropathy and Cognitive Impairment among an Amazon Indigenous Population

Widespread contamination of the Amazon basin with mercury has been reported to occur since at least the mid-80s due to heavy gold mining activity. Although initial studies have indicated that this may lead to deleterious neurological consequences to the indigenous populations living in the region, further research is needed to better characterize the neurological burden of such long-term exposure. With this aim, a cross-sectional exploratory study has been conducted with the Yanomami indigenous population residing in a northern Amazon region. All participants underwent a structured interview; detailed neurological examination, including assessment for cognitive, motor, coordination, and sensory functions; and laboratorial testing for serum hemoglobin, blood glucose, and methylmercury levels in hair samples. This study enrolled 154 individuals of 30.9 ± 16.8 years of age, of which 56.1% were female. Mean methylmercury levels in hair were 3.9 ± 1.7 µg/g. Methylmercury levels in hair > 6.0 µg/g were found in 10.3%. Among participants with hair methylmercury levels ≥ 6.0 μg/g, the prevalences of peripheral neuropathy and reduced cognitive performance were, respectively, 78.8% (95%CI 15-177%, p = 0.010) and 95.9% (95%CI 16-230.8%, p = 0.012) higher than those of individuals with lower levels. These results suggest that chronic mercury exposure may lead to significant and potentially irreversible neurotoxicity to Yanomami population living in the northern Amazon basin.

Potential impacts of reduced seafood consumption on myocardial infarction among coastal First Nations in British Columbia, Canada

The objective of this study is to examine the potential cardiovascular risk of climate-related declines in seafood consumption among First Nations in British Columbia by assessing the combined effects of reduced omega-3 fatty acids and mercury intake from seafood on the risk of myocardial infarction (MI) in 2050 relative to 2009. The data were derived from the First Nations Food, Nutrition, and Environment Study. Seafood consumption among 369 randomly selected participants was estimated, and hair mercury concentrations were measured. Declines in seafood consumption were modelled based on previously projected climate change scenarios, and the associated changes in nutrients and contaminants were used to estimate the cardiovascular risk. Reduced seafood consumption was projected to increase the risk of MI by 4.5%–6.5% among older individuals (≥50 years), by 1.9%–2.6% in men, and by 1.3%–1.8% in women under lower and upper climate change scenarios, respectively. Reduced seafood consumption may have profound cardiovascular implications. Effective strategies are needed to promote sustainable seafood harvests and access to seafood for coastal First Nations.

The Contribution across Three Generations of Mercury Exposure to Attempted Suicide among Children and Youth in Grassy Narrows First Nation, Canada: An Intergenerational Analysis

BACKGROUND

For 60 y, the people of Asubpeeschoseewagong Anishinabek (Grassy Narrows First Nation) have endured the effects of massive mercury (Hg) contamination of their river system, central to their traditions, culture, livelihood, and diet. In the years following the Hg discharge into the English-Wabigoon River system by a chloralkali plant in the early 1970s, there was a dramatic increase in youth suicides. Several authors attributed this increase solely to social disruption caused by the disaster.

OBJECTIVE

This research examined the possible contribution of Hg exposure across three generations on attempted suicides among today's children (5-11 y old) and youth (12-17 y old), using a matrilineal intergenerational paradigm.

METHODS

Information from the 2016-2017 Grassy Narrows Community Health Assessment (GN-CHA) survey was merged with Hg biomonitoring data from government surveillance programs (1970-1997). Data from 162 children/youth (5-17 years of age), whose mothers (n=80) had provided information on themselves, their parents, and children, were retained for analyses. Direct and indirect indicators of Hg exposure included a) grandfather had worked as a fishing guide, and b) mother's measured and estimated umbilical cord blood and childhood hair Hg and her fish consumption during pregnancy with this child. Structural equation modeling (SEM) was used to examine significant links from grandparents (G0) to mothers' exposure and mental health (G1) and children/youth (G2) risk for attempted suicide.

RESULTS

Mothers' (G1) median age was 33 y, 86.3% of grandmothers (G0) had lived in Grassy Narrows territory during their pregnancy, and 52.5% of grandfathers (G0) had worked as fishing guides. Sixty percent of children (G2) were <12 years of age. Mothers reported that among teenagers (G2: 12-17 years of age), 41.2% of girls and 10.7% of boys had ever attempted suicide. The SEM suggested two pathways that significantly linked grandparents (G0) to children's (G2) attempted suicides: a) through mothers' (G1) prenatal and childhood Hg exposure and psychological distress, and b) through maternal fish consumption during pregnancy (G1/G2), which is an important contributor to children's emotional state and behavior.

DISCUSSION

Despite minimal individual information on G0 and G1 past life experiences, the findings support the hypothesis that Hg exposure over three generations contributes to the mental health of today's children and youth. The prevalence of Grassy Narrows youth ever having attempted suicide is three times that of other First Nations in Canada. https://doi.org/10.1289/EHP11301.

Characterizing variability in total mercury hair:blood ratio in the general Canadian population

BACKGROUND/OBJECTIVES

The body burden of mercury in humans can be measured through hair or blood biomarkers. To compare results from different studies, it is often required to convert mercury in hair to an equivalent level in blood, using a default hair:blood ratio of 250:1 by the World Health Organization (WHO). However, the actual ratio may vary within and between populations. The objectives of this study were to analyze the hair:blood mercury ratio in the general Canadian population, explore factors associated with higher/lower ratios, and determine if the standard ratio of 250:1 is supported.

METHODS

The Canadian Health Measures Survey (CHMS) Cycle 5 (2016-2017) measured total mercury (THg) in both hair and blood of 1168 participants 20-59 years of age. We calculated geometric mean (GM) concentrations of THg for this entire sample and subgroups. The subgroups included biological sex, women of childbearing age, race, hair treatments, categories of blood and hair selenium, urinary arsenobetaine/arsenocholine, categories of blood and hair mercury, and food consumption. We calculated a hair:blood ratio for each participant and determined population-level ratios from the GMs of the distributions. Differences by subgroups, and agreement with the WHO ratio of 250:1, were tested. The combined effect of factors on the THg hair:blood ratio was explored using staged regression analysis.

RESULTS

For participants with paired hair and blood mercury measurements, the GM of the hair:blood THg ratio was 293 (95%CI:273-316), and significantly >250. In women of childbearing age, the ratio did not differ from 250. The GMs of the ratio were higher (i.e.>300) for second tertile blood selenium (365, 95%CI:307-433), third and fourth quartiles hair mercury (347, 95%CI:308-390 and 376, 95%CI:336-422), and consumers of shellfish (338, 95%CI:308-371). Shellfish consumption was the only statistically significant factor associated with the hair:blood ratio as identified in the regression model.

CONCLUSIONS

The mean hair:blood THg ratio among Canadians generally exceeded the default ratio of 250:1. Higher ratios were observed in certain subgroups, such as seafood consumers, and shellfish consumption was the most important variable associated with the ratio. Our results suggest that population-specific hair:blood THg ratios be considered, if possible, when converting mercury levels from hair to blood to better characterize the variation around the conversion.

Mercury Exposure in Women of Reproductive Age in Rondônia State, Amazon Region, Brazil

Environmental contamination by mercury (Hg) is a problem of global scale that affects human health. This study's aim was to evaluate Hg exposure among women of reproductive age residing in the Madeira River basin, in the State of Rondônia, Brazilian Amazon. This longitudinal cohort study used linear regression models to assess the effects on Hg levels of breastfeeding duration at 6 months, and of breastfeeding duration and number of new children at 2-year and 5-year. Breastfeeding duration was significantly associated with maternal Hg levels in all regression models (6 months, 2 years and 5 years) and no significant association was observed between the number of children and the change in maternal Hg levels in the 2-year and 5-year models. This longitudinal cohort study evaluated Hg levels and contributing factors among pregnant women from different communities (riverine, rural, mining and urban) in Rondônia, Amazon Region, for 5 years. A well-coordinated and designed national biomonitoring program is urgently needed to better understand the current situation of Hg levels in Brazil and the Amazon.

Determination of Total Mercury and Carbon in a National Baseline Study of Urban House Dust

Mercury (Hg) is one of the top ten chemicals of concern for public health, according to the World Health Organization. This study investigates Hg concentrations in house dust collected from urban single family homes, to better understand typical indoor residential exposures. Using direct solid sample analysis, total Hg and carbon (TC) were determined in the <80 µm fraction of settled dust samples collected under the Canadian House Dust Study. Hg concentrations displayed a log-normal distribution with median/geomean of 0.68/0.70 mg/kg (n = 995). A small subset (<1%) of homes exhibited anomalously high dust Hg concentrations (>9.0 mg/kg). A comparison of Hg concentrations in fresh dust and household vacuum dust collected from the same homes indicated no significant difference in the two sampling methods. Total carbon concentrations displayed a median/geomean of 29.3/28.5% (n = 1011). A significant correlation between total Hg and TC in house dust (p < 0.00001) reflects the association between Hg and organic carbon previously observed in soil and sediments. The results of this study indicate a 10-fold enrichment in house dust compared with the average background concentrations reported for soil and sediments (0.07 mg/kg). The observed enrichment is attributable to Hg emissions from indoor sources and/or Hg carried home from occupational sources.

