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The risk to human health from exposure to certain pollutants through the consumption of fruits, tubers, and fish were evaluated in a settlement located in a Colombian area highly impacted by gold mining activities. The concentrations of mercury (Hg) and arsenic (As) in edible food tissues and methylmercury (MeHg) in fish were determined for risk assessment. A questionnaire-based dietary survey was answered by 178 residents of three population groups: children (CHD), women of childbearing age (WCBA), and the rest of the population (RP). The estimated weekly intake (EWI) of MeHg presented values of 1.9 and 2.4 times higher than the provisional tolerable weekly intake (1.6 μg/kg BW/week) recommended by the FAO/WHO for CH and WCBA, respectively. The results of the HQ values of As and Hg for different food were above the safety level (HQ < 1) for most of the groups. For Hg, the highest HQ values correspond to fish, whereas for As in most of the food, but specially in fruits. The total target hazard quotients (HI) were higher than 1, in all the groups (except for CHD that consume tubers) indicating potential non-carcinogenic health risks. The values of carcinogenic risk (CR) for As through exposure to food ranged from 1.2·10 -4 to 7.7·10 -4 , well above than the safety level of US EPA risk (10 -4 -10 -6 ), suggesting the probability of carcinogenic risk for the entire population via ingestion. Therefore, safety control mechanisms and environmental education strategies should be applied to address food intake, associated with good agricultural practices to provide solutions to protect the health of the residents in areas affected by gold mining activities., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier Inc.)

Few studies have addressed co-occurring methylmercury (MeHg) from maternal origin and ethylmercury (EtHg) from Thimerosal-containing vaccines (TCVs) during infant's neurodevelopment. We studied children (n=1139) from the Western Amazon based on combined (low, intermediate, and high) exposure to chronic MeHg from fish consumption and acute TCV- EtHg. Neurodevelopment outcomes were age of walking and age of talking, and the Bayley Scale of Infant Development (BSID). The Mental Developmental Index (MDI) and Psychomotor Developmental Index (PDI) were measured at six and 24 months of age. Median hair-Hg (HHg) at birth was 6.4µgg(-1) in mothers, and 1.94µgg(-1) in newborns; total (pregnancy and infancy) EtHg exposure ranged from 0 to 187.5µg. The combined (MeHg+EtHg) exposure showed significant differences for MDI but not for PDI; however, there was a significant decrease in both MDI and PDI scores at 24 months. The increase in BSID delays (scores <80) between six and 24 months was not discernible with regards to EtHg or MeHg exposure. We found a statistically significant increase in neurodevelopmental (BSID) delays related to the combined exposure to Hg (MeHg>EtHg). Neurodevelopment delays due to low-doses of organic mercury (albeit undiscernible) are not predictable but can be avoided by choosing low-Hg fish and providing Thimerosal-free vaccines., (Copyright © 2015 Elsevier Inc. All rights reserved.)

