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

Neurobehavioral deficits at age 7 years associated with prenatal exposure to toxicants from maternal seafood diet

To determine the possible neurotoxic impact of prenatal exposure to polychlorinated biphenyls (PCBs), we analyzed banked cord blood from a Faroese birth cohort for PCBs. The subjects were born in 1986-1987, and 917 cohort members had completed a series of neuropsychological tests at age 7 years. Major PCB congeners (118, 138, 153, and 180), the calculated total PCB concentration, and the PCB exposure estimated in a structural equation model showed weak associations with test deficits, with statistically significant negative associations only with the Boston Naming test. Likewise, neither hexachlorobenzene nor p,p'-dichlorodiphenyldichloroethylene showed clear links to neurobehavioral deficits. Thus, these associations were much weaker than those associated with the cord-blood mercury concentration, and adjustment for mercury substantially attenuated the regression coefficients for PCB exposure. When the outcomes were joined into motor and verbally mediated functions in a structural equation model, the PCB effects remained weak and virtually disappeared after adjustment for methylmercury exposure, while mercury remained statistically significant. Thus, in the presence of elevated methylmercury exposure, PCB neurotoxicity may be difficult to detect, and PCB exposure does not explain the methylmercury neurotoxicity previously reported in this cohort.

Lactational transfer of mercury and polychlorinated biphenyls in polar bears

We examined concentrations of total mercury (tHg, inorganic and methylated forms) and polychlorinated biphenyls (PCBs) in blood and milk from free-ranging Southern Beaufort-Chukchi Sea polar bears (Ursus maritimus) to assess maternal transfer of contaminants during lactation and the potential health risk to nursing young. Concentrations of contaminants in the blood of dependent and juvenile animals (ages 1-5 years) ranged from 35.9 to 52.2 μg kg(-1) ww for tHg and 13.9 to 52.2 μg kg(-1) ww (3255.81-11067.79 μg kg(-1) lw) for ΣPCB(7)s, similar to those of adult females, but greater than adult males. Contaminant concentrations in milk ranged from 5.7 to 71.8 μg tHg kg(-1)ww and 160 to 690 μg ΣPCB(11)s kg(-1) ww (547-5190 μg kg(-1) lw). The daily intake levels for tHg by milk consumption estimated for dependent young were below the tolerable daily intake level (TDIL) of tHg established for adult humans. Although the daily intake levels of PCBs through milk consumption for cubs of the year exceeded the TDIL thresholds, calculated dioxin equivalents for PCBs in milk were below adverse physiological thresholds for aquatic mammals. Relatively high concentrations of non-dioxin like PCBs in polar bear milk and blood could impact endocrine function of Southern Beaufort-Chukchi Sea polar bears, but this is uncertain. Transfer of contaminants during mid to late lactation likely limits bioaccumulation of dietary contaminants in female polar bears during spring. As polar bears respond to changes in their arctic sea ice habitat, the adverse health impacts associated with nutritional stress may be exacerbated by tHg and PCBs exposure, especially in ecologically and toxicologically sensitive polar bear cohorts such as reproductive females and young.

The geography of mercury and PCBs in North Carolina's local seafood

Mercury and PCBs are used by non-governmental organizations and federal agencies to inform seafood safety recommendations. Pollution dynamics suggest recommendations on the national scale may be too large to be accurate. We tested softshell and hardshell blue crab, white and pink shrimp, oysters, clams, spot, and mullet from fishers in each of the three North Carolina fishery districts. We measured mercury using EPA method 7473 and PCBs using a commercially available ELISA kit. Over 97% of samples were below the Environmental Protection Agency levels of concern for both mercury and PCBs. Mercury and PCBs have different spatial dynamics, but both differ significantly by water body, suggesting that seafood safety recommendations should occur by water body instead of at the national scale. This finding supports previous research suggesting that differences in water chemistry, terrestrial influence, and flushing time in a particular water body control the contaminant load in locally resident species.

Mercury concentration in the breast milk of Iranian women

Human milk is usually the only source of food for infants during the first 4 to 5 months of their life. In this research, 80 human milk samples were collected from mothers in Tehran, Noushahr and the countryside of Tabriz, Iran, who were not occupationally exposed to mercury. The mean concentration of mercury in breast milk obtained from mothers in the countryside of Tabriz, Noushahr and Tehran was 0.86, 0.15 and 0.12 μg/L, respectively. There was a significant difference in mercury concentration in human breast milk between that from the countryside of Tabriz with that from Tehran and Noushahr. Only 3.7% of infant samples (three infants) had mercury concentration higher than normal versus the WHO recommended limit (0.5 μg g(-1)). The fish consumption of these mothers in Tehran and Noushahr was a factor that significantly affected the mercury concentration in their breast milk. Also, their age affected the mercury levels in breast milk (p = 0.04).

Blood mercury levels among fish consumers residing in areas with high environmental burden

Mercury is a ubiquitous, persistent toxicant found in the environment. In water, mercury bioaccumulates up the food chain and leads to high concentrations in fish. Consumption of contaminated fish is the major source of exposure to mercury in the US. The objective of this study was to enroll persons living in areas selected by the Environmental Protection Agency (EPA) to have high mercury concentrations and who consume at least 6o z of locally caught fish per week to determine the feasibility of monitoring future trends among a population identified as highly exposed. Blood samples were collected at time of interview and analyzed for mercury. Participants (n=287) were enrolled from North Carolina, Maryland, and South Dakota. Participants reported eating an average of five servings of fish per week. The overall geometric mean for total mercury was 0.75 μg L(-1), with North Carolina having the highest mean level (2.02 μg L(-1)). Overall, 42% of the study population had levels greater than the US geometric mean 0.83 μg L(-1). The number of servings of fish consumed was not found to be associated with blood mercury levels. We were able to identify some persons with elevated mercury concentrations living in areas identified by EPA; however, identifying and monitoring a highly exposed population over time would be challenging.

Lead levels in breast milk, blood plasma and intelligence quotient: a health hazard for women and infants

Lead levels in human breast milk and blood plasma or serum were analyzed and qualitatively their intelligence quotient (I.Q.) studied. Samples at different stages of lactation, from 5 days to 51 weeks post partum, were collected from 25 healthy breast-feeding mothers in Ranipet Industrial area of Vellore district of Tamil Nadu and from 25 lactating mothers in the non-industrial areas of the same district. The samples from mothers in non-industrial area showed lower lead levels ranging from 5 to 25 μg/L whereas samples from mothers in industrial area showed higher lead levels ranging between 15 and 44.5 μg/L. It was generally noticed that the lactating mothers from industrial area have lower I.Q. levels compared to mothers from non-industrial area.

Serum vaccine antibody concentrations in children exposed to perfluorinated compounds

CONTEXT

Perfluorinated compounds (PFCs) have emerged as important food contaminants. They cause immune suppression in a rodent model at serum concentrations similar to those occurring in the US population, but adverse health effects of PFC exposure are poorly understood.

OBJECTIVE

To determine whether PFC exposure is associated with antibody response to childhood vaccinations.

DESIGN, SETTING, AND PARTICIPANTS

Prospective study of a birth cohort from the National Hospital in the Faroe Islands. A total of 656 consecutive singleton births were recruited during 1997-2000, [corrected] and 587 participated in follow-up through 2008.

MAIN OUTCOME MEASURES

Serum antibody concentrations against tetanus and diphtheria toxoids at ages 5 and 7 years.

