A Review of Events That Expose Children to Elemental Mercury in the United States

Objective

Concern for children exposed to elemental mercury prompted the Agency for Toxic Substances and Disease Registry and the Centers for Disease Control and Prevention to review the sources of elemental mercury exposures in children, describe the location and proportion of children affected, and make recommendations on how to prevent these exposures. In this review, we excluded mercury exposures from coal-burning facilities, dental amalgams, fish consumption, medical waste incinerators, or thimerosal-containing vaccines.

Data sources

We reviewed federal, state, and regional programs with information on mercury releases along with published reports of children exposed to elemental mercury in the United States. We selected all mercury-related events that were documented to expose (or potentially expose) children. We then explored event characteristics (i.e., the exposure source, location).

Data synthesis

Primary exposure locations were at home, at school, and at other locations such as industrial property not adequately remediated or medical facilities. Exposure to small spills from broken thermometers was the most common scenario; however, reports of such exposures are declining.

Discussion and conclusions

Childhood exposures to elemental mercury often result from inappropriate handling or cleanup of spilled mercury. The information reviewed suggests that most releases do not lead to demonstrable harm if the exposure period is short and the mercury is properly cleaned up.

Recommendations

Primary prevention should include health education and policy initiatives. For larger spills, better coordination among existing surveillance systems would assist in understanding the risk factors and in developing effective prevention efforts.     

A Quantitative Synthesis of Mercury in Commercial Seafood and Implications for Exposure in the United States

Background: Mercury (Hg) is a toxic metal that presents public health risks through fish consumption. A major source of uncertainty in evaluating harmful exposure is inadequate knowledge of Hg concentrations in commercially important seafood.Objectives: We examined patterns, variability, and knowledge gaps of Hg in common commercial seafood items in the United States and compared seafood Hg concentrations from our database to those used for exposure estimates and consumption advice.Methods: We developed a database of Hg concentrations in fish and shellfish common to the U.S. market by aggregating available data from government monitoring programs and the scientific literature. We calculated a grand mean for individual seafood items, based on reported means from individual studies, weighted by sample size. We also compared database results to those of federal programs and human health criteria [U.S. Food and Drug Administration Hg Monitoring Program (FDA-MP), U.S. Environmental Protection Agency (EPA)].Results: Mean Hg concentrations for each seafood item were highly variable among studies, spanning 0.3–2.4 orders of magnitude. Farmed fish generally had lower grand mean Hg concentrations than their wild counterparts, with wild seafood having 2- to12-fold higher concentrations, depending on the seafood item. However, farmed fish are relatively understudied, as are specific seafood items and seafood imports from Asia and South America. Finally, we found large discrepancies between mean Hg concentrations estimated from our database and FDA-MP estimates for most seafood items examined.Conclusions: The high variability in Hg in common seafood items has considerable ramifications for public health and the formulation of consumption guidelines. Exposure and risk analyses derived from smaller data sets do not reflect our collective, available information on seafood Hg concentrations.     

Mercury Exposure and Antinuclear Antibodies among Females of Reproductive Age in the United States: NHANES

Background

Immune dysregulation associated with mercury has been suggested, although data in the general population are lacking. Chronic exposure to low levels of methylmercury (organic) and inorganic mercury is common, such as through fish consumption and dental amalgams.

Objective

We examined associations between mercury biomarkers and antinuclear antibody (ANA) positivity and titer strength.

Methods

Among females 16–49 years of age (n = 1,352) from the National Health and Nutrition Examination Survey (NHANES) 1999–2004, we examined cross-sectional associations between mercury and ANAs (indirect immunofluorescence; cutoff ≥ 1:80). Three biomarkers of mercury exposure were used: hair (available 1999–2000) and total blood (1999–2004) predominantly represented methylmercury, and urine (1999–2002) represented inorganic mercury. Survey statistics were used. Multivariable modeling adjusted for several covariates, including age and omega-3 fatty acids.

