A preliminary study of mercury exposure and blood pressure in the Brazilian Amazon

Blood Mercury and Insulin Resistance in Nondiabetic Koreans (KNHANES 2008-2010)

PURPOSE

Blood mercury levels are associated with inflammation, and chronic low-grade inflammation is a cause of insulin resistance. This study aimed to investigate the association between serum mercury and insulin resistance.

MATERIALS AND METHODS

Subjects from the 2008-2010 Korean National Health and Nutrition Examination Survey were selected (n=29235) and the relevant data of 5388 subjects (2643 males and 2745 females) were analyzed cross-sectionally. Homeostasis Model Assessment for Insulin Resistance (HOMA-IR) was compared according to blood mercury quartiles, and the odds ratio (OR) of having the highest quartile of HOMA-IR according to blood mercury quartiles was calculated.

RESULTS

Blood mercury levels in men and women were 29.4 nmol/L and 20.5 nmol/L, respectively, and fasting blood sugar (FBS), insulin, and HOMA-IR were significantly correlated with blood mercury levels. The correlation was stronger in men than in women. In men, FBS and HOMA-IR showed step-wise increases as the quartiles of blood mercury increased; only HOMA-IR differed significantly in the third and fourth blood mercury quartiles, compared to the first quartile. In women, however, both FBS and HOMA-IR differed significantly in the third and fourth blood mercury quartiles, compared to the first quartile. Among men, the OR of being in the highest HOMA-IR quartile was greatest for the highest blood mercury quartile (OR=1.720, 95% CI; 1.172-2.526), compared with the lowest quartile.

CONCLUSION

In this large population-based study, blood mercury levels were weakly correlated with HOMA-IR and may be a risk factor for insulin resistance in nondiabetic Koreans.

Integrated assessment of artisanal and small-scale gold mining in Ghana--part 1: human health review

This report is one of three synthesis documents produced via an integrated assessment (IA) that aims to increase understanding of artisanal and small-scale gold mining (ASGM) in Ghana. Given the complexities surrounding ASGM, an IA framework was utilized to analyze economic, social, health, and environmental data, and co-develop evidence-based responses with pertinent stakeholders. The current analysis focuses on the health of ASGM miners and community members, and synthesizes extant data from the literature as well as co-authors' recent findings regarding the causes, status, trends, and consequences of ASGM in Ghana. The results provide evidence from across multiple Ghanaian ASGM sites that document relatively high exposures to mercury and other heavy metals, occupational injuries and noise exposure. The work also reviews limited data on psychosocial health, nutrition, cardiovascular and respiratory health, sexual health, and water and sanitation. Taken together, the findings provide a thorough overview of human health issues in Ghanaian ASGM communities. Though more research is needed to further elucidate the relationships between ASGM and health outcomes, the existing research on plausible health consequences of ASGM should guide policies and actions to better address the unique challenges of ASGM in Ghana and potentially elsewhere.

Serum long-chain omega-3 polyunsaturated Fatty acids and future blood pressure in an ageing population

OBJECTIVES

To investigate the associations of serum long-chain omega-3 polyunsaturated fatty acids (PUFA) and hair mercury with future blood pressure in an ageing population.

DESIGN

Prospective study with baseline measurements in 1998-2001 and follow-up measurements in 2005-2008. The linear relationships (β) of baseline serum fatty acids and hair mercury with future systolic and diastolic blood pressure and pulse pressure were analyzed with multiple linear regression models, using log-transformed values.

PARTICIPANTS

181 men and 200 women aged 53-73 y from the Kuopio Ischemic Heart Disease Risk Factor Study (KIHD) population in Eastern Finland, who were free of cardiovascular disease, diabetes or hypertension at baseline.

MEASUREMENTS

Total serum esterified and nonesterified fatty acids and pubic hair mercury were used as markers for exposure. Anthropometric and other lifestyle and health-related data were collected.

RESULTS

The mean serum concentrations were 1.67% (SD 0.92) for eicosapentaenoic acid (EPA), 0.79% (SD 0.16) for docosapentaenoic acid (DPA) and 2.78 (SD 0.92) for docosahexaenoic acid (DHA), of all serum fatty acids. The mean hair mercury concentration was 1.5 µg/g (SD 1.6). We did not find statistically significant associations between the baseline serum long-chain omega-3 PUFA concentrations or hair mercury content and future blood pressure. Hair mercury did not modify the associations with the long-chain omega-3 PUFAs, either.

CONCLUSIONS

Higher serum long-chain omega-3 PUFA concentration, a biomarker of fish or fish oil consumption, may not have an impact on future blood pressure in an ageing population.

Elevated serum ferritin and mercury concentrations are associated with hypertension; analysis of the fourth and fifth Korea national health and nutrition examination survey (KNHANES IV-2, 3, 2008-2009 and V-1, 2010)

The impact of simultaneously elevated serum ferritin and mercury concentrations on hypertension in the general population is not known. To determine the association of serum ferritin and mercury concentrations with hypertension, 6213 subjects (3060 men and 3153 women) over 20 years of age from 2008 to 2010 Korea National Health and Nutrition Examination Survey were divided into tertiles according to serum ferritin and mercury concentrations in each gender. Serum ferritin (258.2 vs. 94.8 pmol/L) and mercury concentrations (28.4 vs. 19.9 nmol/L) were higher in men than in women. Serum ferritin (men; P = 0.029, women; P < 0.001) and mercury (men; P < 0.001, women; P = 0.003) concentrations were significantly associated with the prevalence of hypertension. In addition, significant correlation between serum ferritin and mercury concentrations in both men (r = 0.193, P < 0.001) and women (r = 0.145, P < 0.001) were found. Also, the increase of serum ferritin concentrations were more prominent in men (P < 0.001) than in women (P = 0.017) as the serum mercury tertiles increased after proper adjustments. Furthermore, significantly higher odds ratios of hypertension were found in the second (OR = 1.86, 95% CI; 1.05-3.30), and third (OR = 1.84, 95% CI; 1.01-3.36) tertiles of serum ferritin with the top tertile of serum mercury in men. The current study indicate that serum ferritin and mercury concentrations are associated with the prevalence of hypertension and that simultaneously elevated serum ferritin and mercury concentrations are related to the risk for hypertension in men.

Relationship between Blood Mercury Level and Risk of Cardiovascular Diseases: Results from the Fourth Korea National Health and Nutrition Examination Survey (KNHANES IV) 2008-2009

Limited epidemiologic data is available regarding the cardiovascular effects of mercury exposure. The purpose of this study was to determine the relationship between mercury exposure from fish consumption and cardiovascular disease in a nationally representative sample of Korean adults using the Fourth Korea National Health and Nutrition Examination Survey (KNHANES IV 2008~2009). Survey logistic regression models accounting for the complex sampling were used to estimate the odds ratios (OR) adjusted for fish consumption frequency, age, education, individual annual income, household annual income, body mass index (BMI), waist circumference (WC), alcohol consumption status, and smoking status. The mean blood mercury level in the population was 5.44 μg/L. Trends toward increased blood mercury levels were seen for increased education level (P=0.0011), BMI (P<0.0001), WC (P<0.0001), and fish (i.e., anchovy) consumption frequency (P=0.0007). The unadjusted OR for hypertension in the highest blood mercury quartile was 1.450 [95% confidential interval (CI): 1.106~1.901] times higher than that of the lowest quartile. The fish consumption-adjusted OR for hypertension in the highest blood mercury quartile was 1.550 (95% CI: 1.131~2.123) times higher than that of the lowest quartile, and the OR for myocardial infarction or angina in the highest blood mercury quartile was 3.334 (95% CI: 1.338~8.308) times higher than that of the lowest quartile. No associations were observed between blood mercury levels and stroke. These findings suggest that mercury in the blood may be associated with an increased risk of hypertension and myocardial infarction or angina in the general Korean population.