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., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Objectives: To assess whether polychlorinated biphenyls (PCBs), methylmercury, lead, or parental child-rearing attitudes was most crucial for maladaptive behavior problems, we examined Japanese 30-month-old children followed up from pregnancy., Methods: The Child Behavior Checklist (CBCL) was used to assess the behavior problems in 306 children. The associations of cord-blood total PCBs (ΣPCB), total mercury (THg), and lead with each CBCL subscale were examined by multivariate analyses., Results: The median values in cord blood of the 306 children were 48.3 (5 and 95 percentiles, 18.6-116.3) ng/g-lipid for ΣPCB, 10.2 (4.1-24.5)ng/g for THg, and 1.0 (0.5-1.7)μg/dl for lead. The internalizing score of the CBCL was significantly correlated with ΣPCB (r=0.113) in the children, though no significant correlation was seen between any CBCL score and either THg or lead. The significant correlation disappeared when conducting multiple regression analysis with possible confounders; at that time, the birth order, home environment, and maternal intelligence quotient were significantly related to the internalizing score. Three CBCL scores and ΣPCB levels were significantly higher in the first-born children than in the second-born or following children, and the partial correlation coefficient with the adjustment for all confounders except birth order was significant between the internalizing score and ΣPCB in the latter children (r=0.175)., Conclusions: Internalizing behavior appears to be affected by prenatal exposure to PCBs at low levels. Under lower-level exposures, however, behavior problems may be more strongly associated with parental child-rearing attitudes involved in birth order, than with such hazardous chemicals., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The main objectives of our study were to estimate the impact of a mercury cell chlor-alkali (MCCA) complex in Rosignano Solvay (Tuscany, Italy) on the local environment and to assess mercury exposure of inhabitants living near the plant. Measurement campaigns of atmospheric Hg near the MCCA plant showed that the impact of the emitted Hg from the industry on the terrestrial environment is restricted to a close surrounding area. Total gaseous mercury concentrations in ambient air of inhabited area around the MCCA plant were in the range of 8.0-8.7 ng/m3 in summer and 2.8-4.2 ng/m3 in winter. Peaks of up to 100 ng/m3 were observed at particular meteorological conditions. Background levels of 2 ng/m3 were reached within a radius of 3 km from the plant. Reactive gaseous mercury emissions from the plant constituted around 4.2% of total gaseous mercury and total particulate mercury emission constituted around 1.0% of total gaseous mercury emitted. Analysis of local vegetables and soil samples showed relatively low concentrations of total mercury (30.1-2919 microgHg/kg DW in the soil; <0.05-111 microgHg/kg DW in vegetables) and methylmercury (0.02-3.88 microgHg/kg DW in the soil; 0.03-1.18 microgHg/kg DW in vegetables). Locally caught marine fish and fresh marine fish from the local market had concentrations of total Hg from 0.049 to 2.48 microgHg/g FW, of which 37-100% were in the form of methylmercury. 19% of analysed fish exceeded 1.0 microgHg/g FW level, which is a limit set by the European Union law on Hg concentrations in edible marine species for tuna, swordfish and shark, while 39% of analysed fish exceeded the limit of 0.5 microgHg/g FW set for all other edible marine species. Risk assessment performed by calculating ratio of probable daily intake (PDI) and provisional tolerable daily intake (PTDI) for mercury species for various exposure pathways showed no risks to human health for elemental and inorganic mercury, except for some individuals with higher number of amalgam fillings, while PDI/PTDI ratio for methylmercury and total mercury exceeded the toxicologically tolerable value due to the potential consumption of contaminated marine fish.

Perinatal exposure to methylmercury is known to result in severe neurological effects on the developing fetus and infant, including cerebral palsy, mental retardation, and seizures. Males are more susceptible than females to neurological damage from perinatal methylmercury exposures. Preliminary analyses of data and statistics for the hospitalization rates of males for cerebral palsy in the 17 Canadian Areas of Concern in the Great Lakes basin indicate a possible geographic association with locations with elevated mercury from natural or industrial sources.

Mercury concentrations were measured in paired hair and blood samples from a cohort of about 1000 children examined at birth and at 7 and 14 years of age. The ratio between concentrations in maternal hair (in microg/g) and in cord blood (microg/L) was approximately 200, but samples from the children at age 14 years showed a ratio of about 250. These findings are in accordance with previous data from smaller studies. However, an even higher ratio of about 360 was seen at 7 years of age, suggesting that hair strands at this age retain more mercury. The 95th percentile of the hair-to-blood ratio was between five-fold and nine-fold greater than the 5th percentile. The results were examined in structural equation models to estimate the total imprecision of the individual biomarker results and the possibility that the ratio may not be constant. The hair-to-blood ratio was found to increase at lower mercury concentrations, a tendency that could not be explained by potential confounders, such as alcohol intake or number of amalgam fillings. The total imprecision (coefficient of variation) for the blood determinations averaged about 30%, thereby substantially exceeding normal laboratory imprecision. Yet hair-mercury results had an even greater imprecision, which suggested that preanalytical factors, such as variable sample characteristics, impacted the results. These findings are in accordance with other evidence that the cord blood concentration is a better predictor of neurobehavioral toxicity than is the maternal hair concentration. Although practical for field studies and monitoring purposes, hair-mercury concentration results, therefore, need to be calibrated and interpreted in regard to each specific study setting.

