Urinary Mercury Levels Research Articles

Chronische Quecksilberintoxikation bei Kindern aus zwei Familien durch kosmetische Anwendung einer Bleichcreme seitens der Mütter

We report about two families (A: n = 4, B: n = 5) from the Kosovo-Albanian region where the mothers had been using a skin bleaching cream for cosmetic reasons from a rural market containing 12 % elementary mercury. Elevated mercury levels in urine had first been detected in a survey of school pupils in one son of each family; this led to screening of all family members. Medical history showed no abnormalities in family A. In family B unspecific symptoms occurred such as headache, fatigue and bowel pain. In both families, no symptoms of Feer-syndrome (acrodynia) were observed. Nephrotic syndrome or anemia were excluded by blood analyses. Neurological examination, EEG and physical examination were normal. Using flameless atomic absorption spectroscometry, 24 h urine samples revealed elevated mercury levels with highest values in those female family members who had used the cream for cosmetic purposes (family A, A1: 226, A2: 86, A3: 25, A4: 14 μg/l; family B, B1: 363; B2: 192; B3: 61; B4: 41; B5: 29 μg/l). Reference values for adults are < 7 μg/l in 24 h urine. After antidote treatment with DMPS (2,3 -dimercaptopropane-1-sulfonate, Sodium salt, Dimaval®) with 5 mg/kg bodyweight for 7 days, biomonitoring revealed a mercury level lower than the reference value and the symptoms ceased. In sensitive individuals, a symptom-complex (micromercuralism) with sporadic weakness, fatigue, gastrointestinal disorders, intention tremor (tremor mercuralis), alterations of the personality and memory loss (Erethrismus mercuralis) occur at a concentration of 100 μg/l mercury in urine and 35 μg/l in blood in adults. In the two families, absorption of the mercury in the boys might have occurred through the skin, by breathing or by ingestion.

Biomarkers of Mercury Exposure at a Mercury Recycling Facility in Ukraine

This study evaluates biomarkers of occupational mercury exposure among workers at a mercury recycling operation in Gorlovka, Ukraine. The 29 study participants were divided into three occupational categories for analysis: (1) those who worked in the mercury recycling operation (Group A, n = 8), (2) those who worked at the facility but not in the yard where the recycling was done (Group B, n = 14), and (3) those who did not work at the facility (Group C, n = 7). Urine, blood, hair, and nail samples were collected from the participants, and a questionnaire was administered to obtain data on age, gender, occupational history, smoking, alcohol consumption, fish consumption, tattoos, dental amalgams, home heating system, education, source of drinking water, and family employment in the former mercury mine/smelter located on the site of the recycling facility. Each factor was tested in a univariate regression with total mercury in urine, blood, hair, and nails. Median biomarker concentrations were 4.04 μg/g-Cr (urine), 2.58 μg/L (blood), 3.95 μg/g (hair), and 1.16 μg/g (nails). Occupational category was significantly correlated (p < 0.001) with both blood and urinary mercury concentrations but not with hair or nail mercury. Four individuals had urinary mercury concentrations in a range previously found to be associated with subtle neurological and subjective symptoms (e.g., fatigue, loss of appetite, irritability), and one worker had a urinary mercury concentration in a range associated with a high probability of neurological effects and proteinuria. Comparison of results by occupational category found that workers directly involved with the recycling operation had the highest blood and urinary mercury levels. Those who worked at the facility but were not directly involved with the recycling operation had higher levels than those who did not work at the facility.

