Assessment of mercury exposure and malaria in a Brazilian Amazon riverine community

Small-scale gold mining in the Brazilian Amazon occurs in areas with high rates of malaria transmission. Amazonian populations can be exposed to mercury through direct contact with the mining process and/or through fish consumption. Because of data from experimental studies, we examined the potential for mercury to affect host response to malaria. A cross-sectional survey was done in Jacareacanga, a riverine community in Para state, in a region of intense alluvial gold mining. A sample of 205 persons was selected by cluster sampling from the total population of approximately 2000. A brief medical history and exam were conducted, malaria slides were obtained, and hair samples were taken to measure mercury levels. The average hair mercury level was 8.6 micrograms/g, ranging from 0.3 to 83.2 micrograms/g. The most important predictors of elevated mercury levels were high fish consumption and low income. Although there was no prevalent malaria, the odds of reporting a past malaria infection was four times higher for those also reporting a history of working with mercury.     

Sexual differences in the distribution and retention of organic and inorganic mercury in methyl mercury-treated rats

At 56 days of age, male and female Long-Evans rats received 1 mumole of 203Hg-labeled methyl mercuric chloride per kilogram sc and total, organic, and inorganic mercury contents and concentrations in tissues were determined for up to 98 days postdosing. Whole body clearance of mercury was faster in females than in males, and females attained higher peak percentages of the methyl mercury dose in kidney and brain than did males. Females had significantly higher mean percentages of the mercury dose present in the kidney and brain as organic or total mercury and in brain as inorganic mercury than did males. Males had significantly higher mean percentages of the dose present as organic or total mercury in pelt and whole body than did females. When expressed on a concentration basis, the only significant sexual difference was in the higher average concentration of organic mercury in the kidneys of females. When expressed on a tissue content basis, significant male-female differences in the kinetics (sex X time interactions) of organic mercury retention were found in kidney, brain, skeletal muscle, pelt, and whole body. Significant sex X time interactions in the concentrations of organic mercury were found in kidney, skeletal muscle, and whole body. Kinetics of retention and concentration of inorganic Hg in the pelt differed significantly for males and females. Discordance in degree of statistical significance of differences in mercury contents and concentrations reflected in part differences in relative body composition of males and females. Integrated exposures of tissues of males and females to organic or inorganic mercury were determined by fitting multiexponential retention functions to retention data. Differences in integrated exposure were estimated by the female-to-male ratio of areas under retention curves. Reconstruction of whole body organic and inorganic mercury burdens from constituent tissues indicated that integrated exposures of males and females to inorganic mercury were equal but females had a lower integrated exposure to organic mercury. Integrated exposure of liver to either form of mercury was about equal in males and females. However, the integrated exposure of the brain of females to inorganic mercury was 2.19 times that of males suggesting a sexual difference in accumulation or retention of inorganic mercury in the nervous system. These sexual differences in distribution and retention of organic and inorganic mercury after methyl mercury exposure may underlie reported sexual differences in sensitivity to the toxic effects of methyl mercury.     

Uptake of mercury by the hair of methylmercury-treated newborn mice

Human hair has unique advantages in monitoring environmental exposures to methylmercury. Using newborn Balb/c mice as a model system, the incorporation of methylmercury into the hair was studied and compared with methylmercury distributions in other tissues. Newborn mice were given intraperitoneal injections of 203Hg-labeled methylmercury at designated times according to hair growth stages of the mouse. Animals were sacrificed 2 days after dosing. Distribution of mercury in pelt and other tissues was measured. The level of mercury in pelt was found to correlate with hair growth. The amount of mercury in pelt peaked when hair growth was most rapid and the total amount of mercury in pelt was significantly higher than that in other tissues, constituting 40% of the whole body burden. However, when the hair ceased growing, the amount of mercury in pelt dramatically dropped to 4% of whole body burden and mercury concentrations in other tissues except brain were elevated. Autoradiographic studies with tritium-labeled methylmercury demonstrated that methylmercury concentrated in hair follicles in the skin. Within hair follicles and hairs, methylmercury accumulated in regions that are rich in high-sulfur proteins. The uptake of inorganic mercury (administered as HgCl2) by pelt was also compared with that of methylmercury. The amount of inorganic mercury found in pelt was less than one-half that of methylmercury in animals with growing hair. Cessation of hair growth did not decrease the inorganic mercury level in pelt to the same extent as in the case of methylmercury.     