Results

Sixteen percent of females were ANA positive; 96% of ANA positives had a nuclear speckled staining pattern. Geometric mean (geometric SD) mercury concentrations were 0.22 (0.03) ppm in hair, 0.92 (0.05) μg/L blood, and 0.62 (0.04) μg/L urine. Hair and blood, but not urinary, mercury were associated with ANA positivity (sample sizes 452, 1,352, and 804, respectively), after adjusting for confounders: for hair, odds ratio (OR) = 4.10 (95% CI: 1.66, 10.13); for blood, OR = 2.32 (95% CI: 1.07, 5.03) comparing highest versus lowest quantiles. Magnitudes of association were strongest for high-titer (≥ 1:1,280) ANA: hair, OR = 11.41 (95% CI: 1.60, 81.23); blood, OR = 5.93 (95% CI: 1.57, 22.47).

Conclusions

Methylmercury, at low levels generally considered safe, was associated with subclinical autoimmunity among reproductive-age females. Autoantibodies may predate clinical disease by years; thus, methylmercury exposure may be relevant to future autoimmune disease risk.

Citation

Somers EC, Ganser MA, Warren JS, Basu N, Wang L, Zick SM, Park SK. 2015. Mercury exposure and antinuclear antibodies among females of reproductive age in the United States: NHANES. Environ Health Perspect 123:792–798; http://dx.doi.org/10.1289/ehp.1408751     

松原地区居民汞暴露途径的初步研究

研究分析了松原地区居民发汞含量水平,及市售鱼类、罐装鱼类、肉类、鸡蛋等食品中的汞含量。结果表明,27.26%的受检居民发汞含量超过美国EPA最新制定的标准,表明该调查地区居民具有潜在的汞暴露风险;常食鱼人群的发汞含量显著高于不常食鱼人群的发汞含量,存在显著差异(P<0.01),头发中的汞含量与食鱼量有显著的正相关关系(r=0.243,P<0.05),这说明头发中的汞含量随着食鱼量的增加而增加;不同的饮水来源、食肉的频率、饮用牛奶的习惯对发汞含量没有显著影响;常吃鸡蛋人群的发汞含量显著低于不常吃鸡蛋人群的发汞含量;食鱼是该地区人群汞暴露风险的最主要途径。     

鱼类中砷和汞联合测定方法研究

本文利用双道原子荧光光谱法,对鱼类中砷和汞进行了联合测定研究,样品经硝酸,高氯酸混合酸消化后,以硫脲为预还原剂,将五价砷还原为三价砷,然后同时进行测定,取得了满意结果。本方法具有分析速度快,灵敏度高,干扰少,重现性好,线性范围宽等优点。该方法砷和汞的最低检出限分别为0.47mg/ml和0.10mg/ml,砷和汞的平均回收率分别为96.8%和97.5％。     

Fate and Transport of Mercury in Environmental Media and Human Exposure

Mercury is emitted to the atmosphere from various natural and anthropogenic sources, and degrades with difficulty in the environment. Mercury exists as various species, mainly elemental (Hg⁰) and divalent (Hg²⁺) mercury depending on its oxidation states in air and water. Mercury emitted to the atmosphere can be deposited into aqueous environments by wet and dry depositions, and some can be re-emitted into the atmosphere. The deposited mercury species, mainly Hg²⁺, can react with various organic compounds in water and sediment by biotic reactions mediated by sulfur-reducing bacteria, and abiotic reactions mediated by sunlight photolysis, resulting in conversion into organic mercury such as methylmercury (MeHg). MeHg can be bioaccumulated through the food web in the ecosystem, finally exposing humans who consume fish. For a better understanding of how humans are exposed to mercury in the environment, this review paper summarizes the mechanisms of emission, fate and transport, speciation chemistry, bioaccumulation, levels of contamination in environmental media, and finally exposure assessment of humans.     