RESULTS

Similar to results of prior studies in the United States, the PFCs with the highest serum concentrations were perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). Among PFCs in maternal pregnancy serum, PFOS showed the strongest negative correlations with antibody concentrations at age 5 years, for which a 2-fold greater concentration of exposure was associated with a difference of -39% (95% CI, -55% to -17%) in the diphtheria antibody concentration. PFCs in the child's serum at age 5 years showed uniformly negative associations with antibody levels, especially at age 7 years, except that the tetanus antibody level following PFOS exposure was not statistically significant. In a structural equation model, a 2-fold greater concentration of major PFCs in child serum was associated with a difference of -49% (95% CI, -67% to -23%) in the overall antibody concentration. A 2-fold increase in PFOS and PFOA concentrations at age 5 years was associated with odds ratios between 2.38 (95% CI, 0.89 to 6.35) and 4.20 (95% CI, 1.54 to 11.44) for falling below a clinically protective level of 0.1 IU/mL for tetanus and diphtheria antibodies at age 7 years.

CONCLUSION

Elevated exposures to PFCs were associated with reduced humoral immune response to routine childhood immunizations in children aged 5 and 7 years.

Thyroid dysfunction as a mediator of organochlorine neurotoxicity in preschool children

BACKGROUND

Exposure to organochlorine compounds (OCs) can alter thyroid function in humans, and hypothyroidism during early life can adversely affect a child's neurodevelopment.

OBJECTIVES

In this study we aimed to assess the relationship between developmental organochlorine exposures and thyroid function and the relationship between thyroid function and subsequent neurodevelopment.

METHODS

A population-based birth cohort of 182 children was followed annually up to 5.5 years of age. The assessments included OC concentrations in maternal pregnancy serum and milk, clinical thyroid parameters in maternal and cord serum, and subsequent neuropsychological outcomes of the child, along with sociodemographic cofactors. Resin triiodothyronine uptake ratio (T3RU) was also assessed as an estimate of the amount of thyroxine-binding globulin (TBG) sites unsaturated by thyroxine. The T3RU is high in hyperthyroidism and low in hypothyroidism.

RESULTS

The findings showed consistent inverse and monotonic associations between organochlorine exposure and T3RU after covariate adjustments. We observed no associations with other thyroid parameters. T3RU was positively associated with improved performance on most of the neuropsychological tests. For other thyroid parameters, the findings were less consistent.

CONCLUSIONS

The results suggest that OC exposures may decrease the T3RU during early life, which is a proxy measure of the binding capacity of TBG. In addition, minor decreases of the thyroid function may be inversely associated with a child's neurodevelopment.

Marine food pollutants as a risk factor for hypoinsulinemia and type 2 diabetes

BACKGROUND

Some persistent environmental chemicals are suspected of causing an increased risk of type 2 diabetes mellitus, a disease particularly common after the age of 70. This concern was examined in a cross-sectional study of elderly subjects from a fishing population with elevated contaminant exposures from seafood species high in the food chain.

METHODS

Clinical examinations of 713 Faroese residents aged 70-74 years (64% of eligible population) included fasting plasma concentrations of glucose and insulin, and glycosylated hemoglobin. Lifetime exposure to persistent environmental chemicals from pilot whale and other traditional food was estimated from a dietary questionnaire and by analysis of blood samples for polychlorinated biphenyls (PCBs) and related food contaminants.

RESULTS

Septuagenarians with type 2 diabetes or impaired fasting glycemia tended to have higher PCB concentrations and higher past intake of traditional foods, especially during childhood and adolescence. In nondiabetic subjects, the fasting insulin concentration decreased by 7% (95% CI = -12% to -2%) for each doubling of the PCB concentration after adjustment for sex and body mass index at age 20. Conversely, the fasting glucose concentration increased by 6% (-1% to 13%) for each doubling in PCB. Similar associations were seen in subjects without impaired fasting glycemia, while further adjustment for current body mass index and lipid metabolism parameters attenuated some of the associations.

CONCLUSIONS

Impaired insulin secretion appears to constitute an important part of the type 2 diabetes pathogenesis associated with exposure to persistent lipophilic food contaminants.

Serum concentrations of antibodies against vaccine toxoids in children exposed perinatally to immunotoxicants

BACKGROUND

Polychlorinated biphenyls (PCBs) may cause immunotoxic effects, but the detailed dose-response relationship and possible vulnerable time windows of exposure are uncertain. In this study we applied serum concentrations of specific antibodies against childhood vaccines as sentinels of immunotoxicity.

OBJECTIVES

The main objective was to assess the possible dependence of antibody concentrations against diphtheria and tetanus toxoids in children with regard to prenatal and postnatal PCB exposures.

METHODS

From a cohort of 656 singleton births formed in the Faroe Islands during 1999-2001, children were invited for examination with assessment of serum antibody concentrations at 5 years (before and after a booster vaccination) and at 7 years of age. Total PCB concentrations were determined in serum from ages 5 and 7 years, and data were also available on PCB concentrations in maternal pregnancy serum, maternal milk, and, for a subgroup, the child's serum at 18 months of age.

RESULTS

A total of 587 children participated in the examinations at ages 5 and/or 7 years. At age 5 years, before the booster vaccination, the antidiphtheria antibody concentration was inversely associated with PCB concentrations in milk and 18-month serum. Results obtained 2 years later showed an inverse association of concentrations of antibodies against both toxoids with PCB concentrations at 18 months of age. The strongest associations suggested a decrease in the antibody concentration by about 20% for each doubling in PCB exposure. At age 5 years, the odds of an antidiphtheria antibody concentration below a clinically protective level of 0.1 IU/L increased by about 30% for a doubling in PCB in milk and 18-month serum.

CONCLUSIONS

Developmental PCB exposure is associated with immunotoxic effects on serum concentrations of specific antibodies against diphtheria and tetanus vaccinations. The immune system development during the first years of life appears to be particularly vulnerable to this exposure.

Allergy and sensitization during childhood associated with prenatal and lactational exposure to marine pollutants

BACKGROUND

Breast-feeding may affect the risk of developing allergy during childhood and may also cause exposure to immunotoxicants, such as polychlorinated biphenyls (PCBs), which are of concern as marine pollutants in the Faroe Islands and the Arctic region.

OBJECTIVES

The objective was to assess whether sensitization and development of allergic disease is associated with duration of breast-feeding and prenatal or postnatal exposures to PCBs and methylmercury.

METHODS

A cohort of 656 singleton births was formed in the Faroe Islands during 1999-2001. Duration of breast-feeding and history of asthma and atopic dermatitis were recorded at clinical examinations at 5 and 7 years of age. PCB and mercury concentrations were determined in blood samples obtained at parturition and at follow-up. Serum from 464 children (71%) at 7 years of age was analyzed for total immunoglobulin E (IgE) and grass-specific IgE.

RESULTS

The total IgE concentration in serum at 7 years of age was positively associated both with the concomitant serum PCB concentration and with the duration of breast-feeding. However, the effect only of the latter was substantially attenuated in a multivariate analysis. A raised grass-specific IgE concentration compatible with sensitization was positively associated with the duration of breast-feeding and inversely associated with prenatal methylmercury exposure. However, a history of asthma or atopic dermatitis was not associated with the duration of breast-feeding, although children with atopic dermatitis had lower prenatal PCB exposures than did nonallergic children.

CONCLUSIONS

These findings suggest that developmental exposure to immunotoxicants may both increase and decrease the risk of allergic disease and that associations between breast-feeding and subsequent allergic disease in children may, at least in part, reflect lactational exposure to immunotoxic food contaminants.

