Does ambient air pollution influence biochemical markers of liver injury? Findings of a cross-sectional population-based survey

BACKGROUND

There is limited evidence supporting an adverse effect of ambient air pollution on the liver.

OBJECTIVES

To test the association between exposure to residential air pollution and serum biochemical indicators of liver injury.

METHODS

We used a nationally representative sample of 32,989 participants aged 3-79 years old who participated in the Canadian Health Measures Survey between 2007 and 2019. Cross-sectional associations were assessed by generalized linear mixed models incorporating survey-specific sampling weights.

RESULTS

The joint effect of an interquartile range (IQR) increase in nitrogen dioxide (NO2), ozone (O3) and fine particulate matter (PM2.5) was positively and significantly associated with all measures of liver injury adjusting for age, sex, education, income, smoking, alcohol consumption, body mass index (BMI), total cholesterol, diabetes, hypertension, and physical activity. The ranking of effect sizes from largest to smallest percent increases were 8.72% (95% confidence interval [CI] 7.56, 9.88) for alanine aminotransferase (ALT), 5.54% (95%CI 3.31, 7.77) for gamma-glutamyl transferase (GGT), 4.81% (95%CI 3.87, 5.74) for aspartate aminotransferase (AST), 2.46% (95%CI 0.26, 4.65) for total bilirubin (TBIL) and 1.18% (95%CI 0.62, 1.75) for alkaline phosphatase (ALP). Findings were not significantly different when stratified by age (≤16, >16 yr), sex, smoking (current, other), cholesterol (≤6.18, >6.18 mmol/l) and BMI (<30, ≥30 kg/m2).

DISCUSSION

These findings suggest that ambient air pollution may have a relatively small impact on the liver, but these changes may have significant impact from a population health perspective, considering the ubiquitous nature of air pollution, or for individuals exposed to very high levels of air pollution.

Future temperature-related excess mortality under climate change and population aging scenarios in Canada

OBJECTIVE

Climate change is expected to increase global temperatures. How temperature-related mortality risk will change is not completely understood, and how future demographic changes will affect temperature-related mortality needs to be clarified. We evaluate temperature-related mortality across Canada until 2099, accounting for age groups and scenarios of population growth.

METHODS

We used daily counts of non-accidental mortality for 2000 to 2015 for all 111 health regions across Canada, incorporating in the study both urban and rural areas. A two-part time series analysis was used to estimate associations between mean daily temperatures and mortality. First, current and future daily mean temperature time series simulations were developed from Coupled Model Inter-Comparison Project 6 (CMIP6) climate model ensembles from past and projected climate change scenarios under Shared Socioeconomic Pathways (SSPs). Next, excess mortality due to heat and cold and the net difference were projected to 2099, also accounting for different regional and population aging scenarios.

RESULTS

For 2000 to 2015, we identified 3,343,311 non-accidental deaths. On average, a net increase of 17.31% (95% eCI: 13.99, 20.62) in temperature-related excess mortality under a higher greenhouse gas emission scenario is expected for Canada in 2090-2099, which represents a greater burden than a scenario that assumed strong levels of greenhouse gas mitigation policies (net increase of 3.29%; 95% eCI: 1.41, 5.17). The highest net increase was observed among people aged 65 and over, and the largest increases in both net and heat- and cold-related mortality were observed in population scenarios that incorporated the highest rates of aging.

CONCLUSION

Canada may expect net increases in temperature-related mortality under a higher emissions climate change scenario, compared to one assuming sustainable development. Urgent action is needed to mitigate future climate change impacts.

Do blood metals influence lipid profiles? Findings of a cross-sectional population-based survey

Dyslipidemia, an imbalance of lipids and a major risk factor for cardiovascular disease, has been associated with elevated blood and urine levels of several heavy metals. Using data from a Canadian Health Measures Survey (CHMS), we tested associations between blood levels of cadmium, copper, mercury, lead, manganese, molybdenum, nickel, selenium, and zinc, and the lipids triglycerides (TG), total cholesterol (TC), low density lipoproteins (LDL), high density lipoproteins (HDL) and apolipoproteins A1 (APO A1), and B (APO B). All adjusted associations between single metals and lipids were positive and significant, except for APO A1 and HDL. The joint effect of an interquartile range increase in heavy metals was positively associated with percentage increases of TC, LDL and APO B of 8.82% (95%CI: 7.06, 10.57), 7.01% (95%CI: 2.51, 11.51) and 7.15% (95%CI: 0.51, 13.78), respectively. Future studies are warranted to determine if reducing environmental exposure to heavy metals favorably influences lipid profiles and the risk of cardiovascular disease.

The association between blood PFAS concentrations and clinical biochemical measures of organ function and metabolism in participants of the Canadian Health Measures Survey (CHMS)

Per- and poly-fluoroalkyl substances (PFAS) are ubiquitous and may persist in human tissue for several years. Only a small proportion of PFAS have been studied for human health effects. We tested the association between human blood levels of six PFAS and several clinical measures of organ and metabolic function in a nationally representative sample of 6768 participants aged 3-79 years old who participated in the Canadian Health Measures Survey. Cross-sectional associations were assessed by generalized linear mixed models incorporating survey-specific sampling weights. An increase in perfluorooctanoic acid (PFOA) equivalent to the magnitude of its geometric mean (GM) of 2.0 μg/L was associated with percentage (95% CI) increases in serum enzymes reflecting liver function: aspartate aminotransferase (AST) 3.7 (1.1, 6.4), gamma-glutamyl transferase (GGT) 11.8 (2.5, 21.8), alanine aminotransferase (ALT) 3.2 (0.5, 5.9), and bilirubin 3.6 (2.7, 4.5). A GM increase in perfluorodecanoic acid (PFDA) of 0.2 μg/L was positively associated with percentage increases in GGT, triglycerides, low-density lipoprotein (LDL) cholesterol, total cholesterol, and calcium with respective increases of 15.5 (2.2, 30.4), 7.0 (1.0, 13.2), 10.7 (5.5, 16.1), 2.8 (0.2, 5.3), and 0.8 (0.3, 1.3). PFOA, perfluorooctane sulfonate (PFOS), PFDA and perfluorononanoic acid (PFNA) were positively associated with GGT. All six congeners were positively associated with at least one biomarker of lipid metabolism, and 5 of 6, PFOA, PFOS, PFDA, perfluorohexane sulfonate (PFHxS) and PFNA were positively associated with serum calcium. Exposure to selected PFAS is associated with clinical blood tests reflecting metabolism and the function of several organ systems. These relatively small changes may possibly indicate early pathology that is clinically inapparent and may possibly be of significance in a general population or in individuals exposed to very high levels of PFAS.

Long-term ozone exposure and mortality from neurological diseases in Canada

BACKGROUND

There is increasing interest in the health effects of air pollution. However, the relationships between ozone exposure and mortality attributable to neurological diseases remain unclear.

OBJECTIVES

To assess associations of long-term exposure to ozone with death from Parkinson's disease, dementia, stroke, and multiple sclerosis.

METHODS

Our analyses were based on the 2001 Canadian Census Health and Environment Cohort. Census participants were linked with vital statistics records through 2016, resulting in a cohort of 3.5 million adults/51,045,700 person-years, with 8,500/51,300/43,300/1,300 deaths from Parkinson's/dementia/stroke/multiple sclerosis, respectively. Ten-year average ozone concentrations estimated by chemical transport models and adjusted by ground measurements were assigned to subjects based on postal codes. Cox proportional hazards models were used to calculate hazard ratios (HRs) for deaths from the four neurological diseases, adjusting for eight common demographic and socioeconomic factors, seven environmental indexes, and six contextual covariates.

RESULTS

The fully adjusted HRs for Parkinson's, dementia, stroke, and multiple sclerosis mortalities related to one interquartile range increase in ozone (10.1 ppb), were 1.09 (95% confidence interval 1.04-1.14), 1.08 (1.06-1.10), 1.06 (1.04-1.09), and 1.35 (1.20-1.51), respectively. The covariates did not influence significance of the ozone-mortality associations, except airshed (i.e., broad region of Canada). During the period of 2001-2016, 5.66%/5.01%/ 3.77%/19.11% of deaths from Parkinson's/dementia/stroke/multiple sclerosis, respectively, were attributable to ozone exposure.

CONCLUSIONS

We found positive associations between ozone exposure and mortality due to Parkinson's, dementia, stroke, and multiple sclerosis.

The association between air pollution and COVID-19 related mortality in Santiago, Chile: A daily time series analysis

BACKGROUND

Exposure to ambient air pollution is a risk factor for morbidity and mortality from lung and heart disease.

RESEARCH QUESTION

Does short term exposure to ambient air pollution influence COVID-19 related mortality?

STUDY DESIGN AND METHODOLOGY

Using time series analyses we tested the association between daily changes in air pollution measured by stationary monitors in and around Santiago, Chile and deaths from laboratory confirmed or suspected COVID-19 between March 16 and August 31, 2020. Results were adjusted for temporal trends, temperature and humidity, and stratified by age and sex.