Hair to blood mercury concentration ratios and a retrospective hair segmental mercury analysis in the Northwest Territories, Canada

Concentrations of total mercury were measured in blood and hair samples collected as part of a human biomonitoring project conducted in First Nations communities of the Mackenzie Valley, Northwest Territories, Canada. Hair (n = 443) and blood (n = 276) samples were obtained from six communities in the Dehcho region and three communities in the Sahtú region of the Mackenzie Valley. The aim of this paper was to calculate hair to blood mercury ratios (for matched samples) and determine if: 1) ratios differed significantly between the two regions; 2) ratios differed from the 250:1 ratio proposed by the WHO; and, 3) point estimates of hair to blood mercury ratios could be used to estimate blood mercury concentrations. In addition, this paper aims to determine if there were seasonal patterns in hair mercury concentrations in these regions and if so, if patterns were related to among-season variability in fish consumption. The majority of mercury levels in hair and blood were below relevant health-based guidance values. The geometric mean hair (most recent segment) to blood mercury ratio (stratified by region) was 619:1 for the Dehcho region and 1220:1 for the Sahtú region. Mean log-transformed hair to blood mercury ratios were statistically significantly different between the two regions. Hair to blood ratios calculated in this study were far higher (2-5 times higher) than those typically reported in the literature and there was a large amount of inter-individual variation in calculated ratios (range: 114:1 to 4290:1). Using the 250:1 ratio derived by the World Health Organisation to estimate blood mercury concentrations from hair mercury concentrations would substantially over-estimate blood mercury concentrations in the studied regions. However, geometric mean site-specific hair to blood mercury ratios can provide estimates of measures of central tendency for blood mercury concentrations from hair mercury concentrations at a population level. Mercury concentrations were determined in segments of long hair samples to examine exposure of participants to mercury over the past year. Hair segments were assigned to six time periods and the highest hair mercury concentrations were generally observed in hair segments that aligned with September/October and November/December, whereas the lowest hair mercury concentrations were aligned with March/April and May/June. Mean log-transformed hair mercury concentrations were statistically significantly different between time periods. Between time periods (e.g., September/October vs. March/April), the geometric mean mercury concentration in hair differed by up to 0.22 μg/g, and the upper margins of mercury exposure (e.g., 95th percentile of hair mercury) varied by up to 0.86 μg/g. Results from self-reported fish consumption frequency questionnaires (subset of participants; n = 170) showed total fish intake peaked in late summer, decreased during the winter, and then increased during the spring. Visual assessment of results indicated that mean hair mercury concentrations followed this same seasonal pattern. Results from mixed effects models, however, indicated that variability in hair mercury concentrations among time periods was not best explained by total fish consumption frequency. Instead, seasonal trends in hair mercury concentrations may be more related to the consumption of specific fish species (rather than total wild-harvested fish in general). Future work should examine whether seasonal changes in the consumption of specific fish species are associated with seasonal changes in hair mercury concentrations.

Human urinary biomonitoring in Western Kenya for micronutrients and potentially harmful elements

Spot urinary elemental concentrations are presented for 357 adults from Western Kenya collected between 2016 and 2019 as part of a wider environmental geochemical survey. The aim of this study was to establish population level urinary elemental concentrations in Western Kenya for micronutrients and potentially harmful elements for inference of health status against established thresholds. For elements where thresholds inferring health status were not established in the literature using urine as a non-invasive matrix, this study generated reference values with a 95% confidence interval (RV95s) to contextualise urinary elemental data for this population group. Data are presented with outliers removed based upon creatinine measurements leaving 322 individuals, for sub-categories (e.g. age, gender) and by county public health administrative area. For Western Kenya, reference values with a 95% confidence interval (RV95s) were calculated as follows (μg/L): 717 (I), 89 (Se), 1753 (Zn), 336 (Mo), 24 (Cu), 15.6 (Ni), 22.1 (As), 0.34 (Cd), 0.47 (Sn), 0.46 (Sb), 7.0 (Cs), 13.4 (Ba and 1.9 (Pb). Urinary concentrations at the 25th/75th percentiles were as follows (μg/L): 149/368 (I), 15/42 (Se), 281/845 (Zn), 30/128 (Mo), 6/13 (Cu), 1.7/6.1 (Ni), 2.0/8.2 (As). 0.1/0.3 (Cd), 0.05/0.22 (Sn), 0.04/0.18 (Sb), 1.2/3.6 (Cs), 0.8/4.0 (Ba) and 0.2/0.9 (Pb). Urinary concentrations at a population level inferred excess intake of micronutrients I, Se, Zn and Mo in 38, 6, 57 and 14% of individuals, respectively, versus a bioequivalent (BE) upper threshold limit, whilst rates of deficiency were relatively low at 15, 15, 9 and 18%, respectively. Each of the administrative counties showed a broadly similar range of urinary elemental concentrations, with some exceptions for counties bordering Lake Victoria where food consumption habits may differ significantly to other counties e.g. I, Se, Zn. Corrections for urinary dilution using creatinine, specific gravity and osmolality provided a general reduction in RV95s for I, Mo, Se, As and Sn compared to uncorrected data, with consistency between the three correction methods.

MercuNorth - monitoring mercury in pregnant women from the Arctic as a baseline to assess the effectiveness of the Minamata Convention

Exposure to mercury (Hg) is a global concern, particularly among Arctic populations that rely on the consumption of marine mammals and fish which are the main route of Hg exposure for Arctic populations.The MercuNorth project was created to establish baseline Hg levels across several Arctic regions during the period preceding the Minamata Convention. Blood samples were collected from 669 pregnant women, aged 18-44 years, between 2010 and 2016 from sites across the circumpolar Arctic including Alaska (USA), Nunavik (Canada), Greenland, Iceland, Norway, Sweden, Northern Lapland (Finland) and Murmansk Oblast (Russia). Descriptive statistics were calculated, multiple pairwise comparisons were made between regions, and unadjusted linear trend analyses were performed.Geometric mean concentrations of total Hg were highest in Nunavik (5.20 µg/L)  and Greenland (3.79 µg/L), followed by Alaska (2.13 µg/L), with much lower concentrations observed in the other regions (ranged between 0.48 and 1.29 µg/L). In Nunavik, Alaska and Greenland, blood Hg concentrations have decreased significantly since 1992, 2000 and 2010 respectively with % annual decreases of 4.7%, 7.5% and 2.7%, respectively.These circumpolar data combined with fish and marine mammal consumption data can be used for assessing long-term Hg trends and the effectiveness of the Minamata Convention.

Regionally representative hair mercury levels in Canadian First Nations adults living on reserves

OBJECTIVE

The primary objective of this participatory study was to assess the current body burden of mercury among First Nations adults.

METHODS

The First Nations Food, Nutrition and Environment Study (2008-2018) collected regionally representative data from First Nations adults living on reserves south of the 60th parallel. Mercury was analyzed in hair as a preferred biomarker for prolonged exposure. Hair samples, a 5 mm bundle cut from the occipital region, were collected from the participants who gave consent and measured for total mercury concentrations using cold vapor atomic fluorescence spectrophotometry.

RESULTS

In total, 3404 First Nations adults living in 92 communities provided hair samples. This represents 52.5% of the respondents to the household surveys. The mean hair mercury concentrations were 0.56 μg/g among all participants and 0.34 μg/g among women of childbearing age (WCBA). There were 64 exceedances of Health Canada's mercury biomonitoring guidelines (44 WCBA, 8 women aged 51+ years, 3 men aged 19-50 years, and 9 men aged 51+ years).

CONCLUSION

Current mercury exposure no longer presents a significant clinical health risk in most of the First Nations population south of the 60th parallel across Canada. However, mercury exposure continues to be an ongoing environmental public health concern that requires continued monitoring and assessment. Women of childbearing age (19-50 years) and older individuals living in northern ecozones and Quebec have higher mercury exposures, often exceeding Health Canada's guidelines. Careful risk communication and risk management programs need to focus on northern ecozones and Quebec.