严重铅汞中毒病例报告

目的了解某患者因服用2种仙丹1月余所致疾病原因,为临床治疗提供科学依据。方法采用催化极谱法、冷原子吸收分光光度法,对仙丹及患者血液、尿液进行分析。结果灰色仙丹含铅(以氧化铅计)质量百分比为23.00%,黄色仙丹含汞(以氧化汞计)质量百分比为18.00%;患者停服仙丹37 d后,血铅0.06 mg/L,尿铅0.24 mg/L;血汞0.013mg/L,尿汞0.180 mg/L。对患者进行驱铅、汞及对症支持治疗,康复治疗后,其血液、尿液铅、汞达到正常值,恢复健康,已上岗正常工作。结论根据患者血液、尿液中铅、汞检测结果,确认该患者所患疾病为严重铅、汞中毒引起。     

Exposure to alcoholism in the family: United States, 1988

About 43 percent of U.S. adults--76 million people--have been exposed to alcoholism in the family: they grew up with or married an alcoholic or a problem drinker or had a blood relative who was ever an alcoholic or problem drinker. Exposure was higher among women (46.2 percent) than among men (38.9 percent) and declined with age. Exposure to alcoholism in the family was strongly related to marital status, independent of age: 55.5 percent of separated or divorced adults had been exposed to alcoholism in some family member, compared with 43.5 percent of married, 38.5 percent of never married, and 35.5 percent of widowed persons. Nearly 38 percent of separated or divorced women had been married to an alcoholic, but only about 12 percent of currently married women were married to an alcoholic. These findings are highlights of an analysis of the 1988 National Health Interview Survey on Alcohol that is presented in this report.     

Longitudinal Mercury Monitoring within the Japanese and Korean Communities (United States): Implications for Exposure Determination and Public Health Protection

Background

Estimates of exposure to toxicants are predominantly obtained from single time-point data. Fish consumption guidance based on these data may be incomplete, as recommendations are unlikely to consider impact from factors such as intraindividual variability, seasonal differences in consumption behavior, and species consumed.

Objectives/methods

We studied populations of Korean (n = 108) and Japanese (n = 106) women living in the Puget Sound area in Washington State to estimate mercury exposure based on fish intake and hair Hg levels at two and three time points, respectively. Our goals were to examine changes in hair Hg levels, fish intake behavior, and Hg body burden over time; and to determine if data from multiple time points could improve guidance.

Results/conclusion

More than 50 fish species were consumed, with eight species representing approximately three-fourths of fish consumed by the Japanese and 10 species representing approximately four-fifths of fish intake by the Koreans. Fish species responsible for most Hg intake did not change over time; < 10 species accounted for most of the Hg body burden in each population. Longitudinal variability of hair Hg levels changed slowly across the study period. Japanese with hair Hg levels > 1.2 ppm (mean, 2.2 ppm) consumed approximately 150% more fish than those with levels ≤ 1.2 ppm (mean, 0.7 ppm). However, because many participants consumed substantial amounts of fish while having hair-Hg levels ≤ 1.2 ppm, the nutritional benefits offered from fish consumption should be obtainable without exceeding the RfD. We observed a 100% difference in fish intake between open-ended and 2-week recall fish consumption surveys. Open-ended survey data better represent Hg intake as determined from hair Hg levels. Single time-point fish intake data appear to be adequate for deriving guidance, but caution is warranted, as study is required to determine the significance of the different outcomes observed using the two survey time frames.     

Effects of Mercury Released from Gold Extraction by Amalgamation on Renal Function and Environment in Shanxi,China

We investigated the distribution of mercury and its impacts on the renal function of the residents living in mercury-contaminated area due to gold extraction by amalgamation in some area of Shanxi, China. The results showed that mercury concentrations in contaminated air in four seasons were 79–240 ng/m3. The mercury concentration in the river across contaminated area was also high. The mercury contents in the grain were higher than those in the non-mercury contaminated area. The urinary mercury and urinary β₂-microglobulin for the residents living in the contaminated area were 1.24 ± 3.80 μg/L and 228.98 ± 4.34 μg/g Cr, higher than those in the non-mercury contaminated area.     

