Relation of a seafood diet to mercury, selenium, arsenic, and polychlorinated biphenyl and other organochlorine concentrations in human milk

Biomonitoring of inorganic arsenic species in pregnancy

Exposure assessment of inorganic arsenic is challenging due to the existence of multiple species, complexity of arsenic metabolism, and variety of exposure sources. Exposure assessment of arsenic during pregnancy is further complicated by the physiological changes that occur to support fetal growth. Given the well-established toxicity of inorganic arsenic at high concentrations, continued research into the potential health effects of low-level exposure on maternal and fetal health is necessary. Our objectives were to review the value of and challenges inherent in measuring inorganic arsenic species in pregnancy and highlight related research priorities. We discussed how the physiological changes of pregnancy influence arsenic metabolism and necessitate the need for pregnancy-specific data. We reviewed the biomonitoring challenges according to common and novel biological matrices and discussed how each matrix differs according to half-life, bioavailability, availability of laboratory methods, and interpretation within pregnancy. Exposure assessment in both established and novel matrices that accounts for the physiological changes of pregnancy and complexity of speciation is a research priority. Standardization of laboratory method for novel matrices will help address these data gaps. Research is particularly lacking in contemporary populations of pregnant women without naturally elevated arsenic drinking water concentrations (i.e. <10 µg/l).

Pre- and Postnatal Developmental Exposure to the Polychlorinated Biphenyl Mixture Aroclor 1221 Alters Female Rat Pituitary Gonadotropins and Estrogen Receptor Alpha Levels

Polychlorinated-biphenyls (PCBs) are industrial compounds, which were widely used in manufacturing of electrical parts and transformers. Despite being banned in 1979 due to human health concerns, they persist in the environment. In humans and experimental model systems, PCBs elicit toxicity in part by acting as endocrine-disrupting chemicals (EDCs). Aroclor 1221 (A1221) is a weakly estrogenic PCB mixture known to alter reproductive function in rodents. EDCs can impact hormone signaling at any level of the hypothalamic-pituitary-gonadal (HPG) axis, and we investigated the effects of A1221 exposure during the prenatal and postnatal developmental periods on pituitary hormone and steroid receptor expression in female rats. Examining offspring at 3 ages, postnatal day 8 (P8), P32 and P60, we found that prenatal exposure to A1221 increased P8 neonate pituitary luteinizing hormone beta (Lhb) mRNA and LHβ gonadotrope cell number while decreasing LH serum hormone concentration. No changes in pituitary hormone or hormone receptor gene expression were observed peri-puberty at P32. In reproductively mature rats at P60, we found pituitary follicle stimulating hormone beta (Fshb) mRNA levels increased by prenatal A1221 exposure with no corresponding alterations in FSH hormone or FSHβ expressing cell number. Estrogen receptor alpha (ERα) mRNA and protein levels were also increased at P60, but only following postnatal A1221 dosing. Together, these data illustrate that exposure to the PCB A1221, during critical developmental windows, alters pituitary gonadotropin hormone subunits and ERα levels in offspring at different phases of maturation, potentially impacting reproductive function in concert with other components of the HPG axis.

Correlation between As, Cd, Hg, Pb and Sn concentration in human milk and breastfeeding mothers' food consumption: a systematic review and infants' health risk assessment

Mothers' food and water consumption appear to be determining factors for infants' potentially toxic elements exposure through human milk. Therefore, this systematic review aimed to assess correlations between As, Cd, Hg, Pb and/or Sn concentration in human milk and breastfeeding mothers' food consumption, with later infants' health risk assessment. Estimated Daily Intakes of such elements by infants were also calculated and compared with reference values (RfD or BMDL01). Among 5.663 identified studies, 23 papers remained for analysis. Potentially toxic elements concentration in human milk presented positive correlation with seafood (As, Hg), fresh vegetables (Hg, Cd), cereals (Hg, Cd), cheese, rice, potatoes, private and well-water supply (Pb), wild meat (Pb, Cd) and milk, dairy products, dried fruits and oilseeds (Cd) mothers' consumption. Red meat, caffeinated drinks, and dairy products consume presented negative correlations (Pb). No correlations were found for Sn. Infants from three studies presented high Hg exposition through human milk (> 0. 1 μg/kg PC-1 day-1), as well as observed for Pb in one study (> 0. 5 μg/kg PC-1 day-1). Potentially toxic elements can damage infants' health when they are present in mothers' diet due to the infants' high vulnerability. Therefore, these results raise important issues for public health.Supplemental data for this article is available online at https://doi.org/10.1080/10408398.2022.2056869 .

Concentrations of tetanus and diphtheria antibodies in vaccinated Greenlandic children aged 7-12 years exposed to marine pollutants, a cross sectional study

Previous studies have shown immunotoxic effects of environmental chemicals, and the European Food Safety Authority (EFSA) recently identified a need for more studies on PFAS immunotoxicity in different populations. In the Arctic, populations are exposed to several environmental chemicals through marine diet, and the objective of this study was therefore to examine the association between Greenlandic children's exposure to major environmental chemicals and their concentrations of diphtheria and tetanus vaccine antibodies after vaccination. The study includes cross-sectional data from Greenlandic children aged 7-12 years examined during 2012-2015. A total of 338 children were eligible for the study, and 175 of these had available vaccination records. A parent or guardian participated in a structured interview, and a blood sample from the child was analyzed for specific antibodies against diphtheria and tetanus as well as perfluoroalkyl substances (PFASs), polychlorinated biphenyls (PCBs) and total mercury. Furthermore, for a subgroup, blood samples from pregnancy were available and analyzed for environmental contaminants. The associations between the environmental exposures and antibody concentrations and odds of having antibody concentrations below the protective level were examined in linear and logistic regression models. In crude analyses, elevated concentrations of some of the contaminants were associated with higher concentrations of diphtheria and tetanus antibodies, but the associations were reversed when adjusting for area of residence, and duration of being breastfed and including children with a known vaccination date only. Each 1 ng/mL increase in serum concentrations of perfluorohexane sulfonic acid (PFHxS) and perfluorooctane sulfonic acid (PFOS) was associated with decreases of 78 % (95 % CI: 25-94 %) and 9 % (95 % CI: 2-16 %), respectively, in diphtheria antibody concentrations. Exposure to PCBs and all PFASs was associated with markedly increased odds of having diphtheria antibody concentrations below the protective level. For each 1 ng/mL increase in serum concentrations of PFHxS, PFOS, perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA), odds of not having protective levels of diphtheria antibodies were increased 6.44 times (95 % CI: 1.51-27.36), 1.14 times (95 % CI: 1.04-1.26), 1.96 times (95 % CI: 1.07-3.60), and 5.08 times (95 % CI: 1.32-19.51, respectively. No consistent associations were seen between maternal contaminant concentrations and vaccine antibody concentrations. In conclusion, we found that increased exposure to environmental chemicals among children in this Arctic population were associated with a decrease in post-vaccination antibody concentrations and with increased odds of not being protected against diphtheria despite appropriate vaccination. These findings emphasize the risk of environmental chemical exposures also in this Arctic population.

Marine pollutant exposures and human milk extracellular vesicle-microRNAs in a mother-infant cohort from the Faroe Islands

BACKGROUND/AIMS

Early life exposures to marine contaminants can adversely impact child health but modes of action are unclear. Human milk contains extracellular vesicles (EVs) that can transport biologically relevant cargo from mother to infant, including microRNAs (miRNAs), and may partly mediate the effects of pollutants on child health. However, the role of marine pollutants on miRNA expression in milk EVs is unexplored.

METHODS

We isolated EV RNA from 333 milk samples collected between 2 and 74 days postpartum from a Faroese birth cohort born 1997-2000 and sequenced 2083 miRNAs using a targeted library preparation method. We quantified five perfluoroalkyl substances (PFAS), pesticide metabolite p,p'-dichlorodiphenyldichloroethylene (DDE), and the sum of three major polychlorinated biphenyls (ΣPCBs) in maternal serum at 34 weeks of gestation and maternal hair total mercury (Hg) at birth. We used negative binomial regressions to estimate associations between individual pollutants and 418 reliably expressed EV-miRNAs adjusted for potential confounders. We performed sparse principal components (PCs) analysis to derive the first four components of the EV-miRNA data and examined associations between pollutants and PCs using Bayesian kernel machine regression (BKMR).

RESULTS

We observed no associations between pollutants and individual EV-miRNA expression after controlling the false discovery rate at 0.1. However, BKMR suggested that Hg was positively associated with PC1 and negatively associated with PC3, while ΣPCBs was negatively associated with PC3, and two PFAS were associated with PC4. Exploration of PC loadings followed by pathway analyses suggested that miRNAs in PC1 (miR-200b-3p, miR-664a-3p, miR-6738-5p, miR-429, miR-1236-5p, miR-4464, and miR-30b-5p) may be related to Hg neurotoxicity, while remaining PCs require further research.

CONCLUSIONS

Our findings suggest that groups of milk EV-miRNAs may better serve as environmental biomarkers than individual miRNAs. Future studies are needed to elucidate the role of milk EV-miRNAs in child health following prenatal exposures.