三种典型汞污染源暴露人群的发汞水平调查

[目的]研究典型汞污染源暴露人群的发汞含量,为保护相关人群健康提供依据。[方法]收集浙江某电子废弃物回收区人群发样64份,辽宁某煤矿区人群发样145份、尿样145份,上海某医院医护人员发样62份。采用冷原子吸收法测定发总汞和尿汞含量,采用盐酸-甲苯萃取,气相色谱测定甲基汞含量。[结果]电子废弃物回收区人群中酸洗工人头发总汞含量为1.64μg/g,工业区管理人员为0.84μg/g;当地市民头发甲基汞含量为1.25μg/g,酸洗工人仅为0.23μg/g。辽宁铁岭煤矿区人群发汞含量为煤矿工人0.87μg/g、矿区管理人员0.65μg/g、当地居民0.60μg/g,上述3种人群的尿汞含量分别为12.13、2.74、2.14μg/L;上海某医院不同科室的医务人员发汞含量均低于美国环境保护署规定的发汞安全限值1.0μg/g。[结论]台州电子废弃物回收区和铁岭煤矿区工人存在一定的汞污染暴露风险。     

A nonoccupational outbreak of inorganic mercury vapor poisoning

An outbreak of inorganic mercury vapor poisoning involving 12 people occurred in a trailer park in Mississippi in 1973-74. For information concerning levels of mercury in hair and blood of humans with short-term exposures, these individuals were observed for as long as 10 months after the end of their exposures, and the amount of mercury in their blood and scalp hair was serially measured. Specimens were also obtained from nonexposed individuals in the trailer park. Inorganic mercury was measured in 1-cm segments of hair samples obtained both 6 and 9 months after termination of exposure. Over a 3-month period, the peak amount of inorganic mercury per gram of hair shifted in position from 7 cm to 13 cm from the scalp. The average mercury concentration in newly formed hair (the 4 cm of hair closest to the scalp) decreased fourfold over the same time period. Surface contamination of exposed hair by exogenous mercury also occurred. Levels of inorganic mercury in blood from exposed individuals ranged from 183 to 620 ng/ml and fell to levels similar to those of controls 4 to 6 months after ending exposure. The source of the outbreak was metallic mercury spilled on rugs. Attempts to remove the mercury failed and actually dispersed the metal over a larger surface area. Air mercury levels as high as 1.0 mg/m3 of air were found in one of the contaminated house trailers. Rugs or carpets contaminated with metallic mercury are a significant health risk.     

Comparison of hair with nail as index media for biological monitoring of mercury

Mercury in hair and nails was determined with speciation of chemical forms of mercury. Scalp hair and toenails were sampled once and fingernails were sampled three times from the subjects (18 males and 5 females) whose age ranged from 23 to 56 yr. Total mercury (THg) and inorganic mercury (IHg) were determined by Magos' method with modifications. No sex-related differences were found in mercury levels in hair and nails. In the fingernail samples of three different formation periods, THg and IHg concentrations remained almost constant. Among the three kinds of index media, the highest THg concentration was found in scalp hair followed by fingernails and toenails in the order given, whereas IHg concentrations in scalp hair were similar as those in fingernails but were lowest in toenails. The percent inorganic to total mercury was higher in fingernails than in hair and toenails, which is likely to reflect a possible external contamination with IHg in fingernails. The higher THg concentration in scalp hair than in nails may be attributable to the difference in the chemical composition, in particular sulphur content, and in the blood flow during the formation of hair and nails.     