RESULTS

There were 10,069 COVID-19 related deaths of which 7659 were laboratory confirmed. Using distributed lags, the cumulative relative risk (RR) (95% CI) of mortality for an interquartile range (IQR) increase in CO, NO₂ and PM_2.5 were 1.061 (1.033-1.089), 1.067 (1.023-1.103) and 1.058 (1.034-1.082), respectively There were no significant differences in RR by sex.. In those at least 85 years old, an IQR increase in NO₂ was associated with a 12.7% (95% CI 4.2-22.2) increase in daily mortality.

CONCLUSION

This study provides evidence that daily increases in air pollution increase the risk of dying from COVID-19, especially in the elderly.

The influence of demographic and lifestyle factors on urinary levels of PAH metabolites-empirical analyses of Cycle 2 (2009-2011) CHMS data

Polycyclic aromatic hydrocarbons (PAHs) are a group of compounds formed during the incomplete combustion of organic matter. Several are mutagenic carcinogens; the magnitude of exposure can be assessed by examining urinary levels of PAH metabolites. Data from biomonitoring studies that record urinary PAH metabolite levels, as well as demographic and lifestyle information, can be used to investigate relationships between PAH exposure and variables, such as smoking status, workplace smoking restrictions, age, sex, household income, home age, and occupation. This study analysed creatinine-adjusted urinary PAH metabolite concentrations and questionnaire data from ~1200 individuals aged 16 years and older surveyed in Cycle 2 of the Canadian Health Measures Survey (CHMS). Statistical analyses revealed that smoking status, age, and sex are associated with urinary concentrations of a pyrene metabolite (1-OHP), phenanthrene metabolites (ΣOH-Phen), fluorene metabolites (ΣOH-Flu) and naphthalene metabolites (ΣOH-Nap). More specifically, smoking status, age and sex can collectively account for 30, 24, 52, and 34% of the observed variations in 1-OHP, ΣOH-Phen, ΣOH-Flu and ΣOH-Nap metabolites, respectively (p < 0.001). Analyses of non-smokers revealed weak but significant effects of age, sex, home age, and occupation on urinary levels of selected PAH metabolites (i.e., <7% of observed variation, p < 0.05). The unexplained variation in PAH metabolite levels is most likely related to diet, which was not examined. Although the results revealed significant relationships between urinary PAH metabolite levels and several lifestyle and/or demographic variables, robust examinations of selected effects (e.g., sex, home age, occupation) will require datasets that are balanced with respect to the other highlighted variables. The results can be used to identify remedial measures to reduce exposure and concomitant risk, and/or design follow-up studies to test hypotheses regarding the causes of exposure differences empirically related to sex, age, home age, and occupation.

Short and long-term impact of four sets of actions on acute ischemic stroke management in Rhône County, a population based before-and-after prospective study

Background

Optimizing access to recanalization therapies in acute ischemic stroke patients is crucial. Our aim was to measure the short and long term effectiveness, at the acute phase and 1 year after stroke, of four sets of actions implemented in the Rhône County.

Methods

The four multilevel actions were 1) increase in stroke units bed capacity and development of endovascular therapy; 2) improvement in knowledge and skills of healthcare providers involved in acute stroke management using a bottom-up approach; 3) development and implementation of new organizations (transportation routes, pre-notification, coordination by the emergency call center physician dispatcher); and 4) launch of regional public awareness campaigns in addition to national campaigns. A before-and-after study was conducted with two identical population-based cohort studies in 2006–7 and 2015–16 in all adult ischemic stroke patients admitted to any emergency department or stroke unit of the Rhône County. The primary outcome criterion was in-hospital management times, and the main secondary outcome criteria were access to reperfusion therapy (either intravenous thrombolysis or endovascular treatment) and pre-hospital management times in the short term, and 12-month prognosis measured by the modified Rankin Scale (mRS) in the long term.

Results

Between 2015–16 and 2006–7 periods ischemic stroke patients increased from 696 to 717, access to reperfusion therapy increased from 9 to 23% (p < 0.0001), calls to emergency call-center from 40 to 68% (p < 0.0001), first admission in stroke unit from 8 to 30% (p < 0.0001), and MRI within 24 h from 18 to 42% (p < 0.0001). Onset-to-reperfusion time significantly decreased from 3h16mn [2 h54-4 h05] to 2h35mn [2 h05-3 h19] (p < 0.0001), mainly related to a decrease in delay from admission to imaging. A significant decrease of disability was observed, as patients with mild disability (mRS [0–2]) at 12 months increased from 48 to 61% (p < 0.0001). Pre-hospital times, however, did not change significantly.

Conclusions

We observed significant improvement in access to reperfusion therapy, mainly through a strong decrease of in-hospital management times, and in 12-month disability after the implementation of four sets of actions between 2006 and 2016 in the Rhône County. Reducing pre-hospital times remains a challenge.

The association between air pollution and hospitalization for patients with systemic lupus erythematosus in Chile: A daily time series analysis

Genetic and environmental factors are thought to influence the activity of systemic lupus erythematosus (SLE), but relatively little is known about the effects of ambient air pollution. Using pollution data from air monitoring stations in the urban centers in Santiago Chile, along with daily patient hospitalization data from 2001 to 2012, an association between ambient air pollution and daily hospital admissions for SLE was tested using generalized linear models. Averaged over all regions pollutant mean 24 h concentrations were: 0.96 ppm carbon monoxide (CO), 64 ppb ozone (O₃), 43 ppb nitrogen dioxide (NO₂), 9 ppb sulphur dioxide (SO₂), 29 μg/m³ particulate matter ≤ 2.5 μm in mean aerodynamic diameter (PM_2.5), and 67 μg/m³ particulate matter ≤ 10 μm in diameter (PM₁₀). The relative risk estimates in single pollutant models for an interquartile range (IQR) increase in pollutant were: RR = 1.34 (95% CI: 1.06-1.83) for SO₂, RR = 1.60 (95% CI: 1.15-2.24) for CO, and RR = 1.41 (95% CI: 1.14-1.86) for PM_2.5. In two-pollutant models, the significance of SO₂ and PM_2.5 persisted despite adjustments for each of the other measured pollutants. These findings suggest that acute increases in air pollution increase the risk of hospitalization with a primary diagnosis of SLE.

Associations between blood volatile organic compounds, and changes in hematologic and biochemical profiles, in a population-based study

OBJECTIVE

To investigate the influence of volatile organic compound (VOC) levels in blood, on hematological and serum biochemical parameters in the Canadian population.

METHODS

We tested the association between seven selected VOCs and hematological profiles and serum tests reflecting liver and kidney function and glucose metabolism using a cross-sectional study design in 3950 participants of the Canadian Health Measures Survey from 2012 to 2015. We used generalized linear mixed models adjusting for age, sex, smoking, alcohol consumption, BMI, education and household income.

RESULTS

An increase in blood concentration equivalent to the geometric mean for benzene, ethylbenzene, toluene, m-, p-xylenes, styrene, and total xylenes was associated with 0.68% (95% CI 0.36, 1.0) to 0.91% (95% CI 0.52, 1.3) increase in hemoglobin, and a 1.79% (95% CI 0.96, 2.62) to 4.11% (95% CI 3.11, 5.11) increase in total white blood cell count. Ethylbenzene, toluene, m-, p-xylenes and styrene were positively associated with increased platelet counts. A geometric mean increase for all VOCs was associated with decreases in creatinine. m- and p-xylenes were associated with a significant change in every measured blood cell count and liver function parameter, and in creatinine. Ethylbenzene was also positively associated with an increase in every measured hematologic parameter, two of the three liver function tests, and creatinine. Results were similar when stratified by age, but differed by smoking status and sex.

CONCLUSIONS

This study provides evidence that VOCs in blood, at levels found in the Canadian population, may influence blood cell counts and indicators of liver and kidney function, including an inverse association between serum VOC and creatinine. This novel finding merits further investigation to understand the impact of VOCs on human physiology and population health.

Correlations of phthalate metabolites in urine samples from fertile and infertile men: Free-form concentration vs. conjugated-form concentration

In previous studies, the total content of urinary phthalate metabolites was commonly used to evaluate human exposure to phthalates. However, phthalate metabolites are mainly present in urine in two forms, conjugated and free. These metabolite forms in urine are more relevant to the biotransformation pathways of the phthalates in humans. Therefore, the concentration of these forms is more relevant to exposure related health outcomes than total content. In this study, instead of measuring total content, the free- and conjugated-form concentrations of phthalate metabolites in the urine of fertile and infertile men were measured. The main metabolites in urine of both groups are monoethyl phthalate (MEP) and the di-(2-ethylhexyl) phthalate (DEHP) metabolites. The geometric means of their both conjugated- and free-forms in the infertile group were higher than in the fertile group, specifically, 24.3 and 43.4 μg/g creatinine vs 8.5 and 28.9 μg/g creatinine, respectively, for MEP, and 50.0 and 9.1 μg/g creatinine vs 39.1 and 8.4 μg/g creatinine, respectively for total DEHP metabolites. We investigated the correlations of free- and conjugated-form phthalate metabolite concentrations between the infertile and fertile group as well as among different phthalate metabolites. The results showed that there was a statistically significant difference between the infertile and fertile group for monobenzyl phthalate (MBzP) in both free-form and conjugated-form. However, there was only a statistically significant difference between the two groups for conjugated-form MEP and MEHP, and no statistically significant difference between the two groups for free-form MEP and MEHP. The results of the Pearson correlation test revealed that the correlations between DEHP metabolites and the correlations between mid-sized phthalate metabolites (mono-n-butyl phthalate (MnBP), mono-isobutyl phthalate (MiBP) and mono-benzyl phthalate (MBzP)) were stronger than between these two clusters of metabolites. This study is the first attempt to examine possible effects of conjugated-form concentrations of phthalate metabolites on human fertility. The results of this study suggest that conjugated-form and free-form concentrations of urinary phthalate metabolites may be appropriate biomarkers for assessing human exposure to phthalates and association with health outcomes.