Concentrations and determinants of lead, mercury, cadmium, and arsenic in pooled donor breast milk in Spain

AIM

To measure concentrations of lead (Pb), mercury (Hg), cadmium (Cd), and arsenic (As) in longitudinally collected donor breast milk samples and to determine associated factors.

METHODS

Pb, Hg, Cd, and As concentrations were measured in 242 pooled breast milk samples from 83 donors to a Human Milk Bank in Spain, in 2015-2018, determining their association with the donors' sociodemographic profile, dietary and lifestyle habits, and post-partum time, among other factors, and with the nutritional characteristics of samples. Mixed-effect linear regression was used to identify predictors of Hg and As concentrations in breast milk and mixed-effect logistic regression to identify predictors of the presence of Pb and Cd.

RESULTS

As was the element most frequently detected in milk samples (97.1%), followed by Hg (81.2%), Pb (50.6%), and Cd (38.0%). Their median breast milk concentrations were 1.49 μg/L, 0.26 μg/L, 0.14 μg/L, and <0.04 μg/L, respectively. Concentrations of As were higher in breast milk from primiparous donors, while Hg was higher in donors with a greater intake of fatty fish and meat and lower in samples collected after a longer post-partum time and with higher lactose content. Detection of Pb was higher among multiparous donors, those gaining weight since before pregnancy, and ex-smokers and was lower in samples collected more recently and from donors with greater intake of red meat and eggs. Cd detection was higher for donors with university education and those with greater intake of fried and canned food and more frequent use of hand cream and was lower for donors with greater bread intake.

CONCLUSIONS

These findings reveal relatively high As concentrations, moderate Hg concentrations, and low Pb and Cd concentrations in pooled donor breast milk. Several factors including post-partum time, parity, smoking habit, and the intake of certain food items were associated with the metal content of milk samples.

Levels of mercury in Moroccan breast milk and the affecting factors: CONTAMILK study

This study aims to evaluate the level of mercury in the breast milk of Moroccan mothers and its association with several maternal parameters and habits, and to estimate the daily intake of the newborns. Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the concentrations of mercury in 70 colostrum samples. Indeed, a structured questionnaire was administrated during milk collection to report data concerning the maternal socioeconomic and anthropometric parameters, as well as dietary habits and smoking habits in the family, etc. The median of mercury in breast milk was 3,56 μg/L (range 1.64-124 μg/L) and exceeded normal levels of 1.7 μg/l, suggested by the World health organization in 99% of milk samples. Significant associations were found between mercury levels and the occurrence of previous miscarriages, anemia before pregnancy and vitamin & mineral supplementation during pregnancy, as well the frequency of consumption of cereals and the use of lipstick. The estimated daily intake was higher than the tolerable daily intake of the World health organization and the European food safety authority in 30% of newborns. These results need to be confirmed by multicenter studies to investigate the levels of mercury in the breast milk of the Moroccan population.

Maternal methylmercury exposure through rice ingestion and child neurodevelopment in the first three years: a prospective cohort study in rural China

BACKGROUND

Rice is an important dietary source for methylmercury; however, rice does not contain the same beneficial nutrients as fish. Our main objective was to assess associations of prenatal methylmercury exposure through rice ingestion with child neurodevelopment in rural China.

METHODS

Eligible peripartum women were enrolled (n = 391), provided peripartum hair samples, and children's neurodevelopment was assessed at 12 months (n = 264, 68%) and 36 months (n = 190, 48%) using the Bayley Scales of Infant Development, 2nd Edition, including the Mental Developmental Index (MDI) and the Psychomotor Developmental Index (PDI). Associations between prenatal methylmercury exposure during the third trimester [log2 maternal hair total mercury (THg)] and child's neurodevelopment were assessed using linear mixed models for repeated measures.

RESULTS

In adjusted models, a doubling in maternal hair THg corresponded to a 1.3-point decrement in the MDI score [95% confidence interval (CI): - 2.6, - 0.14], and a 1.2-point decrement in the PDI score (95% CI: - 2.6, 0.14). Overall, adverse associations between maternal hair THg and MDI scores attenuated over time. However, associations were robust and stable over time among children whose primary caregiver was their parent(s). During the study follow-up, an increasing proportion of children were raised by grandparents (12 months: 9% versus 36 months: 27%), a trend associated with rural-to-urban parental migration for work.

CONCLUSIONS

For young children living in rural China, a biomarker of prenatal methylmercury exposure was associated with decrements in cognitive function assessed between 12 and 36 months of age. Changes in the family structure over the study follow-up time interval potentially impacted children's sensitivity to prenatal methylmercury exposure.

Human milk extracellular vesicle miRNA expression and associations with maternal characteristics in a population-based cohort from the Faroe Islands

Human milk plays a critical role in infant development and health, particularly in cognitive, immune, and cardiometabolic functions. Milk contains extracellular vesicles (EVs) that can transport biologically relevant cargo from mother to infant, including microRNAs (miRNAs). We aimed to characterize milk EV-miRNA profiles in a human population cohort, assess potential pathways and ontology, and investigate associations with maternal characteristics. We conducted the first study to describe the EV miRNA profile of human milk in 364 mothers from a population-based mother-infant cohort in the Faroe Islands using small RNA sequencing. We detected 1523 miRNAs with ≥ one read in 70% of samples. Using hierarchical clustering, we determined five EV-miRNA clusters, the top three consisting of 15, 27 and 67 miRNAs. Correlation coefficients indicated that the expression of many miRNAs within the top three clusters was highly correlated. Top-cluster human milk EV-miRNAs were involved in pathways enriched for the endocrine system, cellular community, neurodevelopment, and cancers. miRNA expression was associated with time to milk collection post-delivery, maternal body mass index, and maternal smoking, but not maternal parity. Future studies investigating determinants of human EV-miRNAs and associated health outcomes are needed to elucidate the role of human milk EV-miRNAs in health and disease.

Environmental chemical exposures among Greenlandic children in relation to diet and residence

The objective of this study was to identify geographic, dietary, and other predictors for childhood exposure to perfluoroalkyl substances (PFASs), polychlorinated biphenyls (PCBs), and methylmercury in Greenlandic children. The study includes cross-sectional data from 367 Greenlandic children aged 7 to 12 years examined during 2012-2015. A parent or guardian participated in a structured interview, and a blood sample from the child was analysed for PFASs, PCBs and total mercury. Predictors for the environmental exposures were identified using linear regression. Area of residence was found to have the strongest explanatory power, accounting for 24% to 68% of the variance in the serum concentrations. Information about diet was available for two-thirds of the children, and among these, consumption of traditional Greenlandic food accounted for 2% to 10% of the variance in the biomarker concentrations. Models including all predictors associated with at least one of the environmental chemicals explained 19% to 54% of the total variance. In conclusion, area is a likely proxy for a traditional marine diet, and together area and diet constitute the most important predictors of exposure to methylmercury, PCBs and PFASs among Greenlandic children.

Sex-specific effects of developmental exposure to polychlorinated biphenyls on neuroimmune and dopaminergic endpoints in adolescent rats

Exposure to environmental contaminants early in life can have long lasting consequences for physiological function. Polychlorinated biphenyls (PCBs) are a group of ubiquitous contaminants that perturb endocrine signaling and have been associated with altered immune function in children. In this study, we examined the effects of developmental exposure to PCBs on neuroimmune responses to an inflammatory challenge during adolescence. Sprague Dawley rat dams were exposed to a PCB mixture (Aroclor 1242, 1248, 1254, 1:1:1, 20 μg/kg/day) or oil control throughout pregnancy, and adolescent male and female offspring were injected with lipopolysaccharide (LPS, 50 μg/kg, ip) or saline control prior to euthanasia. Gene expression profiling was conducted in the hypothalamus, prefrontal cortex, striatum, and midbrain. In the hypothalamus, PCBs increased expression of genes involved in neuroimmune function, including those within the nuclear factor kappa b (NF-κB) complex, independent of LPS challenge. PCB exposure also increased expression of receptors for dopamine, serotonin, and estrogen in this region. In contrast, in the prefrontal cortex, PCB exposure blunted or induced irregular neuroimmune gene expression responses to LPS challenge. Moreover, neither PCB nor LPS exposure altered expression of neurotransmitter receptors throughout the mesocorticolimbic circuit. Almost all effects were present in males but not females, in agreement with the idea that male neuroimmune cells are more sensitive to perturbation and emphasizing the importance of studying both male and female subjects. Given that altered neuroimmune signaling has been implicated in mental health and substance abuse disorders that often begin during adolescence, these results highlight neuroimmune processes as another mechanism by which early life PCBs can alter brain function later in life.

Joint and independent neurotoxic effects of early life exposures to a chemical mixture: A multi-pollutant approach combining ensemble learning and g-computation

BACKGROUND

Exposure to mercury (Hg) is associated with adverse developmental effects. However, Hg occurs with a multitude of chemicals. We assessed the associations of developmental exposure to multiple pollutants with children's neurodevelopment using a novel approach.