Effects of maternal smoking and exposure to methylmercury on brain-derived neurotrophic factor concentrations in umbilical cord serum

Brain-derived neurotrophic factor (BDNF) is a neurotrophin essential for neuronal survival and differentiation. We examined the concentration of BDNF in cord serum from newborns exposed to methylmercury (MeHg) and polychlorinated biphenyls (PCB) in utero by maternal consumption of whale meat. The cohort consisted of 395 singleton births (206 boys and 189 girls), gestational age ranging from 38 to 42 weeks. Serum BDNF was measured by sandwich ELISA. Maternal smoking habits and other relevant factors were obtained by interviewing the mothers. The exposure to MeHg was estimated from Hg concentrations in cord blood, whereas exposure to PCB was estimated based on maternal serum concentrations. Only MeHg exposure affected the serum BDNF, which decreased in a concentration-dependent manner in girls born to nonsmoking mothers. Maternal smoking significantly increased BNDF in girls but not in boys. For further statistical analyses, we used the serum BDNF concentration as a continuous outcome variable in supervised regression models. Serum BDNF concentration increased with gestational age, increased by maternal smoking, decreased slightly with MeHg exposure, and maternal smoking enhanced the decrease in serum BDNF induced by MeHg exposure. Cord blood BDNF has been reported to increase in association with perinatal brain injuries and has been proposed as a possible predictive marker of neurodevelopmental outcomes. The negative effect that MeHg seems to exert on cord blood BDNF concentration could endanger compensatory responses to an adverse impact and therefore deserves attention.

Direct assessment of cumulative aryl hydrocarbon receptor agonist activity in sera from experimentally exposed mice and environmentally exposed humans

BACKGROUND

Aryl hydrocarbon receptor (AhR) ligands adversely affect many biological processes. However, assessment of the significance of human exposures is hampered by an incomplete understanding of how complex mixtures affect AhR activation/inactivation.

OBJECTIVES

These studies used biological readouts to provide a broader context for estimating human risk than that obtained with serum extraction and gas chromatography/mass spectroscopy (GC/MS)-based assays alone.

METHODS

AhR agonist activity was quantified in sera from dioxin-treated mice, commercial human sources, and polychlorinated biphenyl (PCB)-exposed Faroe Islanders using an AhR-driven reporter cell line. To validate relationships between serum AhR agonist levels and biological outcomes, AhR agonist activity in mouse sera correlated with toxic end points. AhR agonist activity in unmanipulated ("neat") human sera was compared with these biologically relevant doses and with GC/MS-assayed PCB levels.

RESULTS

Mouse serum AhR agonist activity correlated with injected dioxin dose, thymic atrophy, and heptomegaly, validating the use of neat serum to assess AhR agonist activity. AhR agonist activity in sera from Faroe Islanders varied widely, was associated with the frequency of recent pilot whale dinners, but did not correlate with levels of PCBs quantified by GC/MS. Surprisingly, significant "baseline" AhR activity was found in commercial human sera.

CONCLUSIONS

An AhR reporter assay revealed cumulative levels of AhR activation potential in neat serum, whereas extraction may preclude detection of important non-dioxin-like biological activity. Significant levels of AhR agonist activity in commercial sera and in Faroe Islander sera, compared with that from experimentally exposed mice, suggest human exposures that are biologically relevant in both populations.

Health assessment of artisanal gold miners in Tanzania

In 2003 UNIDO (United Nations Industrial Development Organization) conducted an environmental and health assessment in a small-scale mining area in Tanzania. BGS (British Geological Survey) performed the environmental assessment. The Institute of Forensic Medicine - University of Munich performed the health assessment. The results of the medical, neurological and neuro-psychological examination of 180 participants from the affected area of Rwamagasa and 31 controls were analyzed. Urine, blood and hair samples were analyzed to detect the level of mercury body burden. Mercury concentrations in the bio-monitors urine, blood and hair were statistically significantly higher in the exposed population from Rwamagasa compared to the control group from Katoro. Only amalgam burners showed mercury levels above the toxicological threshold limits. A speciation of mercury in hair indicated that mainly elemental mercury vapor contributed to the high body burden of the artisanal miners. 104 amalgam-burners, the most exposed population group, were examined. 25 of these workers were found to be intoxicated. Small-scale mining is a serious health hazard for amalgam burners. Reduction of the exposure is essential to prevent further damage.

Exposure assessment of breast-fed infants in the Czech Republic to indicator PCBs and selected chlorinated pesticides: area-related differences

The aim of our study was to obtain data on the exposure of breast-fed infants to polychlorinated biphenyls (PCBs) and selected organochlorine pesticides (OCPs) in different urban areas of the Czech Republic. The PCB and OCP levels were determined in 90 human milk samples collected in seven urban areas in 1999-2000 according to the WHO protocol. The estimated daily intake (EDI) was calculated for each of the analytes and compared with the respective tolerable daily intake (TDI). Significant local differences in the sum of 35 PCB congeners analyzed (total PCBs) as well as in the most prominent indicator congeners 138, 153, and 180 values were observed, with the highest levels being found in breast milk samples from mothers living in the vicinity of a former plant using PCBs in Uherské Hradiste (median and ranges 3410 and 1448-13,754 ng g(-1)lipid weight (lw)). Non-exposed mothers from the same area had about threefold lower levels (median and ranges 1073 and 757-2139 ng/g lw, respectively). The lowest levels of total PCBs were found in Telc (median and ranges 480 and 293-731 ng g(-1)lw, respectively). In all study areas, EDIs for PCBs in breast-fed infants exceeded the TDI of 0.4 microg kg(-1)bwd(-1) recommended in the Czech Republic. EDI for HCB exceeded the recommended TDI of 0.16 microg kg(-1), EDI for DDT was slightly below TDI of 10 microg kg(-1) bw d(-1) and HCHs EDI was negligible. The database of analytical results from this study was used for Bayesian modeling of breast-fed infant exposure to PCBs and OCPs during the recommended 6 months of exclusive breastfeeding.

Hair mercury levels in Amazonian populations: spatial distribution and trends

BACKGROUND

Mercury is present in the Amazonian aquatic environments from both natural and anthropogenic sources. As a consequence, many riverside populations are exposed to methylmercury, a highly toxic organic form of mercury, because of their intense fish consumption. Many studies have analysed this exposure from different approaches since the early nineties. This review aims to systematize the information in spatial distribution, comparing hair mercury levels by studied population and Amazonian river basin, looking for exposure trends.

METHODS

The reviewed papers were selected from scientific databases and online libraries. We included studies with a direct measure of hair mercury concentrations in a sample size larger than 10 people, without considering the objectives, approach of the study or mercury speciation. The results are presented in tables and maps by river basin, displaying hair mercury levels and specifying the studied population and health impact, if any.

RESULTS

The majority of the studies have been carried out in communities from the central Amazonian regions, particularly on the Tapajós River basin. The results seem quite variable; hair mercury means range from 1.1 to 34.2 microg/g. Most studies did not show any significant difference in hair mercury levels by gender or age. Overall, authors emphasized fish consumption frequency as the main risk factor of exposure. The most studied adverse health effect is by far the neurological performance, especially motricity. However, it is not possible to conclude on the relation between hair mercury levels and health impact in the Amazonian situation because of the relatively small number of studies.

CONCLUSIONS

Hair mercury levels in the Amazonian regions seem to be very heterogenic, depending on several factors. There is no obvious spatial trend and there are many areas that have never been studied. Taking into account the low mercury levels currently handled as acceptable, the majority of the Amazonian populations can be considered exposed to methylmercury contamination. The situation for many of these traditional communities is very complex because of their high dependence on fish nutrients. It remains difficult to conclude on the Public Health implication of mercury exposure in this context.