The Amazon rain forest extends over an area of 7.8x10(6)km(2) in nine countries. It harbors a diverse human population distributed in dense cities and isolated communities with extreme levels of infrastructure. Amazonian forest people, either autochthons or frontier riparians (ribeirinhos) living in isolated areas, share the same environment for survival and nutritional status. The peculiarities of the hydrological cycle determine disease patterns, agricultural conditions, and food availability. Feeding strategies depend heavily on cassava products and fish. These two foods carry toxic substances such as linamarin (naturally present in cassava) and monomethyl mercury (MMHg) (bioconcentrated in fish flesh) that cause neurotoxic diseases in other parts of the world but not in Amazonia, where neurotoxic cases of food origin are rare and not related to these staples. While cassava detoxification processes may partly explain its safe consumption, the Hg concentrations in Amazonian fish are within traditionally safe limits for this population and contribute to an important metabolic interaction with cassava. The gold rush of the 1970s and 1980s brought large-scale environmental disruption and physical destruction of ecosystems at impact points, along with a heavy discharge of metallic Hg. The discharged Hg has not yet impacted on MMHg concentrations in fish or in hair of fish consumers. Hair Hg concentration, used as a biomarker of fish consumption, indicates that the Amazonian riparians are acquiring an excellent source of protein carrying important nutrients, the lack of which could aggravate their existing health problems. Therefore, in a scenario of insufficient health services and an unhealthy environment, food habits based on fish consumption are part of a successful survival strategy and recommendations for changes are not yet justifiable.

French Guiana, like its neighbors, suffers from environmental pollution with methylmercury from gold mining activities, and Amerindian communities are particularly affected. A neurological and a neurospsychological evaluation were carried out in children of three Amerindian communities with various levels of pollution: 156 children from the Upper Maroni (high exposure), 69 from Camopi on the Oyapock river (median exposure), and 153 from Awala on the Atlantic coast (low exposure). Exposure to methylmercury was measured by determination of total mercury in the hair of the children and their mothers (geometric mean, 12.7 microg/g in Upper Maroni). No major neurologic signs were observed in the children examined. After adjustment for potential confounders, we found a dose-dependent association between maternal hair mercury level and increased deep tendon reflexes, poorer coordination of the legs, and decreased performance in the Stanford-Binet Copying score, which measures visuospatial organization. In this last test, the frequency of rotation errors was high in the 5-6 years age group and increased with mercury exposure. These associations depended on the sex of child and were stronger among boys. The interpretation of these results is limited mainly by the cross-sectional design of the study. It identifies specific neurological and neuropsychological deficits, in some cases modulated by sex, which are consistent with known targets of mercury neurotoxicity., (2002 Elsevier Science (USA))

The purpose of this retrospective study was to examine the effect of methylmercury pollution on the sex ratio of offspring at birth and of fetuses at stillbirth in Minamata City, Japan, in the 1950s when severe and widespread methylmercury pollution was experienced. In 4 of 5 years from 1955 to 1959 when methylmercury pollution was most severe, lower numbers of male offspring at birth were observed in the city population. The offspring sex distributions from 1950 to 1969 by 5-year period were calculated in the overall population of Minamata City, in the most prevalent area, in fishermen (most heavily exposed occupation group) and among Minamata disease patients using data from birth certificates. We also similarly calculated the sex ratio of stillborn fetuses in the city population using Kumamoto Prefecture's vital statistics on still-birth. Decreases in male births were observed in offspring in the overall city population, in fishermen, and in maternal Minamata disease patients in the city in 1955-1959, when the methylmercury pollution was most severe. An increase in the proportion of male stillborn fetuses in the city was observed at the time. It is possible that male fetuses were more susceptible to the pollution than their female counterparts, and this could be a cause for the lower numbers of male offspring at birth., (Copyright 2001 Academic Press.)

Fish consumption is an important source of protein among indigenous communities in Amazonian Brazil. Exposures to mercury via fish were studied in an indigenous community of the Munduruku reserve, located in the Tapajós River basin in the state of Pará, one of the oldest and most productive gold mining areas in the Amazon region. This study summarizes the results of mercury (Hg) analyses of fish consumed by inhabitants of the Munduruku settlement of Sai Cinza. The most frequently consumed fish, reported by 330 persons interviewed for this study, were tucunaré, pacu, jaraqui, traíra, aracu, matrinchã, and caratinga. The mean mercury concentration in carnivorous fish was 0.297 microg.g(-1) while in noncarnivorous fish mean mercury concentration was 0.095 microg.g(-1). Only in caratinga was there a significant relationship between fish size, weight, and mercury levels. Levels of methylmercury in the tucunaré averaged 0.170 microg.g(-1), while in traíra the mean level of methylmercury was 0.212 microg.g(-1). Although the levels of Hg in fish consumed by the Sai Cinza community are below the Brazilian limit value for consumption, the high rates and amounts of fish consumed by this population are relevant to evaluating risks of mercury contamination for communities with limited food resources., (Copyright 2000 Academic Press.)