METHODS

Hg, polychlorinated biphenyls (PCBs), and perfluoroalkyl substances were measured in maternal and children's blood at 5-years (n=449 and 419). At 7-years, children were administered Boston Naming Test (BNT) and the Strengths and Difficulties Questionnaire (SDQ). We used the G-formula combined with SuperLearner to estimate independent and joint effects of chemicals at both ages. We constructed flexible exposure-response relationships and assessed interactions.

RESULTS

Most chemicals showed negative relationships with BNT scores. An inter-quartile range (IQR) increase in maternal Hg and perfluorooctanoic acid (PFOA) was associated with 0.15 standard deviation [SD] (95% Confidence Interval [CI]: -0.29,-0.03) and 0.14 SD (95%CI: -0.26,-0.05) lower scores in BNT, whereas a joint IQR increase in the mixture of chemicals was associated with 0.48 SD (95%CI: -0.69,-0.25) lower scores in BNT. An IQR increase in PFOA was associated with 0.11 SD (95%CI: 0.02,0.26) higher total SDQ difficulties scores. Maternal ∑PCBs concentrations were associated with lower SDQ scores (β=-0.09 SD; 95%CI: -0.19,0), whereas 5-years ∑PCBs showed a negative association (β=-0.09 SD; 95%CI: -0.21,0). Finally, a joint IQR increase in the mixture was associated with 0.22 SD (95%CI: 0.04,0.4) higher SDQ scores.

CONCLUSIONS

Using a novel statistical approach, we confirmed associations between prenatal mercury exposure and lower cognitive function. The potential developmental effects of PFASs need additional attention.

Physico-chemical properties and gestational diabetes predict transplacental transfer and partitioning of perfluoroalkyl substances

BACKGROUND

Per- and polyfluoroalkyl substances (PFASs) are a growing public health concern. Some longer chain PFASs bioaccumulate and many compounds persist in the environment for long time periods. Recent studies have established their ability to pass through placenta, yet data on the transplacental transfer efficiency and partitioning of short and long chain PFASs in blood matrices are limited.

OBJECTIVES

To assess predictors of the partitioning of 17 PFAS compounds detected in the maternal serum, umbilical cord serum and whole cord blood samples from matched mother-newborn pairs from two Faroe Islands cohorts.

METHODS

We examined 151 mother-newborn pairs from two successive Faroese birth cohorts. Cord:maternal serum (transplacental transfer) and serum:whole cord blood (blood partitioning) ratios were estimated for 17 PFAS compounds. We also examined the relationships of these ratios with maternal, newborns', and physico-chemical properties using multivariable regression analyses.

RESULTS

Moderate to high correlations were observed between maternal and cord serum PFAS concentrations (ρ: 0.41 to 0.95), indicating significant transfer of these compounds from the mother to the fetus. Median transplacental transfer ratios were generally below 1, except for perfluorooctane sulfonamide (FOSA), and ranged between 0.36 for perfluorodecanoate (PFDA) and perfluoroundecanoate (PFUnDA) and 1.21 for FOSA. Most PFASs exhibited a preference to the serum component of the blood, except FOSA and perfluoroheptanoate (PFHpA), with blood partitioning ratios ranging from 0.36 for FOSA to 2.75 for PFUnDA. Both the functional groups and carbon chain length of different PFASs were important predictors of transplacental transfer and blood partitioning. We observed a U-shaped relationship between transplacental transfer ratios and carbon chain length for perfluorocarboxylates and perfluorosulfonates. Importantly, gestational diabetes was also a strong predictor of transplacental transfer ratios, with significantly higher transfer in mothers with gestational diabetes.

CONCLUSIONS

Our findings provide a better understanding of the transplacental transfer and blood partitioning of a large number of PFAS compounds. Results elucidate the importance of chemical structure for future risk assessments and choice of appropriate blood matrices for measurement of PFAS compounds.

Concentration of mercury, cadmium, and lead in breast milk from Norwegian mothers: Association with dietary habits, amalgam and other factors

Mercury (Hg), cadmium (Cd), and lead (Pb) are of great concern for food safety and infants are especially sensitive to exposure to the maternal body burden. We quantified these elements in breast milk from Norwegian mothers and determined their association with dietary habits, maternal amalgam fillings, and smoking. Breast milk (n = 300) from the Norwegian Human Milk Study (HUMIS) was analyzed using triple quadrupole inductively coupled plasma mass spectrometry, after an acidic decomposition using microwave technique. We used multiple linear regression to examine predictors of Hg and Cd in breast milk, and logistic regression to test predictors of Pb above the quantification limit. The median breast milk concentrations (minimum - maximum) were 0.20 μg Hg/kg (<0.058-0.89), 0.057 μg Cd/kg (0.017-1.2), and <0.67 μg Pb/kg (<0.2-7.5). Cadmium showed no significant relation with any exposure variable investigated. Lead was associated with intake of liver and kidneys from game. For Hg concentration in breast milk, number of amalgam fillings and high fish consumption were significant predictors (p < 0.001). We detected a significant association (p < 0.01) between Hg in breast milk and maternal consumption of Atlantic halibut, lean fish, mussels and scallops and lifetime consumption of crab. Seafood intake alone explained 10% of variance, while together with amalgam explained 46% of variance in Hg concentration in breast milk. Our findings emphasize the importance of following consumer advice with respect to fish and seafood and points to amalgam as an important source for Hg exposure.

Dietary risk factors for inflammatory bowel diseases in a high-risk population: Results from the Faroese IBD study

Background

The Faroe Islands currently have the highest recorded inflammatory bowel disease (IBD) incidence in the world.

Objective

This study investigated environmental risk factors for IBD in the Faroese population.

Methods

Environmental exposure data including lifestyle risk factors and neurotoxicants collected for over 30 years were retrieved from the Children's Health and the Environment in the Faroes (CHEF) cohorts including mainly mother–child pairs, with exposure data collected from pregnant mothers. For lifestyle risk factors, the incidence of IBD and ulcerative colitis (UC) was calculated as the rate ratio (RR) with 95% confidence intervals (CI) in exposed versus non-exposed persons. For neurotoxicants RR was calculated for persons with high versus low exposure.

Results

Six cohorts included 5698 persons with complete follow-up data and at least one exposure, and 37 were diagnosed with IBD. For pilot whale/blubber, the RR was 1.02 (95% CI, 0.48–2.18); RR of 1.01 for fish (95% CI, 0.35–2.91); and of the pollutants studied, a statistical significantly increased risk was found for 1,1,1,-trichloro-2,2-bis-(p-chlorophenyl) ethane (p,p'-DDT); RR 3.04 (95% CI, 1.12–8.30). RRs were 1.96 (95% CI, 1.03–3.73) for smoking and 1.10 (95% CI, 0.55–2.19) for alcohol intake.

Conclusion

The high IBD incidence is unlikely to be caused by special dietary habits or by environmental pollutants.

Total, organic, and inorganic mercury in human breast milk: levels and maternal factors of exposure, systematic literature review, 1976-2017

This systematic review summarizes the finding of 58 studies from 33 countries, which assessed mercury concentrations in breast milk and the factors related to the level of contamination. We performed a literature search in Pubmed, Science Direct, and Google Scholar databases for studies published between 1976 and 2017 that are monitoring and measuring mercury in human breast milk and investigating the associated factors. Then, we extracted more information about the aim of the study, the country, samples size, time of lactation, mercury concentration, and other data. Most of the studies used mature milk or colostrum for analysis and in about 60% of them, the concentrations exceed significantly the limit set by the World Health Organization (WHO) of 1.7 µg/l; In addition, many factors and parameters were related to the level of mercury contamination in breast milk. Periodic monitoring surveys are recommended in each country to evaluate the level of mercury in milk of lactating women and to estimate the level of exposure of newborns.

Multiple low-level exposures: Hg interactions with co-occurring neurotoxic substances in early life

All chemical forms of Hg can affect neurodevelopment; however, low levels of organic Hg (methylmercury-MeHg and ethylmercury-EtHg in Thimerosal-containing vaccines, hereafter 'TCV') exposures during early life (pregnancy and lactation) co-occur with other environmental neurotoxic substances. These neurotoxicants may act in parallel, synergistically, or antagonistically to Hg. Nevertheless, the risks of neurotoxicity associated with multiple neuro-toxicants depend on type, time, combinations of exposure, and environmental and/or genetic-associated factors. Neurological developmental disorders, delays in cognition and behavioral outcomes associated with multiple exposures (which include Hg) may show transient or lasting outcomes depending on constitutional and/or environmental factors that can interact to neutralize, aggravate or attenuate these effects; often these studies are challenging to interpret. During pregnancy and lactation, fish-MeHg exposure is frequently confounded with the opposing effects of neuroactive nutrients (in fish) that lead to positive, negative, or no effects on neurobehavioral tests. In infancy, exposures to acute binary mixtures (TCV- EtHg and Al-adjuvants in infant immunizations) are associated with increased risks of tics and other developmental disorders. Despite the certitude that promulgates single environmental neurotoxicants, empirical comparisons of combined exposures indicate that Hg-related outcome is uneven. Hg in combination with other neurotoxic mixtures may elevate risks of neurotoxicity, but these risks arise in circumstances that are not yet predictable. Therefore, to achieve the goals of the Minamata treaty and to safeguard the health of children, low levels of mercury exposure (in any chemical form) needs to be further reduced whether the source is environmental (air- and food-borne) or iatrogenic (pediatric TCVs).

