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Background: The World Health Organization (WHO) recommends a mercury (Hg) hair-to-blood ratio of 250 for the conversion of Hg hair levels to those in whole blood. This encouraged the selection of hair as the preferred analyte because it minimizes collection, storage, and transportation issues. In spite of these advantages, there is concern about inherent uncertainties in the use of this ratio., Objectives: To evaluate the appropriateness of the WHO ratio, we investigated total hair and total blood Hg concentrations in 1333 individuals from 9 First Nations (Aboriginal) communities in northern Québec, Canada., Methods: We grouped participants by sex, age, and community and performed a 3-factor (M)ANOVA for total Hg in hair (0-2 cm), total Hg in blood, and their ratio. In addition, we calculated the percent error associated with the use of the WHO ratio in predicting blood Hg concentrations from hair Hg. For group comparisons, Estimated Marginal Means (EMMS) were calculated following ANOVA., Results: At the community level, the error in blood Hg estimated from hair Hg ranged -25% to +24%. Systematic underestimation (-8.4%) occurred for females and overestimation for males (+5.8%). At the individual level, the corresponding error range was -98.7% to 1040%, with observed hair-to-blood ratios spanning 3 to 2845., Conclusions: The application of the ratio endorsed by the WHO would be unreliable for determining individual follow-up. We propose that Hg exposure be assessed by blood measurements when there are human health concerns, and that the singular use of hair and the hair-to-blood concentration conversion be discouraged in establishing individual risk., (Crown Copyright © 2014. Published by Elsevier Inc. All rights reserved.)

Maternal mercury (Hg) and lead (Pb) blood concentrations were measured in a total of 442 samples taken from pregnant and delivering women in 10 Caribbean countries. Hg was detected in all 10 countries with the geometric mean ranging from a low of 0.83 μg L(-1) (Jamaica) to a high of 3.13 μg L(-1) (Grenada). When compared to comparable U.S. and Canadian data, Hg concentrations in Caribbean women are on average more than 2 times higher. With the exception of St. Kitts & Nevis, Pb was detected in at least one of the samples taken from the other 9 countries with two countries-Grenada and St. Vincent - having Pb detected in ≥60% of those sampled. In these two countries, the Pb concentrations ranged from a low of 1.17 μg dL(-1) (Grenada) to a high of 1.98 μg dL(-1) (St. Vincent). Compared to comparable U.S. and Canadian data, Pb concentrations in Caribbean women are generally higher than that measured in North America. This study confirms that neonates in the Caribbean are being exposed to both Hg and Pb and highlights the need to implement surveillance programs that continuously monitor, intervene, and evaluate the levels of these toxic elements to ensure that they are reduced as far as possible.

Background: Studies conducted in the Faeroe Islands and Japan suggest a negative impact of mercury on heart rate variability (HRV) among children while the results regarding blood pressure (BP) are less consistent., Objective: To assess the impact of mercury on HRV and BP among Nunavik Inuit children., Methods: A cohort of 226 children was followed from birth to 11 years old. Mercury concentration in cord blood and in blood and hair at 11 years old were used as markers of prenatal and childhood exposure, respectively. HRV was measured using ambulatory 2 h-Holter monitoring while BP was measured through a standardized protocol. Simple regression was used to assess the relationship of mercury to BP and HRV parameters. Multiple linear regressions were performed adjusting for covariates such as age, sex, birth weight, body mass index (BMI), height, total n-3 fatty acids, polychlorinated biphenyls (PCB 153), lead, selenium and maternal smoking during pregnancy., Results: Median cord blood mercury and blood mercury levels at 11 years old were 81.5 nmoL/L (IQR:45.0–140.0) and 14.5 nmol/L (IQR: 7.5–28.0), respectively. After adjusting for the covariates, child blood mercury was associated with low frequency (LF) (b = 0.21, p = 0.05), the standard deviation of R–R intervals (SDNN) (b = 0.26, p = 0.02), the standard deviation of R–R intervals measured over 5 min periods (SDANN) (b = 0.31, p = 0.01) and the coefficient of variation of R–R intervals (CVRR) (b = 0.06,p = 0.02). No significant association was observed with BP., Conclusion: Mercury exposure during childhood seems to affect HRV among Nunavik Inuit children at school age.