Combined exposure to lead, inorganic mercury and methylmercury shows deviation from additivity for cardiovascular toxicity in rats

Environmental exposure to metal mixtures in the human population is common. Mixture risk assessments are often challenging because of a lack of suitable data on the relevant mixture. A growing number of studies show an association between lead or mercury exposure and cardiovascular effects. We investigated the cardiovascular effects of single metal exposure or co-exposure to methylmercury [MeHg(I)], inorganic mercury [Hg(II)] and lead [Pb(II)]. Male Wistar rats received four different metal mixtures for 28 days through the drinking water. The ratios of the metals were based on reference and environmental exposure values. Blood and pulse pressure, cardiac output and electrical activity of the heart were selected as end-points. While exposure to only MeHg(I) increased the systolic blood pressure and decreased cardiac output, the effects were reversed with combined exposures (antagonism). In contrast to these effects, combined exposures negatively affected the electrical activity of the heart (synergism). Thus, it appears that estimates of blood total Hg levels need to be paired with estimates of what species of mercury dominate exposure as well as whether lead co-exposure is present to link total blood Hg levels to cardiovascular effects. Based on current human exposure data and our results, there may be an increased risk of cardiac events as a result of combined exposures to Hg(II), MeHg(I) and Pb(II). This increased risk needs to be clarified by analyzing lead and Hg exposure data in relation to cardiac electrical activity in epidemiological studies.

Assessment of dietary fish consumption in pregnancy: comparing one-, four- and thirty-six-item questionnaires

OBJECTIVE

Fish consumption influences a number of health outcomes. Few studies have directly compared dietary assessment methods to determine the best approach to estimating intakes of fish and its component nutrients, including DHA, and toxicants, including methylmercury. Our objective was to compare three methods of assessing fish intake.

DESIGN

We assessed 30 d fish intake using three approaches: (i) a single question on total fish consumption; (ii) a brief comprehensive FFQ that included four questions about fish; and (iii) a focused FFQ with thirty-six questions about different finfish and shellfish.

SETTING

Obstetrics practices in Boston, MA, USA.

SUBJECTS

Fifty-nine pregnant women who consumed ≤2 monthly fish servings.

RESULTS

Estimated intakes of fish, DHA and Hg were lowest with the one-question screener and highest with the thirty-six-item fish questionnaire. Estimated intake of DHA with the thirty-six-item questionnaire was 4·4-fold higher (97 v. 22 mg/d), and intake of Hg was 3·8-fold higher (1·6 v. 0·42 μg/d), compared with the one-question screener. Plasma DHA concentration was correlated with fish intake assessed with the one-question screener (Spearman r = 0·27, P = 0·04), but not with the four-item FFQ (r = 0·08, P = 0·54) or the thirty-six-item fish questionnaire (r = 0·01, P = 0·93). In contrast, blood and hair Hg concentrations were similarly correlated with fish and Hg intakes regardless of the assessment method (r = 0·35 to 0·52).

CONCLUSIONS

A longer questionnaire provides no advantage over shorter questionnaires in ranking intakes of fish, DHA and Hg compared with biomarkers, but estimates of absolute intakes can vary by as much as fourfold across methods.

Influence of polyunsaturated fatty acids on blood pressure, resting heart rate and heart rate variability among French Polynesians

OBJECTIVE

To analyze the associations between marine n-3 polyunsaturated fatty acids (PUFAs) and blood pressure (BP), resting heart rate (HR), and heart rate variability (HRV) in a population highly exposed to methylmercury through the diet.

METHODS

Concentrations of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in erythrocytes membranes were measured in 180 French Polynesian adults (≥18 years) residing in Tubuai, which is a community with a traditional lifestyle, or Papeete, which has a modern lifestyle. HRV was measured using a 2-hour ambulatory electrocardiogram (Holter). Resting HR and BP were measured using standardized protocols and pulse pressure (PP) was calculated as systolic BP - diastolic BP. The associations between n-3 PUFAs and the dependent variables were studied using simple and multiple linear regressions.

RESULTS

Increasing DHA concentration was associated with lower resting HR (β = -2.57, p = 0.005) and diastolic BP (β = -1.96, p = 0.05) and higher HRV in multivariable models. Specifically, DHA was associated with high frequency (HF; β = 0.19, p = 0.02) and the square root of the mean squared differences of successive R-R intervals (difference between two consecutive R waves; rMSSD; β = 0.08, p = 0.03), which are specific indices of the parasympathetic activity of the autonomic nervous system.

CONCLUSION

DHA was associated with lower BP and resting HR and higher HRV among French Polynesians who are also exposed to high methylmercury levels.

Blood and urine levels of heavy metal pollutants in female and male patients with coronary artery disease

BACKGROUND

Heavy metal pollutants such as cadmium (Cd), lead (Pb), and mercury (Hg) are rarely the subjects of cardiovascular research although they have been suspected for decades to negatively impact the circulatory system.

METHODS

Apart from detailed anamnestic data, urinary levels of Cd and full blood levels of Pb and Hg were measured in 53 female (mean age: 68.04±7.03 years) and 111 male (mean age: 60.68±11.43 years) nonsmoking or never-smoking patients with angiographically verified and precisely quantified coronary artery disease (CAD).

RESULTS

Although Cd was quantifiable in 68.3% of subjects, only 34.1% of these patients exceeded the critical 1 μg/L Human Biomonitoring (HBM)-I level. Median Pb (20 μg/L) and Hg (0.55 μg/L) levels were lower than the HBM-I, as well as reference levels of Pb. Wine consumption was the main source for Pb, fish and wine consumption for Hg, and previous nicotine abuse for Cd. There was no correlation between Cd, Pb, or Hg and severity of CAD although severity correlated positively with atherosclerosis parameters (uric acid, creatinine, triglycerides, blood urea nitrogen, C-reactive protein) and negatively with high density lipoprotein cholesterol.

CONCLUSION

Cd levels detected in CAD patients were high compared to German and European reference levels but it could not be proven that urine levels of Cd and blood levels of Hg or Pb played a major role in the genesis of CAD, particularly when compared to well-known biomarkers such as blood pressure, glucose, and lipids.

Mercury speciation in hair of children in three communities of the Amazon, Brazil

Children from riverside communities located downstream of gold mining areas may be chronically exposed to relatively high levels of MeHg through the consumption of fish of this region. The objective of this study was to evaluate and compare levels of THg and MeHg in hair of children less than 12 years in communities near mines in the municipality of Itaituba and in communities far from prospecting areas in the city of Abaetetuba. The communities of Itaituba (Barreiras and São Luiz do Tapajós) had THg mean levels of 5.64±5.55  μg·g(-1) (0.43-27.82) and 11.41±7.16  μg.g(-1) (1.08-28.17), respectively, and an average count of MeHg relative to THg of 92.20% and 90.27%, respectively. In the Maranhão community, the THg average concentrations results were 2.27±2.11  μg·g(-1) (0.13-9.54) and the average values were 93.17% for MeHg. Children of Itaituba had average levels of mercury above the limit established by the World Health Organization (10  μg·g(-1)) and the strong correlation coefficient between the communities (R=0.968 and P=0.0001) suggests the hair as an excellent biomarker of human exposure to organic mercury in riverside populations of the Tapajós, which has the intake of fish daily as main source of protein dietary.