Human biomonitoring results of contaminant and nutrient biomarkers in Old Crow, Yukon, Canada

Several large-scale human biomonitoring projects have been conducted in Canada, including the Canadian Health Measures Survey (CHMS) and the First Nations Biomonitoring Initiative (FNBI). However, neither of these studies included participants living in the Yukon. To address this data gap, a human biomonitoring project was implemented in Old Crow, a fly-in Gwich'in community in the northern Yukon. The results of this project provide baseline levels of contaminant and nutrient biomarkers from Old Crow in 2019. Samples of hair, blood, and/or urine were collected from approximately 44% of community residents (77 of 175 adults). These samples were analyzed for contaminants (including heavy metals and persistent organic pollutants (POPs)), and nutrients (including trace elements and omega-3 fatty acids). Levels of these analytes were compared to health-based guidance values, when available, and results from other human biomonitoring projects in Canada. Levels of lead (GM 0.64 μg/g creatinine in urine/24 μg/L blood), cadmium (GM 0.32 μg/g creatinine in urine/0.85 μg/L blood), and mercury (GM < LOD in urine/0.76 μg/L blood/0.31 μg/g hair) were below select health-based guidance values for more than 95% of participants. However, compared to the general Canadian population, elevated levels of some contaminants, including lead (approximately 2× higher), cobalt (approximately 1.5× higher), manganese (approximately 1.3× higher), and hexachlorobenzene (approximately 1.5× higher) were observed. In contrast, levels of other POPs, including insecticides such as dichlorodiphenyltrichloroethane (DDT), its metabolite, dichlorodiphenyldichloroethylene (DDE), and polychlorinated biphenyls (PCBs) were similar to, or lower than, those reported in the general Canadian population. This study can be used along with future biomonitoring programs to evaluate the effectiveness of international initiatives designed to reduce the contaminant burden in the Arctic, including the Stockholm Convention and the Minamata Convention. Regionally, this project complements environmental monitoring being conducted in the region, informing local and regional traditional food consumption advisories.

Effects of Speciation, Cooking and Changes in Bioaccessibility on Methylmercury Exposure Assessment for Contrasting Diets of Fish and Marine Mammals

Uptake of the neurotoxicant monomethylmercury (MeHg) from fish and marine mammals continues to present a public health concern in Canada and elsewhere. However, fish and marine mammals are key diet items contributing to food security for some Indigenous populations in Canada. Mercury (Hg) exposure is estimated assuming that 100% of Hg is methylated, that 100% will be absorbed by the consumer and that cooking does not affect MeHg concentrations. Some of these assumptions do not correspond to our current state of knowledge. The aim of this study was to assess the impact of additional variables on Hg exposure equation using probabilistic risk analysis. New variables tested were (1) the proportion of methylated Hg compared to total Hg (pMeHg, %), (2) the relative absorption factor (RAF, %) expressed as bioaccessibility and (3) the mass loss factor (MLF, unitless) that represents the loss of moisture during cooking, known to increase MeHg concentration in fish and mammals. For the new variables, data from literature were used in order to set point estimate values that were further used in the probabilistic risk analysis. Modelling results for both fish and marine mammals indicate that adding these new variables significantly influenced estimates of MeHg exposure (Mood's median test, p < 0.05). This study highlights that the evaluation of exposure to MeHg is sensitive to pMeHg, RAF and MLF, and the inclusion of these variables in risk assessment should be considered with care. Further research is needed to provide better food-dependent, population-specific estimates of RAF and MLF before formal inclusion in exposure estimates.

Seasonal variations in exposure to methylmercury and its dietary sources among pregnant Inuit women in Nunavik, Canada

Among populations living in close connection with the sea, rivers and lakes for subsistence, diet varies according to local monthly wildlife species availability and food preferences. This may lead to variations in methylmercury (MeHg) exposure over a year, although no biomonitoring studies have documented this issue in Circumpolar populations, the most exposed to international Hg emissions. Our aim was to characterize seasonal variations in MeHg exposure among pregnant Inuit women from Nunavik and to identify country foods responsible for these variations. Between October 2016 and March 2017, 97 participants were recruited. Blood mercury (Hg) was tested and hair Hg was measured by centimeter as a surrogate for monthly MeHg exposure over the past year. Latent class growth analysis was conducted to identify groups of pregnant women with similar hair Hg monthly trajectories. Country foods consumption was documented by season. Seasonal daily intakes of MeHg were estimated based on concentrations in country foods. Retrospective monthly hair Hg analyses revealed that MeHg exposure was lowest in winter, and highest in summer and early fall months. Three latent classes (groups) of pregnant women with similar trajectories of monthly hair Hg variations were identified: high (n = 20, 21%), moderate (n = 38, 41%) and low variation (n = 35, 38%). Beluga meat was the country food contributing to most of daily MeHg intake, primarily during summer and fall, and was the only one associated with the odds of being classified into moderate and high variation groups (OR 95% CI: 1.19 [1.01-1.39] and 1.25 [1.04-1.50]). These findings underscore the importance of monthly variations in exposure to MeHg due to the seasonality of local foods consumed and responsible for elevated MeHg exposure. Further studies critically need to understand local diet fluctuations over a year to adequately assess MeHg exposure, adopt timely preventive interventions and evaluate the effectiveness of the Minamata Convention.

Temporal variation of total mercury levels in the hair of pregnant women from the Maternal-Infant Research on Environmental Chemicals (MIREC) study

Prenatal exposure to total mercury (T-Hg) comes from both natural and anthropogenic sources. T-Hg can cross the blood-brain and placental barriers, and may be associated with future neurological and physiological dysfunctions. Scalp hair is an optimal and non-invasive indicator of chronic T-Hg exposure. As part of the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, hair samples from 350 women were collected within weeks after giving birth, to determine temporal variations in T-Hg levels from preconception to delivery, and to compare these levels to corresponding levels measured in other matrices (maternal and umbilical cord blood, and infant's meconium). A maximum of 12 one-cm hair segments were cut starting at the scalp; segments closer to the scalp reflected recent exposure (within the last month). For proper comparison, the hair segments were matched with the collection dates for other matrices. GM hair T-Hg levels greatly decreased during pregnancy, from 0.26 μg g^-1 (preconception or full-length hair) to 0.18 μg g^-1 (at delivery or segments closer to the scalp). A similar decreasing trend was found for T-Hg in maternal blood: 1st trimester (0.60 μg L^-1) to 3rd trimester (0.47 μg L^-1). The median hair-to-blood ratios of T-Hg levels varied from 364 (1st trimester), to 408 (3rd trimester), to 229 (cord blood). Very low T-Hg levels were detected in meconium. Mercury levels in blood and hair correlated with consumption of large predatory fish.

Mercury exposure, cardiovascular disease, and mortality: A systematic review and dose-response meta-analysis

BACKGROUND

There is evidence that exposure to mercury (Hg) may be a risk factor for cardiovascular disease (CVD).

OBJECTIVE

To conduct a systematic review of published studies and a meta-analysis of the results to examine the associations between chronic Hg exposure and CVD outcomes.

METHODS

We searched PubMed, Embase, and TOXLINE using previously developed strategies. Studies were selected according to a priori-defined inclusion criteria, and their qualities were assessed. Study estimates were extracted, and subgroup analyses were conducted to explore potential sources of heterogeneity: 1) fatal vs. nonfatal events, 2) cohort study vs. non-cohort study, and 3) inorganic Hg vs. methyl mercury (MeHg). Dose-response meta-analyses were conducted for MeHg exposure and fatal/nonfatal ischemic heart disease (IHD), stroke, and all CVD.

RESULTS

A total of 14 studies reporting results collected from more than 34,000 participants in 17 countries were included in the meta-analysis. Hg exposure was associated with an increase in nonfatal IHD (relative risk (RR): 1.21 (0.98, 1.50)), all-cause mortality (RR: 1.21 (0.90, 1.62)), CVD mortality (RR: 1.68 (1.15, 2.45)), and mortality due to other heart diseases (RR: 1.50 (1.07, 2.11)). No association was observed between Hg exposure and stroke. A heterogeneous relationship was found between studies reporting fatal and nonfatal outcomes and between cohort and non-cohort studies. However, these differences were mainly due to differences in Hg exposure level. Occupational inorganic Hg exposure was associated with similar increases in different mortality outcomes. A J-shaped relationship between Hg exposure and different fatal/nonfatal outcomes was observed, with turning points at hair Hg concentrations of 1 μg/g for IHD and 2 μg/g for stroke and all CVD.

CONCLUSION

Chronic exposure to Hg was associated with an increased risk of all-cause mortality and fatal/nonfatal IHD. The risk of multiple cardiovascular endpoints starts to increase consistently at a hair Hg concentration of 2 μg/g.