Mercury exposure in a high fish eating Bolivian Amazonian population with intense small-scale gold-mining activities

Methylmercury exposure in Amazonian communities through fish consumption has been widely documented in Brazil. There is still a lack of data in other Amazonian countries, which is why we conducted this study in the Bolivian Amazon basin. Simple random sampling was used from a small village located in the lower Beni River, where there is intense gold mining and high fish consumption. All participants were interviewed and hair samples were taken to measure total mercury concentrations. The hair mercury geometric mean in the general population was 3.02 μg/g (CI: 2.69–3.37; range: 0.42–15.65). Age and gender were not directly associated with mercury levels. Fish consumption showed a positive relation and so did occupation, especially small-scale gold mining. Hair mercury levels were lower than those found in Brazilian studies, but still higher than in non-exposed populations. It is necessary to assess mercury exposure in the Amazonian regions where data is still lacking, using a standardized indicator.     

Inorganic and organic mercury in blood,urine and hair in low level mercury vapour exposure

Summary Fourteen Japanese females exposed to elemantal mercury vapour of concentration; 0.001–0.019 mg Hg/m³, were examined for inorganic and organic mercury concentrations in red blood cells, plasma, urine, and hair. Examinations were conducted the times; at 0,4 and 8 months of mercury exposure. No significant change of inorganic and organic mercury in urine was observed for three examinations. Both inorganic and organic mercury in plasma, and only organic mercury in red blood cells, increased significantly after commencement of mercury work. The hair organic mercury values stayed constant. The intake of organic mercury was judged as constant from the constancy of hair mercury values, and the change of organic mercury concentrations in plasma and red blood cells must have been elicited from the intake of elemental mercury. The reason why the increase of plasma mercury values did not reflect to urine mercury values was discussed.Supported by the grant from the Japanese Ministry of Education     

宁波市262例居民发汞含量的调查

目的了解长江三角洲地区典型工业城市宁波居民的汞蓄积情况及其分布特征。方法于2004年10月—2005年3月在宁波市3个中心城区——江东、江北、海曙收集262份样品。用冷蒸气原子吸收法测定头发样品中的总汞含量。结果头发样品中总汞为0．217—5．792mg／kg，平均为1．176mg／kg；偏正态分布，发汞含量主要集中在0．5—1．75ms／ks。与其他城市相比较，发现宁波居民发汞值处于中偏低水平。结论宁波居民发汞平均值处于相对较低的水平，但仍存在一定风险；发汞值与年龄和性别均无显著相关关系。     

松花江汞污染综合治理后儿童发汞含量的调查

目的　了解松花江主要汞污染源综合治理后 ,环境汞污染现状及儿童体内汞蓄积水平。方法　设对照组与观察组 ,分别采集地面水、土壤、粮食、鱼及儿童头发 ,测定汞含量 ,并分别与 1 982年 (治理前 )和 1 992年 (即治理1 0年后 )汞含量水平比较。结果　观察组水、土壤、鱼汞含量显著低于 1 982年及 1 992年 (P <0 0 1 ) ;与对照组比较差异无统计学意义 (P >0 0 5 ) ,均未超过相应的卫生标准。观察组粮食汞含量与 1 982年及 1 992年相比明显降低 (P <0 0 1 ) ,但明显高于对照组 (P <0 0 5 )。观察组儿童发汞明显低于 1 982年及 1 992年 ,与对照组比较差异无统计学意义 (P >0 0 5 )。结论　松花江汞污染综合治理后环境汞污染状况已明显改善 ,未发现儿童体内汞蓄积现象。     

Scalp hair as a biomarker in environmental and occupational mercury exposed populations: suitable or not?

Hair is a well-established and widely used matrix for measuring mercury exposure of an individual. Although a variety of washing procedures to remove external mercury contamination have been proposed, no standardized procedures are available yet. In this study, different washing reagents like l-cysteine (Cys), 2-mercaptoethanol (ME), and disodium diaminoethanetetra acetate (EDTA) were used to find out if it is possible to remove mercury contamination from human scalp hair spiked with HgCl2 solutions at different concentrations. It was found that the external mercury contamination could not be fully washed off even using reagents with high affinity to mercury like l-cysteine and ME. However, for the well-pulverized CRM hair samples some of the endogenous mercury was washed off. It suggests that hair is not a suitable biomarker for evaluation of total mercury exposure especially in people like mercury miners or gold miners/burners associated with serious external Hg exposure. However, hair still can be used as an indicator for methyl mercury exposure because, generally, there is almost no exogenous contamination of methyl mercury in hair.     