The Influence of Arsenic, Lead, and Mercury on the Development of Cardiovascular Diseases

As a group, cardiovascular disease (CVD) is the leading cause of death worldwide. It killed twice as many people as infectious and parasitic disease and three times as many people as all forms of cancer. There are other crucial risk factors next to the major risk factors identified by the Framingham Heart Study. In the last few years, detailed studies showed the correlation between environmental pollution and the development of CVD. The question, which environmental toxin is particularly harmful, is answered by CERCLA Priority List of Hazardous Substances with the following toxins: arsenic, lead, and mercury. The effect of these potential toxic metals on the development of cardiovascular diseases includes pathomechanisms as the accumulation of free radicals, damage of endothelial nitric oxide synthase, lipid peroxidation, and endocrine influences. This leads to the damage of vascular endothelium, atherosclerosis, high blood pressure, and an increased mortality from cardiovascular diseases. The cardiovascular effects of arsenic, lead, and mercury exposure and its impact on cardiovascular mortality need to be included in the diagnosis and the treatment of CVD.

Associations between plasma persistent organic pollutant levels and blood pressure in Inuit adults from Nunavik

BACKGROUND

Recent evidence suggests that exposure to persistent organic pollutants (POPs) increases the risk of hypertension in environmentally exposed populations. High POP levels have been detected in Arctic populations and the exposure is related to high consumption of fish and marine mammals, which represent the traditional diet of these populations.

OBJECTIVE

We examined the associations between polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides and hypertension among Inuit from Nunavik (Quebec, Canada).

METHODS

A complete set of data was obtained for 315 Inuit≥18years who participated in the "Santé Québec" health survey that was conducted in the 14 villages of Nunavik in 1992. Fourteen polychlorinated biphenyls (PCBs) and 8 OC pesticides or their metabolites were measured in plasma samples using gas chromatography with electron capture detection. Blood pressure (BP) was measured using a standardized protocol and information regarding anti-hypertensive medication was obtained through questionnaires. The associations between log-transformed POPs and hypertension (systolic BP≥140mmHg, diastolic BP≥90mmHg or anti-hypertensive medication) were analyzed using multiple logistic regressions.

RESULTS

Total PCBs as well as the sum of non-dioxin-like PCBs were significantly associated with higher risk of hypertension. Furthermore, the risk of hypertension increased with higher plasma concentrations of congeners 101, 105, 138 and 187. Models adjusted for BP risk factors became significant after including n-3 polyunsaturated fatty acids (PUFAs) and further adjustment for lead and mercury did not change the results. Regarding OC pesticides, p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) was associated with increased risk of hypertension while inverse associations were observed with p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT), β-hexachlorocyclohexane (HCH) and oxychlordane.

CONCLUSIONS

Some PCB congeners were associated with higher risk of hypertension in this highly exposed population. Most associations became significant after including n-3 PUFAs in the models. However, the analyses of OC pesticides revealed divergent results, which need to be confirmed in further cohort and experimental studies.

Impact of forested fallows on fertility and mercury content in soils of the Tapajós River region, Brazilian Amazon

Recent research on slash-and-burn agriculture conducted in the Amazonian basin has suggested that soils must be left under forested fallows for at least 10 to 15 years to regain fertility levels comparable to non-disturbed forests in order to allow for short cycle crop cultivation. However, small scale farmers tend nowadays to re-burn secondary forests as soon as after 3 to 5 years, thus could contribute to further reduce soil fertility and could enhance the transfer of mercury (Hg) naturally present in soils of the region towards water courses. The present research project sets out to characterize the impact of forested fallows of differing age and land-use history on soils properties (fertility and Hg contents) in the region of the Tapajós River, an active pioneer front of the Brazilian Amazon. To do this, soil samples in forested fallows of variable age and in control primary forests were retrieved. In general, soil fertility of grouped forested fallows of different ages was similar to that of the primary forests. But when discriminating soils according to their texture, forested fallows on coarse grained soils still had much higher NH4/NO3 ratios, NH4 and Ca contents than primary forests, this even 15 years after burning. The impact of repeated burnings was also assessed. Fallows on coarse grained soils showed an impoverishment for all variables related to fertility when the number of burnings was 5 or more. For fallows on fine grained soils that underwent 5 or more burnings, NO3 contents were low although a cation enrichment was observed. Total soil Hg content was also sensitive to repeated burnings, showing similar losses for forested fallows established on both types of soil. However, Hg linked to coarse particles appeared to migrate back towards fine particles at the surface of coarse grained soils in fallows older than 7 years.

Reference levels of blood mercury and association with metabolic syndrome in Korean adults

PURPOSE

Mercury (Hg) is a nonessential and toxic metal that is widely distributed in the environment. This study was performed to estimate the representative blood Hg level, to determine the contributing factors to Hg exposure, and to analyze the association of blood Hg with metabolic syndrome in Korean adults.

METHODS

Mercury exposure is assessed by total Hg concentration in blood. A total of 2,114 healthy adults who have not been exposed to Hg occupationally were sampled by the multistaged, sex-, and age-stratified probability method. Information was collected regarding the subjects' demographic characteristics, lifestyles, and past medical history. The participants then underwent physical examination and blood sampling.

RESULTS

The geometric mean concentration of Hg in whole blood was 3.90 μg/L, which was significantly influenced by sex, age, smoking, alcoholic consumption, residence area, and seafood intake after adjustment for confounders. Significant increases in body mass index, waist circumference, diastolic blood pressure, total cholesterol, and triglyceride were observed according to the blood Hg levels after adjustment for covariates. Also, Hg exposure was significantly associated with metabolic syndrome and their components such as obesity and increased fasting glucose.

CONCLUSION

The blood Hg level in Korean adults is higher than that in USA and other Western countries, while it is similar to or lower than that in other Asian countries. The blood Hg level is influenced by sociodemographic factors and individual lifestyles including dietary habits. Furthermore, blood Hg is associated with metabolic syndrome, in which Hg exposure may play a role as a possible risk factor for cardiovascular diseases.

Blood cadmium, mercury, and lead and metabolic syndrome in South Korea: 2005-2010 Korean National Health and Nutrition Examination Survey

INTRODUCTION

We present data from the Korean National Health and Nutrition Examination Survey 2005-2010 regarding the association between levels of blood cadmium, mercury, and lead and metabolic syndrome (MS) in a representative sample of the adult South Korean population. MS is defined as a cluster of disorders including central obesity, glucose intolerance, hypertension, low high-density lipoprotein cholesterol, and high triglycerides.

METHODS

The analysis was restricted to participants ≥20 years of age who completed the health examination survey, including blood lead, cadmium, and mercury measurements. Odds ratios (ORs) for MS were calculated for log2 -transformed blood metal levels and tertiles thereof after covariate adjustment.

RESULTS

No significant results were observed in females. In males, adjusted ORs indicated that a doubling of blood cadmium resulted in a 23.0% increase in the risk of MS. Male subjects in the highest tertile of blood cadmium were 36.7% more likely to have MS versus those in the lowest tertile. There were no significant ORs for having MS or its components in any of the models of blood lead and mercury levels after covariate adjustment.