Do acute changes in ambient air pollution increase the risk of potentially fatal cardiac arrhythmias in patients with implantable cardioverter defibrillators?

BACKGROUND

Daily changes in ambient air pollution have been associated with cardiac morbidity and mortality. Precipitating a cardiac arrhythmia in susceptible individuals may be one mechanism. We investigated the influence of daily changes in air pollution in the Province of Ontario, Canada on the frequency of discharges from implantable cardio defibrillators (ICDs) which occur in response to potentially life threatening arrhythmias.

METHODS

Using a case- crossover design, we compared ambient air pollution concentrations on the day of an ICD discharge to other days in the same month and year in 1952 patients. We adjusted for weather, lagged the exposure data from 0 to 3 days, and stratified the results by several patient-related characteristics.

RESULTS

Median (interquartile range) for ozone (O₃), fine particulate matter (PM_2.5), sulphur dioxide (SO₂) and nitrogen dioxide (NO₂) were 26.0 ppb (19.4, 33.0), 6.6 μg/m³ (4.3, 10.6), 1.00 ppb (0.4,2.1), 10.0 ppb (6.0,15.3) respectively. Unlagged odds ratios (95%) for an ICD discharge associated with an interquartile range increase in pollutant were 0.97 (0.86, 1.09) for O₃, 0.99 (0.92, 1.06) for PM_2.5, 0.97 (0.91, 1.03) for SO₂, and 1.00 (0.89, 1.12) for NO₂.

CONCLUSION

We found no evidence that the concentrations of ambient air pollution observed in our study were a risk factor for potentially fatal cardiac arrhythmias in patients with ICDs.

The Association Between Air Pollution and Hospitalization of Patients With Idiopathic Pulmonary Fibrosis in Chile: A Daily Time Series Analysis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) causes progressive dyspnea, hypoxemia, and death within a few years. Little is known about the effect of air pollution on disease exacerbations.

RESEARCH QUESTION

Are acute increases in air pollution a risk factor for hospitalization of patients with a primary diagnosis of IPF.

STUDY DESIGN AND METHODS

Hospital admissions for IPF are coded J84.1 by the International Classification of Disease, 10th Revision. Using ambient air pollution and climate data from seven air monitoring stations distributed in the seven urban centers in Santiago, Chile, along with daily patient hospitalization data from 2001 to 2012, a linear association between daily ambient air pollution and daily J84.1 hospital admissions was tested using generalized linear models.

RESULTS

Average pollutant levels for all regions were as follows: carbon monoxide was 0.96 ppm, ozone was 64 ppb, nitrogen dioxide (NO₂) was 43 ppb, sulfur dioxide was 9 ppb, particulate matter < 2.5 μm in diameter was 29 μg/m³ and particulate matter < 10 μm in diameter (PM₁₀) was 67 μg/m³. For the combined Santiago area, relative risk estimates of J84.1 hospitalizations for all pollutants (except ozone), adjusted for age, sex, and weather were statistically significant. In the two-pollutant models, the significance of NO₂ and PM₁₀ persisted despite adjustments for each of the other measured pollutants.

INTERPRETATION

Our findings suggest that acute increases in air pollution are a risk factor for hospitalization of patients with a primary diagnosis of IPF.

Effect of industrial point-source air pollutants on fractional exhaled nitric oxide in healthy volunteers

BACKGROUND

Few studies have examined the effects of industrial, fixed-site sources of air pollution on lung inflammation in nearby residents. We investigated the effects of short-term exposure to ambient air near a steel plant on the fractional exhaled concentration of nitric oxide (FeNO), a measure of airway inflammation, in healthy volunteers.

METHODS

A cross-over study design was used. Fifty-nine non-smoking participants (mean age 24 years) were randomly assigned to each of two 5-day exposure scenarios: breathing ambient air adjacent to a steel plant or 5 km away at a college campus site. FeNO and on-site air pollutants were measured daily. Mixed effects linear regression models were used for data analysis, adjusting for sex, temperature, humidity and day of week.

RESULTS

Compared with the college site, PM _2.5, ultrafine PM, SO₂, NO₂ and CO levels were significantly greater near the steel plant. FeNO was 15.3% (95% CI, 6.6%, 24.8%) higher near the plant compared to the college site.

CONCLUSIONS

Exposure to ambient air near a steel plant was associated with increased airway inflammation as measured by exhaled nitric oxide.

Comparison of tris(2-ethylhexyl) phosphate and di(2-ethylhexyl) phosphoric acid toxicities in a rat 28-day oral exposure study

Tris(2-ethylhexyl) phosphate (TEHP, CAS no. 78-42-2) is a plasticizer and a flame retardant, while di(2-ethylhexyl) phosphoric acid (DEHPA, CAS no. 298-07-7) is an oil additive and extraction solvent. Publicly-available information on repeated exposure to these two related organophosphate compounds is fragmentary. Hence, adult male and female Fischer rats were exposed to TEHP (300, 1000 and 3000 mg/kg body weight [BW]/day) or DEHPA (20, 60 and 180 mg/kg BW/day) by gavage for 28 consecutive days, to assess and compare their toxicities. Although significantly impaired BW gains and evidence of TEHP enzymatic hydrolysis to DEHPA were observed only in males, exposures to the highest TEHP and DEHPA doses often resulted in similar alterations of hematology, serum clinical chemistry and liver enzymatic activities in both males and females. The squamous epithelial hyperplasia and hyperkeratosis observed in the non-glandular forestomach of rats exposed to the middle and high DEHPA doses were most likely caused by the slightly corrosive nature of this chemical. Although tubular degeneration and spermatid retention were observed only in the testes of males exposed to the highest TEHP dose, numerous periodic acid-Schiff stained crystalline inclusions were observed in testis interstitial cells at all TEHP dose levels. No-observed-adverse-effect levels for TEHP and DEHPA are proposed, but the lower serum pituitary hormone levels resulting from TEHP and DEHPA exposures and the perturbations of testicular histology observed in TEHP-treated males deserve further investigation. Improved characterization of the toxicity of flame retardants will contribute to better informed substitution choices for legacy flame retardants phased-out over health concerns.

Maternal blood biomarkers and adverse pregnancy outcomes: a systematic review and meta-analysis

Background: Pregnancy is a vulnerable period for the mother and the infant and exposures to environmental chemicals in utero can influence neonatal morbidity and mortality. There is a momentum toward understanding and exploring the current maternal biological mechanisms specific to in utero effects, to improve birth outcomes. This study aims to examine the current understanding of the role of biomarkers that may be associated with term of pregnancy, infant birth weights and infant development in utero.Methods: Electronic searches were conducted in PubMed, Embase, OvidMD, and Scopus databases; and all relevant research articles in English were retrieved. Studies were selected if they evaluated maternal blood plasma/serum biomarkers proposed to influence adverse birth outcomes in the neonate. Data were extracted on characteristics, quality, and odds ratios from each study and meta-analysis was conducted.Results: A total of 54 studies (35 for meta-analysis), including 43,702 women, 50 plasma markers and six descriptors of birth outcomes were included in the present study. The random effect point estimates for risk of adverse birth outcomes were 1.61(95%CI: 1.39-1.85, p < 0.0001) for inflammation-related biomarkers and 1.65(95%CI: 1.22-2.25, p = 0.0013) for growth factor/hormone-related biomarkers. All subgroups of plasma markers showed significant associations with adverse birth outcomes with no apparent study bias.Conclusions: The two subsets of plasma markers identified in this study (inflammation-related and growth factor/hormone-related) may serve as potentially valuable tools in the investigation of maternal molecular mechanisms, especially select pathways underlying inflammatory and immunological mediation in terms of modulating adverse infant outcomes. Future large, prospective cohort studies are needed to validate the promising plasma biomarkers, and to examine other maternal biological matrices such as cervicovaginal fluid and urine.

Profiles and monthly variations of selected volatile organic compounds in indoor air in Canadian homes: Results of Canadian national indoor air survey 2012-2013

Volatile organic compounds (VOCs) are important pollutants in indoor air. A major survey campaign was carried out over a 24-month period in 2012 and 2013 to monitor 88 selected VOCs in 3524 Canadian residential homes as part of the Canadian Health Measures Survey (CHMS). Among the 88 VOCs six (limonene, decamethylcyclopentasiloxane, toluene, hexanal, nonanal and α-pinene) were present in the highest concentrations with a combined geometric mean value (63.22 μg/m³) accounting for more than half (54%) of the sum of all 88 VOCs. The geometric means of the majority of the VOCs obtained from this study were not significantly different from the levels of VOCs that were measured in a previous CHMS data collection cycle between 2009 and 2011. This study also further confirmed higher concentrations of the majority of measured VOCs in apartments compared to houses; and of several tobacco-related VOCs (benzene, styrene, naphthalene, 2-butanone, 2-methyl-1,3-butadiene, 2-furancarboxaldehyde, 2,5-dimethylfuran, benzofuran and phenol) in smoking homes. Furthermore, concentrations of aromatic and aliphatic hydrocarbons were higher in winter and in the months of June and July. Oxygenated hydrocarbons such as aldehydes, alcohols and ketones, on the other hand, were found to be higher in warmer months and peaked in summer months. These results provide valuable information on the levels of selected VOCs of which many have been monitored for the first time in Canadian homes, and can be used to estimate population exposure.