Objectives: To assess the efficacy of a public health intervention to reduce blood mercury (Hg) concentration levels in pregnant Bermudian women., Methods: In 2003, we conducted a study entitled "Prenatal exposure of the Bermudian Population to Environmental Contaminants" which provided Bermuda's first baseline data on prenatal exposure to several environmental contaminants, including Hg. The mean Hg concentration from 42 healthy newborns measured in umbilical cord blood was 41.3 nmol/L, ranging from 5-160 nmol/L. This concentration was much higher than expected, being approximately 8 times the general levels found in Canada and the U.S. Furthermore, we estimated that 85% of total Hg measured was in the form of methylmercury (MeHg), indicating that seafood consumption was the primary source of Hg exposure during pregnancy in Bermuda. Locally sourced seafood was identified as the most significant possible contributory source of Hg exposure. In 2005 the authors began a complementary research programme to study the levels of Hg in local commercial fish species. Coming out of this research were specific local fish consumption guidelines issued by the Department of Health advising pregnant women to avoid those local fish species found to be high in Hg while still encouraging consumption of fish species having lower Hg levels., Results: In 2010, under another research initiative, we returned to Bermuda to carry out another evaluation of Hg in human blood. Hg was measured in the blood of 49 pregnant women. The arithmetic mean Hg blood concentration was 6.6 nmol/L and the geometric mean 4.2 nmol/L. The maximum concentration found was 24 nmol/L., Conclusions: Hg exposure of Bermudian pregnant women has dropped significantly by a factor of around 5 since the foetal cord blood study in 2003.

Background: Populations which diet is rich in seafood are highly exposed to contaminants such as mercury, which could affect cardiovascular risk factors, Objective: To assess the associations between mercury and blood pressure (BP), resting heart rate (HR) and HR variability (HRV) among French Polynesians, Methods: Data were collected among 180 adults (≥ 18 years) and 101 teenagers (12-17 years). HRV was measured using a two-hour ambulatory electrocardiogram (Holter) and BP was measured using a standardized protocol. The association between mercury and HRV and BP parameters was studied using analysis of variance (ANOVA) and analysis of covariance (ANCOVA) RESULTS: Among teenagers, the high frequency (HF) decreased between the 2nd and 3rd tertile (380 vs. 204 ms2, p = 0.03) and a similar pattern was observed for the square root of the mean squared differences of successive R-R intervals (rMSSD) (43 vs. 30 ms, p = 0.005) after adjusting for confounders. In addition, the ratio low/high frequency (LF/HF) increased between the 2nd and 3rd tertile (2.3 vs. 3.0, p = 0.04). Among adults, the standard deviation of R-R intervals (SDNN) tended to decrease between the 1st and 2nd tertile (84 vs. 75 ms, p = 0.069) after adjusting for confounders. Furthermore, diastolic BP tended to increase between the 2nd and 3rd tertile (86 vs. 91 mm Hg, p = 0.09). No significant difference was observed in resting HR or pulse pressure (PP) CONCLUSIONS: Mercury was associated with decreased HRV among French Polynesian teenagers while no significant association was observed with resting HR, BP, or PP among teenagers or adults.