CONCLUSION

The association between blood cadmium level and MS was significant regardless of the type of variable (continuous or categorical) among men with lower blood cadmium levels. Thus, blood cadmium levels were robust risk factors for MS in men. To our knowledge, this is the first report of an association between cadmium exposure and MS.

Associations of blood and urinary mercury with hypertension in U.S. adults: the NHANES 2003-2006

BACKGROUND

Few studies have examined the association between hypertension and mercury exposure in the general population. We examined cross-sectional associations between blood (mainly methylmercury) or urinary mercury (mainly inorganic mercury) and hypertension in representative U.S. adults and effect modifications by dietary omega-3 fatty acids and serum selenium.

METHODS

We examined 6607 adults aged 20 years or older, using the National Health and Nutrition Examination Survey (NHANES) from 2003/2004 to 2005/2006 (2201 adults were available for urinary mercury from NHANES 2003-2006; 2117 available for serum selenium from NHANES 2003-2004 aged 40 years or older). The average of omega-3 fatty acids from two 24-h recalls was calculated.

RESULTS

The weighted prevalence of hypertension was 32.2%. The geometric means (95% confidence intervals) of blood total and urinary mercury were 1.03 (0.95, 1.11)μg/L and 0.51 (0.47, 0.54)μg/L, respectively. The adjusted odds ratios for a doubling increase in blood mercury and urinary mercury were 0.94 (0.87 to 1.01) and 0.87 (0.78 to 0.99), respectively, after adjusting for potential confounders. The associations remained similar, even after adjusting for either omega-3 fatty acids or selenium or both. No significant effect modification by either omega-3 fatty acids or selenium was observed.

CONCLUSIONS

In this cross-sectional study of the U.S. general population, we found no association of hypertension with blood mercury but a suggestive inverse association with urinary mercury. Future prospective studies are warranted to confirm these findings.

Exposure to persistent organic pollutants and risk of hypertension among Inuit from Greenland

BACKGROUND

Exposure to persistent organic pollutants (POPs) is of concern in Arctic populations since these contaminants accumulate in fish and marine mammals, which is an important part of the traditional diet of these populations. Epidemiological and experimental studies have reported significant associations between POPs and increased blood pressure (BP) in populations with different degrees of exposure.

OBJECTIVE

We aimed to assess the risk of hypertension related to increasing levels of polychlorinated biphenyls (PCBs) and organochlorine (OC) pesticides.

METHODS

Fifteen PCBs and 11 OC pesticides or their metabolites were determined in plasma of 1614 Inuit adults ≥ 18 years living in 9 towns and 13 villages in Greenland. BP was measured using a standardized protocol. The risk of hypertension was estimated through logistic regression using POPs as continuous variables (log-transformed). Hypertension was defined as systolic BP ≥ 140 mm Hg, diastolic BP ≥ 90 mm Hg and/or antihypertensive treatment.

RESULTS

Overall, the odd ratios (ORs) of hypertension were not statistically significant for dioxin-like PCBs, non-dioxin-like PCBs and OC pesticides after adjusting for confounders. Once the analyses were stratified by age category (18-39 and ≥ 40 years), increased risk of hypertension was observed for total dioxin-like PCBs among the youngest [OR: 1.34 (95% CI: 1.03-1.74)] while a borderline protective effect was observed for total non-dioxin-like PCBs [OR: 0.81 (95% CI: 0.66-0.99)] among the oldest. Higher risk of hypertension was also associated with increasing p,p'-dichlorodiphenyltrichloroethane (DDT) concentrations among the youngest [OR: 1.42 (95% CI: 1.08-1.85)].

CONCLUSION

Overall, no significant associations were observed between PCBs, OC pesticides and blood pressure in this highly exposed population although the associations differed by age category.

Methylmercury and elemental mercury differentially associate with blood pressure among dental professionals

Methylmercury-associated effects on the cardiovascular system have been documented though discrepancies exist, and most studied populations experience elevated methylmercury exposures. No paper has investigated the impact of low-level elemental (inorganic) mercury exposure on cardiovascular risk in humans. The purpose of this study was to increase understanding of the association between mercury exposure (methylmercury and elemental mercury) and blood pressure measures in a cohort of dental professionals that experience background exposures to both mercury forms. Dental professionals were recruited during the 2010 Michigan Dental Association Annual Convention. Mercury levels in hair and urine samples were analyzed as biomarkers of methylmercury and elemental mercury exposure, respectively. Blood pressure (systolic, diastolic) was measured using an automated device. Distribution of mercury in hair (mean, range: 0.45, 0.02-5.18 μg/g) and urine (0.94, 0.03-5.54 μg/L) correspond well with the US National Health and Nutrition Examination Survey. Linear regression models revealed significant associations between diastolic blood pressure (adjusted for blood pressure medication use) and hair mercury (n=262, p=0.02). Urine mercury results opposed hair mercury in many ways. Notably, elemental mercury exposure was associated with a significant systolic blood pressure decrease (n=262, p=0.04) that was driven by the male population. Associations between blood pressure and two forms of mercury were found at exposure levels relevant to the general population, and associations varied according to type of mercury exposure and gender.

Association between methylmercury and cardiovascular risk factors in a native population of Quebec (Canada): a retrospective evaluation

BACKGROUND

Epidemiological evidence suggests a negative impact of methylmercury (MeHg) on cardiovascular risk factors such as blood pressure (BP) and heart rate (HR). This issue is of concern in Arctic populations such as in the Inuit of Nunavik since this contaminant is accumulated in fish and marine mammals, which still represent the subsistence diet of this population.

OBJECTIVE

We examined the associations between MeHg and BP and resting HR among Inuit adults.

METHODS

The "Santé Quebec" health survey was conducted in 1992 in the 14 villages of Nunavik and a complete set of data was obtained for 313 Inuit adults≥18 years. Blood samples were collected in order to determine total mercury, lead, total polychlorinated biphenyls (PCBs), n-3 polyunsaturated fatty acids (PUFAs), fasting glucose and lipid profile while socio-demographic variables were obtained through questionnaires. Anthropometric measurements as well as BP and resting HR were obtained using standardised protocols. Pulse pressure (PP: systolic BP minus diastolic BP) was also calculated. Multiple linear regression was used in order to determine the change in the dependent variables associated with the quartiles of MeHg concentration, taking the quartile 1 as reference.

RESULTS

The mean age of the participants was 38±14 years and the sample was composed of 132 men (42.2%) and 181 women (57.8%). MeHg geometric mean was 15.4 μg/L (95%CI: 13.9-17.0) and levels ranged from 0.8 to 112.0 μg/L. Resting HR increased linearly across quartiles of blood MeHg concentration after adjusting for confounders (p for trend=0.02). An increase of 6.9 beats per minute (bpm) between the 4th and 1st quartile was observed after adjusting for confounders. No significant association was observed between blood MeHg and systolic BP, diastolic BP or PP.

CONCLUSIONS

MeHg was associated with increasing resting HR after considering traditional risk factors as well as other contaminants (lead and total PCBs) and n-3 PUFAs. In contrast, no significant association with blood pressure was observed in this study.