Exposure to traffic and mortality risk in the 1991-2011 Canadian Census Health and Environment Cohort (CanCHEC)

There is evidence that local traffic density and living near major roads can adversely affect health outcomes. We aimed to assess the relationship between local road length, proximity to primary highways, and cause-specific mortality in the 1991 Canadian Census Health and Environment Cohort (CanCHEC). In this long-term study of 2.6 million people, based on completion of the long-form census in 1991 and followed until 2011, we used annual residential addresses to determine the total length of local roads within 200 m of postal code representative points and the postal code's distance to primary highways. The association between exposure to traffic and cause-specific non-accidental mortality was estimated using Cox proportional hazards models, adjusting for individual covariates and contextual factors, including census division-level proportion in high school, the percentage of recent immigrants, and neighborhood income. We performed sensitivity analyses, including adjustment for exposure to PM_2.5, NO₂, or O₃, restricting to subjects in core urban areas, and spatial variation by climatic zone. The hazard ratio (HR) for all non-accidental mortality associated with an interquartile increase in length of local roads was 1.05 (95% CI 1.04, 1.05), while for an interquartile range increase in proximity to primary highways, the HR was 1.03 (95% CI 1.02, 1.04). HRs by traffic quartile increased with increasing lengths of local roads, as well as with closer proximity to primary highways, for all mortality causes. The associations were stronger within subjects' resident in urban core areas, attenuated by adjustment for PM_2.5, and HRs showed limited spatial variation by climatic zone. In the CanCHEC cohort, exposure to higher road density and proximity to major traffic roads was associated with increased mortality risk from cerebrovascular and cardiovascular disease, ischemic heart disease, COPD, respiratory disease, and lung cancer, with unclear results for diabetes.

Is residential ambient air limonene associated with asthma? Findings from the Canadian Health Measures Survey

Asthma is a common chronic disease. Exposure to limonene is commonplace because it may be used in the manufacture of personal care products and household cleaners. We investigated the influence of limonene on asthma in a population-based sample of approximately 3000 Canadians. During the Canada Health Measures Survey, carried out between 2012 and 2013, participants were asked if they wheezed or had a diagnosis of asthma, and underwent spirometry and measurement of the fraction of exhaled nitric oxide (FeNO). These variables were tested for an association with limonene concentrations measured in their household air samples, using linear regression analysis A 100% increase in air limonene concentration was associated with an approximate 17% adjusted relative increase wheezing with an odds ratio of 1.17 (95%CI 1.16, 1.18). The percent change in FeNO for a 100% increase in limonene was twice as large for children, 2.89% (95% CI 1.88, 4.43) compared to adults, 1.44% (95%CI 1.16, 1.79). Among boys, the odds ratio was 1.50 (95%CI 1.48, 1.52) between a 100% increase in limonene and a diagnosis of asthma. This study provides evidence that household exposure to limonene may increase the prevalence of asthma in the general population.

A PCR-based quantitative assay for the evaluation of mRNA integrity in rat samples

Reverse Transcription quantitative real-time PCR (RT-qPCR) is applied to quantify gene transcript levels in a wide range of investigations. Proper assessment of RNA integrity is essential for reliable assessment of gene expression levels, as RNA molecules are acutely vulnerable to degradation. However, RNA quality control measures are still infrequently reported in rat toxicological studies, which impede proper evaluation of gene expression data reliability. The high operational cost of microfluidic capillary electrophoresis systems along with paucity of alternative methods for the quantitative assessment of rat RNA integrity constitute potential hurdles to the systematic implementation and reporting of RNA integrity assessment in rat studies. This manuscript describes the adaptation of an alternative RT-qPCR-based 3':5' assay as an additional option for the quantitative assessment of rat RNA integrity. Two PCR primer sets were designed on the 3' and 5' regions of a rat housekeeping gene to evaluate RNA integrity by measuring the relative expression (3':5' ratio) of these amplicons. The 3':5' ratios were then compared to Agilent Bioanalyzer's RNA integrity number (RIN) for a wide range of RNA samples originating from different tissues, cultured cell lines and rat strains that were prepared freshly, stored for years at -80 °C, purchased commercially or intentionally degraded. The 3':5' ratios and RIN values presented similar assessment of RNA integrity status from intact to heavily degraded samples. Based on the LOWESS regression of this large comparison dataset, 3':5' ratio threshold criteria equivalent to RIN cut-off values can be proposed for the selection of RNA samples for RT-qPCR analyses. This qPCR-based assay is easy to implement, cost-effective, and provides a reliable quantification of RNA integrity to assist in the selection of rat RNA samples suitable for downstream RT-qPCR gene expression analyses.

Effect modification of perinatal exposure to air pollution and childhood asthma incidence

Perinatal exposure to ambient air pollution has been associated with childhood asthma incidence, however, less is known regarding the potential effect modifiers in this association. We examined whether maternal and infant characteristics modified the association between perinatal exposure to air pollution and development of childhood asthma.761 172 births occurring between 2006 and 2012 were identified in the province of Ontario, Canada. Associations between exposure to ambient air pollutants and childhood asthma incidence (up to age 6) were estimated using Cox regression models.110,981 children with asthma were identified. In models adjusted for postnatal exposures, second trimester exposures to particulate matter with a diameter ≤2.5 μm (PM2.5) (Hazard Ratio (HR) per interquartile (IQR) increase=1.07, 95% CI: 1.06-1.09) and nitrogen dioxide (NO2) (HR per IQR increase=1.06, 95% CI: 1.03-1.08) were associated with childhood asthma development. Enhanced impacts were found among children born to mothers with asthma, those who smoked during pregnancy, boys, those born preterm, of low birth weight and among those born to mothers living in urban areas during pregnancy.Prenatal exposure to air pollution may have a differential impact on the risk of asthma development according to maternal and infant characteristics.

Associations between long-term PM2.5 and ozone exposure and mortality in the Canadian Census Health and Environment Cohort (CANCHEC), by spatial synoptic classification zone

Studies suggest that long-term chronic exposure to fine particulate matter air pollution can increase lung cancer mortality. We analyzed the association between long term PM_2.5 and ozone exposure and mortality due to lung cancer, ischemic heart disease, and chronic obstructive pulmonary disease, accounting for geographic location, socioeconomic status, and residential mobility. Subjects in the 1991 Canadian Census Health and Environment Cohort (CanCHEC) were followed for 20years, and assigned to regions across Canada based on spatial synoptic classification weather types. Hazard ratios (HR) for mortality, were related to PM_2.5 and ozone using Cox proportional hazards survival models, adjusting for socioeconomic characteristics and individual confounders. An increase of 10μg/m³ in long term PM_2.5 exposure resulted in an HR for lung cancer mortality of 1.26 (95% CI 1.04, 1.53); the inclusion in the model of SSC zone as a stratum increased the risk estimate to HR 1.29 (95% CI 1.06, 1.57). After adjusting for ozone, HRs increased to 1.49 (95% CI 1.23, 1.88), and HR 1.54 (95% CI 1.27, 1.87), with and without zone as a model stratum. HRs for ischemic heart disease fell from 1.25 (95% CI 1.21, 1.29) for exposure to PM_2.5, to 1.13 (95% CI 1.08, 1.19) when PM_2.5 was adjusted for ozone. For COPD, the 95% confidence limits included 1.0 when climate zone was included in the model. HRs for all causes of death showed spatial differences when compared to zone 3, the most populated climate zone. Exposure to PM_2.5 was related to an increased risk of mortality from lung cancer, and both ozone and PM_2.5 exposure were related to risk of mortality from ischemic heart disease, and the risk varied spatially by climate zone.

The associations between phthalate exposure and insulin resistance, β-cell function and blood glucose control in a population-based sample

In developed countries, phthalate exposure is ubiquitous. Previous studies have shown an association between phthalate levels and health effects. To test associations between phthalate exposures, estimated from urinary phthalate metabolites, and insulin resistance, β-cell function and glucose control. Data were obtained from a cross-sectional, nationally representative study; the Canadian Health Measures Survey (CHMS, 2009-2011). Participants under the age of 12, those with diabetes, who were pregnant or who had not fasted overnight were excluded. Fasting blood glucose, insulin, and glycosylated hemoglobin (HbA_1C) levels were measured in a subset of participants, and urine was collected for creatinine and phthalate metabolites. We tested associations between these variables using linear regression analysis. Of 4437 participants (12-79years old), 2119 had fasting glucose measurements and at least one phthalate metabolite above detection limits. MBzP, MCPP, MEHP, MEHHP, MiBP, and the sum of DEHP metabolites were positively associated with increased HbA_1C (p<0.05). DEHP metabolites were positively associated with increased fasting glucose, insulin, HOMA-IR and HOMA-β. An interquartile increase in the sum of log transformed DEHP metabolites was associated with increases in HOMA-IR and HOMA-β of 0.15 (95% CI 0.04, 0.26) and 10.24 (95% CI 3.71, 16.77) respectively. Increased concentrations of all measured phthalate metabolites were associated with reduced blood glucose control. DEHP metabolites were also associated with increased glucose concentrations, and indicators of β-cell function and insulin resistance. Our results suggest that exposure to phthalates may possibly impair control of blood glucose and thereby predispose to pre-diabetes.