Human exposure to methylmercury (MeHg), a known neurotoxin, is primarily from fish consumption. As part of a large study examining the association between MeHg exposure and child development in a population with high fish consumption we examined school-age behavior using the Achenbach Child Behavior Checklist (CBCL). The CBCL Total T score was a primary endpoint and was reported earlier to show no adverse association with prenatal or postnatal MeHg exposure. In this study we analyzed the T scores of the CBCL subscales to determine if more discrete aspects of measured behavior were associated with exposure. The Seychelles Child Development Study (SCDS) is a prospective, double blind, longitudinal evaluation of over 700 children. The index of prenatal exposure was maternal hair total mercury (T-Hg) in a segment growing during gestation. Postnatal exposure was T-Hg in the child's hair taken at 66 months of age. The child's primary caregiver completed the CBCL during the 66-month evaluation. No association between prenatal or postnatal MeHg exposure and the CBCL subscales was found. In Seychellois children exposed to MeHg from consumption of ocean fish we found no association between either prenatal or postnatal MeHg exposure and behavior as measured by the CBCL subscales., (Copyright 2000 Academic Press.)

The Seychelles Child Development Study has been unable to confirm any relationship between maternal exposure to MeHg during pregnancy and adverse developmental outcomes. In this report, 87 children from a pilot cohort were evaluated at 9 years of age. Each child was given a battery testing specific cognitive, visual motor, and motor skills using standardized psychometric and neuro-psychological tests. The results indicated no adverse association between maternal MeHg exposure and any developmental outcome measure. For three endpoints (Boston Naming Test and two tests of visual motor coordination), enhanced performance in males was associated with increasing prenatal MeHg exposure. A secondary analysis including both prenatal MeHg and postnatal MeHg exposure was done even though we lacked postnatal hair for about 35% of the cohort. The results of the secondary analysis mirrored the outcomes of the primary analysis regarding prenatal exposure but were less robust. The results of this study are consistent with earlier findings from the 66-month evaluations of the SCDS Main cohort. Since MeHg is neurotoxic, this effect is likely due to other factors associated with consumption of fish., (Copyright 2000 Academic Press.)

Research at the University of Rochester (U of R) has been focused on mercury for nearly half a century. Initially studies focused on dosimetry, especially the accuracy of measuring exposure, and experimental work with animal models. Clinical studies in human populations started when the U of R mercury group was asked to assist with dosimetry in the Iraq epidemic of 1971-1972. Initial clinical studies described the effects of methylmercury (MeHg) poisoning on adults and children. A dose-response curve for prenatal exposure was determined and it suggested that relatively low exposures might be harmful to the fetus. Since most human exposure to MeHg is dietary from fish consumption, these theoretical dangers had far-reaching implications. After Iraq, the Rochester team pursued exposure from fish consumption in both adults and children. Populations with high fish consumption were identified in Samoa and Peru for studying adults and in Peru and the Seychelles islands for studying children. The possible health threat to the fetus from maternal fish consumption quickly became the focus of research efforts. This paper reviews the Rochester experience in studying human exposure to MeHg from fish consumption.

It is important to follow up on the health status of inhabitants living in the methyl mercury-polluted area surrounding Minamata City, paying particular attention to diseases not only of the central nervous system but also of other organs. We have been carrying out such concentric studies for more than 10 years. We have previously studied the cause-specific standard mortality ratios in Minamata disease patients and reported that the SMRs for liver disease and renal disease were significantly raised in male and female patients, respectively. It was also found that complications arising from diabetes could be due to the large number of old people among the autopsy cases. The next step was to clarify the actual prevalence and incidence of liver disease, renal disease, and diabetes mellitus epidemiologically among the population in this area. The aim of this study was to determine the actual prevalence of these diseases and complaints, and to investigate the contribution of various risk factors to these diseases in this area. The study was a population-based cross-sectional mass screening survey. A case-control study was designed to estimate the role of various risk factors including methyl mercury exposure for these diseases. A mass multiple health examination survey was performed in 1500 subjects aged 40 years and older in Tsunagi Town, neighboring Minamata City, every summer since 1984. Tsunagi Town is located in a methyl mercury-polluted area and there are 36.9 certified Minamata disease patients per 1000 population. Data concerning liver disease, renal disease, and diabetes mellitus were collected on the basis of urine, hematological, physical, and ultrasonographic examinations. Data on risk factors and subjective complaints were collected by interview and other measures. The prevalence of these diseases was not higher in this methyl mercury-polluted area compared with other areas in Japan, contrary to what was expected based on standard mortality ratios and pathological findings. There were no positive correlations between those diseases and methyl mercury exposure. On the other hand, the population in the polluted area had more and a greater variety of complaints than those in the nonpolluted area. It is possible that not only neurological subjective complaints but also nonspecific complaints of the population in the polluted area might be influenced by past methyl mercury exposure. This health surveillance in the population living in a methyl mercury-polluted area must be maintained in the future., (Copyright 2000 Academic Press.)