Microscopy and microanalysis of hematological parameters in common carp, Cyprinus carpio, inhabiting a polluted lake in North East India

Optical and scanning electron microscopy (SEM) of red blood cells (RBCs) of common carp, Cyprinus carpio, inhabiting a polluted lake in Northeast India revealed a number of abnormalities. About 7% of the RBC showed the presence of a micronucleus, besides the presence of some bi-nucleated and abnormally shaped nuclei. RBCs, white blood cells, and hemoglobin content were found to be reduced significantly as compared to the control. SEM showed the presence of spherocytes, early stages of echinocytes, cytoplasmic blebbing, erythrocytes with contraction from one side, abnormal shape of erythrocytes (hexagonal/pentagonal/tetragonal), development of lobopodial projections, cell rupture, membrane internalization, and formation of ring-shaped RBC. Energy dispersive X-ray spectroscopy (EDS) showed the presence of a considerable percentage of silicon and lead in erythrocytes of the fish collected from the polluted lake, in contrast to a negligible concentration of the two elements in control fish. Significance of the study in relation to fish health in a polluted body of water and the importance of SEM, EDS, and light microscopy in utilizing hematological parameters as pollution indicators are discussed.

Occupational dermatitis in hairdressers: do they claim workers' compensation?

BACKGROUND

Hairdressers are one of the largest occupational groups attending our Occupational Dermatology Clinic. However, few seek workers' compensation for their occupational dermatitis.

OBJECTIVES

To retrospectively analyse and compare workers' compensation claims data and diagnosed disease data for occupational contact dermatitis in hairdressers from 1993 to 2009, for the state of Victoria, Australia.

PATIENTS/MATERIALS/METHODS

Data from the Occupational Dermatology Clinic database, the Compensation Research Database and the Australian Bureau of Statistics were used in this study.

RESULTS

The clinic database identified 157 hairdressers and apprentices with a confirmed diagnosis of occupational contact dermatitis assessed between 1993 and 2009. Forty-six unique claims for occupational contact dermatitis from 46 individuals were identified from the Compensation Research Database over the same time period. Hairdressers in the 15-24-year age group were significantly over-represented in the claims data relative to the diagnosed disease data (p < 0.01). The median cost per claim was AU$1421, and the median time off work per claim was 20 days.

CONCLUSION

Increased efforts are needed to reduce the incidence of occupational contact dermatitis in hairdressers in Australia, and to ensure that hairdressers with occupational contact dermatitis are aware of their compensation entitlements. Reliance on workers' compensation data for disease surveillance may lead occupational health and safety regulators to underestimate the magnitude of the problem of occupational contact dermatitis in the hairdressing profession.

Mercury exposure and risk of hypertension in US men and women in 2 prospective cohorts

Cross-sectional studies and animal experiments suggest that methylmercury exposure could increase the risk of hypertension. This relationship has not been evaluated in large prospective studies. Using data from previous nested case-control studies in 2 separate prospective cohorts, we measured toenail mercury, a valid biomarker of long-term methylmercury exposure, among 6045 US men and women free of hypertension at baseline. Geometric mean toenail mercury concentrations were 0.08 μg/g in the lowest quintile and 0.74 μg/g in the highest quintile, the latter corresponding with exposures ≈2.0-fold higher than the US Environmental Protection Agency reference dose. Participants were followed prospectively (mean±SD follow-up, 14.9±7.9 years) for a new self-report of physician-diagnosed hypertension (3540 cases), shown to be >95% sensitive and specific for diagnosing hypertension in these cohorts as compared with review of medical charts and direct blood pressure measurement, respectively. After adjustment for demographic, clinical, and lifestyle risk factors, the hazard ratio (95% CI) for incident hypertension in the highest versus lowest quintile of mercury exposure was 0.96 (0.84-1.09) in women, 0.82 (0.62-1.08) in men, and 0.94 (0.84-1.06) in both cohorts combined. Findings were similar when more extreme categories of mercury were compared (across deciles, with geometric mean levels in highest decile ≈2.9-fold higher than the reference dose) and in analyses stratified by fish or omega-3 consumption, selenium levels, body mass index, and age. These findings from 2 separate large prospective cohort studies do not support any clinically apparent adverse effects of methylmercury exposure on the risk of hypertension in men or women, including at levels ≤2.5-fold higher than the reference dose.

Toxic effects of mercury on the cardiovascular and central nervous systems

Environmental contamination has exposed humans to various metal agents, including mercury. This exposure is more common than expected, and the health consequences of such exposure remain unclear. For many years, mercury was used in a wide variety of human activities, and now, exposure to this metal from both natural and artificial sources is significantly increasing. Many studies show that high exposure to mercury induces changes in the central nervous system, potentially resulting in irritability, fatigue, behavioral changes, tremors, headaches, hearing and cognitive loss, dysarthria, incoordination, hallucinations, and death. In the cardiovascular system, mercury induces hypertension in humans and animals that has wide-ranging consequences, including alterations in endothelial function. The results described in this paper indicate that mercury exposure, even at low doses, affects endothelial and cardiovascular function. As a result, the reference values defining the limits for the absence of danger should be reduced.

The association between blood pressure and whole blood methylmercury in a cross-sectional study among Inuit in Greenland

BACKGROUND

The Inuit in Greenland have a high average consumption of marine species and are highly exposed to methylmercury, which in other studies has been related to hypertension. Data on the relation between methylmercury and hypertension is limited, especially in populations subjected to a high exposure of methylmercury. We examined the relation between whole blood mercury and blood pressure (BP) in Inuit in Greenland.

METHODS

A cross-sectional population-based study among adult Inuit in Greenland was performed in 2005-2009. Information on socio-demography, lifestyle, BP, blood samples and clinical measurements was obtained - the latter after overnight fasting. BP was measured according to standardized guidelines. Whole blood mercury concentration was used as a marker of exposure. The analyses were restricted to Inuit aged 30-69 years with four Greenlandic grandparents (N = 1,861). Multivariate regression analyses with inclusion of confounders were done separately for men and women with the omission of participants receiving anti-hypertensive drugs, except for logistic regression analyses of the relation between mercury and presence of hypertension (yes/no).

RESULTS

The mean whole blood mercury level was 20.5 μg/L among men and 14.7 μg/L among women. In multivariate analyses adjusted for confounders, diastolic BP decreased with increasing mercury concentration. In men diastolic BP decreased significantly for each four-fold increase in mercury concentration (Beta = -0.04, standard error = 0.01, p = 0.001), while no relation between mercury and diastolic BP was found among women. For systolic BP, a similar non-statistically significant result was seen only for men (Beta = -0.02, standard error = 0.01, p = 0.06). A relation between mercury and hypertension was only found in men; the odds ratio for hypertension was 0.99 (95% CI: 0.98-0.99). No relation between quintiles of mercury and hypertension was found. The relationship between mercury and BP parameters may be non-linear: In analyses of quintiles of mercury the overall effect of mercury on BP parameters was only statistically significant for diastolic BP among men (Wald test, p = 0.01), however pairwise comparisons showed that some quintiles were not statistically different. This result is supported by LOESS modelling.

CONCLUSIONS

No adverse associations between whole blood mercury and blood pressure were found. With increasing whole blood mercury concentrations, diastolic BP and the risk of hypertension decreased among men in the study: this may be explained by confounding by exercise or unknown factors.