Non-invasive matrices in human biomonitoring: a review

Humans and other living organisms are exposed to a variety of chemical pollutants that are released into the environment as a consequence of anthropogenic activities. Environmental pollutants are incorporated into the organism by different routes and can then be stored and distributed in different tissues, which leads to an internal concentration that can induce different alterations, adverse effects and/or diseases. Control measures should be taken to avoid these effects and human biomonitoring is a very useful tool that can contribute to this aim. Human biomonitoring uses different matrices to measure the target chemicals depending on the chemical, the amount of matrix necessary for the analysis and the detection limit (LOD) of the analytical technique. Blood is the ideal matrix for most chemicals due to its contact with the whole organism and its equilibrium with organs and tissues where chemicals are stored. However, it has an important disadvantage of being an invasive matrix. The development of new methodology and modern analytical techniques has allowed the use of other matrices that are less or non-invasive, such as saliva, urine, meconium, nails, hair, and semen or breast milk. The presence of a chemical in these matrices reflects an exposure, but correlations between levels in non-invasive matrices and blood must be established to ensure that these levels are related to the total body burden. The development of new biomarkers that are measurable in these matrices will improve non-invasive biomonitoring. This paper reviews studies that measure Cd, Pb, Hg, polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs), organochlorine pesticides and phthalates in non-invasive matrices, the most used techniques for measurements and what alternative techniques are available.

Elimination half-lives of polychlorinated biphenyl congeners in children

The elimination kinetics of polychlorinated biphenyls (PCBs) in humans is difficult to assess in observational studies, because PCB exposure is never completely abolished. In a community with high dietary PCB exposures from whale blubber, we examined two groups of children with increased body burdens from breast-feeding. Follow-up was from ages 4.5 to 7.5 years (99 subjects) and 7 to 14 years (101 subjects). The calculations were performed by the use of structural equation models, with adjustment for body weight and dietary blubber intake as the main source of postnatal exposure. As a likely result of background exposures, apparent elimination half-lives were unexpectedly long when based on results from all cohort members. Subjects with exposures above the median and in the highest quartile showed half-lives of about 3-4 years for CB-138 and 4.5-5.5 years for CB-105 and CB-118; 6.5-7.5 years for CB-156, CB-170, and CB-187; and 7-9 years for CB-153 and CB-180. The longest half-lives correspond to elimination of the parent PCB solely with a daily fat excretion rate of 1-2 g, whereas shorter half-lives assume metabolic break-down.

Persistent, bioaccumulative and toxic substances in fish: human health considerations

Fish are important dietary items that provide essential nutrients. Fish however, bioaccumulate monomethyl mercury (MMHg) and organo-halogenated pollutants (OHP) that are persistent bioaccumulative and toxic substances (PBTS). Unlike man-made OHP, MMHg is mainly of natural origin but background concentrations of aquatic systems are determined by the environmental Hg-methylating potential. Industrial activities can modulate environmental discharges and fish bioaccumulation of PBTS. Fish and seafood consumption are associated with human body load of PBTS, but farming practices that utilize fishmeal increase the terrestrial food chain resulting in farm-animal accumulation of PBTS. These substances are neurotoxic and endocrine active that can impact humans and wild life, but chemical characteristics of MMHg and OHP modulate interactions with animal tissues. MMHg is protein reactive with a faster metabolism (months) than OHP that are stored and slowly (years) metabolized in fat tissues. Except for brain-Hg, neither Hg nor OHP in tissues are markers of toxic effects; however, deficits in neurobehavioral test-scores of children have been shown in some fish-eating populations. These deficits are transient and within normal range, and are not prodromes of neurological diseases. Although population studies show that consumption of fish at current levels of contamination do not explain neurological disorders, endocrine activity remains controversial. Understanding risk of hazard caused by fish-PBTS consumption requires a wide range of expertise. We discuss chemical, toxic, metabolic, and ecological characteristics associated with PBTS in fish. There are proven health outcome derived from fish consumption, while risk of exposure to avoidable PBTS is a chance that can be minimized by societal actions.

Polychlorinated biphenyls, organochlorine pesticides and neurodevelopment

PURPOSE OF REVIEW

Although environmental levels of polychlorinated biphenyls and certain organochlorine pesticides--hexachlorobenzene, dichlorodiphenyl trichloroethane and its primary metabolite, dichlorodiphenyl dichloroethene--are generally on the decline, early-life exposures to these prevalent contaminants continue. The review will describe current understanding of the potential neurodevelopmental consequences of low-level exposures to these contaminants.

RECENT FINDINGS

Animal models suggest that early-life exposures to polychlorinated biphenyls, dichlorodiphenyl trichloroethane/dichlorodiphenyl dichloroethene or hexachlorobenzene are associated with decreased cognitive or behavioral function in later development. Despite almost 30 years of research, however, results of human studies are inconsistent regarding the nature of the observed effects and their persistence over time. Overall, epidemiologic studies support modest associations of primarily prenatal polychlorinated biphenyl exposures with differences in neuromotor development, decrements in cognition and behavioral deficits, particularly regarding attention and impulse control. There are limited published human data regarding potential neurodevelopmental toxicities of early-life exposures to dichlorodiphenyl trichloroethane/dichlorodiphenyl dichloroethene and hexachlorobenzene.

SUMMARY

Exposures to polychlorinated biphenyls, dichlorodiphenyl trichloroethane/dichlorodiphenyl dichloroethene and hexachlorobenzene are likely detrimental to neurodevelopment. Effective control of exposure is complicated by variable exposure sources and variable contaminant levels in food, particularly fish, for which it is important to balance the risk of contaminants with nutritional benefits.

Dental caries in Faroese children exposed to polychlorinated biphenyls

The effects of exposure to polychlorinated biphenyls (PCBs) on dental caries of first permanent molars in children in the Faroe Islands, where the population is exposed to PCBs in their traditional diet, were evaluated. This study was part of a cohort study aimed at determining developmental risks resulting from the consumption of contaminated seafood. One hundred and fourteen children from a birth cohort of 182 mother-child pairs, aged 9-10 years, were examined. Caries scoring was performed according to WHO criteria; cavitated and noncavitated lesions were included. Exposure assessment was based on the PCB concentrations in maternal milk samples. Data from the project data set provided information on various confounding factors. Mean maternal milk PCB concentration was 2205 (range 70-11,150)ng/g lipids. The number of carious surfaces of first permanent molars correlated with milk PCB concentration (r=0.26, p=0.01). In multivariate linear regression analysis, PCB exposure was significantly related to caries susceptibility. The findings support an association between children's PCB exposure and caries prevalence.

Mercury in breast milk - a health hazard for infants in gold mining areas?