Aboriginal populations from Quebec (Canada) are exposed to higher mercury levels than southern regions since these populations consume high quantities of fish. Epidemiological evidence suggests a detrimental impact of mercury on cardiovascular risk factors such as heart rate variability (HRV) and blood pressure (BP). The objective of this study was to assess the impact of mercury exposure on BP, resting heart rate (HR) and HRV among Cree adults. Data were collected among 791 adults≥18 years old living in seven communities of the James Bay. Blood mercury and hair levels were used as biomarkers of recent and long-term exposure. BP was measured through a standardised protocol while HRV was derived from a 2-h Holter monitoring assessment. The relationship between mercury and the outcomes was studied using ANOVA and ANCOVA analysis. Geometric mean of blood mercury and hair mercury concentration was 17.0 nmol/L (95%CI: 6.1-44.0) and 2.36 nmol/g (95%CI: 2.09-2.65); respectively. After adjusting for confounders, blood mercury was associated with HRV parameters such as LF (β=0.21, P=0.0002), HF (β=0.15, P=0.004) and LF/HF (β=0.06, P=0.003). Similar associations were observed with hair mercury. In contrast, no significant association was observed between blood mercury or hair mercury and BP after adjusting for confounders. In conclusion, mercury exposure seems to affect HRV among Cree adults even after considering fish nutrients (n-3 fatty acids and selenium) and other contaminants (lead and polychlorinated biphenyls) that are also present in the traditional diet of this population., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Epidemiological evidence suggests a negative impact of methylmercury on the cardiovascular system, but findings regarding the effect on blood pressure (BP) are not consistent. We aimed to study the impact of mercury levels on BP among Nunavik Inuit adults. The health survey Qanuippitaa? was conducted in Nunavik (northern Quebec, Canada), and data were obtained from 732 Inuit > or = 18 years of age. Anthropometric blood samples, as well as systolic BP and diastolic BP, were assessed. Pulse pressure (systolic BP-diastolic BP) was calculated. Mercury blood concentration was used as a biomarker of recent exposure. Simple relations between mercury and BP parameters were studied by using the Pearson correlation, whereas multiple regressions were performed to control for confounders. Mean age of the participants was 34.3 years (95% CI: 33.6 to 34.9 years). Systolic BP, diastolic BP, and pulse pressure means were 117 mm Hg (95% CI: 116 to 118 mm Hg), 73 mm Hg (95% CI: 72 to 74 mm Hg), and 43 mm Hg (95% CI: 42 to 44 mm Hg), respectively. Mercury mean was 50.2 nmol/L. In multivariable analyses, mercury was associated with systolic BP (beta=2.14; P=0.0004), whereas the association with diastolic BP was near the significance level (beta=0.96; P=0.069). In conclusion, mercury is associated with increasing BP and pulse pressure among Nunavik Inuit adults after considering the effect of fish nutrients (n-3 fatty acids and selenium) and other confounders.

Background: Omega-3 polyunsaturated fatty acids (n-3 PUFAs) may protect against dementia, although epidemiologic studies have yielded inconclusive results. Fish is the main dietary source of n-3 PUFAs and is sometimes contaminated with mercury. This neurotoxicant may modify the association with dementia., Objective: We evaluated the association of erythrocyte membrane total n-3 PUFAs, docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and blood mercury with the incidence of dementia and Alzheimer disease (AD) in the Canadian Study of Health and Aging (CSHA) with adjustment for confounders including apolipoprotein E epsilon4 (APOE epsilon4) status., Design: The CSHA is a cohort study of a representative sample of persons aged > or =65 y, conducted from 1991 to 2002. A subsample of 663 nondemented CSHA subjects with a complete clinical examination, blood samples, and follow-up information was eligible for prospective analyses on laboratory measurements. Of these, 149 were incident cases of dementia, including 105 with AD., Results: In adjusted Cox regression models with age as the time scale, there were no associations between total n-3 PUFAs, DHA, or EPA and dementia or AD. In contrast, a mercury concentration in the highest quartile was associated with a reduced risk of dementia (hazard ratio: 0.53; 95% CI: 0.33, 0.88). However, significant risk reductions were limited to subjects with concentrations of both n-3 PUFAs and mercury that were above the median. There was no modification of risk by APOE epsilon4 status., Conclusions: No associations between n-3 PUFAs and dementia or AD were found. The results regarding mercury may indicate a spurious association.