Reproductive Function in a Population of Young Faroese Men with Elevated Exposure to Polychlorinated Biphenyls (PCBs) and Perfluorinated Alkylate Substances (PFAS)

Semen quality may be adversely affected by exposure to environmental chemicals such as polychlorinated biphenyls (PCBs) and perfluorinated alkylate substances (PFASs) that are persistent and may act as endocrine disrupting compounds. The aim of this study was to explore whether PCBs or PFASs exposure were associated with abnormalities in semen quality or reproductive hormones in Faroese men. This population based cross-sectional study includes 263 Faroese men (24⁻26 years) who delivered a semen sample for assessment of sperm concentration, total sperm count, semen volume, morphology and motility. A blood sample was drawn and analyzed for reproductive hormones, PCBs and PFASs. Exposure to ∑PCBs and perfluorooctane sulfonate (PFOS) was positively associated with sex hormone-binding globulin (SHBG) and luteinizing hormone (LH). In addition, total testosterone (T) was positively associated with ∑PCB. Both PCBs and PFOS appear to lead to increased SHBG, perhaps mediated via the liver. The higher total T associated with PCB may represent a compensatory adaption to elevated SHBG levels to maintain an unchanged free testosterone concentration. The positive association to LH for both PCBs and PFOS may indicate a direct adverse effect on the testosterone producing Leydig cells.

Sex differences in effects of gestational polychlorinated biphenyl exposure on hypothalamic neuroimmune and neuromodulator systems in neonatal rats

Polychlorinated biphenyls (PCBs) are ubiquitous in the environment and exposure to them is associated with immune, endocrine and neural dysfunction. Effects of PCBs on inflammation and immunity are best described in spleen and blood, with fewer studies on neural tissues. This is an important gap in knowledge, as molecules typically associated with neuroinflammation also serve neuromodulatory roles and interact with hormones in normal brain development. The current study used Sprague-Dawley rats to assess whether gestational PCB exposure altered hypothalamic gene expression and serum cytokine concentration in neonatal animals given an immune challenge. Dams were fed wafers containing a mixture of PCBs at an environmentally relevant dose and composition (20 μg/kg, 1:1:1 Aroclor 1242:1248:1254) or oil vehicle control throughout their pregnancy. One day old male and female offspring were treated with an inflammatory challenge (lipopolysaccharide, LPS, 50 μg/kg, sc) or saline vehicle control approximately 3.5 h prior to tissue collection. Across both basal and activated inflammatory states, PCB exposure caused greater expression of a subset of inflammatory genes in the hypothalamus and lower expression of genes involved in dopamine, serotonin, and opioid systems compared to oil controls. PCB exposure also altered reactions to inflammatory challenge: it reversed the normal decrease in Esr2 hypothalamic expression and induced an abnormal increase in IL-1b and IL-6 serum concentration in response to LPS. Many of these effects were sex specific. Given the potential long-term consequences of neuroimmune disruption, our findings demonstrate the need for further research.

Micronutrients in Human Milk: Analytical Methods

Exclusive breastfeeding is recommended by the WHO for the first 6 mo of life because human milk protects against gastrointestinal infections and supplies balanced and adequate nutrient contents to the infant. However, reliable data on micronutrient concentrations in human milk are sparse, especially because some micronutrients are affected by maternal diet. Microbiological and competitive protein-binding assays, nuclear magnetic resonance or inductively coupled plasma spectroscopy, and chromatographic analyses are among the methods that have been applied to human-milk micronutrient analysis. However, the validation or evaluation of analytical methods in terms of their suitability for the complex human-milk matrix has been commonly ignored in reports, even though the human-milk matrix differs vastly from blood, plasma, or urine matrixes. Thus, information on the validity, accuracy, and sensitivity of the methods is essential for the estimation of infant and maternal intake requirements to support and maintain adequate milk micronutrient concentrations for healthy infant growth and development. In this review, we summarize current knowledge on methods used for analyzing water- and fat-soluble vitamins as well as iron, copper, zinc, iodine, and selenium in human milk and their different forms in milk; the tools available for quality control and assurance; and guidance for preanalytical considerations. Finally, we recommend preferred methodologic approaches for analysis of specific milk micronutrients.

In vivo and in vitro methods for evaluating soil arsenic bioavailability: relevant to human health risk assessment

Arsenic (As) is the most frequently occurring contaminant on the priority list of hazardous substances, which lists substances of greatest public health concern to people living at or near U.S. National Priorities List site. Accurate assessment of human health risks from exposure to As-contaminated soils depends on estimating its bioavailability, defined as the fraction of ingested As absorbed across the gastrointestinal barrier and available for systemic distribution and metabolism. Arsenic bioavailability varies among soils and is influenced by site-specific soil physical and chemical characteristics and internal biological factors. This review describes the state-of-the science that supports our understanding of oral bioavailability of soil As, the methods that are currently being explored for estimating soil As relative bioavailability (RBA), and future research areas that could improve our prediction of the oral RBA of soil As in humans. The following topics are addressed: (1) As soil geochemistry; (2) As toxicology; (3) in vivo models for estimating As RBA; (4) in vitro bioaccessibility methods; and (5) conclusions and research needs.

Secondary sex ratio in relation to exposures to polychlorinated biphenyls, dichlorodiphenyl dichloroethylene and methylmercury

This study was undertaken to assess the potential impact of maternal exposures to polychlorinated biphenyl (PCB), dichlorodiphenyl dichloroethylene (DDE) and methylmercury on the secondary sex ratios (the ratio of male to female live births) over a span of 23 years. The study includes prospective data from three Faroese birth cohorts, with a total of 2,152 healthy mother–child dyads recruited between 1986 and 2009. The Faroe Islands is a subarctic fishing community, where pilot whale meat and blubber are part of the traditional marine diet. Exposures were measured in maternal hair, serum or umbilical cord blood. Confounder adjusted logistic regression models were used to assess the associations between maternal exposures and the secondary sex ratio. A doubling in ΣPCB, p,p’-DDE and mercury concentrations were associated with increased odds by 8% (95% CI = 0–16%), 7% (95% CI = 0–14%) and 9% (95% CI = 2–17%), respectively, of giving birth to a boy. In conclusion, maternal exposure to ΣPCB, DDE and methylmercury was associated with a slightly increased secondary sex ratio. The impact of paternal exposures could not be taken into account and deserves attention.

Gestational diabetes and offspring birth size at elevated environmental pollutant exposures

BACKGROUND

Gestational diabetes mellitus (GDM) is associated with increased availability of glucose and macronutrients in fetal circulation and macrosomia. Therefore, the role of GDM in the association between metabolism-disrupting chemicals and birth size deserves attention.

OBJECTIVE

We examined whether GDM may mediate or modify the associations between maternal environmental pollutant exposures and offspring birth size measures.

METHODS

We analyzed 604 Faroese pregnant women and their offsprings born in 1997-2000. Maternal pregnancy serum concentrations of organochlorine compounds (OCs: polychlorinated biphenyl (PCB) congeners and dichlorodiphenyldichloroethylene (DDE)), and five perfluoroalkyl substances (PFASs), and hair and cord blood mercury concentrations were measured. We used regression (single-pollutants) and structural equation models (SEMs) (multiple-pollutant analyses using latent constructs of OCs, PFASs and mercury) to estimate the associations with GDM and birth size measures, accounting for mediation and/or effect modification by GDM.

RESULTS

Serum-DDE and hair-mercury concentrations were associated with GDM (adjusted OR per concentration doubling: 1.29; 95% CI: 0.94, 1.77 for DDE, and 0.79; 95% CI: 0.62, 0.99 for mercury), but in multiple pollutant-adjusted SEMs only a positive association between OC exposure and GDM remained significant (change in GDM odds per OC doubling: 0.45; 95% CI: 0.05, 0.86). PCB and overall OC exposure were positively associated with head circumference (SEM; mean change per OC doubling: 0.13cm; 95% CI, 0.01. 0.25). Overall PFAS exposure was inversely associated with birth weight (SEM; mean change per PFAS doubling: -169g; 95% CI: -359, 21), and for many single-PFASs we found a pattern of inverse associations with birth weight and head circumference in boys, and positive or null associations in girls. None of the environmental pollutants was associated with offspring length. GDM neither modified nor mediated the associations with birth size measures.

CONCLUSIONS

We found associations with GDM and offspring birth size to be specific to the environmental pollutant or pollutant group. Associations with birth size measures appear to be independent of GDM occurrence.