Using a geographic information system to assess local scale methylmercury exposure from fish in nine communities of the Eeyou Istchee territory (James Bay, Quebec, Canada)

Exposure to methylmercury is a concern for those who rely on fish as a traditional food in the Eeyou Istchee territory of James Bay, Quebec, Canada, because industrial land uses overlap with community water bodies where fish are harvested. Consequently, this study assessed if traditional practices, particularly fishing, increased the risk of exposure to methylmercury from the consumption of locally harvested fish. We designed a geographic information system (GIS) that included land use and fish methylmercury tissue concentrations to assess clustering of potential hot spots. We also used generalized linear models to assess the association of fish consumption to blood organic-mercury concentrations, and logistic regression models to assess the probability of fish exceeding the safety threshold for methylmercury tissue concentrations in areas of high intensity land use. The GIS demonstrated significant clustered hot spots around regions of hydroelectric and mining land use. Our results also revealed that adult consumption of pike, lake trout and/or walleye, and child consumption of pike or walleye were significantly associated with blood organic-mercury concentrations. Further, large fish harvested in a community with high intensity land use yielded a 77% probability that the fish exceeded the safety threshold. From a human exposure perspective, our study highlights the need for further research on children who consume fish from this region.

Blood mercury and plasma polychlorinated biphenyls concentrations in pregnant Inuit women from Nunavik: Temporal trends, 1992-2017

The Inuit of Nunavik (Northern Quebec, Canada) are exposed to polychlorinated biphenyls (PCBs) and mercury (Hg) through their consumption of marine country foods. A temporal trend study was initiated in 1992 to monitor circulating levels of PCBs and Hg in pregnant Inuit women, since the fetus is most at risk of adverse health effects. We set out (1) to describe temporal trends of PCBs and Hg levels in pregnant Nunavik women between 1992 and 2017; (2) to determine the prevalence of participants exceeding the guidance values in 2017; (3) to investigate relations between marine country food intake and contaminant levels over the study period. A total of 559 pregnant women provided a blood sample for contaminant analysis from 1992 to 2017. PCB congeners were quantified in plasma (serum) by gas chromatography (GC) coupled to electron capture detection or mass spectrometry (MS). We determined whole blood mercury concentration by cold vapor atomic absorption or inductively-coupled plasma MS. We performed multilevel modeling to assess temporal trends in contaminant levels and relations with marine country food consumption. Concentrations of total PCBs and Hg decreased by 84% and 65% between 1992 and 2017, respectively. Nevertheless, 10% and 22% of women in 2017 exceeded guidance values for PCBs and Hg, respectively. While the decline in marine country food intake is the only factor associated with decreasing Hg levels, other factors may explain the decline in PCB levels. Despite the significant decline in PCBs and Hg levels from 1992 to 2017, exposure to these contaminants is still quite prevalent among pregnant Nunavik women. Most of the decline in Hg exposure is likely due to a shift away from marine country foods to store-bought foods, which is a concern given the cultural and nutritional importance of country foods and the high food insecurity that prevails in Nunavik.

Human biomonitoring of metals in sub-Arctic Dene communities of the Northwest Territories, Canada

A human biomonitoring project investigating environmental exposures to metals from hair, blood and urine samples was implemented in the Northwest Territories, Canada, between January 2016 and March 2018. This study reports the metal biomarker levels from nine Dene communities located in the Dehcho and Sahtú regions to identify contaminants of interest. Levels of metals in the urine (n = 198), blood (n = 276) and hair (n = 443) samples were generally similar to those seen in other biomonitoring studies in Canada, but lead levels in blood (GM = 16 μg/L; 95th percentile = 71 μg/L) and urine (GM = 0.59 μg/L, 0.69 μg/g of creatinine; 95th percentile = 4.2 μg/L, 4.0 μg/g of creatinine) were higher than those observed in the Canadian Health Measure Survey (CHMS, cycles 2 and 5). Hair mercury (but not blood mercury) appeared higher than observed in participants from the CHMS cycle 5. The vast majority of participants had biomarker levels below the biomonitoring guidance values established for mercury and lead. Based on a comparative analysis of biomarker statistics relative to a nationally-representative survey, metals and essential trace elements of particular interest for follow-up research include: lead, manganese, mercury, and selenium. This project provided baseline biomarker levels in participating regions, which is essential to track changes in the future, and identify the contaminants to prioritize for further investigation of exposure determinants.

Subsistence fishing in the Eeyou Istchee (James Bay, Quebec, Canada): A regional investigation of fish consumption as a route of exposure to methylmercury

Fishing is part of the traditional activities of Indigenous people in Canada. However, it is also a route of exposure to methylmercury, a known neurotoxicant, and this is a concern for those who rely on fish as part of their diet. The probable weekly intake (PWI) of methylmercury from six species of fish was calculated for Indigenous community members (N = 1406), grouped by age and sex, and compared to Canadian and international provisional reference doses to assess exposure. Mixed-effects regression models were also used to estimate the input of methylmercury into the blood, and Hazard Quotients (HQ) were used to assess potential effects. Of the species of fish in our study, walleye and lake trout contributed the most to methylmercury intake. There was a positive association between the consumption of walleye and the total blood mercury concentrations of mercury in women and men (R²_A = 0.40 and 0.47, respectively), and to a lesser extent, children. Similar results were observed for the consumption of lake trout. The 95th-percentile HQ for girls (3.16) and boys (3.18) from the consumption of lake trout was relatively high, and to a lesser extent, so was the HQ for walleye and pike. The consumption of some species of fish increases the exposure to methylmercury, however, taking a balanced approach, there are health benefits associated with the consumption of fish that must be considered. To mitigate future exposure to methylmercury, we recommend follow-up blood monitoring and local-geospatial-based assessments.

A descriptive analysis of blood mercury test results in British Columbia to identify excessive exposures

OBJECTIVE

The objective of this study was to describe who in British Columbia (BC) is tested for blood mercury, the distribution of their results, and the adequacy of follow-up testing.

METHODS

The BC Centre for Disease Control (BCCDC) obtained records of clinician-ordered analyses of blood mercury conducted by BC laboratories during 2009 and 2010. We conducted a descriptive analysis with statistical testing of who was tested, the distribution of their blood mercury concentrations, whose results exceeded Health Canada's proposed guidance values (8 μg/L (40 nmol/L) for children/adolescents ≤ 18 years and women 19-49 years, and 20 μg/L (100 nmol/L) for other adults), and patterns of repeat testing.

RESULTS

Mercury test results for 6487 individuals were reviewed. Adults ≥ 50 years had the highest testing rates. The median blood mercury concentration for all tested persons was 1.8 μg/L. Nine percent of women aged 19-49 years had results exceeding Health Canada's provisional guidance value of 8 μg/L. Data from one of BC's two biomarker laboratories indicated that some residents of Vancouver and nearby suburbs have higher exposure to mercury than other BC residents. Of 127 individuals who had results in 2009 exceeding provisional guidance values, only 45% were tested again within 12 months.

CONCLUSION

Collating and analyzing all clinical biomarker testing such as blood mercury at a provincial population level allows for assessment of the adequacy and appropriateness of follow-up testing and suggests which regional and demographic strata are at higher levels of exposure.

Towards a better understanding of the benefits and risks of country food consumption using the case of walruses in Nunavik (Northern Quebec, Canada)

Food insecurity affects Inuit communities. One solution is to consume locally harvested foods, named country foods. However, some country foods are not eaten as often as before, and pressures including contaminants and environmental changes threaten the health of Arctic fauna, thus its suitability for local consumption. By combining Inuit Knowledge with laboratory data, our study assessed the benefits and risks of walrus consumption by Inuit in Nunavik, Québec, Canada. It aimed to increase understanding of: 1) the hunt of healthy Atlantic walruses (Odobenus rosmarus rosmarus); 2) the safe preparation of walruses; 3) the nutritional benefits and risks of consuming walruses. To do so, we interviewed 34 hunters and Elders from Nunavik. Levels of mercury, omega-3 polyunsaturated fatty acids and selenium were evaluated from locally harvested walruses. Through the Nunavik Trichinellosis Prevention Program, a total of 755 Atlantic walrus samples, collected between 1994 and 2013, were tested for Trichinella nativa. Information on botulism was reviewed. While interviews informed on how to select healthy walruses and prepare them for consumption, laboratory analyses revealed that walruses had elevated levels of omega-3 fatty acids and selenium but low levels of mercury compared to some other wildlife. Only 3% of the 755 walruses were infected with T. nativa. Most walruses' infections were found within individuals from the South East Hudson Bay stock, where Inuit have thus decided to stop hunting since mid-2000s. Finally, although the number of outbreaks of trichinellosis related to the consumption of walruses has significantly reduced in Nunavik, botulism could continue to be an issue when igunaq (i.e. aged walrus) is not properly prepared. With the support of the Nunavik Trichinellosis Prevention Program and transmission of Inuit knowledge on igunaq preparation, the consumption of Atlantic walruses has the potential to help address issues related to food insecurity in Nunavik in the future.