Background: Mercury is a contaminant that reaches high levels in Nunavik (North of Quebec). It is transformed into methylmercury (MeHg) and accumulated in marine mammals and predator fish, an important part of the traditional Inuit diet. MeHg has been suggested to affect BP in adults and children while the influence on HRV has only been studied in children. We aimed to assess the impact of MeHg levels on HRV and BP in Inuit adults from Nunavik., Methods: In the fall of 2004, the <> Health Survey was conducted in Nunavik (Quebec, Canada) and information on HRV was collected among 280 adults aged 40 years and older. Indicators of the time and frequency domains of HRV were derived from a 2-hour Holter recording. BP was measured according to the Canadian Coalition for High Blood Pressure technique. Pulse pressure (PP) was the difference between systolic (SBP) and diastolic blood pressure (DBP). Blood mercury concentration was used as exposure biomarker. Statistical analysis was conducted through linear regression and multivariable linear regression was used to control for confounders., Results: Mercury was negatively correlated with low frequency (LF) (r = -0.18; p = 0.02), the standard deviation of RR intervals (SDNN) (r = -0.14; p = 0.047) and the coefficient of variation of RR intervals (CVRR) (r = -0.18; p = 0.011) while correlations with other HRV parameters did not reach statistical significance. After adjusting for confounders, the association with LF (beta = -0.006; p = 0.93) became non significant. However, the association with SDANN became statistically significant (beta = -0.086; p = 0.026) and CVRR tended to decrease with blood mercury concentrations (beta = -0.057; p = 0.056). Mercury was positively correlated with SBP (r = 0.25; p < 0.0001) and PP (r = 0.33; p < 0.0001). After adjusting for confounders, these associations remained statistically significant (beta SBP = 4.77; p = 0.01 and beta PP = 3.40; p = 0.0036). Moreover, most of the HRV parameters correlated well with BP although SBP the best before adjustment for mercury exposure., Conclusion: The results of this study suggest a deleterious impact of mercury on BP and HRV in adults. SBP and PP increased with blood mercury concentrations while SDANN decreased with blood mercury concentrations.

Background: Arctic populations are exposed to mercury, lead and cadmium through their traditional diet. Studies have however shown that cadmium exposure is most often attributable to tobacco smoking. The aim of this study is to examine the trends in mercury, lead and cadmium exposure between 1992 and 2004 in the Inuit population of Nunavik (Northern Québec, Canada) using the data obtained from two broad scale health surveys, and to identify sources of exposure in 2004., Methods: In 2004, 917 adults aged between 18 and 74 were recruited in the 14 communities of Nunavik to participate to a broad scale health survey. Blood samples were collected and analysed for metals by inductively coupled plasma mass spectrometry, and dietary and life-style characteristics were documented by questionnaires. Results were compared with data obtained in 1992, where 492 people were recruited for a similar survey in the same population., Results: Mean blood concentration of mercury was 51.2 nmol/L, which represent a 32% decrease (p < 0.001) between 1992 and 2004. Mercury blood concentrations were mainly explained by age (partial r2 = 0.20; p < 0.0001), and the most important source of exposure to mercury was marine mammal meat consumption (partial r2 = 0.04; p < 0.0001). In 2004, mean blood concentration of lead was 0.19 mumol/L and showed a 55% decrease since 1992. No strong associations were observed with any dietary source, and lead concentrations were mainly explained by age (partial r2 = 0.20.; p < 0.001). Blood cadmium concentrations showed a 22% decrease (p < 0.001) between 1992 and 2004. Once stratified according to tobacco use, means varied between 5.3 nmol/L in never-smokers and 40.4 nmol/L in smokers. Blood cadmium concentrations were mainly associated with tobacco smoking (partial r2 = 0.56; p < 0.0001), while consumption of caribou liver and kidney remain a minor source of cadmium exposure among never-smokers., Conclusion: Important decreases in mercury, lead and cadmium exposure were observed. Mercury decrease could be explained by dietary changes and the ban of lead cartridges use likely contributed to the decrease in lead exposure. Blood cadmium concentrations remain high and, underscoring the need for intensive tobacco smoking prevention campaigns in the Nunavik population.