PCBs and OCPs in human milk in Eastern Siberia, Russia: Levels, temporal trends and infant exposure assessment

The aim of our study is to investigate the spatial distribution of polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), dichlorodiphenyltrichloroethane (p,p'-DDT) and its metabolites, α- and γ-isomers of hexachlorocyclohexane (HCH) in 155 samples of human milk (HM) from Eastern Siberia (six towns and seven villages in Irkutsk Region, one village of the Republic of Buryatia and one town in Zabaikal'sk Region, Russia), and to examine the dietary and social factors influencing the human exposure to the organochlorines. The median and range of the concentration of six indicator PCBs in HM in 14 localities in Eastern Siberia (114 (19-655) ng g^-1 lipids respectively) are similar to levels in the majority of European countries. However, in one village, Onguren, the median and range of levels of six indicator PCBs (1390 (300-3725) ng g^-1 lipids) were comparable to levels measured in highly contaminated populations. The Lake Baikal seals are highly exposed to persistent organic pollutants (POPs) and could be a potential source of PCB and DDT exposure in the Onguren cohort via the consumption of the Lake Baikal seal tissue. The location of food production in areas exposed to the emissions of local POP sources can also significantly influence POP levels in HM samples from industrialized areas. Estimated daily intakes (EDI) of HCH and HCB for infants are considerably lower or close to acceptable daily intake (ADI). The EDI of total DDTs and total PCBs are higher than ADI.

Behavioral difficulties in 7-year old children in relation to developmental exposure to perfluorinated alkyl substances

BACKGROUND

Perfluorinated alkyl substances (PFAS) are suspected endocrine disruptors that are highly persistent and neurotoxic in animals. Human epidemiological studies of exposure-related deviations of children's behaviors are sparse. We assessed the associations between prenatal, 5- and 7-year PFAS exposures and behavioral problem scores in 7-year Faroese children.

METHODS

Concentrations of perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA), perfluorooctane sulfonate (PFOS), and perfluorohexane sulfonic acid (PFHxS) were measured in maternal serum and in serum from children at ages 5 and 7years (n=539, 508, and 491, respectively). We used multivariable regressions and structural equations models to estimate the covariate-adjusted associations between serum-PFAS concentrations and behavioral difficulties, as assessed by the strengths and difficulties questionnaire (SDQ) at age 7.

RESULTS

Serum-PFOS and PFHxS concentrations declined over time, whereas PFOA, PFNA, and PFDA tended to increase. No associations were observed between prenatal PFAS concentrations and SDQ scores. However, a two-fold increase in 5-year serum-PFOA, PFNA, and PFDA concentrations was associated with increases in total SDQ scores by 1.03 (95% CI: 0.11, 1.95), 0.72 (95% CI: 0.07, 1.38) and 0.78 points (95% CI: 0.01, 1.55), respectively. For SDQ subscales, significant associations were found in regard to hyperactivity, peer relationship, and conduct problems, as well as internalizing and externalizing problems and autism screening composite scores. Cross-sectional analyses at age 7years showed possible sex-dimorphic associations between PFAS concentrations and SDQ scores, where girls had consistently positive associations with SDQ scores whereas boys exhibited a pattern of negative or null associations.

CONCLUSIONS

Higher serum PFAS concentrations at ages 5- and 7-years, but not prenatally, were associated with parent-reported behavioral problems at age 7.

Metal contents of marine turtle eggs (Chelonia mydas; Lepidochelys olivacea) from the tropical eastern pacific and the implications for human health

Concentrations of eight elements were measured in Chelonia mydas and Lepidochelys olivacea eggs collected along the Pacific coast of Panama. Manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), and mercury (Hg) concentrations were similar to previous reports of these species from around the world, while lead (Pb) was lower than previous reports. Cd posed the highest health risk to people who regularly eat the eggs, with average consumption rates leading to target hazard quotients (THQ) of up to 0.35 ± 0.15. Our conclusions indicate that current turtle egg consumption in isolated, coastal Pacific communities may pose a health concern for young children, and that youth and young adults should limit their consumption of turtle eggs to reduce their total intake of nonessential metals.

Children's white blood cell counts in relation to developmental exposures to methylmercury and persistent organic pollutants

BACKGROUND

To explore possible markers of developmental immunotoxicity, we prospectively examined 56 children to determine associations between exposures to methylmercury and persistent organic pollutants since birth and the comprehensive differential counts of white blood cells (WBC) at age 5 years.

MATERIALS AND METHODS

Extended differential count included: neutrophils, eosinophils, basophils, lymphocytes (includingT cells, NK cells, and B cells), and monocytes. Organochlorine compounds (OCs) including polychlorinated biphenyls (PCBs) and pesticides, five perfluoroalkyl substances (PFASs), and total mercury (Hg) were measured in maternal (n=56) and children's blood at 18 months (n=42) and 5 years (n=54). We constructed latent functions for exposures at three different ages using factor analyses and applied structural equation models adjusted for covariates.

RESULTS

Prenatal mercury exposure was associated with depleted total WBC, especially for lymphocytes, where a one standard deviation (SD) increase in the exposure was associated with a decrease by 23% SD (95% CI: -43, -4) in the cell count. Prenatal exposure to OCs was marginally associated with decreases in neutrophil counts. In contrast, the 5-year PFASs concentrations were associated with higher basophil counts (B=46% SD, 95% CI: 13, 79). Significantly reduced subpopulations of lymphocytes such as B cells, CD4-positive T helper cells and CD4 positive recent thymic emigrants may suggest cellular immunity effects and dysregulation of T-cell mediated immunity.

CONCLUSION

Developmental exposure to environmental immunotoxicants appears to have different impacts on WBC counts in childhood.

Early-life exposures to persistent organic pollutants in relation to overweight in preschool children

Current knowledge on obesogenic effects of persistent organic pollutants (POPs) is equivocal. We therefore evaluated the associations between early-life POP exposures and body mass index (BMI) in 444 Faroese children born in 2007-2009. POPs were measured in maternal 2-week postpartum serum and child age-5 serum. Linear regression and generalised linear models assessed the associations with continuous and dichotomous BMI z-scores, respectively, at ages 18 months and/or 5 years. Maternal serum concentrations of HCB, PFOS and PFOA were associated with increased BMI z-scores and/or overweight risk (i.e. BMI z-score≥85th WHO percentile). No clear association was found for maternal serum-PCBs, p,p'-DDE, PFHxS, PFNA and PFDA. In cross-sectional analyses, we observed a pattern of inverse associations between child serum-POPs and BMI z-scores at age 5, perhaps due to reverse causation that requires attention in future prospective analyses. Findings in this recent cohort support a role of maternal exposure to endocrine disruptors in the childhood obesity epidemic.

Serum concentrations of PCBs and OCPs among prepubertal Korean children

Although children are more vulnerable than adults to environmental hazards, due to their physiological and behavioral characteristics, few studies have assessed their internal exposure to persistent organic pollutants (POPs). The objective of this study was to determine the serum levels of certain polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) among pre-pubertal children in Korea and examine their variation with age and gender. We analyzed a total of 51 POPs in 214 children (age range, 7-9 years), using data from the Ewha Birth and Growth Cohort Study. To examine change over time, POP concentrations were measured at both 7 and 9 years of age in a sub-cohort of 26 children. The median and interquartile range (IQR, 25th to 75th percentiles) data for the sum of PCB congeners was 26.44 ng/g lipid (18.27-37.63 ng/g lipid). The median (IQR) concentration for the sum of OCPs was 74.82 ng/g lipid (51.11-112.45 ng/g lipid). Our results showed significant increases in serum concentrations of total PCBs with age (p = 0.0001), no gender dependence of total PCBs (p = 0.38) and total OCPs (p = 0.12), and strong correlations between individual POPs. Childhood exposure to POPs was relatively low compared to other studies carried out in different countries. However, even though the use of POPs has been banned since 2001, our results indicated that children in the general population are still exposed to various POPs. Because long-term, low-level exposure to POPs in the general population remains a concern for human health, future research should examine major routes of exposure and identification of risk factors.

Mercury Accumulation in Harbour Seals from the Northeastern Pacific Ocean: The Role of Transplacental Transfer, Lactation, Age and Location

Mercury (Hg) bioaccumulates in the aquatic food chain in the form of methylmercury, a compound well known for its neurotoxicity. We analyzed total mercury (THg) in hair collected from 209 harbour seals captured at 10 sites in British Columbia (Canada) and Washington State (USA) between 2003 and 2010. In addition, laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) allowed for a highly refined analysis of THg accumulation over time by examining nine whiskers taken from 4- to 6-week-old pups. We estimate that THg concentrations in pups increased sharply at a point corresponding to mid- to late gestation of their time in utero (4.7 ± 0.8 and 6.6 ± 1.3 µg/g dry weight (dw), respectively), and then again at the onset of nursing (8.1 ± 1.3 µg/g dw). These abrupt changes highlight the importance of both pre- and post-natal THg transfer from the mother to the growing fetus and the newborn pup. While THg levels varied among sites, hair analyses from seals collected at the same site demonstrated the influence of age in THg accumulation with pups (5.3 ± 0.3 µg/g) and juveniles (4.5 ± 0.5 µg/g) having lower levels than those in adults (8.3 ± 0.8 µg/g). Our results revealed that 33 % of the pups sampled (n = 167) had THg levels that surpassed a mammalian hair threshold for neurochemical alterations. This study suggests that Hg could represent a health concern to marine wildlife, especially as atmospheric emissions of this toxic element from human activities in the Pacific Rim and worldwide continue.