Serum long-chain n-3 polyunsaturated fatty acids, methylmercury and blood pressure in an older population

Fish or fish oil consumption has been associated with lower blood pressure. Fish may also contain methylmercury, which has been associated with cardiovascular diseases and higher blood pressure. Our aim was to study the associations of serum long-chain n-3 polyunsaturated fatty acids (PUFA) eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA), mainly reflecting fish or fish oil intake, and hair mercury concentration with blood pressure. Data were available for 848 men and 909 women from the Kuopio Ischaemic Heart Disease Risk Factor Study, aged 53-73 years. We excluded participants with ischemic heart disease, stroke, diabetes or hypertension treatment, leaving 396 men and 372 women. Log-transformed values were used to study the associations. The mean serum concentrations were 1.63% (s.d. 0.91) for EPA, 0.77% (s.d. 0.16) for DPA and 2.73% (s.d. 0.90) for DHA of all serum fatty acids. Multivariate-adjusted serum EPA+DPA+DHA was associated with lower systolic blood pressure (β = -4.50, 95% confidence interval (CI) -8.02 - -0.99) and pulse pressure (β = -4.41, 95% CI -6.95 - -1.87), but not with diastolic blood pressure (β = -0.45, 95% CI -2.31-1.52). The associations were similar with EPA, DPA and DHA evaluated individually. The mean hair mercury concentration was 1.42 μg g(-1) (s.d. 1.54). Hair mercury was not associated with blood pressure and it did not modify the association between PUFA and blood pressure. These results suggest that higher serum long-chain n-3 PUFA concentration has a modest inverse association with blood pressure in older men and women.

Short-term effect of severe exposure to methylmercury on atherosclerotic heart disease and hypertension mortality in Minamata

Recent studies suggest potential adverse effects of methylmercury exposure on myocardial infarction and hypertension, although the evidence is still limited. We thus evaluated this association using age-standardized mortality ratios (ASMRs) in Minamata, where severe methylmercury poisoning had occurred. We obtained mortality data from annual vital statistics and demographic statistics from census. We then compared mortality of atherosclerotic heart disease including degenerative heart disease and hypertension in Minamata-city with those in Kumamoto Prefecture, which includes Minamata city, as a control. We estimated ASMRs and 95% confidence intervals (CIs) during the period from 1953 to 1970. ASMRs of atherosclerotic heart disease were continuously decreased during the period from 1953 to 1967. In contrast, the ASMR of hypertension was significantly elevated during the period from 1963 to 1967 (SMR=1.38, CI; 1.06-1.80); but they decreased later. Although dilution is present in this ecological study, our study supports the notion that methylmercury exposure induces hypertension.

Evaluation of glutathione S-transferase GSTM1 and GSTT1 polymorphisms and methylmercury metabolism in an exposed Amazon population

Over the last decades, the presence of methylmercury (MeHg) in the Amazon region of Brazil and its adverse human health effects have given rise to much concern. The biotransformation of MeHg occurs mainly through glutathione (GSH) in the bile mediated by conjugation with glutathione S-transferases (GST). Epidemiological evidence has shown that genetic polymorphisms may affect the metabolism of MeHg. The aim of this study was to evaluate the association between GST polymorphisms, GSH, and Hg levels in blood (B-Hg) and in hair (H-Hg) of an Amazon population chronically exposed to the metal through fish consumption. Blood and hair samples were collected from 144 volunteers (71 men, 73 women). B-Hg and H-Hg levels were determined by inductively coupled plasma-mass spectrometry, and GSH levels were evaluated by a spectrophotometric method. GSTM1 and T1 genotyping evaluation were carried out by multiplex polymerase chain reaction (PCR). Mean levels of B-Hg and H-Hg were 37.7 ± 24.5 μg/L and 10.4 ± 7.4 μg/g, respectively; GSH concentrations ranged from 0.52 to 2.89 μM/ml of total blood. Distributions for GSTM1/T1, GSTM1/GSTT1*0, GSTM1*0/T1, and GSTM1*0/GSTT1*0 genotypes were 35.4, 22.2, 25.0, and 17.4%, respectively. GSTT1 genotype carriers presented lower levels of B-Hg and H-Hg when compared to other genotypes carriers. In addition, GSTM1*0/GSTT1*0 individuals presented higher Hg levels in blood and hair than subjects presenting any other genotypes. There appeared to be no evidence of an effect of polymorphisms on GSH levels. Therefore, our data suggest that GST polymorphisms may be associated with MeHg detoxification.

Biomarkers of methylmercury exposure immunotoxicity among fish consumers in Amazonian Brazil

BACKGROUND

Mercury (Hg) is a ubiquitous environmental contaminant with neurodevelopmental and immune system effects. An informative biomarker of Hg-induced immunotoxicity could aid studies on the potential contribution to immune-related health effects.

OBJECTIVES

Our objectives were to test the hypothesis that methylmercury (MeHg) exposures affect levels of serum biomarkers and to examine interactions between Hg and selenium (Se) in terms of these responses.

METHODS

This cross-sectional epidemiological study assessed adults living along the Tapajós River, a system long affected by MeHg. We measured antinuclear (ANA) and antinucleolar (ANoA) autoantibody levels and eight cytokines in serum samples (n = 232). Total Hg (including MeHg) and Se were measured in blood, plasma, hair, and urine.

RESULTS

The median (range) total Hg concentrations were 14.1 μg/g (1.1-62.4), 53.5 μg/L (4.3-288.9), 8.8 μg/L (0.2-40), and 3.0 μg/L (0.2-16.1) for hair, blood, plasma, and urine, respectively. Elevated titers of ANA (but not ANoA) were positively associated with MeHg exposure (log-transformed, for blood and plasma), unadjusted [odds ratio (OR) = 2.6; 95% confidence interval (CI): 1.1, 6.2] and adjusted for sex and age (OR = 2.9; 95% CI: 1.1, 7.5). Proinflammatory [interleukin (IL)-6 and interferon (IFN)-γ], anti-inflammatory (IL-4), and IL-17 cytokine levels were increased with MeHg exposure; however, in the subset of the population with elevated ANA, proinflammatory IL-1β, IL-6, IFN-γ, and tumor necrosis factor (TNF)-α and anti-inflammatory (IL-4) cytokine levels were decreased with MeHg exposure. Although Se status was associated with MeHg level (correlation coefficient = 0.86; 95% CI: 0.29, 1.43), Se status was not associated with any changes in ANA and did not modify associations between Hg and ANA titers.

CONCLUSIONS

MeHg exposure was associated with an increased ANA and changes in serum cytokine profile. Moreover, alterations in serum cytokine profiles differed based on ANA response, suggesting a specific phenotype of MeHg susceptibility. Further research on the potential health implications of these observed immunological changes is warranted.

Social communication network analysis of the role of participatory research in the adoption of new fish consumption behaviors

The formulation and communication of fish advisories are highly complex because of the potential conflict between the nutritional and toxicological issues associated with fish consumption. Government and organization-sponsored fish advisories have had limited success in changing behaviors. Participatory approaches may enhance the understanding of complex issues and the adoption of new behaviors. Here we used social network analysis to investigate the adoption of dietary changes within the context of a community participatory research project. In the Brazilian Amazon, many communities are highly exposed to methylmercury from fish consumption. A participatory intervention based on dietary changes aimed at reducing methylmercury exposure while maintaining fish consumption was initiated in 1995. In 2001, we collected data on individual participation in the research, on the discussion network regarding mercury issues and on changes in fish consumption from 96 of the 110 village households. More than half of men and women had adopted new fish consumption behavior to reduce mercury exposure. Adoption was associated with participation in the research project for both women and men, and with a higher number of discussion partners about mercury issues for women. Adoption was likewise associated with the presence of a female communication partner in the personal networks of both men and women. At the household level, men and women who considered their spouse as a discussion partner were more likely to adopt than those who did not. Opinion le]adership was associated with change in fish consumption only for women. We discuss the contribution of community participation and communication networks to overcome the difficulties in generating complex messages that take into account both health benefits and risks of fish consumption. We also discuss the relevance of building preventive health programs based on participatory research approaches and the roles and relations specific to men and women.