Mercury exposure and premature mortality in the Grassy Narrows First Nation community: a retrospective longitudinal study

BACKGROUND

Little is known about the influence of toxic exposures on reduced life expectancy in First Nations people in Canada. The Grassy Narrows First Nation community have lived with the consequences of one of the worst environmental disasters in Canadian history. In the early 1960s, 10 000 kg of mercury (Hg) was released into their aquatic ecosystem. Although Hg concentration in fish, their dietary staple, decreased over time, it remains high. We aimed to examine whether elevated Hg exposure over time contributes to premature mortality (younger than 60 years) in this community.

METHODS

We did longitudinal and case-control analyses with data for individuals of the Grassy Narrows First Nation community. In 2019, the community obtained their historical Hg biomarker data from a government surveillance programme, which was then shared with the authors. A matched-pair approach allowed us to compare longitudinal hair Hg concentration between cases (individuals who died aged younger than 60 years) and controls (individuals who lived beyond 60 years). Matching criteria included year of birth (allowing 2 years either side), sex, and a minimum of four hair Hg concentration measures, of which at least two were in the same year. Analyses included change-point detection, interrupted time series, mixed models, and Cox survival models.

FINDINGS

We analysed data collected between Jan 1, 1970, and Jan 31, 1997, for 657 individuals (319 women and 338 men, born between 1884 and 1991) for whom we assembled a retrospective database of yearly measures of hair Hg concentration (n=3603). Hair Hg concentration decreased over time. A subgroup of 222 individuals (107 women and 115 men) reached or could have reached 60 years old by August, 2019. There was an increased risk of dying at a younger age among those with at least one hair Hg measure of 15 μg/g or more (adjusted hazard ratio 1·55, 95% CI 1·11-2·16; p=0·0088). Among the deceased individuals (n=154), longevity decreased by 1 year with every 6·25 μg/g (4·35-14·29) increase in hair Hg concentration. Analyses of 36 matched pairs showed that hair Hg concentration of those who died aged younger than 60 years was 4·7 times higher (3·4-5·9) than controls.

INTERPRETATION

The consistent findings between our different analyses support an association between long-term Hg exposure from freshwater fish consumption and premature mortality in this First Nation community. There is a need to do risk-benefit analyses of freshwater fish consumption in environmentally contaminated regions.

FUNDING

Canadian Institutes of Health Research.

Regional variations in human chemical exposures in Canada: A case study using biomonitoring data from the Canadian Health Measures Survey for the provinces of Quebec and Ontario

The Canadian Health Measures Survey (CHMS), an ongoing national health survey conducted in two-year cycles, collects extensive biomonitoring data that is used to assess the exposure of Canadians to environmental chemicals of concern. Combining data from multiple cycles of the CHMS allows for the calculation of robust regional estimates of chemical concentrations in blood and urine. The objective of this work was to compare biomarkers of exposure to several environmental chemicals for the provinces of Quebec and Ontario, two major CHMS regions, as well as the entire CHMS (representing Canada) minus Quebec (CMQ), and the entire CHMS minus Ontario (CMO), and to interpret differences between regions. Geometric means and 95th percentiles of blood and/or urinary concentrations of 45 environmental chemicals or their metabolites for Ontario, Quebec, CMQ, and CMO were calculated by combining the two most recent cycles of data available for a chemical (cycles 1 and 2, or cycles 2 and 3) from the first three cycles of the CHMS (2007-2013). Weighted one-way ANOVA was used to test the differences between regional estimates. After applying a Bonferonni-Holm adjustment for multiple comparisons, the following measures were significantly higher in Quebec as compared to Ontario and CMQ: blood lead, urinary lead and the urinary polyaromatic hydrocarbon (PAH) metabolites, 9-hydroxyfluorene, 1-hydroxyphenanthrene, 2- hydroxyphenanthrene and 3-hydroxyphenanthrene. In Quebec compared to CMQ only, urinary 2-hydroxfluorene, 3-hydroxyfluorene, 2-hydroxynaphthalene, and 4-hydroxyphenanthrene were higher. The concentration of urinary fluoride was significantly higher in Ontario as compared to Quebec and CMO. Blood manganese and urinary fluoride were significantly lower in Quebec compared to CMQ, and blood and urinary selenium were significantly lower in Ontario compared to CMO. Regional differences in tobacco use, age of dwellings and drinking water fluoridation are among the possible contributing factors to some of the observed differences. In conclusion, this is the first study where biomonitoring data from multiple cycles of CHMS were combined in order to generate robust estimates for subsets of the Canadian population. Such assessments can contribute to a regional-level prioritization of control measures to reduce the exposure of Canadians to chemicals in their environment.

Exposure to toxic metals and polychlorinated biphenyls of adolescents and adults from two atolls in the Tuamotu Archipelago (French Polynesia)

The atoll of Hao, part of the Tuamotu Archipelago in French Polynesia, hosted an air base which was used by France Air Force and Naval Aviation during the nuclear tests. Following the publication of a report in 2012 indicating widespread contamination of the atoll, we conducted a biomonitoring survey to assess the exposure to toxic metals and polychlorinated biphenyls (PCBs) of Hao residents and residents of Makemo, a nearby atoll without any known sources of industrial pollution. Adults and adolescents (≥12 years) randomly sampled from Hao (n = 275) and Makemo (n = 268) provided blood samples for contaminant analyses. Whole blood samples were analysed for cadmium, lead and total mercury by inductively coupled plasma mass spectrometry. Plasma concentrations of PCBs were measured by gas chromatography mass spectrometry. Face-to-face interviews were conducted to document lifestyle and a food-frequency questionnaire was used to document dietary habits. Concentrations of contaminants were compared between atolls and associations with sociodemographic and personal characteristics of the participants were investigated. A significantly higher mean (geometric) of blood lead concentration was observed in Hao compared to Makemo (3.75 vs 3.40 μg/L, P = 0.02), whereas similar concentrations were noted for cadmium (0.49 vs 0.50 μg/L, P = 0.58) and mercury (11.4 vs 11.5 μg/L, P = 0.78). Mean total PCBs plasma concentration was significantly higher in Hao than in Makemo participants (0.75 vs 0.32 μg/L, P < 0.001). A significant proportion of participants exceeded toxicological reference values for mercury and lead in both atolls. The higher body burden of PCBs and Pb in Hao compared to Makemo residents may be linked to past air base activities in Hao. According to international standards, PCBs exposure is low; however, exposure to both mercury and lead is high and further investigations are required to identify specific sources of exposure.

Total, methyl and inorganic mercury concentrations in blood and environmental exposure sources in newcomer women in Toronto, Canada

Measurements of total blood Hg (tHg), often used as a proxy for methyl Hg (MeHg) concentrations, are most commonly the focus of population-based studies. Data on Hg species in biomarkers can allow for a more nuanced characterization of environmental exposure sources and risk but their availability is limited, especially for newcomer populations. The purpose of the Metals in Newcomer Women (MNW) study was to address existing data gaps on metal concentrations and exposure sources in newcomer women (19-45 years) and to examine tHg, MeHg and inorganic Hg (iHg) in the blood of East and South Asian women recently arrived to Toronto. Study participants were recruited in 2015 (n = 211). Total Hg concentrations were determined using both ICP-Q-MS and isotope dilution (ID)-SPME-GC-ICP-MS. A sample subset (n = 76) was chosen for the analysis of blood MeHg and iHg concentrations (also using ID-SPME-GC-ICP-MS). Hierarchical regression models were used to assess associations between blood tHg concentrations and environmental exposure factors for MNW participants. For the sample subset, a log-linear model was used to examine associations between blood iHg and MeHg concentrations and fish consumption patterns. The geometric mean (GM) blood tHg concentration was 1.05 µg/L (95% CI: 0.88-1.25), which was elevated compared to Canadian-born women (GM: 0.57 µg/L; 95% CI: 0.49-0.66), in a specialized data analysis of the Canadian Health Measures Survey (CHMS). GM concentrations for iHg and MeHg were 0.21 µg/L (95% CI: 0.16-0.28) and 2.66 µg/L (95% CI: 2.00-3.55), respectively. Significant distal determinants associated with blood tHg concentrations were: level of educational attainment, having lived in a coastal/fishing community prior to arrival, and global region of origin. Use of iron supplements and consumption of higher mercury fish species were also associated with tHg concentrations in the fully adjusted model. The study results demonstrate that blood Hg concentrations in newcomer women are slightly elevated, with some individuals in exceedance of recommended concentrations for women of reproductive age. The consumption of fish species low in Hg is recommended for newcomer women, especially those who consume fish frequently.