Prenatal exposure to persistent organochlorine pollutants is associated with high insulin levels in 5-year-old girls

BACKGROUND

Several persistent organochlorine pollutants (POPs) possess endocrine disrupting abilities, thereby potentially leading to an increased risk of obesity and metabolic diseases, especially if the exposure occurs during prenatal life. We have previously found associations between prenatal POP exposures and increased BMI, waist circumference and change in BMI from 5 to 7 years of age, though only among girls with overweight mothers.

OBJECTIVES

In the same birth cohort, we investigated whether prenatal POP exposure was associated with serum concentrations of insulin and leptin among 5-year-old children, thus possibly mediating the association with overweight and obesity at 7 years of age.

METHODS

The analyses were based on a prospective Faroese Birth Cohort (n=656), recruited between 1997 and 2000. Major POPs, polychlorinated biphenyls (PCBs), p,p'-dichlorodiphenyldichloroethylene (DDE) and hexachlorobenzene (HCB), were measured in maternal pregnancy serum and breast milk. Children were followed-up at the age of 5 years where a non-fasting blood sample was drawn; 520 children (273 boys and 247 girls) had adequate serum amounts available for biomarker analyses by Luminex® technology. Insulin and leptin concentrations were transformed from continuous to binary variables, using the 75th percentile as a cut-off point. Multiple logistic regression was used to investigate associations between prenatal POP exposures and non-fasting serum concentrations of insulin and leptin at age 5 while taking into account confounders.

RESULTS

Girls with highest prenatal POP exposure were more likely to have high non-fasting insulin levels (PCBs 4th quartile: OR=3.71; 95% CI: 1.36, 10.01. DDE 4th quartile: OR=2.75; 95% CI: 1.09, 6.90. HCB 4th quartile: OR=1.98; 95% CI: 1.06, 3.69) compared to girls in the lowest quartile. No significant associations were observed with leptin, or among boys. A mediating effect of insulin or leptin on later obesity was not observed.

CONCLUSION

These findings suggest, that for girls, prenatal exposure to POPs may play a role for later development of metabolic diseases by affecting the level of insulin.

Effect of seafood mediated PCB exposure on desaturase activity and PUFA profile in Faroese septuagenarians

Polychlorinated biphenyl (PCB) exposure may affect serum concentrations of polyunsaturated fatty acids (PUFAs) by inhibiting desaturases ∆5 and ∆6 that drive their synthesis from precursor fatty acids. Such changes in the composition of fatty acids may affect cardiovascular disease risk, which is thought to increase at elevated PCB exposures. This population-based cross-sectional study examined 712 Faroese men and women aged 70-74 years. The serum phospholipid fraction of fasting blood samples was used to determine the PUFA profile, including linoleic acid, dihomo-γ-linolenic acid, arachidonic acid, eicosatrienoic acid, and other relevant fatty acids. Ratios between precursor and metabolite fatty acids were used as proxies for ∆5 and ∆6 desaturase activity. Tertiles of serum-PCB concentrations were used in multiple regression analyses to determine the association between the exposure and desaturase activity. In multiple regression models, PCB exposure was inversely related to the estimated Δ6 desaturase activity resulting in accumulation of precursor fatty acids and decrease in the corresponding product PUFAs. A positive association between PCB and Δ5 desaturation was also found. A relative increase in EA was also observed, though only in the third tertile of PCB exposure. Non-linear relationships between the exposure and the desaturase activity were not found. Consuming fish and seafood may not be translated into beneficial fatty acid profiles if the diet simultaneously causes exposure to PCBs. Although the desaturase estimates were likely influenced by dietary intakes of product PUFAs, the association between PCB exposure and ∆6 desaturase activity is plausible and may affect cardiovascular disease risk.

Spatial and temporal trends of the Stockholm Convention POPs in mothers' milk -- a global review

Persistent organic pollutants (POPs) have been of environmental and health concern for more than half a century and have their own intergovernmental regulation through the Stockholm Convention, from 2001. One major concern is the nursing child's exposure to POPs, a concern that has led to a very large number of scientific studies on POPs in mothers' milk. The present review is a report on the assessment on worldwide spatial distributions of POPs and of their temporal trends. The data presented herein is a compilation based on scientific publications between 1995 and 2011. It is evident that the concentrations in mothers' milk depend on the use of pesticides and industrial chemicals defined as POPs. Polychlorinated biphenyls (PCBs) and "dioxins" are higher in the more industrialized areas, Europe and Northern America, whereas pesticides are higher in Africa and Asia and polybrominated diphenyl ethers (PBDEs) are reported in higher concentrations in the USA. POPs are consequently distributed to women in all parts of the world and are thus delivered to the nursing child. The review points out several major problems in the reporting of data, which are crucial to enable high quality comparisons. Even though the data set is large, the comparability is hampered by differences in reporting. In conclusion, much more detailed instructions are needed for reporting POPs in mothers' milk. Temporal trend data for POPs in mothers' milk is scarce and is of interest when studying longer time series. The only two countries with long temporal trend studies are Japan and Sweden. In most cases, the trends show decreasing concentrations of POPs in mothers' milk. However, hexabromocyclododecane is showing increasing temporal concentration trends in both Japan and Sweden.

Estimated exposure to arsenic in breastfed and formula-fed infants in a United States cohort

BACKGROUND

Previous studies indicate that concentrations of arsenic in breast milk are relatively low even in areas with high drinking-water arsenic. However, it is uncertain whether breastfeeding leads to reduced infant exposure to arsenic in regions with lower arsenic concentrations.

OBJECTIVE

We estimated the relative contributions of breast milk and formula to arsenic exposure during early infancy in a U.S.

METHODS

We measured arsenic in home tap water (n = 874), urine from 6-week-old infants (n = 72), and breast milk from mothers (n = 9) enrolled in the New Hampshire Birth Cohort Study (NHBCS) using inductively coupled plasma mass spectrometry. Using data from a 3-day food diary, we compared urinary arsenic across infant feeding types and developed predictive exposure models to estimate daily arsenic intake from breast milk and formula.

RESULTS

Urinary arsenic concentrations were generally low (median, 0.17 μg/L; maximum, 2.9 μg/L) [corrected] but 7.5 times higher for infants fed exclusively with formula than for infants fed exclusively with breast milk (β = 2.02; 95% CI: 1.21, 2.83; p < 0.0001, adjusted for specific gravity). Similarly, the median estimated daily arsenic intake by NHBCS infants was 5.5 times higher for formula-fed infants (0.22 μg/kg/day) than for breastfed infants (0.04 μg/kg/day). Given median arsenic concentrations measured in NHBCS tap water and previously published for formula powder, formula powder was estimated to account for ~ 70% of median exposure among formula-fed NHBCS infants.

CONCLUSIONS

Our findings suggest that breastfed infants have lower arsenic exposure than formula-fed infants, and that both formula powder and drinking water can be sources of exposure for U.S. infants.

Spermatogenic capacity in fertile men with elevated exposure to polychlorinated biphenyls

BACKGROUND

Endocrine disrupting industrial chemicals, such as polychlorinated biphenyls (PCBs), are suspected to adversely affect male reproductive functions.

OBJECTIVES

The Faroe Islands community exhibits an unusually wide range of exposures to dietary contaminants, and in this setting we examined the possible association between PCB exposure and semen quality and reproductive hormones in fertile Faroese men.

METHODS

Participants in this cross-sectional study include 266 proven fertile men residing in the Faroe Islands. PCB levels and hormone profiles were measured in serum samples taken at the clinical examination that included semen quality parameters.

RESULTS

A significant positive association was seen between serum-PCB and the testosterone/estradiol ratio (p=0.04). In the unadjusted analyses, elevated PCB exposure was associated with increased serum concentrations of SHBG (p=0.01) and FSH (p=0.05). We found no association between the serum PCB concentration and the semen quality variables.

CONCLUSION

In this population of highly exposed fertile men, the current serum-PCB concentration was associated with higher androgen/estrogen ratio. Further studies are needed to establish the findings and further document PCB-associated hormonal effects, any time windows of increased susceptibility, and the role of PCB in sub-fecundity.

Amyloid domains in the cell nucleus controlled by nucleoskeletal protein lamin B1 reveal a new pathway of mercury neurotoxicity

Mercury (Hg) is a bioaccumulating trace metal that globally circulates the atmosphere and waters in its elemental, inorganic and organic chemical forms. While Hg represents a notorious neurotoxicant, the underlying cellular pathways are insufficiently understood. We identify amyloid protein aggregation in the cell nucleus as a novel pathway of Hg-bio-interactions. By mass spectrometry of purified protein aggregates, a subset of spliceosomal components and nucleoskeletal protein lamin B1 were detected as constituent parts of an Hg-induced nuclear aggregome network. The aggregome network was located by confocal imaging of amyloid-specific antibodies and dyes to amyloid cores within splicing-speckles that additionally recruit components of the ubiquitin-proteasome system. Hg significantly enhances global proteasomal activity in the nucleus, suggesting that formation of amyloid speckles plays a role in maintenance of protein homeostasis. RNAi knock down showed that lamin B1 for its part regulates amyloid speckle formation and thus likewise participates in nuclear protein homeostasis. As the Hg-induced cascade of interactions between the nucleoskeleton and protein homeostasis reduces neuronal signalling, amyloid fibrillation in the cell nucleus is introduced as a feature of Hg-neurotoxicity that opens new avenues of future research. Similar to protein aggregation events in the cytoplasm that are controlled by the cytoskeleton, amyloid fibrillation of nuclear proteins may be driven by the nucleoskeleton.