This research is focused on prenatal and early postnatal mercury (Hg) exposure among the riverside people along the Upper Madeira river in the Amazon. Linear regression models were developed to predict the hair Hg concentration in infants. The independent variables included in the model of Group 1 (87 pairs of mothers and their infants) were the average maternal hair Hg concentration and maternal age. Group 2 (31 pairs) included maternal segmental hair Hg concentrations. For the segmental hair Hg analysis over time, it was assumed that hair grows at a rate of 11 cm per month. Thus, information on the timing of the dates of pregnancy and breast feeding from the birth history was used to cut the hair strands into segments, making them correspond to the mother's reproductive stage of life (31 pairs of mothers and their infants). Breast milk Hg concentration results were included with segmental and average maternal hair Hg concentration values (22 and 44 pairs of mothers and their infants, respectively). The models including the breast milk Hg concentration indicated that 61 and 55% of the variability of the infant hair Hg concentrations were due to the independent variables: segmental maternal hair Hg with breast milk Hg and average maternal hair Hg with breast milk Hg, respectively. The regression coefficients were in the range of 0.19 to 0.90, and P values were in the range of 0.0001 to 0.1490. Further recommendations include fish advisories to prevent critical Hg exposures during reproductive life and investigation of neurobehavioral performance of this study population., (Copyright 2000 Academic Press.)

To quantify rapid and precise proximo-distal movements, we have developed a simple system (eurythmokinesimeter or EKM) which requires the subject to touch alternately the center of proximal and distal targets with a stylus. Ninety-six participants, including 30 controls subjects, 36 Cree subjects exposed to mercury, 21 subjects with Parkinson disease, 6 with presumed cerebellar deficit, and 3 with essential tremor, participated in the study. A total of nine measures, including precision, imprecision, contact duration, unsureness, tremor, transit time, irregularity, speed, and Fitts' constant, were calculated. Test-retest reliability was above 0.8 for most measures and above 0.9 for many measures. Correlations between measures and number of outliers with respect to the control group distribution for each measure were used to reduce the set of measures to five (i.e., precision, imprecision, tremor, Fitts' constant, and irregularity). An ANOVA on the three largest groups generated significant results for tremor, Fitts' constant, and irregularity between the Cree and the control subjects and on Fitts' constant and irregularity between the subjects with Parkinson's disease and the control subjects. Three subgroups of the same mean age composed of six subjects each were selected. One was composed of Cree subjects with the highest level of mercury exposure, another with Cree subjects having a low level of mercury exposure, and a third with control subjects. An ANOVA on these three groups revealed a significant difference between both groups of Cree subjects and the control group for Fitts' constant and irregularity. These preliminary results suggest that the EKM system is able to discriminate the performance of different groups of subjects., (Copyright 1999 Academic Press.)

To quantify rapid alternating movements (RAMs) we used a simple prototype developed in our laboratory that requires the subject to rotate two hand-held foam spheres connected to optical encoders via flexible rods. Ninety-six participants, including 30 control subjects, 36 Cree subjects exposed to methylmercury, 21 subjects with Parkinson's disease, 6 subjects with cerebellar deficits, and 3 subjects with essential tremor, were involved in the study (though data for 5 were later removed). Twelve characteristics were developed and calculated from the raw data. Conditions examined included two hands at natural cadence (NC2), right and left hands separately at fast cadence (FCl), and both hands at fast cadence (FC2). Two ratios (FC2/NC2) and (FC2/FC1) combining these conditions were also examined. Test-retest reliability was >0.80 for most characteristics but was <0.70 for some characteristics, especially in the conditions executed at normal cadence. Correlations between characteristics and numbers of outliers with respect to the control group distribution were used to reduce the set of characteristics from 12 to 7 (i.e., duration, range, maximum slope, similarity in shape, smoothness, sharpness, and coherence). ANOVAs on the three largest groups generated significant results for most characteristics in the three conditions and the two ratios for Cree subjects and subjects with Parkinson's disease. ANOVAs on 3 age-matched groups (n=6) suggest that methylmercury affects the performance of the Cree subjects with the higher exposure, especially in terms of smoothness, sharpness, and coherence. These preliminary results suggest that this test is sufficiently specific and sensitive to characterize the performance of different groups of subjects. Ratios tend to improve discrimination for Cree subjects in a few characteristics but not for patients with Parkinson's disease., (Copyright 1999 Academic Press.)