Increased coronary heart disease and stroke hospitalisations from ambient temperatures in Ontario

OBJECTIVE

To assess the associations between ambient temperatures and hospitalisations for coronary heart disease (CHD) and stroke.

METHODS

Our study comprised all residents living in Ontario, Canada, 1996-2013. For each of 14 health regions, we fitted a distributed lag non-linear model to estimate the cold and heat effects on hospitalisations from CHD, acute myocardial infarction (AMI), stroke and ischaemic stroke, respectively. These effects were pooled using a multivariate meta-analysis. We computed attributable hospitalisations for cold and heat, defined as temperatures above and below the optimum temperature (corresponding to the temperature of minimum morbidity) and for moderate and extreme temperatures, defined using cut-offs at the 2.5^th and 97.5^th temperature percentiles.

RESULTS

Between 1996 and 2013, we identified 1.4 million hospitalisations from CHD and 355 837 from stroke across Ontario. On cold days with temperature corresponding to the 1^st percentile of temperature distribution, we found a 9% increase in daily hospitalisations for CHD (95% CI 1% to 16%), 29% increase for AMI (95% CI 15% to 45%) and 11% increase for stroke (95% CI 1% to 22%) relative to days with an optimal temperature. High temperatures (the 99^th percentile) also increased CHD hospitalisations by 6% (95% CI 1% to 11%) relative to the optimal temperature. These estimates translate into 2.49% of CHD hospitalisations attributable to cold and 1.20% from heat. Additionally, 1.71% of stroke hospitalisations were attributable to cold. Importantly, moderate temperatures, rather than extreme temperatures, yielded the most of the cardiovascular burdens from temperatures.

CONCLUSIONS

Ambient temperatures, especially in moderate ranges, may be an important risk factor for cardiovascular-related hospitalisations.

The influence of polycyclic aromatic hydrocarbons on lung function in a representative sample of the Canadian population

We investigated the associations between exposure to polycyclic aromatic hydrocarbons (PAHs) and selected respiratory physiologic measures in cycles 2 and 3 of the Canadian Health Measures Survey, a nationally representative population sample. Using generalized linear mixed models, we tested the association between selected PAH metabolites and 1-second forced expiratory volume (FEV₁), forced vital capacity (FVC), and the ratio between the two (FEV₁/FVC) in 3531 people from 6 to 79 years of age. An interquartile change in urinary PAH metabolite was associated with significant decrements in FEV₁ and FVC for eight PAHs, 2-hydroxynapthalene, 1-, and 2-hydroxyphenanthrene, 2-, 3-, and 9-hydroxyfluorene and 3- and 4-hydroxyphenanthrene. Exposure to PAH may negatively affect lung function in the Canadian population.

Maternal exposure to ambient air pollution and risk of early childhood cancers: A population-based study in Ontario, Canada

BACKGROUND

There are increasing concerns regarding the role of exposure to ambient air pollution during pregnancy in the development of early childhood cancers.

OBJECTIVE

This population based study examined whether prenatal and early life (<1year of age) exposures to ambient air pollutants, including nitrogen dioxide (NO₂) and particulate matter with aerodynamic diameters ≤2.5μm (PM_2.5), were associated with selected common early childhood cancers in Canada.

METHODS

2,350,898 singleton live births occurring between 1988 and 2012 were identified in the province of Ontario, Canada. We assigned temporally varying satellite-derived estimates of PM_2.5 and land-use regression model estimates of NO₂ to maternal residences during pregnancy. Incident cases of 13 subtypes of pediatric cancers among children up to age 6 until 2013 were ascertained through administrative health data linkages. Associations of trimester-specific, overall pregnancy and first year of life exposures were evaluated using Cox proportional hazards models, adjusting for potential confounders.

RESULTS

A total of 2044 childhood cancers were identified. Exposure to PM_2.5, per interquartile range increase, over the entire pregnancy, and during the first trimester was associated with an increased risk of astrocytoma (hazard ratio (HR) per 3.9μg/m3=1.38 (95% CI: 1.01, 1.88) and, HR per 4.0μg/m³=1.40 (95% CI: 1.05-1.86), respectively). We also found a positive association between first trimester NO₂ and acute lymphoblastic leukemia (ALL) (HR=1.20 (95% CI: 1.02-1.41) per IQR (13.3ppb)).

CONCLUSIONS

In this population-based study in the largest province of Canada, results suggest an association between exposure to ambient air pollution during pregnancy, especially in the first trimester and an increased risk of astrocytoma and ALL. Further studies are required to replicate the findings of this study with adjustment for important individual-level confounders.

Exposure to air pollution near a steel plant is associated with reduced heart rate variability: a randomised crossover study

BACKGROUND

Epidemiological studies have shown that as ambient air pollution (AP) increases the risk of cardiovascular mortality also increases. The mechanisms of this effect may be linked to alterations in autonomic nervous system function. We wished to examine the effects of industrial AP on heart rate variability (HRV), a measure of subtle changes in heart rate and rhythm representing autonomic input to the heart.

METHODS

Sixty healthy adults were randomized to spend five consecutive 8-h days outdoors in one of two locations: (1) adjacent to a steel plant in the Bayview neighbourhood in Sault Ste Marie Ontario or (2) at a College campus, several kilometers from the plant. Following a 9-16 day washout period, participants spent five consecutive days at the other site. Ambient AP levels and ambulatory electrocardiogram recordings were collected daily. HRV analysis was undertaken on a segment of the ambulatory ECG recording during a 15 min rest period, near the end of the 8-h on-site day. Standard HRV parameters from both time and frequency domains were measured. Ambient AP was measured with fixed site monitors at both sites. Statistical analysis was completed using mixed-effects models.

RESULTS

Compared to the College site, HRV was statistically significantly reduced at the Bayview site by 13% (95%CI 3.6,19.2) for the standard deviation of normal to normal, 8% (95%CI 0.1, 4.9) for the percent normal to normal intervals differing by more than 50 ms, and 15% (95%CI 74.9, 571.2) for low frequency power. Levels of carbon monoxide, sulphur dioxide, nitrogen dioxide, and fine and ultrafine particulates were slightly, but statistically significantly, elevated at Bayview when compared to College. Interquartile range changes in individual air pollutants were significantly associated with reductions in HRV measured on the same day. The patterns of effect showed a high degree of consistency, with nearly all pollutants significantly inversely associated with at least one measure of HRV.

CONCLUSIONS

The significant associations between AP and changes in HRV suggest that ambient AP near a steel plant may impact autonomic nervous system control of the heart.

Ambient Temperature and the Risk of Renal Colic: A Population-Based Study of the Impact of Demographics and Comorbidity

PURPOSE

To examine the impact of ambient temperature on the incidence of emergency department (ED) admissions for acute renal colic and the potential influence demographics and comorbid conditions may have on this.

METHODS

We conducted a population-based time series analysis using linked healthcare databases in Ontario, Canada, which included all residents, aged ≥19 years, who were admitted to an ED from April 2002 to December 2013. The primary outcome was daily number of renal colic emergency department admissions. A distributed lag nonlinear model with 21 days of lag was applied to estimate the cumulative effect of temperature on colic admissions. We estimated risks for cold and heat, defined as temperatures below and above the optimal temperature, which corresponded to the point with minimum risk of colic admissions. We conducted stratified analyses using selected demographics and comorbidities.

RESULTS

During the study period, 423,396 patients presented to an ED with colic. There was a significantly increased risk of colic as ambient temperature increased (rate ratio [RR] = 1.30, 95% confidence interval [CI]: 1.20, 1.42). Subgroup analysis demonstrated an increased risk associated with heat for both genders; however, this risk was more pronounced in males with extreme heat (RR = 1.64 vs 1.22, p = 0.006). In contrast to other age groups, there was an increased risk for those in their 40s (RR = 1.42), 50s (RR = 1.54), and 60s (RR = 1.31) (p = 0.02).

CONCLUSION

Increasing ambient temperature was associated with increased risk of ED visits for colic, particularly in males and those aged 40 to 69 years.