Hair mercury levels versus freshwater fish consumption in household members of Swedish angling societies

Hair mercury levels were determined in 143 individuals from households of members in angling societies in an area of Sweden with many lakes that have freshwater fish with relatively high mercury levels. Thus, the individuals had a potentially high intake of methyl mercury. The mean mercury concentration of pike and perch was approximately 0.7 microg/g. One-third of the subjects consumed these freshwater fish at least once a week. As could be expected, there was a clear increase in hair Hg with reported freshwater fish consumption (P < 0.001). The median mercury level in hair was 0.9 microg Hg/g for the whole group, and for those who reported consumption of freshwater fish at least once a week it was 1.8 microg/g. The highest hair mercury level was 18.5 microg/g, in a man who consumed pike and perch several times per week. Men had higher hair Hg than women, also when stratified for fish consumption. This was verified in 32 couples, of which the man and woman consumed the same fish and reported the same consumption. The median hair mercury level in these 32 couples was 1.3 microg/g for men and 0.8 microg/g for women (P = 0.002). About half of the subjects had hair mercury exceeding 1 microg/g, corresponding to the reference dose (RfD) of 0.1 microg of mercury per kilogram body weight set by the US Environmental Protection Agency. Although the RfD applies to all populations, the most at-risk group at these levels is pregnant women. There were only 2 women (of 12) of fertile age with hair mercury above 1 microg/g. In Sweden pregnant women are advised not to eat perch and pike at all during pregnancy. Since fish is rich in many important nutrients, it is unsatisfactory that fish consumption must be restricted, and thus there is a need to reduce mercury levels in fish.     

Hair mercury value and fish‐eating habit

Mercury levels in the hair segment close to the scalp were well correlated with fish‐eating habits for residents on a small island in the south of Japanese mainlands. Mercury levels changed in segmented hair samples along with the distance from the scalp. The time of sprouting of hair segment in which the mercury level showed the peak coincided well with the peak of catch of fish on the island.     

Lead and cadmium in hair as an indicator of body burden in rats of different age

Summary The purpose of this work was to evaluate whether hair values of lead and cadmium can be used as an indicator of the body burden of these metals in different age groups.The experiments were performed on rats aged 2 and 18 weeks, which received²⁰³pb and^115mcd by intraperitoneal injection. The whole body retention and the retention of these radioisotopes in the hair (including the skin) was determined 7 days later. Younger animals showed a higher retention in the whole body and hair of radioactive lead and cadmium. The hair values when expressed as the percentage of the whole body retention were for²⁰³pb the same in young and adult rats but for^115mcd they were 2 to 3 times higher in young animals than in adults. It is concluded that lead hair values are a good indicator of the total body burden in both age groups. However, the cadmium body burden of young animals would be greatly overestimated if based on hair values only. This findings might be relevant for interpreting results of hair concentrations of lead and cadmium in children.     

Mercury concentration in gray hair

Scalp hair sample were collected from 20 gray-haired males and 7 gray-haired females. Two hair samples, one each of dark hair and gray hair, obtained from each individual were selectively analysed for organic and inorganic mercury concentrations. The following finding were made: 1) In both sexes, total and organic mercury concentrations were significantly higher in gray hair than in dark hair but no difference was observed between dark hair and gray hair for the concentration of inorganic mercury. 2) For males, no significant differences between dark hair and gray hair were found for total, organic or inorganic mercury concentrations. On the other hand, gray hair had significantly higher levels of total, organic and inorganic mercury concentrations than dark hair in females. 3) When comparison was made between the sexes, total, organic and inorganic mercury concentrations were significantly higher in males than in females for dark hair. For gray hair, however, significantly higher levels of total and organic mercury concentrations, but not of inorganic mercury concentrations, were found in males. 4) The proportion of inorganic mercury to total mercury was higher in females than in males for both dark and gray hair. It was also higher in gray hair than in dark hair for females.     

Effect of milk on mercury absorption and gut retention in rats.