Mercury was not regarded as a pollutant of primary importance until many deaths due to mercury poisoning occurred in the 1950s. More recently, adverse health effects have been documented at relatively low exposure levels, and monitoring data must now be interpreted in this light. The Mediterranean basin has been studied in great detail over the past 20 years because of the anomalous natural presence of mercury. Marine animals of this basin have higher mercury body burdens than the same (or similar) species in the Atlantic. The mercury found in marine organisms is mainly in the form of methyl mercury. Long-term and frequent intake of seafood with high mercury levels by populations living in coastal fishing villages is associated with a toxic risk, especially in pregnant women. High blood and hair concentrations of mercury have repeatedly been found in fishermen of Tyrrhenian coastal villages. In some cases these concentrations have been associated with an increase in DNA damage in blood cells. High mercury levels in hair and blood of people from a fishing village of Madeira have also been found. This information deserves renewed scrutiny with regard to preventive efforts needed., (Copyright 1998 Academic Press.)

Within a cohort of 1022 consecutive singleton births in the Faroe Islands, we assessed prenatal methylmercury exposure from the maternal hair mercury concentration. At approximately 7 years of age, 917 of the children underwent detailed neurobehavioral examination. Little risk is thought to occur as long as the hair mercury concentration in pregnant women is kept below 10-20 microg/g (50-100 nmol/l). A case group of 112 children whose mothers had a hair mercury concentration of 10-20 microg/g was therefore matched to children with exposure below 3 microg/g, using age, sex, time of examination, and the mother's score on Raven's Progressive Matrices as matching criteria. The two groups were almost identical with regard to other factors that might affect neurobehavioral performance in this community. On six neuropsychological test measures, the case group showed mild decrements, relative to controls, especially in the domains of motor function, language, and memory. Subtle effects on brain function therefore seem to be detectable at prenatal methylmercury exposure levels currently considered to be safe., (Copyright 1998 Academic Press.)

Mercury releases from gold mining occurred during the 1980s in the Upper Madeira river, a Southern tributary of the Amazon. Downstream from these areas, riverside residents rely on fish consumption for subsistence. In July of 1993, hair samples were collected for mercury analysis from a group of mothers and their infants and one pregnant woman. By assuming a constant rate of hair growth (1.1 cm per month), a temporal profile of the methylmercury exposure was determined for the previous 2 to 3 years. The length of hair segments corresponded to hair growth during pregnancy and the subsequent breastfeeding periods. During all periods, hair mercury concentrations in six mothers were in the range of 4.5-26.8 ppm, slightly lower than those of their infants (8.2-28.4 ppm). Further segmental analyses of hair mercury from another six mothers showed concentrations in the range of 12.2-41.0 ppm during the three trimesters of pregnancy and 4.0-33.5 ppm during breast feeding-slightly lower than their infants (11.6-50.4 ppm). Another four mothers showed hair mercury concentrations in the range of 21. 3-84.4 ppm., (Copyright 1998 Academic Press.)

A total of 191 fishermen and their family (32-82 years) living in some mercury-polluted areas along the Shiranui Sea volunteered for the present study. They made a living by fishery and had formerly eaten the methyl mercury-contaminated fish and shellfish caught there. The questionnaire on subjective symptoms, fish eating habits, and past living history was conducted on the subjects. In addition, they were clinically examined in detail by several neurologists and scalp hair was collected. With six exceptions, all the 185 subjects showed a normal total mercury level in hair (<10 ppm). The ratio of methyl mercury to total mercury was 79-94% on the average for each group examined, suggesting indirect contamination (perhaps through the food chain). Despite their low mercury level in scalp hair, however, the subjects showed various neurological symptoms, particularly, sensory disturbance (such as the glove and stocking type), at a very high rate. Thus, it seems fair to state that, in addition to officially recognized Minamata disease patients, there still exist many people with atypical, slight Minamata disease on the coast of the Shiranui Sea. The current hair mercury level is not necessarily useful as a criterion for diagnosing chronic Minamata disease because of the long lapse of time., (Copyright 1998 Academic Press.)