French Polynesians, like other remote maritime populations are intimately connected to the ocean which nourishes their daily life and culture. Their reliance on fish raises the issue of potential exposure to harmful natural and anthropogenic contaminants as well as providing essential nutrients. The purpose of this study was to assess the risks and benefits of fish consumption in French Polynesia. This cross-sectional study included 195 adults aged 18 years old and over from the Tahiti and Moorea islands. Fatty acids, selenium (Se) and mercury (Hg) blood concentrations were measured in participants and were all very high. Blood concentrations indicate that Hg, Se and omega-3 fatty acids have a common origin, i.e. fish consumption. In comparing the Polynesian group with northern populations, we found that the Polynesian group had levels of Hg similar to those observed in Inuit populations (geometric mean (range): 90.3 (15-420) nmol/L vs. Inuit: m(r): 79.6 (4-560) nmol/L). Similar results were observed with Se blood concentrations. The fatty acid concentration was also similar to that of the Inuit population even though the specific profile of fatty acids differed. For the first time, we report very high blood concentrations of mercury, selenium and omega-3 fatty acids in a fishing population from the South Pacific, comparable to those reported among fishing populations from the Northern hemisphere. Further work is ongoing to better substantiate public health nutritional policies.

The aim of this study was to examine the effects of prenatal and postnatal chronic exposure to mercury (Hg), polychlorinated biphenyls (PCBs) and lead (Pb) on the neuromotor development of preschool children. The study population consisted of 110 preschool Inuit children from Nunavik (Canada). Blood Hg, PCBs and Pb concentrations were measured at birth (cord blood) and at the time of testing. Gross motor functions were evaluated and a neurological examination was performed. Fine neuromotor performance was assessed using quantitative measures of postural hand tremor, reaction time, sway oscillations, as well as alternating and pointing movements. Potential covariates were documented including demographic and familial characteristics, other prenatal neurotoxicants (alcohol, tobacco) and nutrients (selenium (Se), Omega-3 polyunsaturated fatty acids (n-3 PUFA)). Hierarchical multivariate regression analyses were performed, controlling for significant covariates. Gross motor development was not linked to prenatal exposures. However, significant associations were observed between blood Pb concentration at testing time and changes in reaction time, sway oscillations, alternating arm movements and action tremor. For some of these outcomes, neuromotor effects of Pb exposure are observed at blood concentrations below 10 microg/dl. Negative effects of PCBs on neuromotor development were not clearly observed, neither were the potential beneficial effects of n-3 PUFA and selenium. Tremor amplitude was related to blood Hg concentrations at testing time, which corroborate an effect already reported among adults.

St. Lawrence River hunters (Québec, Canada) are exposed to the pollutants, especially mercury, that contaminate birds and fish. However, the health risks of this have remained unclear because of a lack of information about the hunters' duck, geese, and sportfish consumption habits. A nutritional survey was set up to characterize waterfowl and sportfish consumption in St. Lawrence River duck hunters and to estimate their daily exposure to mercury. During the winter of 2000, 512 hunters selected from the Canadian Wildlife Service database completed a self-administered questionnaire. Daily exposure to contaminants was measured using data from the Canadian Wildlife Service (waterfowl) and available data on St. Lawrence River sportfish. The annual average consumption was 7.5 meals of ducks and geese and 8.7 meals of sportfish. The daily exposure to mercury related to waterfowl consumption was below the Canadian tolerable daily intake (TDI) of 0.47 microg/kg body wt/day for all participants. The daily mercury intake associated with fish consumption was greater than the TDI in 2 duck hunters. The daily exposure to mercury was higher than the TDI in 4 participants when both waterfowl and fish consumption were combined. Our results suggest that fish consumption (especially freshwater fish) represents the main source of exposure to pollutants in duck hunters.

The authors conducted a survey during 1992 to evaluate blood levels of lead and mercury in Inuit adults of Nunavik (Arctic Quebec, Canada). Blood samples obtained from 492 participants (209 males and 283 females; mean age = 35 yr) were analyzed for lead and total mercury; mean (geometric) concentrations were 0.42 micromol/l (range = 0.04-2.28 micromol/l) and 79.6 nmol/l (range = 4-560 nmol/l), respectively. Concentrations of omega-3 fatty acid in plasma phospholipids--a biomarker of marine food consumption--were correlated with mercury (r = .56, p < .001) and, to a lesser extent, with blood lead levels (r = .31, p < .001). Analyses of variance further revealed that smoking, age, and consumption of waterfowl were associated with lead concentrations (r2 = .30, p < .001), whereas age and consumption of seal and beluga whale were related to total mercury levels (r2 = .30, p < .001). A significant proportion of reproductive-age women had lead and mercury concentrations that exceeded those that have been reportedly associated with subtle neurodevelopmental deficits in other populations.