Blood metal levels and third trimester maternal plasma matrix metalloproteinases (MMPs)

While it is known that in utero exposure to environmental toxicants, namely heavy metals, can adversely affect the neonate, there remains a significant paucity of information on maternal biological changes specific to metal exposures during pregnancy. This study aims at identifying associations between maternal metal exposures and matrix metalloproteinases (MMPs) that are known to be engaged in pregnancy process. Third trimester maternal plasma (n = 1533) from a pregnancy cohort (Maternal-Infant Research on Environmental Chemicals Study, MIREC) were analyzed for MMP-1,-2,-7,-9 and -10 by affinity-based multiplex protein array analyses. Maternal metal concentrations (mercury, cadmium, lead, arsenic and manganese) in 1st and 3rd trimesters exhibited strong correlations (p < 0.05). Multivariate regression models were used to estimate odds ratio (OR) for the association between metal concentrations in quartiles and high (90%) and low (10%) maternal MMP levels. Significant (p < 0.05) metal exposure-related effects were observed with the different MMP isoform responses. MMP profiles were specific to the trimester at which the maternal blood metals were analyzed. Our findings suggest that the profiles of these MMP isoforms vary with the type of metal exposure, blood metal concentrations and the trimester at which metal levels were determined. These new findings on maternal metal-MMP relationships can guide future explorations on toxicity mechanisms relevant to metal exposure-mediated adverse birth outcomes.

Development of an integrated approach for comparison of in vitro and in vivo responses to particulate matter

Background

Association of particulate matter with adverse health effects has been established in epidemiological studies and animal experiments. Epidemiological studies are difficult to undertake while animal studies are impractical for high-throughput toxicity testing. The ease and rapidity of in vitro tests emphasizes their potential for use in risk assessment of chemicals and particles. We examined the association between in vitro and in vivo responses to ambient particles, to determine the potential of cell-based assays as standalone toxicity screening tools.

Methods

Assays of cytotoxicity and key inflammatory mediators were applied to determine the in vitro biological potency of a panel of urban and mineral particles in J774A.1 macrophages and A549 lung epithelial cells. The particles were also screened for the presence of AhR agonists using the Ah receptor-dependent gene induction assay and for endotoxin using the Limulus amebocyte lysate assay. A subset of the particles with a contrasting in vitro toxicity profile was delivered intratracheally in BALB/c mice to assess their in vivo biological potency. Results from various bioassays were combined within the in vitro and in vivo models. The combined potency measures were examined for associations.

Results

Overall, J774A.1 cells were more sensitive to particle effects than A549 cells. Whereas the combined cytotoxicity estimates were highly correlated between the two cell lines, the combined in vitro inflammatory potency estimates were not, emphasizing functional differences of the two cell types. Secretion of inflammatory markers by J774A.1 cells was correlated with AhR ligand binding profile and endotoxin levels of particles. Particle instillation led to an acute toxicity response in BALB/c mice, with neutrophilia and release of inflammatory mediators. While the combined toxicity estimates were not correlated between in vitro and in vivo models, the combined inflammatory and integrated potency estimates (toxicity and inflammation) approached the threshold for significance (p = 0.052) in a correlation within in vitro and in vivo models, with a ranking of fine particle (DWR1), minerals (TiO₂, CRI) and coarse particles (SRM-, EHC-type) from low to high potency.

Conclusion

Integration of in vitro endpoints shows promise in determining adverse outcomes of particle exposures in vivo. The devised data reduction and computational approach will prove useful in the development of models for assessment of hazard potential of particles; however, distinct models may be needed for particles of different type, such as urban particles vs. mineral particles, nanomaterials.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-016-0152-6) contains supplementary material, which is available to authorized users.

Hospitalizations from Hypertensive Diseases, Diabetes, and Arrhythmia in Relation to Low and High Temperatures: Population-Based Study

Little is known about the extent to which ambient temperatures contribute to the burden of hospitalizations from hypertensive diseases, diabetes, and arrhythmia. To fill this knowledge gap, we conducted a time-series study comprising entire population of Ontario, Canada during 1996–2013. A distributed lag non-linear model was developed to estimate the cumulative effect of temperatures over a 21-day lag period. We computed the burden of hospitalizations attributable to cold and heat. Furthermore, we separated the burden into components related to mild and extreme temperatures. Compared to the temperature with minimum risk of morbidity, cold temperatures (1^st percentile) were associated with a 37% (95% confidence interval: 5%, 78%) increase in hypertension-related hospitalizations whereas no significant association with hot temperatures (99^th percentile) was observed. Cold and hot temperatures were also associated with a 12% (1%, 24%) and a 30% (6%, 58%) increase in diabetes-related hospitalizations, respectively. Arrhythmia was not linked to temperatures. These estimates translate into ~10% of hypertension-related hospitalizations attributable to total cold, and ~9% from mild cold. Similarly, ~11% of diabetes-related hospitalizations were due to total heat, virtually all of which were from mild heat. In conclusion, ambient temperatures, especially in moderate ranges, contribute to excess hospitalizations from hypertension and diabetes.

The modifying effect of socioeconomic status on the relationship between traffic, air pollution and respiratory health in elementary schoolchildren

The volume and type of traffic and exposure to air pollution have been found to be associated with respiratory health, but few studies have considered the interaction with socioeconomic status at the household level. We investigated the relationships of respiratory health related to traffic type, traffic volume, and air pollution, stratifying by socioeconomic status, based on household income and education, in 3591 schoolchildren in Windsor, Canada. Interquartile range changes in traffic exposure and pollutant levels were linked to respiratory symptoms and objective measures of lung function using generalised linear models for three levels of income and education. In 95% of the relationships among all cases, the odds ratios for reported respiratory symptoms (a decrease in measured lung function), based on an interquartile range change in traffic exposure or pollutant, were greater in the lower income/education groups than the higher, although the odds ratios were in most cases not significant. However, in up to 62% of the cases, the differences between high and low socioeconomic groups were statistically significant, thus indicating socioeconomic status (SES) as a significant effect modifier. Our findings indicate that children from lower socioeconomic households have a higher risk of specific respiratory health problems (chest congestion, wheezing) due to traffic volume and air pollution exposure.

Ozone exposure and cardiovascular-related mortality in the Canadian Census Health and Environment Cohort (CANCHEC) by spatial synoptic classification zone

Our objective is to analyse the association between long term ozone exposure and cardiovascular related mortality while accounting for climate, location, and socioeconomic factors. We assigned subjects with 16 years of follow-up in the Canadian Census Health and Environment Cohort (CanCHEC) to one of seven regions based on spatial synoptic classification (SSC) weather types and examined the interaction of exposure to both fine particulate matter (PM2.5) and ground level ozone and cause of death using survival analysis, while adjusting for socioeconomic characteristics and individual confounders. Correlations between ozone and PM2.5 varied across SSC zones from -0.02 to 0.7. Comparing zones using the most populated SSC zone as a reference, a 10 ppb increase in ozone exposure was associated with increases in hazard ratios (HRs) that ranged from 1.007 (95% CI 0.99, 1.015) to 1.03 (95% CI 1.02, 1.041) for cardiovascular disease, 1.013 (95% CI 0.996, 1.03) to 1.058 (95% CI 1.034, 1.082) for cerebrovascular disease, and 1.02 (95% CI 1.006, 1.034) for ischemic heart disease. HRs remained significant after adjustment for PM2.5. Long term exposure to ozone is related to an increased risk of mortality from cardiovascular and cerebrovascular diseases; the risk varies by location across Canada and is not attenuated by adjustment for PM2.5. This research shows that the SSC can be used to define geographic regions and it demonstrates the importance of accounting for that spatial variability when studying the long term health effects of air pollution.

The coexistence of eosinophilic esophagitis with allergic rhinitis

OBJECTIVE

Eosinophilic esophagitis (EoE) is diagnosed with the presence of characteristic esophageal symptoms and eosinophilic infiltration of the esophageal mucosa after other causes of eosinophilia are excluded. EoE has been reported to co-occur with some allergic diseases. In this study, we evaluated the co-existence of EoE in Ear-Nose-Throat (ENT) outpatient clinic patients with allergic rhinitis (AR).

PATIENTS AND METHODS

The study group consists of 67 AR patients (AR group) and the control group (CG) was formed with 53 cases with dyspepsia symptoms. Symptoms of AR and CG groups were compared in terms of endoscopic and histological findings. Moreover, in AR group, accompanying symptoms, immunoglobulin E (IgE), skin prick test (SPT) positivity, Helicobacter pylori (H. pylori) presence, endoscopic findings and biopsy results were compared between patients with EoE and those without.

RESULTS

Seven of the cases with AR were diagnosed with EoE. Reflux symptoms were more common in patients with EoE (71.4%). The presence of H. pylori was similar between groups. Blood IgE levels were significantly higher among EoE patients compared to those without EoE (p = 0.003). SPT positivity was present in the 85.7% of patients with EoE and 50% of the patients without EoE (p = 0.113). Allergens were more likely to be mites Dermatophagoides farinae and Dermatophagoides pteronyssinus in patients with EoE (p = 0.042 and p = 0.034 respectively).

CONCLUSIONS

The most common symptom among patients with EoE is reflux. In AR patients with EoE, serum IgE levels were higher compared to those without EoE. In AR patients with reflux symptoms, high serum IgE levels, and especially in patients whose tests are positive for allergy to mites, referral to a gastroenterologist for EoE evaluation may be recommended.

Infant birth weight and third trimester maternal plasma markers of vascular integrity: the MIREC study

Background: There is paucity of information on mechanisms constituting adverse birth outcomes. We assessed here the relationship between vascular integrity and adverse birth effects.