Implementation of human biomonitoring in the Dehcho region of the Northwest Territories, Canada (2016-2017)

Background

Human biomonitoring represents an important tool for health risk assessment, supporting the characterization of contaminant exposure and nutrient status. In communities where country foods (locally harvested foods: land animals, fish, birds, plants) are integrated in the daily diet, as is the case in remote northern regions where food security is a challenge, such foods can potentially be a significant route of contaminant exposure. To assess this issue, a biomonitoring project was implemented among Dene/Métis communities of the Dehcho region of the Northwest Territories, Canada.

Methods

Participants completed dietary surveys (i.e., a food frequency questionnaire and 24-h recall) to estimate food consumption patterns as well as a Health Messages Survey to evaluate the awareness and perception of contaminants and consumption notices. Biological sampling of hair, urine and blood was conducted. Toxic metals (e.g., mercury, lead, cadmium), essential metals (e.g., copper, nickel, zinc), fatty acids, and persistent organic pollutants (POPs) were measured in samples.

Results

The levels of contaminants in blood, hair and urine for the majority of participants were below the available guidance values for mercury, cadmium, lead and uranium. However, from the 279 participants, approximately 2% were invited to provide follow up samples, mainly for elevated mercury level. Also, at the population level, blood lead (GM: 11 μg/L) and blood cadmium (GM: 0.53 μg/L) were slightly above the Canadian Health Measures Survey data. Therefore, although country foods occasionally contain elevated levels of particular contaminants, human exposures to these metals remained similar to those seen in the Canadian general population. In addition, dietary data showed the importance and diversity of country foods across participating communities, with the consumption of an average of 5.1% of total calories from wild-harvested country foods.

Conclusion

This project completed in the Mackenzie Valley of the Northwest Territories fills a data gap across other biomonitoring studies in Canada as it integrates community results, will support stakeholders in the development of public health strategies, and will inform environmental health issue prioritization.

Electronic supplementary material

The online version of this article (10.1186/s13690-018-0318-9) contains supplementary material, which is available to authorized users.

Blood and hair mercury concentrations among Cree First Nations of Eeyou Istchee (Quebec, Canada): time trends, prenatal exposure and links to local fish consumption

To describe exposure to methylmercury among Cree, focusing on women of childbearing age, we used data from 2 studies. Multiple regression was employed to examine associations between blood and hair mercury concentrations and consumption of locally harvested fish. Approximately 9.9% of non-pregnant women aged 15-44 y and 3.9% of pregnant women required follow-up according to Health Canada's blood mercury guidance value of 40 nmol/L. 8% of hair mercury observations in the non-pregnant women and 2.5% among pregnant women exceeded the equivalent threshold of 10 nmol/g. The geometric mean blood mercury concentration was 12.7 nmol/L in 1,429 persons aged 8 and over, and 17.7 nmol/L in adults aged 18 and older. The proportion of hair mercury concentrations greater than 12.5 nmol/g decreased in all age-sex groups when comparing the 2002-2009 data to published values for 1993-1994. Among women of childbearing age, local fish consumption was associated with increased blood and hair mercury concentrations. While over 90% of women of childbearing age in this population have acceptable levels of mercury, ongoing intake of mercury suggests that their consumption of fish with known high mercury content be minimised. Reducing consumption of fish known to be high in mercury content needs to be balanced with promoting ongoing connection to Cree culture and land-based activities that are also important determinants of health.

Socio-economic inequalities in blood mercury (Hg) and serum polychlorinated biphenyl (PCB) concentrations among pregnant Inuit women from Nunavik, Canada

OBJECTIVE

We examined the relationships between socio-economic characteristics and mercury (Hg) and polychlorinated biphenyl (PCB) concentrations among pregnant Inuit women from Nunavik.

METHOD

We used biomonitoring data from 208 pregnant Inuit women recruited in the 14 villages of Nunavik between September 2011 and December 2013. Blood samples were collected to monitor levels of blood Hg and serum congener PCB-153 (surrogate of total PCB concentration). Ratio of omega 3/omega 6 polyunsaturated fatty acids, a validated biomarker of marine country food consumption, was also measured in red blood cell membranes to determine maternal dietary profile. Data on socio-economic characteristics (income and education), health-related lifestyles, and reproductive history were collected through questionnaires. Association between socio-economic characteristics and contaminant concentrations was assessed using linear regressions.

RESULTS

We observed a significant inverse relationship between education and Hg levels. Lower concentrations of Hg were observed among women who had completed high school compared to women who had not completed high school. However, no association was observed between level of education and concentration of PCBs.

CONCLUSION

Socio-economic disparities in maternal exposure to Hg exist in Nunavik. Further research is needed to determine whether environmental health inequalities also exist in other subgroups of the Nunavik population and in other Indigenous communities in Canada.

Quantitative estimation of mercury intake by toxicokinetic modelling based on total mercury levels in humans

Mercury is a toxic metal that can be disseminated into the environment from both natural and anthropogenic sources. Human exposure to the metal stems mainly from food, and more particularly from the consumption of fish and other seafoods. Examining dietary exposure and measuring mercury levels in body tissues are two ways of estimating exposure to mercury. In this study, we utilized a modelling system consisting of three linear toxicokinetic models for describing the fate of methyl mercury, inorganic mercury, and metallic mercury in the body, in order to estimate daily intake of mercury as measured through total mercury concentrations in the blood. We then compared the results stemming from our modelling system to those of the detailed semi-quantitative food frequency questionnaire (FFQ) of the Norwegian Fish and Game (NFG) Study, a project that focused on dietary mercury exposure. The results indicate that toxicokinetic modelling based on blood levels gave higher daily intake values of mercury compared to those of the FFQ. Furthermore, the former had a wider range of estimates than the latter. The properties of the toxicokinetic model or limitations in the dietary exposure assessment could be posited as reasons for the differences between the respective methods. Moreover, the results may have been influenced by sources of mercury exposure that cannot be described as dietary, such as amalgam fillings.

Blood mercury, lead and cadmium levels and determinants of exposure among newcomer South and East Asian women of reproductive age living in Vancouver, Canada

BACKGROUND

Biomarkers of the reproductive and neuro-developmental toxicants mercury (Hg), lead (Pb) and cadmium (Cd) have been found at higher concentrations in women born outside Canada than in Canadian-born women. We measured blood Hg, Pb and Cd in women ages 19 to 45years living in greater Vancouver (Canada) within five years of their arrival from South Asia (India) or East Asia (mainland China, Hong Kong and Taiwan) and related their biomarker concentration levels with exposures and behaviors since their coming to Canada.

METHODS

Participants were recruited through advertisements in relevant ethnic media, locations and groups. Concentrations of blood Hg, Pb and Cd were analyzed by inductively coupled plasma-mass spectrometry (ICP-Q-MS) and compared with population values. Biomarker concentrations were regressed against exposures and behaviors assessed by culturally-relevant questionnaire.

RESULTS

The study recruited 53 South and 111 East Asian women. Median (95th percentile) blood Pb in South Asians was 1.15 (2.71) μg/dL compared with 1.01 (1.81) μg/dL in East Asians. On the other hand, blood Hg at 2.5 (7.3) μg/L was higher in East Asians compared to 0.20 (0.83) μg/L in South Asians. Blood Cd was also higher in the East Asian group: East 0.53 (1.1) μg/L; South 0.27 (0.82) μg/L. Higher blood Hg was associated with seafood consumption, dental amalgams and traditional remedies; blood Pb with home renovations, sucking on metal jewelry, and cosmetics. Blood Pb and Cd concentrations were inversely associated with dairy consumption.

CONCLUSIONS

Asian women recently arrived in Vancouver had higher blood Hg, Pb and Cd concentrations than same-age Canadian women measured in a national survey. Among South Asian newcomer women of reproductive age, exposure to Cd may continue after arrival. Local exposures to Hg occur through seafood and potentially through ingestion of imported traditional remedies.

Cooking and co-ingested polyphenols reduce in vitro methylmercury bioaccessibility from fish and may alter exposure in humans

Fish consumption is a major pathway for mercury exposure in humans. Current guidelines and risk assessments assume that 100% of methylmercury (MeHg) in fish is absorbed by the human body after ingestion. However, a growing body of literature suggests that this absorption rate may be overestimated. We used an in vitro digestion method to measure MeHg bioaccessibility in commercially-purchased fish, and investigated the effects of dietary practices on MeHg bioaccessibility. Cooking had the greatest effect, decreasing bioaccessibility on average to 12.5±5.6%. Polyphenol-rich beverages also significantly reduced bioaccessibility to 22.7±3.8% and 28.6±13.9%, for green and black tea respectively. We confirmed the suspected role of polyphenols in tea as being a driver of MeHg's reduced bioaccessibility, and found that epicatechin, epigallocatechin gallate, rutin and cafeic acid could individually decrease MeHg bioaccessibility by up to 55%. When both cooking and polyphenol-rich beverage treatments were combined, only 1% of MeHg remained bioaccessible. These results call for in vivo validation, and suggest that dietary practices should be considered when setting consumer guidelines for MeHg. More realistic risk assessments could promote consumption of fish as a source of fatty acids, which can play a protective role against cardiovascular disease.