Influence of mercury exposure on blood pressure, resting heart rate and heart rate variability in French Polynesians: a cross-sectional study

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.

Impact of mercury exposure on blood pressure and cardiac autonomic activity among Cree adults (James Bay, Quebec, Canada)

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.

Evaluation of toxic effects of a diet containing fish contaminated with methylmercury in rats mimicking the exposure in the Amazon riverside population

This study was designed to evaluate the effects of a diet rich in fish contaminated with MeHg, mimicking the typical diet of the Amazon riverside population, in rats. Animals were randomly assigned to one of three groups with eight rats in each group: Group I-control, received commercial ration; Group II-received a diet rich in uncontaminated fish; Group III-received a diet rich in fish contaminated with MeHg. Treatment time was 12 weeks. Oxidative stress markers were evaluated, as well as the effects of this diet on DNA stability, systolic blood pressure (SBP), nitric oxide (NO) levels and histological damage in different tissues. There was a significant increase in SBP values in rats fed with MeHg-contaminated fish diet after the 10th week of the treatment. As far as oxidative stress biomarkers are concerned, no differences were observed in reduced glutathione and protein carbonyl levels, glutathione peroxidase, catalase, superoxide dismutase or δ-aminolevulinate dehydratase activities between the groups of animals receiving contaminated and uncontaminated fish diets. On the other hand, malondialdehyde levels increased significantly in rats fed with contaminated fish. NO levels were similar in all groups. DNA migration showed augmented in rats exposed to contaminated fish and histopathological analyses showed weak but significant leukocyte infiltration. Thus, we conclude that the MeHg-contaminated fish diet induced a slight lipid peroxidation and genotoxicity. However, these effects seem to be much less pronounced than when rats are exposed to aqueous solution containing CH3HgCl. Our findings support the contention that the chemical form of MeHg in fish or fish nutrients such as polyunsaturated fatty acids, Se or vitamin E could minimize the toxic effects of MeHg exposure in fish-eating communities.

A transdisciplinary perspective of chronic stress in relation to psychopathology throughout life span development

The allostatic load (AL) model represents an interdisciplinary approach to comprehensively conceptualize and quantify chronic stress in relation to pathologies throughout the life cycle. This article first reviews the AL model, followed by interactions among early adversity, genetics, environmental toxins, as well as distinctions among sex, gender, and sex hormones as integral antecedents of AL. We next explore perspectives on severe mental illness, dementia, and caregiving as unique human models of AL that merit future investigations in the field of developmental psychopathology. A complimenting transdisciplinary perspective is applied throughout, whereby we argue that the AL model goes beyond traditional stress–disease theories toward the advancement of person-centered research and practice that promote not only physical health but also mental health.

Role of mercury toxicity in hypertension, cardiovascular disease, and stroke

Mercury has a high affinity for sulfhydryl groups, inactivating numerous enzymatic reactions, amino acids, and sulfur-containing antioxidants (N-acetyl-L-cysteine, alpha-lipoic acid, L-glutathione), with subsequent decreased oxidant defense and increased oxidative stress. Mercury binds to metallothionein and substitute for zinc, copper, and other trace metals, reducing the effectiveness of metalloenzymes. Mercury induces mitochondrial dysfunction with reduction in adenosine triphosphate, depletion of glutathione, and increased lipid peroxidation. Increased oxidative stress and reduced oxidative defense are common. Selenium and fish containing omega-3 fatty acids antagonize mercury toxicity. The overall vascular effects of mercury include increased oxidative stress and inflammation, reduced oxidative defense, thrombosis, vascular smooth muscle dysfunction, endothelial dysfunction, dyslipidemia, and immune and mitochondrial dysfunction. The clinical consequences of mercury toxicity include hypertension, coronary heart disease, myocardial infarction, cardiac arrhythmias, reduced heart rate variability, increased carotid intima-media thickness and carotid artery obstruction, cerebrovascular accident, generalized atherosclerosis, and renal dysfunction, insufficiency, and proteinuria. Pathological, biochemical, and functional medicine correlations are significant and logical. Mercury diminishes the protective effect of fish and omega-3 fatty acids. Mercury inactivates catecholaminei-0-methyl transferase, which increases serum and urinary epinephrine, norepinephrine, and dopamine. This effect will increase blood pressure and may be a clinical clue to mercury-induced heavy metal toxicity. Mercury toxicity should be evaluated in any patient with hypertension, coronary heart disease, cerebral vascular disease, cerebrovascular accident, or other vascular disease. Specific testing for acute and chronic toxicity and total body burden using hair, toenail, urine, and serum should be performed.

Neurotoxic sequelae of mercury exposure: an intervention and follow-up study in the Brazilian Amazon

Since 1995, the Caruso Project used an Ecosystem Approach to Human Health to examine mercury (Hg) exposure in fish-eating communities in the Brazilian Amazon and develop interventions to maximise nutrition from traditional diet and minimise toxic risk. In 1995, 2000 and 2006, this study followed fish consumption, Hg levels, and visual and motor functions in 31 villagers. Questionnaires gathered information on socio-demographics and diet. Hair Hg (H-Hg) levels were measured. Visual acuity, colour vision, manual dexterity and grip strength were assessed. Data was analysed using general linear models of repeated measures. Total fish consumption, similar in 1995 and 2000, decreased in 2006. Carnivorous fish consumption initially decreased and then remained stable, whereas non-carnivorous fish consumption first increased and then decreased. H-Hg declined from 17.6 to 7.8 μg/g. Visual functions showed a significant decrease over time, with those with H-Hg ≥ 20 μg/g in 1995 showing greater loss. Motor functions showed initial improvement and then returned to the 1995 performance level. Decrease in Hg exposure is attributed to the intervention and socio-economic changes in the village. While there may be a certain reversibility of motor deficits, visual capacities may decrease progressively with respect to exposure prior to the intervention.

Evaluation of the cardiovascular effects of methylmercury exposures: current evidence supports development of a dose-response function for regulatory benefits analysis

BACKGROUND

The U.S. Environmental Protection Agency (U.S. EPA) has estimated the neurological benefits of reductions in prenatal methylmercury (MeHg) exposure in past assessments of rules controlling mercury (Hg) emissions. A growing body of evidence suggests that MeHg exposure can also lead to increased risks of adverse cardiovascular impacts in exposed populations.

DATA EXTRACTION

The U.S. EPA assembled the authors of this article to participate in a workshop, where we reviewed the current science concerning cardiovascular health effects of MeHg exposure via fish and seafood consumption and provided recommendations concerning whether cardiovascular health effects should be included in future Hg regulatory impact analyses.

DATA SYNTHESIS

We found the body of evidence exploring the link between MeHg and acute myocardial infarction (MI) to be sufficiently strong to support its inclusion in future benefits analyses, based both on direct epidemiological evidence of an MeHg-MI link and on MeHg's association with intermediary impacts that contribute to MI risk. Although additional research in this area would be beneficial to further clarify key characteristics of this relationship and the biological mechanisms that underlie it, we consider the current epidemiological literature sufficiently robust to support the development of a dose- response function.