Breast-feeding can be a source of mercury exposure for infants. The main concern up to now is methyl-mercury exposure of women at child-bearing age. Certain fish species have high levels of methyl-mercury leading to consumer's advisory guidelines in regard of fish consumption to protect infants from mercury exposure passing through breast milk. Little is known about the transfer of inorganic mercury passing through breast milk to infants. Epidemiological studies showed negative health effects of inorganic mercury in gold mining areas. Small-scale gold miners use mercury to extract the gold from the ore. Environmental and health assessments of gold mining areas in Indonesia, Tanzania and Zimbabwe showed a high exposure with inorganic mercury in these gold mining areas, and a negative health impact of the exposure to the miners and the communities. This paper reports about the analysis and the results of 46 breast milk samples collected from mercury-exposed mothers. The median level of 1.87mug/l is fairly high compared to other results from literature. Some breast milk samples showed very high levels of mercury (up to 149mug/l). Fourteen of the 46 breast milk samples exceed 4mug/l which is considered to be a "high" level. US EPA recommends a "Reference Dose" of 0.3mug inorganic mercury/kg body weight/day [United States Environmental Protection Agency, 1997. Volume V: Health Effects of Mercury and Mercury Compounds. Study Report EPA-452/R-97-007: US EPA]. Twenty-two of the 46 children from these gold mining areas had a higher calculated total mercury uptake. The highest calculated daily mercury uptake of 127mug exceeds by far the recommended maximum uptake of inorganic mercury. Further systematic research of mercury in breast milk from small-scale gold mining areas is needed to increase the knowledge about the bio-transfer of mercury from mercury vapour-exposed mothers passing through breast milk to the breast-fed infant.

Environmental chemicals: from the environment to food, to breast milk, to the infant

Food is a source of exposure to many environmental chemicals found in human milk and other biological specimens. Ingestion of foods containing high amounts of animal fat is the main route of human exposure to lipophilic chemicals, such as persistent organic pollutants, which tend to bioaccumulate in the lipid compartment. Bioaccumulation results in increased exposure of these chemicals for humans, but particularly to breastfeeding infants, who are at the top of the food chain. The extent to which food contributes to a person's overall exposure depends on individual dietary habits and the concentrations of chemical residues in the food. These, in turn, are affected by (1) application methods, (2) properties and amounts of the chemical, and (3) preparation, handling, and the properties of the food. Once the food is ingested by the lactating woman, the chemical's pharmacokinetics and the transport mechanisms producing the movement of solutes across mammary alveolar cells determine the passage of chemicals from the blood to the milk. Thus, several factors affect the presence in human milk of environmental chemicals from dietary sources.

Arsenic in the breast milk of lactating women in arsenic-affected areas of West Bengal, India and its effect on infants

Two hundred and twenty-six breast milk samples were collected from lactating women from 3 blocks of North-24 Paragans, one of the arsenic-affected districts of West Bengal, India. Out of 226 samples, only in 39 samples arsenic was detected. Urine, hair, and nail samples were also analyzed to know the arsenic body burden of the lactating women. Arsenic in drinking water was also analyzed. Principle component analysis (PCA) revealed that hair and nail arsenic was highly correlated with water arsenic concentrations, whereas arsenic in urine and breast milk did not cluster with water arsenic. Our present study indicated that among the lactating women who had high arsenic body burden and arsenical skin lesions, they had elevated level of arsenic in their breast milk. Arsenic in hair, nails, and urine samples of infants were analyzed, and the results showed significantly high-body burden of infants in those areas. PCA showed the age-dependent relationship between the hair and nail arsenic concentrations of the mothers and their babies.

Dependence of blood indices of selenium and mercury on estimated fish intake in a national survey of British adults

OBJECTIVE

Contributions of fish and other foods to variance of selenium and mercury status were studied in British adults.

SETTING AND DESIGN

Plasma and red-cell selenium and whole-blood mercury concentrations were measured during the National Diet and Nutrition Survey of Adults aged 19-64 years in mainland Britain, 2000-2001 (n = 1216). Food intake was weighed for seven consecutive days, and foods were combined in groups for data analysis. Four subsidiary groups characterised fish intakes: fried white fish, 'other' white fish, shellfish and oily fish.

RESULTS

Geometric means and 5-95% ranges were: for whole-blood mercury, 5.61 (1.30-22.2) nmol l(-1); for plasma selenium, 1.09 (0.83-1.43) micromol l(-1); for red-cell selenium, 1.64 (1.14-2.40) micromol l(-1). Twenty-eight per cent had no fish intake recorded during 7 days; the remaining 72% had a median intake of 237 g over the 7-day period, 5-95% range 45-780 g. Total fish intake was strongly and directly correlated with blood mercury, and moderately with red-cell and plasma selenium. Thus, sqrt(total fish intake) was correlated with: loge(blood Hg), t = +19.7; loge(plasma Se), t = +9.8; and loge(red-cell Se), t = +9.6, all P < 0.0001. All three biochemical (mercury and selenium) indices were strongly correlated with oily fish intake, and moderately correlated with shellfish and 'other' ( = non-fried) white fish, but none was significantly correlated with fried white fish. Blood mercury was strongly and directly correlated with red-cell and plasma selenium, and both increased with age.

CONCLUSIONS

Dietary fish, especially oily fish, is a strong predictor of blood mercury and selenium in British adults.

Mercury exposure and public health

Mercury is a metal that is a liquid at room temperature. Mercury has a long and interesting history deriving from its use in medicine and industry, with the resultant toxicity produced. In high enough doses, all forms of mercury can produce toxicity. The most devastating tragedies related to mercury toxicity in recent history include Minamata Bay and Niagata, Japan in the 1950s, and Iraq in the 1970s. More recent mercury toxicity issues include the extreme toxicity of the dimethylmercury compound noted in 1998, the possible toxicity related to dental amalgams, and the disproved relationship between vaccines and autism related to the presence of the mercury-containing preservative, thimerosal.

Mercury and lead during breast-feeding

Hg and Pb are of public health concern due to their toxic effects on vulnerable fetuses, persistence in pregnant and breast-feeding mothers, and widespread occurrence in the environment. To diminish maternal and infant exposure to Hg and Pb, it is necessary to establish guidelines based on an understanding of the environmental occurrence of these metals and the manner in which they reach the developing human organism. In the present review, environmental exposure, acquisition and storage of these metals via maternal–infant interaction are systematically presented. Though Hg and Pb are dispersed throughout the environment, the risk of exposure to infants is primarily influenced by maternal dietary habits, metal speciation and interaction with nutritional status. Hg and Pb possess similar adverse effects on the central nervous system, but they have environmental and metabolic differences that modulate their toxicity and neurobehavioural outcome in infant exposure during fetal development. Hg is mainly found in protein matrices of animal flesh (especially fish and shellfish), whereas Pb is mainly found in osseous structures. The potential of maternal acquisition is higher and lasts longer for Pb than for Hg. Pb stored in bone has a longer half-life than monomethyl-mercury acquired from fish. Both metals appear in breast milk as a fraction of the levels found in maternal blood supplied to the fetus during gestation. Habitual diets consumed by lactating mothers pose no health hazard to breast-fed infants. Instead, cows' milk-based formulas pose a greater risk of infant exposure to neurotoxic substances.

Methylmercury exposure and health effects in humans: a worldwide concern

The paper builds on existing literature, highlighting current understanding and identifying unresolved issues about MeHg exposure, health effects, and risk assessment, and concludes with a consensus statement. Methylmercury is a potent toxin, bioaccumulated and concentrated through the aquatic food chain, placing at risk people, throughout the globe and across the socioeconomic spectrum, who consume predatory fish or for whom fish is a dietary mainstay. Methylmercury developmental neurotoxicity has constituted the basis for risk assessments and public health policies. Despite gaps in our knowledge on new bioindicators of exposure, factors that influence MeHg uptake and toxicity, toxicokinetics, neurologic and cardiovascular effects in adult populations, and the nutritional benefits and risks from the large number of marine and freshwater fish and fish-eating species, the panel concluded that to preserve human health, all efforts need to be made to reduce and eliminate sources of exposure.