Associations between Exposure to Persistent Organic Pollutants in Childhood and Overweight up to 12 Years Later in a Low Exposed Danish Population

BACKGROUND

Persistent organic pollutants (POPs) have metabolic disrupting abilities and are suggested to contribute to the obesity epidemic. We investigated whether serum concentrations of POPs at 8-10 years of age were associated with subsequent development of overweight at age 14-16 and 20-22 years.

METHODS

The study was based on data from the European Youth Heart Study, Danish component (1997). Concentrations of several polychlorinated biphenyls (PCBs) and the organochlorine pesticides p,p-dichlorodiphenyldichloroethylene (DDE) and hexachlorobenzene (HCB) were measured in serum from children aged 8-10 years (n = 509). Information on BMI z-scores, waist circumference and % body fat were collected at clinical examinations at ages 8-10, 14-16 and 20-22 years. Multiple linear regression analyses were performed taking potential confounders into account.

RESULTS

Overall, POP serum concentrations were low: median ΣPCB 0.18 µg/g lipid, DDE 0.04 µg/g lipid and HCB 0.03 µg/g lipid. POPs were generally not associated with weight gain at 14-16 and 20-22 years of age, except for an inverse association among the highest exposed girls at 20-22 years of age, which might possibly be explained by multiple testing or residual confounding.

CONCLUSION

This study suggests that, in a low exposed population, childhood serum concentrations of PCB, DDE, and HCB are not associated with subsequent weight gain.

Evolution of DOHaD: the impact of environmental health sciences

Environmental exposures have a significant influence on the chronic health conditions plaguing children and adults. Although the Developmental Origins of Health and Disease (DOHaD) paradigm historically has focused on nutrition, an expanding body of research specifically communicates the effects of chemical exposures on early-life development and the propagation of non-communicable disease across the lifespan. This paper provides an overview of 20 years of research efforts aimed at identifying critical windows of susceptibility to environmental exposures and the signaling changes and epigenetic influences associated with disease progression. DOHaD grants funded by the National Institute of Environmental Health Sciences (NIEHS) in 1991, 2001 and 2011 are identified by grant-analysis software, and each portfolio is analyzed for exposures, disease endpoints, windows of exposure, study design and impact on the field based on publication data. Results show that the 1991 and 2001 portfolios comprised metals, PCBs and air pollutants; however, by 2011, the portfolio has evolved to include or expand the variety of endocrine disruptors, pesticides/persistent organic pollutants and metals. An assortment of brain-health endpoints is most targeted across the portfolios, whereas reproduction and cancer increase steadily over the same time period, and new endpoints like obesity are introduced by 2011. With mounting evidence connecting early-life exposures to later-life disease, we conclude that it is critical to expand the original DOHaD concept to include environmental chemical exposures, and to continue a research agenda that emphasizes defining sensitive windows of exposure and the mechanisms that cause disease.

Exposure to persistent organic pollutants and sperm sex chromosome ratio in men from the Faroe Islands

People in the Arctic as well as fishermen on the polluted Swedish east coast are highly exposed to persistent organic pollutants (POPs). These compounds have been shown to affect the sperm Y:X chromosome ratio. In present study, the aim was to investigate whether polychlorinated biphenyl (PCB) congeners and 1,1,-dichloro-2,2,-bis(p-chlorophenyl)ethane (p,p'-DDE) influence sperm sex chromosome ratio in Faroese men, and whether these men differ regarding Y:X ratio compared to Greenland Inuit and Swedish fishermen. The study population (n=449) consisted of young men from the general population (n=276) as well as proven fertile men (n=173). The Y:X ratio was assessed by fluorescent in situ hybridization. Serum concentrations of POPs were measured using gas chromatography. Associations between POP concentrations and Y:X ratio were calculated using linear and non-linear regression models as well as trend analysis and pairwise comparison of exposure data categorized into quartiles. The selected POPs were associated with Y:X ratio in fertile Faroese men, but not in the total population; p,p'-DDE (95% CI for B=-0.005 to -0.001, p=0.005) and ΣPCB (95% CI for B=-0.005 to -0.001, p=0.012). Since p,p'-DDE and ΣPCB correlated significantly (r=0.927, p<0.001), the results involving the exposure variables can be regarded as a single finding. The Y:X ratio for the total Faroese population was 0.500±0.018, which was statistically significantly lower than in both Inuit and Swedish fishermen (0.512 for both). In conclusion, Faroese men presented with lower Y:X ratio than Greenland Inuit and Swedish fishermen. Although no direct health effects are expected due to the lower Faroese Y:X ratio, it could be indicative of adverse effects on the reproductive system.

Endocrine-disrupting actions of PCBs on brain development and social and reproductive behaviors

Polychlorinated biphenyls are among the most well-studied endocrine-disrupting chemicals (EDCs) for their neurobehavioral effects, especially neurodevelopment and cognitive performance. In addition, past research has demonstrated effects of PCBs on circulating hormones and associated changes in reproductive behaviors. This article will focus on recent advances that have been made in characterizing developmental PCB effects on reproductive function, broader social and affective behaviors, and the neuroendocrine mechanisms behind such changes. In general, PCBs seem to inhibit reproductive function by suppressing multiple aspects of the associated hypothalamic circuitry. Additionally, PCBs may also reduce motivation for social behaviors and induce depressive-like symptoms via overall reductions in dopaminergic and glutamatergic functions in the limbic system. However, more work with human-relevant exposure paradigms is needed to fully support these conclusions.

Autoantibodies associated with prenatal and childhood exposure to environmental chemicals in Faroese children

Methylmercury, polychlorinated biphenyls (PCBs), and perfluorinated compounds (PFCs) are ubiquitous and persistent environmental chemicals with known or suspected toxic effects on the nervous system and the immune system. Animal studies have shown that tissue damage can elicit production of autoantibodies. However, it is not known if autoantibodies similarly will be generated and detectable in humans following toxicant exposures. Therefore, we conducted a pilot study to investigate if autoantibodies specific for neural and non-neural antigens could be detected in children at age 7 years who have been exposed to environmental chemicals. Both prenatal and age-7 exposures to mercury, PCBs, and PFCs were measured in 38 children in the Faroe Islands who were exposed to widely different levels of these chemicals due to their seafood-based diet. Concentrations of IgM and IgG autoantibodies specific to both neural (neurofilaments, cholineacetyltransferase, astrocyte glial fibrillary acidic protein, and myelin basic protein) and non-neural (actin, desmin, and keratin) antigens were measured and the associations of these autoantibody concentrations with chemical exposures were assessed using linear regression. Age-7 blood-mercury concentrations were positively associated with titers of multiple neural- and non-neural-specific antibodies, mostly of the IgM isotype. Additionally, prenatal blood-mercury and -PCBs were negatively associated with anti-keratin IgG and prenatal PFOS was negatively associated with anti-actin IgG. These exploratory findings demonstrate that autoantibodies can be detected in the peripheral blood following exposure to environmental chemicals. The unexpected association of exposures with antibodies specific for non-neural antigens suggests that these chemicals may have toxicities that have not yet been recognized.

Neurotoxicity from prenatal and postnatal exposure to methylmercury

The extent to which postnatal methylmercury exposure contributes to neurobehavioral delays is uncertain. Confounding may occur because the child's dietary exposure likely correlates with the mother's. This conundrum was examined in the Faroese birth cohort 1 born in 1986-1987. Exposure parameters included mercury concentrations in maternal hair at parturition, cord blood, and child blood and hair at the age-7 clinical examination (N=923). In regression analyses, the child's current blood-mercury at age 7 (N=694) showed only weak associations with the neuropsychological test variables, but visuospatial memory revealed a significant negative association. Mutual adjustment caused decreases of the apparent effect of the prenatal exposure. However, such adjustment may lead to underestimations due to the presence of correlated, error-prone exposure variables. In structural equation models, all methylmercury exposure parameters were instead entered into a latent exposure variable that reflected the total methylmercury load. This latent exposure showed significant associations with neurodevelopmental deficits, with prenatal exposure providing the main information. However, postnatal methylmercury exposure appeared to contribute to neurotoxic effects, in particular in regard to visuospatial processing and memory. Thus, addition in the regression analysis of exposure information obtained at a different point in time was not informative and should be avoided. Further studies with better information on exposure profiles are needed to characterize the effects of postnatal methylmercury exposure.

Association between prenatal polychlorinated biphenyl exposure and obesity development at ages 5 and 7 y: a prospective cohort study of 656 children from the Faroe Islands

BACKGROUND

Chemicals with endocrine-disrupting abilities may act as obesogens and interfere with the body's natural weight-control mechanisms, especially if exposure occurs during prenatal life.