A total diet study and probabilistic assessment risk assessment of dietary mercury exposure among First Nations living on-reserve in Ontario, Canada

Methyl Mercury (MeHg) exposure is a global environmental health concern. Indigenous peoples around the world are susceptible to MeHg exposure from often higher fish consumption compared to general populations. The objective of this study was to estimate dietary exposure to methylmercury (MeHg) among First Nations living on-reserve in the province of Ontario, Canada. A total diet study was constructed based on a 24-h recall from the First Nations Food, Nutrition, and Environment Study (FNFNES), and measured contaminant concentrations from Health Canada for market foods, and FNFNES for traditional foods. A probabilistic assessment of annual and seasonal traditional food consumptions was conducted for 1429 adult participants. Results were compared to exposures in the general Canadian population and reference values from Health Canada for adults and women of childbearing age (ages 19-50). Results indicated traditional foods to be the primary contributor to the dietary total MeHg intake (72%). The average dietary total MeHg exposure in the First Nations population in Ontario (0.039μg/kg/d) was 1.6 times higher than the general Canadian population; however, the majority (97.8%) of the population was below the reference values. Mercury concentrations in participants' hair samples (n = 744) ranged from 0.03 to 13.54µg/g, with an average of 0.64µg/g (geometric average of 0.27µg/g). Less than 1% of the population had a hair mercury value above the 6µg/g level, and 1.3% of women of child bearing age had values greater than 2µg/g. Fish species contributing to the MeHg intake included pickerel-walleye, pike, perch and trout. Only 7.9% of the population met the recommended fish consumption rate of two, 3.5oz servings per week from the American Heart Association. Therefore, consumption of lower trophic level fish can be promoted to provide the maximum nutritional benefit with minimal risk of MeHg exposure.

Body burdens, sources and interrelations of selected toxic and essential elements among the nine Cree First Nations of Eeyou Istchee, James Bay region of northern Quebec, Canada

BACKGROUND

this article constitutes a report on the comprehensive Nituuchischaayihtitaau Aschii multi-community environment-and-health study conducted among the Cree peoples (Eeyouch) of northern Quebec, Canada.

OBJECTIVES

to interpret observed concentrations of a suite of chemical elements in a multi-media biological monitoring study in terms of sources and predictors.

METHODS

the concentrations of 5 essential and 6 toxic chemical elements were measured in whole blood, and/or in urine or hair by ICP-MS. Concentrations of essential elements are compared to those considered normal (i.e., required for good health) and, when toxic, deemed acceptable at specified concentrations in public health guidelines. Their dependence on age, sex, the specific community lived-in and diet were explored employing multivariate analysis of variance (MANOVA) involving new variables generated by principle component analysis (PCA) and correspondence analysis (CA).

RESULTS

the 5 most prominent PCA axes explained 67.7% of the variation, compared to 93.0% by 6 main CA factors. Concentrations of the essential elements in whole blood (WB) and iodine(i) and arsenic (As) in urine were comparable to those reported in the recent Canadian Health Measures survey and are assigned to dietary sources. By contrast, WB cadmium (Cd) was elevated even when smoking was considered. Mercury (Hg) concentrations in WB and hair were also higher in adults, although comparable to those observed for other indigenous populations living at northern latitudes. Fish consumption was identified as the prominent source. Of the 5 coastal communities, all but one had lower Hg exposures than the four inland communities, presumably reflecting the type of fish consumed. Use of firearms and smoking were correlated with WB-lead (Pb). The concentrations of both Hg and Pb increased with age and were higher in men, while WB-Cd and smoking prevalence were higher in women when considering all communities. Hg and Pb were low in children and women of reproductive age, with few exceedances of health guidelines. Although individuals with T2D had somewhat lower WB-Cd, there is some indication that Cd may potentiate renal dysfunction in this subgroup. Plots of selected CA axes grouped those elements expected to be in a normal diet and distinguished them from those with well-known unique sources (especially Hg and As in hair; and Hg, Pb and Cd in WB).

CONCLUSIONS

the use of multiple biological media in conjunction with the complementary PCA and CA approaches for constructing composite variables allowed a more detailed understanding of both the sources of the essential and toxic elements in body fluids and the dependencies of their observed concentrations on age, sex, community and diet.

Mercury diminishes the cardiovascular protective effect of omega-3 polyunsaturated fatty acids in the modern diet of Inuit in Canada

BACKGROUND

Inuit in Canada have low reported incidence of myocardial infarction (MI) because of their traditional rich n-3 fatty acids marine diet. They are experiencing rapid nutrition transition and ischemic heart disease is now becoming a health concern.

OBJECTIVES

Our goal was to describe the modern Inuit diet, the eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and methyl mercury (MeHg) intake and estimate their contributions to the risk of MI. We also estimated the effect of promoting the consumption of more traditional food on Inuit's MI risk.

METHODS

We estimated the effect of Inuit diet on MI risk with modelling. Model formulas and assumptions were extracted from various epidemiology studies and literatures. International Polar Year Inuit Health Survey (IHS) was a comprehensive health and nutrition survey conducted in 2007-8 with 2072 participants (aged 18-79) in Canada. Traditional food intake, blood biomarkers values from the IHS served as the baseline parameters of model input.

RESULTS

Inuit traditional diet contained both high level of EPA, DHA and MeHg and their combined net effect was estimated to reduce the relative risk of MI by 1% for men and 2% for women. Arctic char meat provided the largest amount of EPA and DHA. Ringed seal liver was the main source for MeHg. Increase intake of selected fish, like salmon, herring and Arctic char by 75g per day can reduce the relative risk of MI (RR 0.70, 0.78 and 0.90 respectively).

CONCLUSIONS

In the Inuit diet, the beneficial effect on MI of EPA and DHA is diminished by the adverse effect of MeHg. Promoting the increase consumption of fish species with high EPA+DHA and low MeHg may help to prevent MI among Inuit.

New approaches in human health risk assessment

Studies on the precise impact of environmental pollutants on human health are difficult to undertake and interpret, because many genetic and environmental factors influence health at the same time and to varying degrees. Our chapter in the AMAP report was based on new approaches to describe risks and future needs. In this paper, we will introduce the issues associated with risk assessment of single chemicals, and present suggestions for future studies as well as a summary of lessons learned during the health-related parts of the European Union-funded FP7 project ArcRisk (Arctic Health Risks: Impacts on health in the Arctic and Europe owing to climate-induced changes in contaminant cycling, 2009–2014; www.arcrisk.eu).

Associations between omega-3 fatty acids, selenium content, and mercury levels in wild-harvested fish from the Dehcho Region, Northwest Territories, Canada

To better understand the risks and benefits of eating wild-harvested fish from the Northwest Territories, Canada, levels of total mercury (HgT) and selenium (Se) and composition of omega-3 fatty acid (n-3 FA) were measured in muscle tissue of fish harvested from lakes in the Dehcho Region, Northwest Territories, Canada. Average HgT levels ranged from 0.057 mg/kg (cisco) to 0.551 mg/kg (northern pike), while average n-3 FA concentrations ranged from 101 mg/100 g (burbot) to 1,689 mg/100 g (lake trout). In contrast to HgT and n-3 FA, mean Se concentrations were relatively similar among species. Consequently, species such as lake whitefish, cisco, and longnose sucker displayed the highest nutrient levels relative to HgT content. Levels of HgT tended to increase with fish size, while Se and n-3 FA levels were typically not associated with fork length or fish weight. Interestingly, HgT concentration was occasionally inversely related to tissue nutrient content. Significant negative correlations were observed between Hg and n-3 FA for lake trout, northern pike, and walleye. There were also significant negative correlations between Hg and Se noted for lake whitefish, cisco, and northern pike. Samples with the highest nutritional content displayed, on occasion, lower levels of HgT. This study provides valuable information for the design of probabilistic models capable of refining public health messaging related to minimizing Hg risks and maximizing nutrient levels in wild-harvested fish in the Canadian subarctic.