Caffeine N3-demethylation (CYP1A2) in a population with an increased exposure to polychlorinated biphenyls

OBJECTIVE

To investigate the CYP1A2 phenotype distribution in a population with an increased exposure to polychlorinated biphenyls (PCBs) that would likely induce an increased activity of this enzyme. Further, to investigate the effect of sex, smoking, and oral contraceptive use on the CYP1A2 activity.

METHODS

In 305 randomly selected Faroese residents aged 18-60 years, the CYP1A2 activity was determined following oral intake of a caffeine dose and subsequent determination of the urinary metabolites and calculation of the caffeine metabolic ratio (CMR). PCB exposure was assessed by measuring the serum concentration of major congeners.

RESULTS

The CYP1A2 phenotype distribution was unimodal. The CMR was significantly higher both in smoking men and in smoking women, independent of oral contraceptive use, as compared with non-smokers. Among non-smokers, the CMR was significantly higher in women not using oral contraceptives than in those using oral contraceptives; a similar difference could not be established among smokers. The CMR appeared higher in men than in women, but stratified analyses confirmed a significant sex-related difference only among smokers not using oral contraceptives. Overall, the mean CMR in Faroese was significantly higher compared with the mean CMR in Danish historical controls. No association was found with PCB exposure and individual PCB congeners, except for one of three dioxin-like congeners, in confounder-adjusted multiple regression analyses.

CONCLUSION

The CYP1A2 phenotype in Faroese residents was unimodally distributed and showed the inducing effect of smoking and the inhibiting effect of use of oral contraceptives, but a sex-related difference was not apparent after confounder adjustment. There was no statistically significant association between CMR and PCB exposure.

Environmental costs of mercury pollution

Mercury (Hg) has been used for millennia in many applications, primarily in artisanal mining and as an electrode in the chlor-alkali industry. It is anthropogenically emitted as a pollutant from coal fired power plants and naturally emitted, primarily from volcanoes. Its unique chemical characteristics enable global atmospheric transport and it is deposited after various processes, ultimately ending up in one of its final sinks, such as incorporated into deep sediment or bioaccumulated, primarily in the marine environment. All forms of Hg have been established as toxic, and there have been no noted biological benefits from the metal. Throughout time, there have been notable incidents of Hg intoxication documented, and the negative health effects have been documented to those chronically or acutely exposed. Today, exposure to Hg is largely diet or occupationally dependent, however, many are exposed to Hg from their amalgam fillings. This paper puts a tentative monetary value on Hg polluted food sources in the Arctic, where local, significant pollution sources are limited, and relates this to costs for strategies avoiding Hg pollution and to remediation costs of contaminated sites in Sweden and Japan. The case studies are compiled to help policy makers and the public to evaluate whether the benefits to the global environment from banning Hg and limiting its initial emission outweigh the benefits from its continued use or lack of control of Hg emissions. The cases we studied are relevant for point pollution sources globally and their remediation costs ranged between 2,500 and 1.1 million US dollars kg(-1) Hg isolated from the biosphere. Therefore, regulations discontinuing mercury uses combined with extensive flue gas cleaning for all power plants and waste incinerators is cost effective.

Reduced antibody responses to vaccinations in children exposed to polychlorinated biphenyls

BACKGROUND

Developmental exposure to polychlorinated biphenyls (PCBs) has been implicated as a possible cause of deficient immune function in children. This study was designed to assess whether prenatal and postnatal exposure to PCBs impacts on antibody response to childhood immunizations.

METHODS AND FINDINGS

Two birth cohorts were formed in the Faroe Islands, where exposures vary widely, because traditional diets may include whale blubber contaminated with PCBs. Prenatal exposure was determined from maternal concentrations of PCBs in pregnancy serum and milk. Following routine childhood vaccinations against tetanus and diphtheria, 119 children were examined at 18 mo and 129 children at 7 y of age, and their serum samples were analyzed for tetanus and diphtheria toxoid antibodies and for PCBs. The antibody response to diphtheria toxoid decreased at age 18 mo by 24.4% (95% confidence interval [CI], 1.63-41.9; p = 0.04) for each doubling of the cumulative PCB exposure at the time of examination. The diphtheria response was lower at age 7 y and was not associated with the exposure. However, the tetanus toxoid antibody response was affected mainly at age 7 y, decreasing by 16.5% (95% CI, 1.51-29.3; p = 0.03) for each doubling of the prenatal exposure. Structural equation analysis showed that the early postnatal exposure was the most important predictor of a decreased vaccination response.

CONCLUSIONS

Increased perinatal exposure to PCBs may adversely impact on immune responses to childhood vaccinations. The clinical implications of insufficient antibody production emphasize the need for prevention of immunotoxicant exposures.

Serum polychlorinated biphenyl and organochlorine insecticide concentrations in a Faroese birth cohort

A prospective birth cohort of 1022 participants was established in the Faroe Islands over a 21-month period during 1986-1987. We collected questionnaire data on potential persistent organic pollutant (POP) concentration predictors, such as duration of breastfeeding and blubber consumption. To assess the participants' exposure from in utero to 14 years of age to polychlorinated biphenyls (PCBs) and the insecticide p,p'-DDT and its primary degradate p,p'-DDE, we measured 37 PCB congeners and pesticides in 316 umbilical cord samples taken from participants at birth, in 124 serum samples collected from participants at approximately 7 years of age, and in 795 serum samples collected from participants at 14 years of age. Measurements of higher chlorination PCB congeners made on individuals' serum samples collected at 7 years and 14 years were highly correlated (typically r > 0.5, p > 0.01), although their concentrations at 7 years were generally two to three times higher than at 14 years. Similarly, umbilical cord PCB concentrations were correlated with PCB concentrations in both 7- and 14-year serum samples. Sex-specific differences in higher chlorination PCB and p,p'-DDE concentrations were found at 14 years but not at 7 years, although a sex interaction with blubber consumption and nursing duration was observed at both ages. Both duration of breastfeeding and consumption of blubber were significant predictors of serum summationPCB concentrations at 7 and 14 years. Multivariate analyses showed that breastfeeding duration was the primary contributor to serum summationPCB concentrations at 7 years, and blubber consumption was the primary contributor at 14 years. These data suggest that infant exposures from breastfeeding were sufficiently large so that continued exposures to PCBs, p,p'-DDT, and p,p'-DDE through the diet have not fully diluted their contribution to the summationPCB and p,p'-DDE body burden of the children.

Concentrations of polybrominated diphenyl ethers, polychlonnated biphenyls, and polychlorobiphenylols in serum from pregnant Faroese women and their children 7 years later

The objective of this study was to assess blood concentrations of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs), and their polychlorobiphenylol (OH-PCB) metabolites in humans with a high seafood intake. Samples were obtained from pregnant women in the Faroe Islands in 1994-1995 and from their children at 7 years of age to examine maternal transfer of the compounds to their child, age-dependent metabolism, and temporal changes. Maternal serum was dominated by 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), while 2,2',4,4',5,5'-hexabromodiphenyl ether (BDE-153) prevailed in the children's serum seven years later. DecaBDE was present in both mothers and children up to 3 and 6 ng/g lipid weight, respectively. The sigmaPCB concentration in the children averaged about 60% of the concentrations in their mothers, with median levels for both above 1 microg/g lipid weight and .with similar PCB congener patterns. sigmaOH-PCB serum concentrations from the mothers and their children showed ranges of 1.8-36 ng/g wet weight (ww) and 0.49-22 ng/g ww, respectively, with all OH-PCB congener concentrations being lower in the children, except for 2,3,3',4',5-pentachloro-4-biphenylol (4-OH-CB107). Children at 7 years of age are exposed to PCBs at levels only slightly below those of their mothers, and the increased 4-OH-CB107 concentrations in children could be due to age-related differences in PCB metabolism. The PBDE concentrations were similar in both mothers and their children. The main persistent organic pollutant concentrations in the children are most probably due to other environmental exposure than maternal transfer.