Methods and results: Third trimester maternal plasma (n = 144) from the Maternal-Infant Research on Environmental Chemicals Study (MIREC) was analysed for vascular, inflammatory and oxidative stress markers by HPLC-fluorescence, protein array and EIA method. Analysis of the <25th and >75th percentile birth weight subgroups revealed markers associated with birth weight (ETs, MMP-9, VEGF, and 8-isoPGF-2α) and gestational age (ET-1, MMP-2, and VEGF).

Conclusions: Mechanistic insights into adverse birth outcome pathways can be achieved by integrating information on multiple biomarkers, physiology using systems biology approach.

Assessment of the effect of cold and hot temperatures on mortality in Ontario, Canada: a population-based study

BACKGROUND

Ambient high temperature is associated with death; however, heat-related risk of death has not been quantified systematically in Ontario, the most populous province in Canada. Less is known about cold-related risk in this population. Our objective was to quantify the health impact from cold and hot temperatures in Ontario.

METHODS

The study population consisted of all residents of Ontario who died between Jan. 1, 1996, and Dec. 31, 2010, from any nonaccidental cause. A case-crossover analysis was applied to assess the relation between daily temperature fluctuation and deaths from nonaccidental and selected causes in cold (December-February) and warm (June-August) seasons, respectively, adjusting for various potential confounders. Risk estimates were obtained for each census division, then pooled across Ontario. We examined potential effect modification for selected comorbidities and sociodemographic characteristics.

RESULTS

In warm seasons, each 5°C increase in daily mean temperature was associated with a 2.5% increase in nonaccidental deaths (95% confidence interval [CI] = 1.3% to 3.8%) on the day of exposure (lag 0). In cold seasons, each 5°C decrease in daily temperature was associated with a 3.0% (95% CI 1.8% to 4.2%) increase in nonaccidental deaths, which persisted over 7 days (lag 0-6). The cold-related effects (lag 0-6) were stronger for cardiovascular-related deaths (any cardiovascular death: 4.1%, 95% CI 2.3% to 5.9%; ischemic heart disease: 5.8%, 95% CI 3.6% to 8.1%), especially among people less than 65 years of age (8.0%, 95% CI 3.0% to 13.0%). Conversely, heat most strongly increased respiratory-related deaths during admission to hospital (26.0%, 95% CI 0% to 61.4%). Across Ontario, each 5°C change in daily temperature was estimated to induce 7 excess deaths per day in cold seasons and 4 excess deaths in warm seasons.

INTERPRETATION

Heat contributed to excess deaths in Ontario, although the effect of cold weather appeared to be greater. Further work is required to better define high-risk subgroups, which might include the homeless and people with inadequately heated housing.

Within- and between-city contrasts in nitrogen dioxide and mortality in 10 Canadian cities; a subset of the Canadian Census Health and Environment Cohort (CanCHEC)

The independent and joint effects of within- and between-city contrasts in air pollution on mortality have been investigated rarely. To examine the differential effects of between- versus within-city contrasts in pollution exposure, we used both ambient measurements and land use regression models to assess associations with mortality and exposure to nitrogen dioxide (NO2) among ~735,600 adults in 10 of the largest Canadian cities. We estimated exposure contrasts partitioned into within- and between-city contrasts, and the sum of these as overall exposures, for every year from 1984 to 2006. Residential histories allowed us to follow subjects annually during the study period. We calculated hazard ratios (HRs) adjusted for many personal and contextual variables. In fully-adjusted, random-effects models, we found positive associations between overall NO2 exposures and mortality from non-accidental causes (HR per 5 p.p.b.: 1.05; 95% confidence interval (CI): 1.03-1.07), cardiovascular disease (HR per 5 p.p.b.: 1.04; 95% CI: 1.01-1.06), ischaemic heart disease (HR per 5 p.p.b.: 1.05; 95% CI: 1.02-1.08) and respiratory disease (HR per 5 p.p.b.: 1.04; 95% CI: 0.99-1.08), but not from cerebrovascular disease (HR per 5 p.p.b.: 1.01; 95% CI: 0.96-1.06). We found that most of these associations were determined by within-city contrasts, as opposed to by between-city contrasts in NO2. Our results suggest that variation in NO2 concentrations within a city may represent a more toxic mixture of pollution than variation between cities.

Synoptic weather types and aeroallergens modify the effect of air pollution on hospitalisations for asthma hospitalisations in Canadian cities

Pollution levels and the effect of air pollution on human health can be modified by synoptic weather type and aeroallergens. We investigated the effect modification of aeroallergens on the association between CO, O3, NO2, SO2, PM10, PM2.5 and asthma hospitalisation rates in seven synoptic weather types. We developed single air pollutant models, adjusted for the effect of aeroallergens and stratified by synoptic weather type, and pooled relative risk estimates for asthma hospitalisation in ten Canadian cities. Aeroallergens significantly modified the relative risk in 19 pollutant-weather type combinations, reducing the size and variance for each single pollutant model. However, aeroallergens did not significantly modify relative risk for any pollutant in the DT or MT weather types, or for PM10 in any weather type. Thus, there is a modifying effect of aeroallergens on the association between CO, O3, NO2, SO2, PM2.5 and asthma hospitalisations that differs under specific synoptic weather types.

Assessment of urinary metabolite excretion after rat acute exposure to perfluorooctanoic acid and other peroxisomal proliferators

Perfluorooctanoic acid (PFOA) is a persistent environmental contaminant. Activation of the peroxisome proliferator activated receptor alpha (PPARα) resulting from exposure to PFOA has been extensively studied in rodents. However, marked differences in response to peroxisome proliferators prevent extrapolation of rodent PPARα activation to human health risks and additional molecular mechanisms may also be involved in the biological response to PFOA exposure. To further explore the potential involvement of such additional pathways, the effects of PFOA exposure on urinary metabolites were directly compared with those of other well-known PPARα agonists. Male rats were administered PFOA (10, 33, or 100 mg/kg/d), fenofibrate (100 mg/kg/d), or di(2-ethylhexyl) phthalate (100 mg/kg/d) by gavage for 3 consecutive days and allowed to recover for 4 days, and overnight urine was collected. Greater urinary output was observed exclusively in PFOA-treated rats as the total fraction of PFOA excreted in urine increased with the dose administered. Assessment of urinary metabolites (ascorbic acid, quinolinic acid, 8-hydroxy-2'-deoxyguanosine, and malondialdehyde) provided additional information on PFOA's effects on hepatic glucuronic acid and tryptophan-nicotinamide adenine dinucleotide (NAD) pathways and on oxidative stress, whereas increased liver weight and palmitoyl-CoA oxidase activity indicative of PPARα activation and peroxisomal proliferation persisted up to day five after the last exposure.

The association between ambient air quality and cardiac rate and rhythm in ambulatory subjects

BACKGROUND

Acute increases in ambient air pollution have been associated with increased hospitalization for cardiac diseases and stroke. Triggering of cardiac arrhythmia by changes in air quality could theoretically predispose individuals to cardiac arrest or heart failure, or stroke through precipitation of atrial fibrillation. We investigated the association between air quality and cardiac rate and rhythm characteristics measured by ambulatory cardiac monitoring.

METHODS AND RESULTS

Daily ambient 3-h maximum concentrations of ozone, nitrogen dioxide and fine particulate matter, and an index summarizing these pollutants called the Air Quality Health Index (AQHI) were compared to the results of 24-h ambulatory cardiac monitoring performed for clinical purposes in 8662 patients and analyzed at the University of Ottawa Heart Institute, Canada, between 2004 and 2009. An interquartile increase in the daily 3 h- maximum AQHI was associated with a 0.9% (95% CI 0.3%, 1.5%) increase in the daily maximum heart rate and a 1.17% (95% CI 1.07%, 1.29%) increase in heart block frequency. An interquartile increase in NO2 was associated with an increase in the percentage of time in atrial fibrillation of 4.39% (-0.15, 9.15) among those ≤50 years old, and 7.1% (0.24, 14.5) among males.

CONCLUSIONS

We found evidence that air pollution may affect cardiac rate and rhythm. This may be one mechanism partially explaining the increase in strokes and cardiac events observed on days of higher air pollution.

Residential exposure to volatile organic compounds and lung function: results from a population-based cross-sectional survey

Exposure to residential volatile organic compounds (VOCs) is ubiquitous in homes, and may influence respiratory health with important public health implications. To investigate the association between VOCs measured in residential indoor air and lung function in the Canadian population Cycle 2 of the Canadian Health Measures Survey - a population based cross-sectional survey designed to be representative of the Canadian population - was carried out between 2009 and 2011. Of the 84 VOCs measured, 47 were detectable in at least 50% of homes and ten were negatively associated with lung function: decanal, 2-furancarboxaldehyde, hexanal, nonanal, octanal, benzene, styrene, α-pinene, 2-methyl-1,2-butadiene and naphthalene. Differences were observed between males and females, as well as by age, and significant associations were most frequent in those under 17 years. These results provide evidence that some VOCs measured indoors are negatively associated with lung function in the Canadian population.

Indirect adjustment for multiple missing variables applicable to environmental epidemiology

OBJECTIVES

Develop statistical methods for survival models to indirectly adjust hazard ratios of environmental exposures for missing risk factors.