CONCLUSIONS

We recommend the development of a dose- response function relating MeHg exposures with MIs for use in regulatory benefits analyses of future rules targeting Hg air emissions.

Mercury exposure and risk of cardiovascular disease in two U.S. cohorts

BACKGROUND

Exposure to methylmercury from fish consumption has been linked to a potentially increased risk of cardiovascular disease, but evidence from prior studies is equivocal. Beneficial effects of the ingestion of fish and selenium may also modify such effects.

METHODS

Among subjects from two U.S. cohorts (a total of 51,529 men and 121,700 women) whose toenail clippings had been stored, we prospectively identified incident cases of cardiovascular disease (coronary heart disease and stroke) in 3427 participants and matched them to risk-set-sampled controls according to age, sex, race, and smoking status. Toenail mercury and selenium concentrations were assessed with the use of neutron-activation analysis. Other demographic characteristics, cardiovascular risk factors, fish consumption, and lifestyle habits were assessed by means of validated questionnaires. Associations between mercury exposure and incident cardiovascular disease were evaluated with the use of conditional logistic regression.

RESULTS

Median toenail mercury concentrations were 0.23 μg per gram (interdecile range, 0.06 to 0.94) in the case participants and 0.25 μg per gram (interdecile range, 0.07 to 0.97) in the controls. In multivariate analyses, participants with higher mercury exposures did not have a higher risk of cardiovascular disease. For comparisons of the fifth quintile of mercury exposure with the first quintile, the relative risks were as follows: coronary heart disease, 0.85 (95% confidence interval [CI], 0.69 to 1.04; P=0.10 for trend); stroke, 0.84 (95% CI, 0.62 to 1.14; P=0.27 for trend); and total cardiovascular disease, 0.85 (95% CI, 0.72 to 1.01; P=0.06 for trend). Findings were similar in analyses of participants with low selenium concentrations or low overall fish consumption and in several additional sensitivity analyses.

CONCLUSIONS

We found no evidence of any clinically relevant adverse effects of mercury exposure on coronary heart disease, stroke, or total cardiovascular disease in U.S. adults at the exposure levels seen in this study. (Funded by the National Institutes of Health.).

Protective properties of quercetin against DNA damage and oxidative stress induced by methylmercury in rats

Aim of the study was to find out whether consumption of quercetin (QC), an abundant flavonoid in the human diet, protects against DNA damage caused by exposure to organic mercury. Therefore, rats were treated orally with methylmercury (MeHg) and the flavonoid with doses that reflect the human exposure. The animals received MeHg (30 μg/kg/bw/day), QC (0.5-50 mg/kg/bw/day), or combinations of both over 45 days. Subsequently, the glutathione levels (GSH) and the activities of glutathione peroxidase (GPx) and catalase (CAT) were determined, and DNA damage was measured in hepatocytes and peripheral leukocytes in single cell gel electrophoresis assays. MeHg decreased the concentration of GSH and the activity of GPx by 17 and 12%, respectively and caused DNA damage to liver and blood cells, while with QC no such effects were seen. When the flavonoid was given in combination with MeHg, the intermediate and the highest concentrations (5.0 and 50.0 mg/kg/bw/day) were found to cause DNA protection; DNA migration was reduced by 54 and 65% in the hepatocytes and by 27 and 36% in the leukocytes; furthermore, the reduction in GSH and GPx levels caused by MeHg treatment was restored. In summary, our results indicate that consumption of QC-rich foods may protect Hg-exposed humans against the adverse health effects of the metal.

Mercury exposure and children's health

Acute or chronic mercury exposure can cause adverse effects during any period of development. Mercury is a highly toxic element; there is no known safe level of exposure. Ideally, neither children nor adults should have any mercury in their bodies because it provides no physiological benefit. Prenatal and postnatal mercury exposures occur frequently in many different ways. Pediatricians, nurses, and other health care providers should understand the scope of mercury exposures and health problems among children and be prepared to handle mercury exposures in medical practice. Prevention is the key to reducing mercury poisoning. Mercury exists in different chemical forms: elemental (or metallic), inorganic, and organic (methylmercury and ethyl mercury). Mercury exposure can cause acute and chronic intoxication at low levels of exposure. Mercury is neuro-, nephro-, and immunotoxic. The development of the child in utero and early in life is at particular risk. Mercury is ubiquitous and persistent. Mercury is a global pollutant, bio-accumulating, mainly through the aquatic food chain, resulting in a serious health hazard for children. This article provides an extensive review of mercury exposure and children's health.

Mercury exposure and children's health

Acute or chronic mercury exposure can cause adverse effects during any period of development. Mercury is a highly toxic element; there is no known safe level of exposure. Ideally, neither children nor adults should have any mercury in their bodies because it provides no physiological benefit. Prenatal and postnatal mercury exposures occur frequently in many different ways. Pediatricians, nurses, and other health care providers should understand the scope of mercury exposures and health problems among children and be prepared to handle mercury exposures in medical practice. Prevention is the key to reducing mercury poisoning. Mercury exists in different chemical forms: elemental (or metallic), inorganic, and organic (methylmercury and ethyl mercury). Mercury exposure can cause acute and chronic intoxication at low levels of exposure. Mercury is neuro-, nephro-, and immunotoxic. The development of the child in utero and early in life is at particular risk. Mercury is ubiquitous and persistent. Mercury is a global pollutant, bio-accumulating, mainly through the aquatic food chain, resulting in a serious health hazard for children. This article provides an extensive review of mercury exposure and children's health.

Mercury in the Tapajós River basin, Brazilian Amazon: a review

This paper presents a review about mercury contamination and human exposure in the Tapajós River basin (Brazil), one of the major tributaries of the Amazon impacted by traditional gold mining from the mid 1980s. The most recent review in this region was published more than ten years ago and since then many articles about environment and especially human populations have revealed new aspects of mercury toxicology. Additionally, new biomarkers of mercury exposure and toxicity have been studied in these populations. However, there are still many open, about both mercury's biogeochemical cycle and mercury health risks. Further environmental and human risk research directions are proposed.

Mercury exposure and oxidative stress in communities of the Brazilian Amazon

This study was designed to assess possible associations between biomarkers of mercury (Hg) exposure and oxidative stress in fish-eating Amazonian communities. Clinical samples were obtained from riparians living in the Brazilian Amazon. Biomarkers of oxidative stress (glutathione - GSH, glutathione peroxidase - GSH-Px, catalase - CAT, activity and reactivation index of delta-aminolevulinate dehydratase - ALA-D (R%) were determined in blood. Total Hg was measured in whole blood (B-Hg), plasma (P-Hg) and hair (H-Hg). Association between biomarkers of Hg exposure and oxidative stress were examined using multiple regression models, including age, gender, alcohol consumption, smoking status, fish consumption and then stratified for gender. Significant inverse relations were observed between GSH-Px, GSH, CAT, ALA-D activity and B-Hg or H-Hg (p<0.05). ALA-D reactivation index was positively related to B-Hg (p<0.0001). P-Hg was directly related to ALA-D reactivation index and inversely associated with GSH-Px, GSH, and ALA-D activity (p<0.05). When stratified for gender, women showed significant inverse associations between all biomarkers of Hg exposure and CAT (p<0.05) or GSH (p<0.05), while for men only P-Hg showed a significant inverse relation with GSH (p<0.001). Our results clearly demonstrated an association between Hg exposure and oxidative stress. Moreover, for B-Hg, P-Hg and H-Hg gender differences were present.