Effects of breast feeding on neuropsychological development in a community with methylmercury exposure from seafood

Breastfeeding has been associated with an advantage to infant neurobehavioral development, possibly in part due to essential nutrients in breast milk. However, breast milk may be contaminated by environmental neurotoxicants, such as methylmercury. In the Faroe Islands, where maternal consumption of pilot whale may cause transfer of marine toxicants into breast milk, a cohort of 1022 consecutive singleton births was generated during 1986-87. Methylmercury exposure was assessed from mercury concentrations in cord blood and in the hair of the child at age 12 months, and the duration of breastfeeding was recorded. At approximately 7 years of age, 917 (90%) of the children underwent detailed neurobehavioral examination. After adjustment for confounders, breastfeeding was associated with only marginally better neuropsychological performance on most tests. These associations were robust even after adjustment for cord-blood and hair mercury concentration at age 1 year. Thus, in this cohort of children with a relatively high prenatal toxicant exposure and potential exposure to neurotoxicants through breast milk, breastfeeding was associated with less benefits on neurobehavioral development than previously published studies though not associated with a deficit in neuropsychological performance at age 7. Although the advantage may be less, Faroese women can still safely breastfeed their children.

Polybrominated diphenyl ethers and traditional organochlorine pollutants in fulmars (Fulmarus glacialis) from the Faroe Islands

The observed high-level burdens of organohalogens among the residents of the Faroe Islands, needs to be explained. Long-finned pilot whale (Globicephala melas) blubber and meat are known sources of environmental exposure. The present study focus on the organohalogen contamination of the fulmar (Fulmarus glacialis). The compounds quantified in fulmar muscle, fat, and egg are PCBs, DDTs, hexachlorobenzene (HCB), and polybrominated diphenyl ethers (PBDEs). The dominating pollutants are the 4,4'-DDT metabolite 4,4'-DDE and the two PCB congeners, CB-153 and CB-180, which are present in geometric mean concentrations of 7100, 4700 and 2500 ng/g lipid weight (l.w.), respectively, in adult fulmar muscle. 4,4'-DDT and HCB concentrations are approximately 250 ng/gl.w., each. Concentrations in the eggs are about 50% of the fulmar muscle levels, due to differences in lipid amounts, 4% in muscle and 10% in the eggs, the exposure contribution on a fresh weight basis is almost the same. As a result, both the egg and the adult fulmar muscle may lead to a significant exposure risk, if consumed by humans. BDE-153, the most abundant PBDE congener in fulmar muscle, with a geometric mean concentration of 6.5 ng/gl.w., is much lower than the individual PCB congeners and 4,4'-DDE concentrations. In the adult fulmar muscle, the relative PBDE congener pattern is different from that previously observed in biota, with BDE-153 and BDE-154 as the dominating congeners, rather than BDE-47. In contrast, BDE-47 is the most abundant congener in juvenile muscle and subcutaneous fat. The summation operatorPBDE concentrations are almost the same in egg, muscle (adult and juvenile) and subcutaneous fat (juvenile). For the polybrominated biphenyl (BB-153) the concentrations are considerably higher in the adult bird and egg than in the juvenile bird; this is also seen for the PCB and 4,4'-DDE concentrations. PCB concentrations found in fulmar egg and muscle are in the same range as seen in the pilot whale, i.e. 590-5700 ng/gl.w. for CB-153. Hence humans are also exposed to PCBs at a reasonable degree via intake of fulmar and/or fulmar egg and not only via pilot whale blubber.

A retrospective study of PBDEs and PCBs in human milk from the Faroe Islands

BACKGROUND

Persistent organic pollutants (POPs) in wildlife and humans remain a cause of global concern, both in regard to traditional POPs, such as the polychlorinated biphenyls (PCBs), and emerging POPs, such as the polybrominated diphenyl ethers (PBDEs). To determine the time related concentrations, we analyzed human milk for these substances at three time points between 1987 and 1999. Polychlorobiphenylols (OH-PCBs), the dominating class of PCB metabolites, some of which are known to be strongly retained in human blood, were also included in the assessment.

METHODS

We obtained milk from the Faroe Islands, where the population is exposed to POPs from their traditional diet (which may include pilot whale blubber). In addition to three pools, nine individual samples from the last time point were also analyzed. After cleanup, partitioning of neutral and acidic compounds, and separation of chemical classes, the analyses were carried out by gas chromatography and/or gas chromatography/mass spectrometry.

RESULTS

Compared to other European populations, the human milk had high PCB concentrations, with pool concentrations of 2300 ng/g fat 1987, 1600 ng/g fat in 1994, and 1800 ng/g fat in 1999 (based on the sum of eleven major PCB congeners). The nine individual samples showed great variation in PCB concentrations. The OH-PCBs were present in trace amounts only, at levels of approximately 1% of the PCB concentrations. The PBDE concentrations showed a clear increase over time, and their concentrations in human milk from 1999 are among the highest reported so far from Europe, with results of individual samples ranging from 4.7 to 13 ng/g fat

CONCLUSION

Although remote from pollution sources, the Faroe Islands show high concentrations of POPs in human milk, particularly PCBs, but also PBDEs. The PBDEs show increasing concentrations over time. The OH-PCB metabolites are poorly transferred to human milk, which likely is related to their acidic character.

Cadmium, lead and mercury in human milk from Slovakia

The objective of this study was to investigate Cd, Pb, and Hg levels in the breast milk of 158 lactating healthy women who were not occupationally exposed and living in eight environmentally different polluted locations of the Slovak Republic. Levels of these metals were examined in relation to selected parameters, such as: location, mother's age, parity, number of mother's teeth fillings, newborn's gender and birth weight, and smoking habits in the family. Cd and Pb levels in human milk and reconstituted infant formula were determined by GFAAS. Hg levels were measured by amalgamation technique AAS. The average concentrations of Cd, Pb and Hg in breast milk samples, taken on the 4th postpartum day, were 0.43, 4.7 and 0.94 microg/kg, respectively, and those in infant formula (n = 10) were 0.40, 5.0 and 0.25 microg/kg, respectively. Dietary weekly intakes of Cd, Pb, and Hg from breast milk and infant formula in newborn babies were also estimated. Whereas the calculated average dietary intakes of Cd, Pb, and Hg in newborn babies from breast milk and infant formula were all far lower than the appropriate PTWI values recommended by WHO/FAO, two individual breast milk samples for Pb and one breast milk sample for Hg exceeded the PTWI values. Regarding the studied parameters, only the active/passive smoking of the mother at home significantly increased Pb levels in breast milk and amalgam teeth fillings increased Hg levels in breast milk.