Deaths From Secondhand Smoke Exposure in the United States: Economic Implications

Objectives. We estimated the number of deaths attributable to secondhand smoke (SHS), years of potential life lost (YPLL), and value of lost productivity for different US racial/ethnic groups in 2006.Methods. We determined the number of SHS–related deaths among nonsmokers from 2 adult and 4 infant conditions using an epidemiological approach. We estimated adult SHS exposure using detectable serum cotinine. For each death, we determined the YPLL and the value of lost productivity.Results. SHS exposure resulted in more than 42 000 deaths: more than 41 000 adults and nearly 900 infants. Blacks accounted for 13% of all deaths but 24% to 36% of infant deaths. SHS–attributable deaths resulted in a loss of nearly 600 000 YPLL and $6.6 billion of lost productivity, or $158 000 per death. The value of lost productivity per death was highest among Blacks ($238 000) and Hispanics ($193 000).Conclusions. The economic toll of SHS exposure is substantial, with communities of color having the greatest losses. Interventions need to be designed to reduce the health and economic burden of smoking on smokers and nonsmokers alike and on particularly vulnerable groups.Exposure to secondhand smoke (SHS) has been linked to several fatal illnesses among infants and adults.1 Worldwide, 603 000 deaths have been attributed to SHS exposure.2 In the United States, the Centers for Disease Control and Prevention reported that 46 000 adults died from ischemic heart disease (IHD) and 3400 adults died from lung cancer annually between 2000 and 2004 as a result of SHS exposure.1,3 In addition, 776 infants were reported to have died as a result of maternal exposure in utero each year.1,3 Premature death results in years of productive life lost as well as economic losses.Active smoking has been shown to place a disproportionately high burden on communities of color,4 including Blacks and Hispanics.5,6 Blacks have also been shown to be more likely to be exposed to SHS.7–9 However, the economic impact of SHS exposure on different racial/ethnic groups has yet to be examined.Previous studies have estimated the impact of SHS exposure on mortality using self-report exposure measures or assuming that those who live with smokers are exposed, but these measures yield much lower exposure estimates than biomarker-determined exposure. In 2003 to 2004, 14.8% of adults reported home or work exposure, but fully 42.4% had detectable serum cotinine.8 Several recent studies have examined the association between cotinine levels and cardiovascular disease and reported a greater risk of cardiovascular disease among SHS–exposed adults than among those not exposed.10,11The purpose of this study was to estimate the number of SHS–attributable deaths, years of potential life lost (YPLL), and the value of lost productivity for different US racial/ethnic groups in 2006. We estimated the number of SHS–attributable deaths for adults using cotinine-measured SHS exposure for the first time.     

人体发汞值与汞摄入量关系的探讨

根据对１２１０份发汞测得的结果认为发汞值属正偏态分布，但可以通过对数变换成为对数正态分布进行统计分析。发汞值与日均汞摄入量有关，监测发汞值可以推算人体环境汞暴露的水平，并提出了推算的方法。     

Scalp hair and urine mercury content of children in the Northeast United States: the New England Children's Amalgam Trial

Children may be at particular risk from toxic effects of mercury (Hg). Previous studies of hair (organic) and urine (inorganic) Hg levels in US children were unable to assess Hg levels while accounting for exposure to amalgam dental restorations. This analysis describes, over a 5-year period, levels and correlates/predictors of scalp hair (H-Hg) and urinary (U-Hg) mercury in 534 New England Children's Amalgam Trial (NECAT) participants, aged 6-10 years and without exposure to dental amalgam at baseline. RESULTS: Mean H-Hg levels were between 0.3 and 0.4 microg/g over 5 years. 17-29% of children had H-Hg levels > or = 0.5 microg/g, and 5.0 to 8.5% of children had levels > or = 1 microg/g, in any given study year. In adjusted models, fish consumption frequency was the most robust predictor of high H-Hg. U-Hg mean levels were between 0.7 and 0.9 microg/g creatinine over two years. The percentage of those with U-Hg > or 2.3 microg/g creatinine ranged from 4% to 6%. Number of amalgam restorations had a significant dose-response relationship with U-Hg level. Daily gum chewing in the presence of amalgam was associated with high U-Hg.     