The retention of 203Hg was studied six days after a single oral or intraperitoneal administration to six week old female albino rats fed rat's diet or milk. After oral administration rats on milk diet had a two times higher retention of mercury in the gut-free carcass and a 23 times higher retention in the gut than animals on rat's diet. Changes in diet had very little influence on mercury retention after intraperitoneal administration. The higher gut and carcass rentions of mercury in animals on milk diet could be prevented or reduced by transferring rats from milk diet to rat's diet several days after an oral dose of mercury. These results might be relevant for interpreting high gut and carcass retention after oral administration of some metals in suckling and changes which occur at weaning.     

Factors contributing to the difference of hair mercury concentrations between the sexes

Scalp hair samples were collected by mail from 97 married couples who were living in several places in Okinawa-prefecture and supposedly had no specific exposure to mercury compounds. They were selectively analysed for organic and inorganic mercury content and the difference of hair mercury concentration between the sexes was discussed in relation to the frequency of fish intake, fish species, drinking habits and permanent-wave hair treatment. Results obtained were as follows: 1) The increase in hair levels of organic and inorganic mercury concentrations was roughly proportional to the dietary intake of fish in the range from none or low to moderate frequencies for both husbands and wives. However, this increase was not proportional to the dietary intake of fish in the range from moderate to high frequencies, showing almost the same level irrespective of the frequency of fish intake. 2) Though husbands and wives had dietary consumption patterns quite similar to each other, husbands were found to have higher hair organic mercury levels than wives, the average values being 6.40 ppm with a standard deviation of 4.69 ppm for husbands and 2.86 ppm with a standard deviation of 1.97 ppm for wives, respectively. The difference was statistically significant. No significant difference between the sexes was detected for inorganic mercury concentrations. However, a highly significant positive correlation coefficient for organic mercury and also a significant positive correlation coefficient for inorganic mercury were found between husbands and wives. 3) Hair without permanent-wave treatment showed higher levels of organic mercury concentrations than hair with permanent-wave treatment for both husbands and wives. Drinkers also had higher levels of hair mercury as compared to non-drinkers. However, the lower levels of organic mercury concentrations in women's hair than in men's hair were not fully explained by these factors. 4) Both men and women who showed higher hair levels of organic mercury had a preference for highly predatory fish such as tuna and bonito, which probably contributed most to the human intake of mercury.     

Trace element status in healthy subjects switching from a mixed to a lactovegetarian diet for 12 mo.

The consequences of a change from a mixed to a lactovegetarian diet for 12 mo on trace element concentrations in plasma, hair, urine, and feces were studied in 16 women and 4 men. After the diet shift, intakes of zinc and magnesium did not change but that of selenium decreased by 40%. Three months after the diet shift, plasma and hair concentrations of zinc, copper, and selenium had decreased but those of magnesium had increased and the concentrations of mercury, lead, and cadmium in hair were lower. Also, the excretion of zinc, copper, and magnesium in urine, and that of selenium in urine and feces had decreased. Only small changes occurred during the remaining lactovegetarian-diet period. Three years later trace element concentrations had reverted towards baseline concentrations; copper values were similar to baseline concentrations but data for magnesium were slightly higher, and more complex patterns were observed for zinc and selenium. It is concluded that a shift to a lactovegetarian diet changes trace element status.     

Mercury and selenium distribution in a defined area and in its population.

In the Amiata Mountain area of Tuscany, Italy, a survey has examined the concentrations of mercury and selenium in the environment, in the food chain, and in human biological samples of blood, urine, and hair. This area was selected for study because of its large mineral deposits and concentration of elements, e.g., iron, copper, silver, antimony, and particularly mercury. Subjects consisted of a group with high occupational exposure to mercury vapor, a group randomly exposed to mercury dust, and a group nonoccupationally exposed to mercury. The selenium and mercury contents in all samples were determined by nondestructive neutron activation analysis, and results showed that the human metabolism of mercury is different from that of selenium and that the selenium retention in man could be influenced by the mercury intake. Furthermore, a great part of selenium introduced through the diet passes into the blood, where it is mainly associated with blood cells.