Persistent chemicals found in breast milk and their possible interactions

Chlorinated dibenzo-p-dioxins (CDDs), hexachlorobenzene, dichlorodiphenyl dichloroethane (p,p'-DDE), methylmercury, and polychlorinated biphenyls (PCBs) were selected as an important subset of persistent chemicals detected in breast milk for the purpose of reviewing data on their joint toxic actions following oral exposure. Epidemiological studies of possible health hazards associated with exposure to biopersistent chemicals in breast milk identify mild neurodevelopmental deficits as a possible health hazard. However, the studies did not analyze all the components of the above defined mixture, and, therefore, they are not directly useful for the purposes of conducting exposure-based assessments of hazards associated with this mixture. For this purpose, component-based methodology such as binary weight-of-evidence, the hazard index (HI) and the target-organ toxicity dose (TTD) approaches are recommended. Weight-of-evidence evaluation of the limited animal studies' data on interactions among CDDs, hexachlorobenzene, p,p-DDE, methylmercury, and PCBs indicates that the data are inadequate to warrant a concern for deviations from the additivity assumption. Further, exposure-based health assessments are used, in conjunction with evaluation of community-specific health outcome data, consideration of community health concerns, and biomedical judgement, to assess the degree of public health hazard presented by mixtures of substances released into the environment.

High arsenic groundwater: mobilization, metabolism and mitigation--an overview in the Bengal Delta Plain

The widespread occurrence of high inorganic arsenic in natural waters is attributed to human carcinogen and is identified as a major global public health issue. The scale of the problem in terms of population exposure (36 million) and geographical area coverage (173 x 10(3) Km2) to high arsenic contaminated groundwater (50-3200 microgL(-1)) compared to the National drinking water standard (50 microgL(-1)) and WHO recommended provisional limit (10 microgL(-1)) is greatest in the Holocene alluvium and deltaic aquifers of the Bengal Delta Plain (Bangladesh and West Bengal, India). This large-scale 'natural' high arsenic groundwater poses a great threat to human health via drinking water. Mobilization, metabolism and mitigation issues of high arsenic groundwater are complex and need holistic approach for sustainable development of the resource. Mobilization depends on the redox geochemistry of arsenic that plays a vital role in the release and subsequent transport of arsenic in groundwater. Metabolism narrates the biological response vis-à-vis clinical manifestations of arsenic due to various chemical and biological factors. Mitigation includes alternative source for safe drinking water supply. Drinking water quality regulatory standards as well as guidelines are yet to cover risk assessments for such metal toxicity. Lowering of the ingested inorganic arsenic level and introduction of newer treatment options (implementation of laterite, the natural material) to ensure safe water supply (arsenic free and/or low arsenic within permissible limit) are the urgent need to safe guard the mass arsenic poisoning and internal arsenic related health problems.

Consequences of acute and chronic exposure to arsenic in children

Arsenic is a toxic chemical and may cause adverse health effects in children and adults. It is known to affect the nervous, gastrointestinal, and hematological systems and cause skin and internal cancers in people exposed to levels greater than 300 ppb in their drinking water. For most people, the major exposure to arsenic comes from food (8 to 14 microg inorganic arsenic per day), but when the arsenic level in water is elevated, drinking water becomes the predominant source of exposure. Because it is very difficult to limit arsenic exposure from food, it would be wise to limit arsenic exposure from those more controllable sources. Pediatricians should ascertain the levels of arsenic in drinking water of patients with high arsenic levels, using the supplier or, in the case of private wells, a professional water-testing laboratory assay. The Safe Drinking Water Act does not cover private wells or those water systems with less than 15 hook-ups or those that serve less than 25 people. Pediatricians should instruct parents to use prepared baby formulas or prepare them using water with the arsenic removed and to curtail playing time for younger children in places that have sand containing large amounts of arsenic. Such procedures will limit arsenic exposure to a minimum.

Patterns of PCDDs and PCDFs in human milk and food and their characterization by artificial neural networks

Artificial neural network (ANN) has been recently introduced as a tool for data analysis. In this study, Kohonen's self-organizing maps (SOMs), a special type of neural network, were applied to a set of PCDD/PCDF concentrations found in 54 human milk and 83 food samples, which were collected in a number of countries all over the world. Data were obtained from the scientific literature. The purpose of the study was to find a potential relationship between PCDD/PCDF congener profiles in human milk and the dietary habits of the different countries in which samples were collected. The comparison of the SOM component planes for human milk and foodstuffs indicates that those countries with a greater fish consumption show also higher PCDD/PCDF concentrations in human milk. SOMs enable both the visualization of sample units and the visualization of congener distribution.

Assessment of xenoestrogenic exposure by a biomarker approach: application of the E-Screen bioassay to determine estrogenic response of serum extracts

BACKGROUND

Epidemiological documentation of endocrine disruption is complicated by imprecise exposure assessment, especially when exposures are mixed. Even if the estrogenic activity of all compounds were known, the combined effect of possible additive and/or inhibiting interaction of xenoestrogens in a biological sample may be difficult to predict from chemical analysis of single compounds alone. Thus, analysis of mixtures allows evaluation of combined effects of chemicals each present at low concentrations.

METHODS

We have developed an optimized in vitro E-Screen test to assess the combined functional estrogenic response of human serum. The xenoestrogens in serum were separated from endogenous steroids and pharmaceuticals by solid-phase extraction followed by fractionation by high-performance liquid chromatography. After dissolution of the isolated fraction in ethanol-DMSO, the reconstituted extract was added with estrogen-depleted fetal calf serum to MCF-7 cells, the growth of which is stimulated by estrogen. After a 6-day incubation on a microwell plate, cell proliferation was assessed and compared with the effect of a 17-beta-estradiol standard.

RESULTS AND CONCLUSIONS

To determine the applicability of this approach, we assessed the estrogenicity of serum samples from 30 pregnant and 60 non-pregnant Danish women thought to be exposed only to low levels of endocrine disruptors. We also studied 211 serum samples from pregnant Faroese women, whose marine diet included whale blubber that contain a high concentration of persistent halogenated pollutants. The estrogenicity of the serum from Danish controls exceeded the background in 22.7 % of the cases, while the same was true for 68.1 % of the Faroese samples. The increased estrogenicity response did not correlate with the lipid-based concentrations of individual suspected endocrine disruptors in the Faroese samples. When added along with the estradiol standard, an indication of an enhanced estrogenic response was found in most cases. Thus, the in vitro estrogenicity response offers a promising and feasible approach for an aggregated exposure assessment for xenoestrogens in serum.

Six interaction profiles for simple mixtures

The Agency for Toxic Substances and Disease Registry (ATSDR) has a program for chemical mixtures that encompasses research on chemical mixtures toxicity, health risk assessment, and development of innovative computational methods. ATSDR prepared a guidance document that instructs users on how to conduct health risk assessment on chemical mixtures (Guidance Manual for the Assessment of Joint Toxic Action of Chemical Mixtures). ATSDR also developed six interaction profiles for chemical mixtures. Two profiles were developed for persistent environmental chemicals that are often found in contaminated fish and also can be detected in human breast milk. The mixture included chlorinated dibenzo-p-dioxins, hexachlorobenzene, dichlorodiphenyl dichloroethane, methyl mercury, and polychlorinated biphenyls. Two profiles each were developed for mixtures of metals and mixtures of volatile organic chemicals (VOCs) that are frequently found at hazardous waste sites. The two metal profiles dealt with (a) lead, manganese, zinc, and copper; and (b) arsenic, cadmium, chromium, and lead; the two VOCs mixtures dealt with (a) 1,1,1-trichloroethane, 1,1-dichloroethane, trichloroethylene, and tetrachloroethylene; and (b) benzene, ethylbenzene, toluene, and xylenes (BTEX). Weight-of-evidence methodology was used to assess the joint toxic action for most of the mixtures. Physiologically based pharmacokinetic modeling was used for BTEX. In most cases, a target-organ toxicity dose modification of the hazard index approach is recommended for conducting exposure-based assessments of noncancer health hazards.