METHODS

A partitioned regression approach for linear models is applied to time to event survival analyses of cohort study data. Information on the correlation between observed and missing risk factors is obtained from ancillary data sources such as national health surveys. The relationship between the missing risk factors and survival is obtained from previously published studies. We first evaluated the methodology using simulations, by considering the Weibull survival distribution for a proportional hazards regression model with varied baseline functions, correlations between an adjusted variable and an adjustment variable as well as selected censoring rates. Then we illustrate the method in a large, representative Canadian cohort of the association between concentrations of ambient fine particulate matter and mortality from ischemic heart disease.

RESULTS

Indirect adjustment for cigarette smoking habits and obesity increased the fine particulate matter-ischemic heart disease association by 3%-123%, depending on the number of variables considered in the adjustment model due to the negative correlation between these two risk factors and ambient air pollution concentrations in Canada. The simulations suggested that the method yielded small relative bias (<40%) for most cohort designs encountered in environmental epidemiology.

CONCLUSIONS

This method can accommodate adjustment for multiple missing risk factors simultaneously while accounting for the associations between observed and missing risk factors and between missing risk factors and health endpoints.

Metal composition of fine particulate air pollution and acute changes in cardiorespiratory physiology

BACKGROUND

Studying the physiologic effects of components of fine particulate mass (PM2.5) could contribute to a better understanding of the nature of toxicity of air pollution.

OBJECTIVES

We examined the relation between acute changes in cardiovascular and respiratory function, and PM2.5-associated-metals.

METHODS

Using generalized linear mixed models, daily changes in ambient PM2.5-associated metals were compared to daily changes in physiologic measures in 59 healthy subjects who spent 5-days near a steel plant and 5-days on a college campus.

RESULTS

Interquartile increases in calcium, cadmium, lead, strontium, tin, vanadium and zinc were associated with statistically significant increases in heart rate of 1-3 beats per minute, increases of 1-3 mmHg in blood pressure and/or lung function decreases of up to 4% for total lung capacity.

CONCLUSION

Metals contained in PM2.5 were found to be associated with acute changes in cardiovascular and respiratory physiology.

Association of weather and air pollution interactions on daily mortality in 12 Canadian cities

It has been well established that both meteorological attributes and air pollution concentrations affect human health outcomes. We examined all cause nonaccident mortality relationships for 28 years (1981-2008) in relation to air pollution and synoptic weather type (encompassing air mass) data in 12 Canadian cities. This study first determines the likelihood of summertime extreme air pollution events within weather types using spatial synoptic classification. Second, it examines the modifying effect of weather types on the relative risk of mortality (RR) due to daily concentrations of air pollution (nitrogen dioxide, ozone, sulfur dioxide, and particulate matter <2.5 μm). We assess both single- and two-pollutant interactions to determine dependent and independent pollutant effects using the relatively new time series technique of distributed lag nonlinear modeling (DLNM). Results display dry tropical (DT) and moist tropical plus (MT+) weathers to result in a fourfold and twofold increased likelihood, respectively, of an extreme pollution event (top 5 % of pollution concentrations throughout the 28 years) occurring. We also demonstrate statistically significant effects of single-pollutant exposure on mortality (p < 0.05) to be dependent on summer weather type, where stronger results occur in dry moderate (fair weather) and DT or MT+ weather types. The overall average single-effect RR increases due to pollutant exposure within DT and MT+ weather types are 14.9 and 11.9 %, respectively. Adjusted exposures (two-way pollutant effect estimates) generally results in decreased RR estimates, indicating that the pollutants are not independent. Adjusting for ozone significantly lowers 67 % of the single-pollutant RR estimates and reduces model variability, which demonstrates that ozone significantly controls a portion of the mortality signal from the model. Our findings demonstrate the mortality risks of air pollution exposure to differ by weather type, with increased accuracy obtained when accounting for interactive effects through adjustment for dependent pollutants using a DLNM.

Changing air mass frequencies in Canada: potential links and implications for human health

Many individual variables have been studied to understand climate change, yet an overall weather situation involves the consideration of many meteorological variables simultaneously at various times diurnally, seasonally, and yearly. The current study identifies a full weather situation as an air mass type using synoptic scale classification, in 30 population centres throughout Canada. Investigative analysis of long-term air mass frequency trends was completed, drawing comparisons between seasons and climate zones. We find that the changing air mass trends are highly dependent on the season and climate zone being studied, with an overall increase of moderate ('warm') air masses and decrease of polar ('cold') air masses. In the summertime, general increased moisture content is present throughout Canada, consistent with the warming air masses. The moist tropical air mass, containing the most hot and humid air, is found to increase in a statistically significant fashion in the summertime in 46% of the areas studied, which encompass six of Canada's ten largest population centres. This emphasises the need for heat adaptation and acclimatisation for a large proportion of the Canadian population. In addition, strong and significant decreases of transition/frontal passage days were found throughout Canada. This result is one of the most remarkable transition frequency results published to date due to its consistency in identifying declining trends, coinciding with research completed in the United States (US). We discuss relative results and implications to similar US air mass trend analyses, and draw upon research studies involving large-scale upper-level air flow and vortex connections to air mass changes, to small-scale meteorological and air pollution interactions. Further research is warranted to better understand such connections, and how these air masses relate to the overall and city-specific health of Canadians.

Extreme ambient temperatures and cardiorespiratory emergency room visits: assessing risk by comorbid health conditions in a time series study

BACKGROUND

Extreme ambient temperatures are an increasing public health concern. The aim of this study was to assess if persons with comorbid health conditions were at increased risk of adverse cardiorespiratory morbidity during temperature extremes.

METHODS

A time series study design was applied to 292,666 and 562,738 emergency room (ER) visits for cardiovascular and respiratory diseases, respectively, that occurred in Toronto area hospitals between April 1st 2002 and March 31st 2010. Subgroups of persons with comorbid health conditions were identified. Relative risks (RRs) and their corresponding 95% confidence intervals (CIs) were estimated using a Poisson regression model with distributed lag non-linear model, and were adjusted for the confounding influence of seasonality, relative humidity, day-of-the-week, outdoor air pollutants and daily influenza ER visits. Effect modification by comorbid health conditions was tested using the relative effect modification (REM) index.

RESULTS

Stronger associations of cardiovascular disease ER visits were observed for persons with diabetes compared to persons without diabetes (REM = 1.12; 95% CI: 1.01 - 1.27) with exposure to the cumulative short term effect of extreme hot temperatures (i.e. 99th percentile of temperature distribution vs. 75th percentile). Effect modification was also found for comorbid respiratory disease (REM = 1.17; 95% CI: 1.02 - 1.44) and cancer (REM = 1.20; 95% CI: 1.02 - 1.49) on respiratory disease ER visits during short term hot temperature episodes. The effect of extreme cold temperatures (i.e. 1st percentile of temperature distribution vs. 25th percentile) on cardiovascular disease ER visits were stronger for individuals with comorbid cardiac diseases (REM = 1.47; 95% CI: 1.06 - 2.23) and kidney diseases (REM = 2.43; 95% CI: 1.59 - 8.83) compared to those without these conditions when cumulated over a two-week period.

CONCLUSIONS

The identification of those most susceptible to temperature extremes is important for public health officials to implement adaptation measures to manage the impact of extreme temperatures on population health.

Risk assessment for cardiovascular and respiratory mortality due to air pollution and synoptic meteorology in 10 Canadian cities

Synoptic weather and ambient air quality synergistically influence human health. We report the relative risk of mortality from all non-accidental, respiratory-, and cardiovascular-related causes, associated with exposure to four air pollutants, by weather type and season, in 10 major Canadian cities for 1981 through 1999. We conducted this multi-city time-series study using Poisson generalized linear models stratified by season and each of six distinctive synoptic weather types. Statistically significant relationships of mortality due to short-term exposure to carbon monoxide, nitrogen dioxide, sulphur dioxide, and ozone were found, with significant modifications of risk by weather type, season, and mortality cause. In total, 61% of the respiratory-related mortality relative risk estimates were significantly higher than for cardiovascular-related mortality. The combined effect of weather and air pollution is greatest when tropical-type weather is present in the spring or summer.

A cohort study of intra-urban variations in volatile organic compounds and mortality, Toronto, Canada

This study investigated associations between long-term exposure to ambient volatile organic compounds (VOCs) and mortality. 58,760 Toronto residents (≥35 years of age) were selected from tax filings and followed from 1982 to 2004. Death information was extracted using record linkage to national mortality data. Land-use regression surfaces for benzene, n-hexane, and total hydrocarbons were generated from sampling campaigns in 2002 and 2004 and assigned to residential addresses in 1982. Cox regression was used to estimate relationships between each VOC and non-accidental, cardiovascular, and cancer mortality. Positive associations were observed for each VOC. In multi-pollutant models the benzene and total hydrocarbon signals were strongest for cancer. The hazard ratio for cancer that corresponded to an increase in the interquartile range of benzene (0.13 μg/m(3)) was 1.06 (95% CI = 1.02-1.11). Our findings suggest ambient concentrations of VOCs were associated with cancer mortality, and that these exposures did not confound our previously reported associations between NO2 and cardiovascular mortality.