Spatial and Temporal Variation in the Diet of Tree Swallows: Implications for Trace-Element Exposure After Habitat Remediation

Emerging aquatic insects play a key role in transporting aquatic contaminants into terrestrial ecosystems. Tree swallows are frequently the focus of studies examining this movement because they are thought to forage heavily on emerging aquatic insects when breeding in riparian areas. We examined the tree swallow diet to determine if trace elements from a recently remediated coal fly ash spill were moving into the terrestrial ecosystem. We collected bolus samples from adult tree swallows as they entered the nest box to feed their young. Despite strategically locating boxes in riparian areas, we found that the consumption of insects with an aquatic larval stage ranged from 28 to 75 % of insects among colonies. We also found significant differences among colonies in the taxa found in bolus samples. Chironomidae (midges) were the primary emerging aquatic insects consumed by tree swallows, whereas Ephemeroptera were brought to nestlings infrequently. The consumption of insects with an aquatic larval stage, Chironomidae in particular, was positively correlated with exposure to trace elements from the spill. Bolus samples from the spill site contained greater concentrations of many trace elements compared with reference locations, but concentrations of most elements were lower than levels thought to cause reproductive impairment. These results support the hypothesis that emerging aquatic insects transport trace elements to terrestrial consumers and that Chironomidae play an important role in this movement. Our results also indicate that it is important to assess the composition of the diet and to not infer exposure to trace elements based on nesting location.     

A New Method for Total Mercury and Methyl Mercury Analysis in Muscle of Seawater Fish

In this work we have developed a cost-effective method for the analysis of methyl mercury (MeHg) in seawater fish muscle. The novelty of this method lies in the use of microwave-assisted extraction with acidic solution (HCl), addition of toluene, and subsequent extraction with cysteine acetate solution where only MeHg is present because of its affinity for cysteine groups. MeHg in cysteine phase and total mercury in the homogenate muscle tissue were determined using a direct Hg analyzer (DMA-80). Validation, precision, and accuracy of the method were evaluated and monitored with a tuna fish certified reference material (CRM 463) containing MeHg.     

Ranking the contributions of commercial fish and shellfish varieties to mercury exposure in the United States: Implications for risk communication

Fish and shellfish have important nutritional benefits, and US per capita seafood consumption has increased substantially since 2002. Recent research has reinforced concerns about adverse effects of methylmercury exposure, suggesting that methylmercury doses associated with typical US rates of fish consumption may pose measurable risks, with no threshold. These converging trends create a need to improve risk communication about fish consumption and mercury. The analysis performed here identifies the relative importance of different fish and shellfish as sources of mercury in the US seafood supply and proposes improved consumer advice, so that the public can benefit from fish consumption while minimizing mercury exposure. I have quantified contributions to total mercury in the US seafood supply by 51 different varieties of fish and shellfish, then ranked and sorted the 51 varieties in terms of relative impact. Except for swordfish, most fish with the highest mercury levels are relatively minor contributors to total inputs. Tuna (canned light, canned albacore and fresh/frozen varieties) accounts for 37.4 percent of total mercury inputs, while two-thirds of the seafood supply and nine of the 11 most heavily consumed fish and shellfish are low or very low in mercury. Substantial improvement in risk communication about mercury in fish and seafood is needed; in particular, several population subsets need better guidance to base their seafood choices more explicitly on mercury content. I have sorted the 51 seafood varieties into six categories based on mercury levels, as a framework for improving risk communication in this regard.