OBJECTIVE

We examined the association between prenatal exposure to polychlorinated biphenyls (PCBs) and p,p'-dichlorodiphenyldichloroethylene (DDE) and subsequent obesity at 5 and 7 y of age.

DESIGN

From 1997 to 2000, 656 pregnant Faroese women were recruited. PCB and DDE were measured in maternal serum and breast milk, and children's weight, height, and waist circumference (WC) were measured at clinical examinations at 5 and 7 y of age. The change in body mass index (BMI) from 5 to 7 y of age was calculated. Analyses were performed by using multiple linear regression models for girls and boys separately, taking into account maternal prepregnancy BMI.

RESULTS

For 7-y-old girls who had overweight mothers, PCB was associated with increased BMI (β = 2.07, P = 0.007), and PCB and DDE were associated with an increased change in BMI from 5 to 7 y of age (PCB: β = 1.23, P = 0.003; DDE: β = 1.11, P = 0.008). No association was observed with BMI in girls with normal-weight mothers. PCB was associated with increased WC in girls with overweight mothers (β = 2.48, P = 0.001) and normal-weight mothers (β = 1.25, P = 0.04); DDE was associated with increased WC only in girls with overweight mothers (β = 2.21, P = 0.002). No associations were observed between PCB or DDE and BMI in 5-y-old girls. For boys, no associations were observed.

CONCLUSIONS

Results suggest that prenatal exposure to PCB and DDE may play a role for subsequent obesity development. Girls whose mothers have a high prepregnancy BMI seem most affected.

Total and methyl-mercury in hair and milk of mothers living in the city of Porto Velho and in villages along the Rio Madeira, Amazon, Brazil

High fish consumption and extended breastfeeding are hallmarks of traditional lifestyle in Western Amazonia. We studied sources of mercury exposure, fish-methylmercury (meHg) and dental-amalgam filling, in 75 urban and 82 rural lactating mothers. Total mercury was determined in all samples while meHg concentrations were determined in subsamples of milk (45) and hair (27) of urban mothers living in Porto Velho (PV) and in hair (46) and milk (37) of mothers living in traditional communities (TC) of the Rio Madeira. The TC mothers showed significantly higher median hair-Hg concentrations (8.2μgg(-1)) than PV mothers (1.3μgg(-1)). Median total Hg in milk of PV mothers (0.36ngg(-1)) was significantly lower (p=0.0000) than that found in milk of TC mothers (2.30ngg(-1)). The median meHg concentrations in milk of TC mothers were also significantly higher (1.0ngg(-1)) than in milk of PV mothers (0.07ngg(-1)). For urban mothers with low fish consumption rates (and relatively higher dental amalgam fillings) the proportion of inorganic Hg in milk was higher (85%) than in TC (62%). In TC mothers 51% of breast milk Hg concentrations were above 2ngg(-1) (world median concentrations), contrasting with 8% in PV mothers. Despite this, there was no significant correlation between total Hg concentrations in milk and either amalgam filling or daily fish consumption. Socioeconomic changes occurring in Western Amazonia are causing changes in fish-eating habits of urban mothers. However, traditional lifestyle and attendant high fish consumption in riverine populations can still impact total Hg and methylmercury concentrations in mothers' milk and hair.

Mercury concentration in breast milk and infant exposure assessment during the first 90 days of lactation in a midwestern region of Brazil

Breast milk samples collected from 18 nursing mothers between the 15th and 90th day of lactation were digested in nitric acid in a microwave, and total mercury (THg) levels were quantified by atomic fluorescence spectrometry. Participants responded to a 24-h dietary recall questionnaire on the 74th and 76th day of lactation and to a Food Frequency Questionnaire querying the frequency of fish intake over the last 90 days. Usual intake was estimated using the PC-SIDE software package. A meal of fish was offered on the 75th day of lactation. Mothers' individual mean THg levels ranged from <0.76 to 22.7 ng/mL during the period, and the mean level for all samples (n = 142) was 6.47 ±6.04 ng/mL. The multilevel mixed linear model used showed high heterogeneity of the mercury levels among the mothers, and THg levels did not change significantly over the period under study. However, a significant increase in THg levels was observed after the intervention with the fish meal. Exposure increased for most infants on the 90th day of lactation, with intakes exceeding the THg provisional tolerable weekly intake (PTWI) at least once during the period for 77.8 % of samples. Mothers consumed mostly food from the fat and grain groups, and a significant correlation was detected between consumption of food of these groups and breast milk THg levels (p = 0.006 and 0.007). A significant correlation was also found between vegetable consumption and carbohydrate intake and THg levels in the samples (p = 0.015 and 0.045, respectively). No correlation was found between mothers' daily fish consumption frequency and THg levels. Although this study showed that mercury intake by infants during lactation may exceed the toxicologically safe exposure level (PTWI), we nevertheless believe that the benefits of lactation for both the mother and the infant outweigh the eventual risks that this exposure may represent.

Reproductive hormone profile and pubertal development in 14-year-old boys prenatally exposed to polychlorinated biphenyls

Because polychlorinated biphenyls (PCBs) are thought to cause endocrine disruption, we examined 438 adolescent boys from a birth cohort in the Faroe Islands, where PCB exposures are elevated. We measured PCBs and p,p'-dichlorodiphenyldichloroethylene (DDE) in cord blood and in serum from clinical examination at age 14. Higher prenatal PCB exposure was associated with lower serum concentrations of both luteinizing hormone (LH) and testosterone. In addition, sex hormone binding globulin (SHBG) was positively associated with both prenatal and concurrent PCB exposures. The PCB-SHBG association was robust to covariate adjustment. In a structural equation model, a doubling in prenatal PCB exposure was associated with a decrease in LH of 6% (p=0.03). Prenatal exposure to PCB and DDE showed weak, non-significant inverse associations with testicular size and Tanner stage. DDE was highly correlated with PCB and showed slightly weaker associations with the hormone profile. These findings suggest that delayed puberty with low serum-LH concentrations associated with developmental exposure to non dioxin-like PCBs may be due to a central hypothalamo-pituitary mechanism.

Changes in body burden of mercury, lead, arsenic, cadmium and selenium in infants during early lactation in comparison with placental transfer

The developing brains of both fetuses and infants are susceptible to environmental contaminants. However, the contribution of breast-feeding to the element body burden in infants remains unclear. The main objective of this study was to investigate the changes in body burden of elements such as methylmercury, lead, arsenic, cadmium, and selenium in infants during a 3-month breast-feeding period compared with placental transfer of the elements. Element concentrations were measured in maternal and umbilical cord (fetus) red blood cells (RBCs) at parturition and in infant RBCs at 3 months. Most of the mercury in RBCs is in the methyl form, and the total mercury concentration in RBCs reflects methylmercury exposure. The mercury level in cord RBCs was approximately 1.5 times higher than that in mothers, while in infants, it declined by approximately 60% after 3-months' breast-feeding. The cord selenium level was similar to the maternal level, but declined approximately 75% after 3-months' breast-feeding in infants. Lead and arsenic concentrations in cord RBCs were about 60% of the maternal levels, and remained constant until the 3-month study period. The cadmium level in cord RBCs was about 20% of that in maternal RBCs, and remained almost constant until the end of the 3-month study period. In conclusion, although pregnant women should pay attention to avoid high methylmercury exposure, element exposure through breast-feeding does not pose any great concern in this population.

Increased serum concentrations of persistent organic pollutants among prediabetic individuals: potential role of altered substrate oxidation patterns

CONTEXT

There is a need for a better understanding of the potential role of persistent organic pollutants (POPs) in the pathogenesis of type 2 diabetes.

OBJECTIVE

Our objective was to determine the association of serum concentrations of POPs with early signs of type 2 diabetes in regard to glucose and lipid metabolism.

RESEARCH DESIGN AND METHODS

In this cross-sectional study, we used recent studies of 148 Danish middle-aged normoglycemic, prediabetic, and diabetic individuals examined by the euglycemic-hyperinsulinemic clamp technique with indirect calorimetry; 66 of these individuals also had an i.v. glucose tolerance test. Concentrations of POPs were analyzed in banked serum from the participants. Associations with basal and insulin-stimulated glucose and lipid metabolism were assessed after adjustment for age, sex, and body fat percentage.

RESULTS

Individuals with prediabetes and diabetes had higher serum concentrations of several POPs compared with normoglycemic individuals. In the nondiabetic population, higher POPs levels were associated with elevated fasting plasma glucose concentrations as well as reduced glucose oxidation, elevated lipid oxidation, and elevated serum concentrations of free fatty acids (P < 0.05). We found no associations of POPs with first-phase insulin secretion, hepatic or peripheral insulin sensitivity, or nonoxidative glucose metabolism.

CONCLUSIONS

Diabetic and prediabetic individuals have elevated serum concentrations of POPs. In nondiabetic individuals, POPs exposure is related to altered substrate oxidation patterns with lower glucose oxidation and higher lipid oxidation rates. These findings indicate that POPs may affect peripheral glucose metabolism by modifying pathways involved in substrate partitioning rather than decreasing insulin-dependent glucose uptake.