There is growing evidence that heavy metals, in general, and mercurial compounds, in particular, are immunotoxic to the human immune system. The major focus of our study is to demonstrate that methylmercuric chloride (MeHgCl) kills human lymphocytes by inducing apoptosis. T-cells exposed to 0.6-5 microM MeHgCl for 24 h were analyzed by flow cytometry. Methylmercury-treated cells exhibited increased Hoechst 33258 fluorescence while maintaining their ability to exclude the vital stain 7-aminoactinomycin. Furthermore, T-cells exposed to methylmercury exhibited changes in light scatter patterns that included decreased forward light scatter and increased side light scatter. The light scatter and fluorescent changes were consistent with morphological alterations displayed by cells during apoptosis. Cell death was further evaluated by assessing annexin V binding to the plasma membrane. Methylmercury-treated cells exhibited increased annexin V binding indicative of phosphatidylserine translocation to the outer leaflet of the plasma membrane. Using the fluorescent probe DiOC6(3), we noted that methylmercury exposure resulted in a decrease in mitochondrial transmembrane potential (Psim). Since a low Psim is associated with altered mitochondrial function, we also determined if exposure to methylmercury potentiated reactive oxygen species (ROS) generation. We noted that treated cells generated ROS, as evidenced by oxidation of hydroethidine and the generation of the fluorescent product, ethidium. Finally, we evaluated the effect of methylmercury on T-cell GSH content utilizing the fluorescent probe monochlorobimane; in the presence of MeHgCl, there is a marked loss in reduced cell thiols. The results of the study indicate that a key event in the induction of T-cell apoptosis by mercuric compounds is depletion in the thiol reserve which predisposes cells to ROS damage and at the same time activates death signaling pathways., (Copyright 1998 Academic Press.)

Suriname is experiencing a revival of small scale gold mining activities, with about 10,000 to 15,000 workers involved in 1996. The estimated production in 1995 is at least 10,000 kg crude gold. Gold is extracted with mercury and methods used are comparable with those described for gold mining in the Amazon Basin. Since no data exist on the internal mercury exposure of workers in Suriname a study was performed. A group of mercury-exposed Maroons, who are principally involved in the mining located in the tropical rainforest, is compared with nonexposed Maroons living in a non-gold mining area. Blood and urine samples of both groups were analyzed for total mercury using an atomic absorption spectrometer with an FIAS hydride system. In the study 28 exposed and 17 controls with a comparable mean age (P=0.544; exposed 27+/-7.2 years, n=26; controls 26+/-7.7 years, n=17), all males, participated. The urine levels for both groups differ statistically significantly from each other (P<0.001; exposed mean 27.5+/-21.1 microg/g creatinine; controls mean 5. 2+/-2.9 microg/g creatinine). This is, however, not the case with the blood levels (P=0.036: exposed mean 18.1+/-11.0 microg/L, n=25; controls mean 26.8+/-14.6 microg/L, n=16). In contrast with blood the urine total mercury levels in this study confirm, on a group basis, exposure to mercury as described for individuals working in the gold mining in the Amazon Basin., (Copyright 1998 Academic Press.)

Amalgamation has been used for more than 4500 years in mining processes. Mercury has been extensively used in South America by Spanish colonizers for precious metal recovery. It is estimated that between 1550 and 1880, nearly 200,000 metric tonnes of mercury was released to the environment. During the present gold rush, Brazil is first in South America and second in the world in gold production (with 90% coming from informal mining or garimpos). At least 2000 tonnes of mercury has been released to the environment in the present gold rush. From the mid 1980s, environmental research has been carried out in impacted Amazon rivers, later followed by human exposure studies. The river basins studied were the Tapajós, Madeira, and Negro, but also some man-made reservoirs and areas in central Brazil. The analyses mainly involved sediments, soil, air, fish, human hair, and urine. The results show high variability, perhaps related to biological diversity, biogeochemical differences in the river basins, and seasonal changes. High mercury values also occur in some areas with no known history of gold mining. The results available document a considerable impact on environmental mercury concentrations and frequent occurrence of human exposure levels that may lead to adverse health effects., (Copyright 1998 Academic Press.)