An Ecological and Human Biomonitoring Investigation of Mercury Contamination at the Aamjiwnaang First Nation

The Aamjiwnaang First Nations community is located in Canada's 'Chemical Valley' situated in southwest Ontario near Sarnia. Mercury pollution in the region has been known since the 1940s but little is known about levels in the environment and area residents. The current study, using ecological and human exposure assessment methods, was conducted at the community's request to help fill these gaps. First, Canada's National Pollutant Release Inventory and the U.S. Toxics Release Inventory were queried to investigate mercury releases from area facilities. In 2010, 700 pounds of mercury were emitted into the air, 25 pounds were released into water bodies, and 93 thousand pounds were disposed of on-site via underground injections or into landfills, and together these show continued releases into the region. Second, mercury levels were measured in stream sediment and nearby soil from sites at Aamjiwnaang (n = 4) and off Reserve (n = 19) in Canada and the U.S. during three seasons that spanned 2010-2011. Total mercury in sediment across all sites and sampling seasons ranged from 5.0 to 398.7 µg/kg, and in soils ranged from 1.2 to 696.2 µg/kg. Sediment and soil mercury levels at Aamjiwnaang were higher than the reference community, and Aamjiwnaang's Talfourd Creek site had the highest mercury levels. Third, a biomonitoring study was performed with 43 mother-child pairs. Hair (mean ± SD of all participants: 0.18 ± 0.16 µg/g) and blood (1.6 ± 2.0 µg/L) mercury levels did not differ between participants studied on- and off-Reserve, likely because of limited seafood intake (<1 serving/week). Urine mercury levels (0.5 ± 0.8 µg/L) were significantly higher (1.5-2.5 times) in mother-child pairs living on-Reserve versus those living off-Reserve. In general, the study links evidence of mercury sources, environmental fate, and human exposures, and in doing so it shows that mercury levels in ecological and human samples are similar to values found in other areas, though there are some trends and evidence of contamination at Aamjiwnaang that warrant attention.

Maternal and fetal exposure to cadmium, lead, manganese and mercury: The MIREC study

Given the susceptibility of the fetus to toxicants, it is important to estimate their exposure. Approximately 2000 pregnant women were recruited in 2008-2011 from 10 cities across Canada. Cd, Pb, Mn and total Hg were measured in maternal blood from the 1st and 3rd trimesters, umbilical cord blood, and infant meconium. Nutrient intakes of vitamin D, iron, and calcium (Ca) were assessed using a food frequency questionnaire and a dietary supplement questionnaire. Median concentrations in 1st trimester maternal blood (n = 1938) were 0.20, 8.79 and 0.70 μg/L for Cd, Mn and Hg, respectively, and 0.60 μg/dL for Pb. While the median difference between the paired 1st and 3rd trimester concentrations of Cd was 0, there was a significant decrease in Pb (0.04 μg/dL) and Hg (0.12 μg/L) and an increase in Mn (3.30 μg/L) concentrations over the course of the pregnancy. While Cd was rarely detected in cord blood (19%) or meconium (3%), median Pb (0.77 μg/dL), Mn (31.87 μg/L) and Hg (0.80 μg/L) concentrations in cord blood were significantly higher than in maternal blood. Significant negative associations were observed between estimated Ca intake and maternal Cd, Pb, Mn and Hg, as well as cord blood Pb. Vitamin D intake was associated with lower maternal Cd, Pb, and Mn as well as Pb in cord blood. Even at current metal exposure levels, increasing dietary Ca and vitamin D intake during pregnancy may be associated with lower maternal blood Pb and Cd concentrations and lower Pb in cord blood.

An overview of human biomonitoring of environmental chemicals in the Canadian Health Measures Survey: 2007-2019

Human biomonitoring (HBM) is used to indicate and quantify exposure by measuring environmental chemicals, their metabolites or reaction products in biological specimens. The biomonitoring component of the Canadian Health Measures Survey (CHMS) is the most comprehensive initiative providing general population HBM data in Canada. The CHMS is an ongoing cross-sectional direct measures survey implemented in 2-year cycles. It provides nationally-representative data on health, nutritional status, environmental exposures, and related risks and protective characteristics. The survey follows a robust planning, design and sampling protocol as well as a comprehensive quality assurance and quality control regime implemented for all aspect of the survey to ensure the validity of the HBM results. HBM blood and urine data are available for CHMS cycles 1 (2007-2009), 2 (2009-2011) and 3 (2012-2013). Field collection has been completed for cycle 4 (2014-2015), with cycle 5 (2016-2017) in progress and cycle 6 planning (2018-2019) being finalized. Biomonitoring results for 279 chemicals are expected over the six cycles of the CHMS (220 in individual blood, urine or hair samples, and 59 in pooled serum samples). The chemicals include metals and trace elements, polychlorinated biphenyls (PCBs), organochlorines, flame retardants, perfluoroalkyl substances, volatile organic compounds (VOCs) and metabolites, environmental phenols, triclocarban, acrylamide, pesticides (e.g., triazines, carbamates, organophosphates, phenoxy, pyrethroids) and/or their metabolites, chlorophenols, polycyclic aromatic hydrocarbon (PAH) metabolites, phthalates and alternate plasticizer metabolites, and tobacco biomarkers. Approximately one half of the chemicals measured in individual blood and urine samples over the first three cycles were detected in more than 60% of samples. CHMS biomonitoring data have been used to establish baseline HBM concentrations in Canadians; inform public health, regulatory risk assessment and management decisions; and fulfil national and international reporting requirements. Concurrent efforts are underway in Canada to develop statistically- and risk-based concepts and tools to interpret biomonitoring data.

Reducing Periconceptional Methylmercury Exposure: Cost-Utility Analysis for a Proposed Screening Program for Women Planning a Pregnancy in Ontario, Canada

BACKGROUND

The assessment of neurodevelopmental effects in children associated with prenatal methylmercury exposure, from contaminated fish and seafood in the maternal diet, has recently been strengthened by adjustment for the negative confounding resulting from co-exposure to beneficial polyunsaturated fatty acids (PUFAs).

OBJECTIVES

We aimed to determine the cost-effectiveness of a periconceptional screening program of blood mercury concentration for women planning to become pregnant in Ontario, Canada. Fish intake recommendations would be provided for those found to have blood mercury levels above the intervention threshold.

METHODS

Analysis was conducted using a combined decision tree/Markov model to compare the proposed screening intervention with standard care from a societal perspective over a lifetime horizon. We used the national blood mercury distributions of women 20-49 years of age reported in the Canadian Health Measures Survey from 2009 through 2011 to determine the cognitive deficits associated with prenatal methylmercury exposure for successful planned pregnancies. Outcomes modeled included the loss in quality of life and the remedial education costs. Value of information analysis was conducted to assess the underlying uncertainty around the model results and to identify which parameters contribute most to this uncertainty.

RESULTS

The incremental cost per quality-adjusted life year (QALY) gained for the proposed screening intervention was estimated to be Can$18,051, and the expected value for a willingness to pay of Can$50,000/QALY to be Can$0.61.

CONCLUSIONS

Our findings suggest that the proposed periconceptional blood mercury screening program for women planning a pregnancy would be highly cost-effective from a societal perspective. The results of a value of information analysis confirm the robustness of the study's conclusions.

Examining the Impact of a Public Health Message on Fish Consumption in Bermuda

Background

In 2003 mean cord blood mercury concentrations in pregnant Bermudian women exceeded levels associated with adverse health outcomes in children. The principal mercury source was local fish species. Public health messages were developed suggesting pregnant women reduce consumption of fish species with higher mercury concentrations (e.g. swordfish), substituting species containing lower mercury concentrations, and elevated omega-3 fatty acids (e.g. anchovies). Recent evidence indicates mercury concentrations in Bermuda’s pregnant women have fallen five- fold.

Objectives

Assess whether changes in women’s fish eating patterns during pregnancy are consistent with the public health messaging. Determine who is making changes to their diet during pregnancy and why.

Methods

Mixed methods study with a cross-sectional survey of 121 pregnant women, including 13 opened-ended interviews. Health system, social vulnerability, public health messaging, and socio-demographic variables were characterized and related to changes in fish consumption during pregnancy. Qualitative data were coded according to nutritional advice messages, comprehension of communication strategies, and sources of information.

Results

95% of women surveyed encountered recommendations about fish consumption during pregnancy. 75% reported modifying fish eating behaviors because of recommendations. Principal sources of information about fish consumption in pregnancy were health care providers and the Internet. 71% of women reported reducing consumption of large fish species with greater mercury levels, but 60% reported reduced consumption of smaller, low mercury fish. No participant mentioned hearing about the benefits of fish consumption. More frequent exposure to public health messages during pregnancy was associated with lower reported consumption. Bermudian born women were less likely to reduce consumption of large fish species during pregnancy.

Conclusions

In Bermuda, public health messages advocating reduced consumption of larger, higher mercury-containing fish species appear effective, but masked the nutritional value message of small fish species, with low mercury concentration. Adjustment is needed to better balance the risk communication.