We conducted this study to evaluate blood levels of lead, mercury, and organochlorine compounds in newborns in the Province of Quebec. During 1993 to 1995, we carried out a survey in 10 hospitals located in southern Quebec. During that time, umbilical cord blood samples were obtained from 1109 newborns, and we analyzed each for lead, mercury, 14 polychlorinated biphenyl congeners, and 11 chlorinated pesticides. We used the geometric mean and 95% confidence interval (CI) to describe the results. Mean concentrations of lead and mercury in cord blood were 0.076 micromol/l (95% CI = 0.074, 0.079) and 4.82 nmol/l (95% CI = 4.56, 5.08), respectively. The mean concentrations of total polychlorinated biphenyls (Aroclor 1260) and dichlorodiphenyl dichloroethylene were 0.514 microg/I (95% CI = .493, 0.536) and 0.412 microg/l (95% CI = 0.390, 0.435), respectively. We observed a statistically significant relationship between maternal age and cord blood concentrations of (a) lead, (b) mercury, (c) polychlorinated biphenyls, and (d) dichlorodiphenyl dichloroethylene. In addition, maternal smoking during pregnancy was associated with cord blood lead levels. The cord blood concentrations of lead, mercury, polychlorinated biphenyls, and dichlorodiphenyl dichloroethylene we measured in our study were the lowest levels recently reported in industrialized countries. The results of this study underline the role of public health authorities in the evaluation of biological levels of environmental contaminants among children for the assessment of risk of adverse health effects.

This article documents the exposure to environmental contaminants within sub-groups of the Canadian population who are considered to be at risk as a result of the food they eat. We measured the concentrations of polychlorinated biphenyls (PCBs) and mercury in the blood drawn from the umbilical cords of newborns in various Aboriginal communities, in a coastal community and in the general population. Average concentrations of Aroclor 1260 ranged between 0.3 and 2.0 micrograms/L and were clearly highest among the Inuit of Nunavik and Baffin Island and among the Montagnais of Quebec. In these groups, we found contaminant levels in the blood of newborns that exceed the threshold beyond which cognitive impairments are expected to result. Average concentrations of mercury ranged between 1.0 and 14.2 micrograms/L; the Inuit of Nunavik and the NWT exhibited the highest exposure levels. A portion of the Nunavik and NWT Inuit had concentrations beyond the critical threshold for the appearance of neurological consequences. The variations in exposure levels resulted from the different nutritional practices of these Canadian sub-groups.

Ocean fish are an important staple food for many Caribbean persons. Some species, however, have high Hg concentration levels and represent a significant source of Hg exposure. This study assessed Hg concentrations in fish species commonly caught and consumed in Barbados as well as Hg exposure of those who work in the fishing industry. Total Hg concentrations were measured in 100 fish samples. Human Hg concentrations were determined from hair snippets taken from 46 fisher folk and fish consumption habits evaluated using interview-administered questionnaires. Mercury levels varied by fish species with predatory fish species having the highest concentrations. Low Hg concentrations were found in dolphinfish (Coryphaena hippurus) and flyingfish (Hirundichthys affinis). Reported fish consumption rates were high and varied significantly between men and women, 2675 ± 1600 and 1275 ± 600 (g/week), respectively (p= 0.01). The median hair Hg concentration was 3.1 ± 2.3 μg/g (range: 0.01–15.6 μg/g) and significantly associated with consumption of “high-risk” fish species (p= .02). These results show that it is possible to make informed choices concerning fish consumption habits in order to maximize benefits while minimizing the effect of Hg exposures, especially for sensitive groups such as pregnant women and infants. [ABSTRACT FROM AUTHOR]

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