Color vision was evaluated in twenty-one mercury exposed workers and referents matched for sex, age, tobacco smoking, and alcohol habits. The Lanthony 15 Hue desaturated panel (D-15 d) was applied. In the workers, mean urinary Hg (HgU) was 115+/-61.5 microg/g creatinine; in all but one the values exceeded the biological limit (BEI) proposed by the American Conference of Governmental Industrial Hygienists. A dose-related subclinical color vision impairment was observed in Hg-exposed workers compared to the referents. Just after the survey, working conditions were improved. Twelve months later the workers were reexamined. Mean HgU was 10.0 microg/g creatinine and in no subjects was the BEI exceeded. Color perception was significantly improved compared to the first examination and, furthermore, no differences were observed between exposed workers and referents. The results add evidence that the color vision loss observed during the first part of the study was related to Hg exposure and, moreover, show that this effect is reversible. These data indicate that metallic Hg can induce a reversible impairment in color perception. This suggests that color vision testing should be included in studies on the early effects of Hg. The possibility of applying the D-15 d as an early effect index in the biological monitoring of Hg exposed workers should also be entertained., (Copyright 1998 Academic Press.)

The present study aimed to evaluate methylmercury in fish and human hair samples from an important hydroelectrical reservoir, Balbina (Brazil, Amazon). It presents a quite intense fishing activity and there is no known goldmining activity in its watershed. Fish and human hair were analyzed with a new extraction technique and measured by GC-ECD. Analytical quality was checked through intercomparisons between two laboratories with local samples and certified standards from IAEA. Methylmercury in hair ranged from 2.0 to 21.6 microg . g-1 with a mean of 8.76+/-5.20 microg . g-1 (N=20), while the methylmercury percentages were above 90. Fish presented methylmercury levels ranging from 0.03 to 0.9 microg small middle dot g-1 wet wt with a mean of 0.24+/-0.18 microg small middle dot g-1 wet wt (N=32), which is below the limit established for food by Brazilian legislation (0.5 microg small middle dot g-1 wet wt) and methylmercury mean percentages were above 95%. The total mean daily methylmercury intake ranged from 11 to 55 microg for 70% of the sampled population from the village based on a daily consumption of about 110 g of fish with methylmercury concentrations in the range of 0.1 to 0.5 microg . g-1. This calculation is consistent with methylmercury concentrations in hair samples in the range of 2.6 to 13.1 microg . g-1., (Copyright 1998 Academic Press.)

The methylmercury exposure of patients with congenital or infantile Minamata disease is known only from a small number of analyses of umbilical cords. Four laboratories in Japan have analyzed a total of 176 samples of umbilical cord tissue obtained from Minamata. The highest concentrations were seen in cord tissue from children born during 1950-1965, i.e., the peak period of acetaldehyde production in Minamata before installation of waste water treatment. Twenty-four samples from patients diagnosed with Minamata disease showed a median mercury concentration of 1.63 microg/g and differed significantly from levels seen in cord tissue from control children. However, children diagnosed with mental retardation had mercury concentrations in cord that were intermediate between the two other groups. Using regression coefficients obtained at a study conducted at the Faroe Islands, the median cord mercury concentration from the children with Minamata disease is estimated to correspond to about 216 microg/L cord blood and 41 microg/g in maternal hair. Based on correlations reported in the literature, the median daily mercury intake of the women whose children developed Minamata disease can then be estimated at about 225 microg. Although these children had fully developed Minamata disease, the estimates of median mercury levels are only four to five times higher than current mercury exposure limits., (Copyright 1998 Academic Press.)

Sources of bias were examined in a study of neurobehavioral effects of intrauterine exposure to methyl mercury in the Faroe Islands. The cohort of 1000 children was born during a 21-month period and did not differ from Faroese births in general as regards major obstetrical parameters. However, high mercury concentrations in the cord blood was associated with increased birth weight, presumably because other constituents of marine fish may cause a prolongation of the gestation period. Thus, children with high mercury exposures were somewhat protected against low birth weight and its associated neurobehavioral risks. Less than 25% of the women indicated occasional alcohol drinking during pregnancy, thus suggesting a limited fetal exposure to this neurobehavioral risk factor. However, maternal alcohol drinking caused a decrease in mercury concentrations in cord blood, probably because of a toxicokinetic interaction between ethanol and mercury. Any alcohol-related effect on neurobehavioral development would then be associated with lower levels of mercury exposures. The effects of these confounders would tend to bias the results of the study toward the null hypothesis.

The effects of methylmercuric chloride, mercuric chloride, and phenylmercuric acetate (10(-6) - 10(-3) mole/liter) on thrombin-induced release of adenine nucleotides from washed pig platelets were investigated. The inhibitory effects of mercurials were always reached when the higher thrombin concentration (0.74 units NIH/ml) was used. Incubation of washed pig platelets with methylmercuric chloride caused a decrease of intracellular level of platelet ATP and statistically significant changes in ATP/ADP ratio.