Urinary Mercury Levels in Children with Amalgam Fillings

Woods et al. (2007) reported on exposure to dental amalgam fillings and urinary mercury excretion in children. They stated that “urinary mercury concentrations are widely used as a measure of mercury exposure from dental amalgam fillings.” We would like to point out some caveats about interpreting the results of mercury in urine. Clarkson and Magos (2006) and others (Mutter et al. 2007; Nilsson and Nilsson 1986; Nuttal 2004) noted that urinary mercury is a rough indicator of mercury from dental amalgams. In fact, the urinary mercury concentration is unlikely to be a robust biological indicator for prolonged exposure to mercury vapor from dental amalgam. Previous postmortem studies in humans have shown that mercury levels originating from dental amalgam surfaces and retained in tissues are higher in brain regions and thyroid than those measured in renal cortex (Guzzi et al. 2006). These findings are consistent with the fact that kidneys are the major contributors of urinary mercury (Magos and Clarkson 2006; Nuttal 2004), and the concentrations of mercury in urine may not reflect the tissue retention of mercury in more sensitive tissues such as brain and endocrine glands. This might explain the association between an increased frequency and severity of clinical symptoms among individuals with dental amalgams and consistently reduced levels of excretion of total mercury in urine (Minoia et al. 2006; Nilsson and Nilsson 1986). In addition, Woods et al. (2007) listed several factors that may be involved in the differences in urinary mercury concentrations between the sexes. However, they did not mention bruxism in the text. Bruxism has an important causative role in the increased concentration of mercury in urine (Barregard et al. 1995). Because various reports have suggested that bruxing behavior may increase the urinary levels of mercury (Isacsson et al. 1997), Woods et al. should have included it as a potential confounder factor. As a result of their randomized trials, Woods et al. (2007) evaluated the influence of sex on mercury excretion rates. They found that girls have a more significant increase in the rate of mercury excreted in urine than boys. Thus, this association might confer a lower mercury toxicity risks in girls. Our experience regarding the care and treatment of adverse mercury amalgam events among adult individuals does not support the hypothesis that males might be more susceptible than females to the adverse events caused by long-term exposure to mercury vapor from amalgams (Guzzi et al. 2005). Our findings, which were derived from an ongoing study regarding clinically significant adverse events occurred in 289 adults patients due to mercury amalgam fillings, showed that females are two to three times more likely to develop local (e.g., lichenoid contact stomatitis) or systemic adverse health outcomes (e.g., skin disorders) compared with males [217 of 289 were women (75.09%) with a median age of 43; 72 of 289 were men (24.91%) with a median age of 40.5; female to male ratio, 3.1:1]. Therefore, in our experience, adult females were more likely to be affected by prolonged exposure to mercury vapor released from dental amalgams. Moreover, given that inorganic mercury [Hg2+] binds mainly to thiol ligands [–SH] as homocysteine (Bridges and Zalups 2004), we suggest that future clinical trials addressing the role of sex in mercury excretion should include an evaluation of serum homocysteine, which is higher in males than in females and might account for an increased tissue retention of mercury (Novembrino et al. 2006). Finally, Woods et al. (2007) did not consider the importance of determining whether the exposure to mercury vapor emitted from amalgams may affect the immune system of children (Pigatto and Meroni 2006). Indeed, mercury-induced immunotoxicity arises far earlier than overt toxicity in the renal and central nervous systems.

Cognitive Dysfunction Associated with Elemental Mercury Ingestion and Inhalation: A Case Study

A 63-year-old man with a history of alcohol dependence ingested elemental mercury as a suicide gesture. Serial abdominal X-rays showed gradual but incomplete clearance of mercury from the colon. Routine chest X-ray showed evidence of punctate radiopaque materials in the lower lobe of the right lung. Blood and urine mercury levels both exceeded thresholds considered to be associated with cognitive dysfunction. Elicited cognitive deficits were most prominent in processing speed, flexibility, and response inhibition. Semantic fluency, visuospatial processing, and recall memory for visual and low-context verbal material were also affected. The deficits may have been attributable primarily to alcohol abuse. Elemental mercury is not readily absorbed from the gastrointestinal tract; however, mercury vapor, which was inhaled inadvertently, readily crosses the blood-brain barrier and is neurotoxic. We argue, therefore, that mercury toxicity is more likely than not to have been a factor contributing to the patient's cognitive dysfunction.

Mercury Levels in Newborns and Infants After Receipt of Thimerosal-Containing Vaccines

Thimerosal is a mercurial preservative that was widely used in multidose vaccine vials in the United States and Europe until 2001 and continues to be used in many countries throughout the world. We conducted a pharmacokinetic study to assess blood levels and elimination of ethyl mercury after vaccination of infants with thimerosal-containing vaccines. Blood, stool, and urine samples were obtained before vaccination and 12 hours to 30 days after vaccination from 216 healthy children: 72 newborns (group 1), 72 infants aged 2 months (group 2), and 72 infants aged 6 months (group 3). Total mercury levels were measured by atomic absorption. Blood mercury pharmacokinetics were calculated by pooling the data on the group and were based on a 1-compartment first-order pharmacokinetics model. For groups 1, 2, and 3, respectively, (1) mean +/- SD weights were 3.4 +/- 0.4, 5.1 +/- 0.6, and 7.7 +/- 1.1 kg; (2) maximal mean +/- SD blood mercury levels were 5.0 +/- 1.3, 3.6 +/- 1.5, and 2.8 +/- 0.9 ng/mL occurring at 0.5 to 1 day after vaccination; (3) maximal mean +/- SD stool mercury levels were 19.1 +/- 11.8, 37.0 +/- 27.4, and 44.3 +/- 23.9 ng/g occurring on day 5 after vaccination for all groups; and (4) urine mercury levels were mostly nondetectable. The blood mercury half-life was calculated to be 3.7 days and returned to prevaccination levels by day 30. The blood half-life of intramuscular ethyl mercury from thimerosal in vaccines in infants is substantially shorter than that of oral methyl mercury in adults. Increased mercury levels were detected in stools after vaccination, suggesting that the gastrointestinal tract is involved in ethyl mercury elimination. Because of the differing pharmacokinetics of ethyl and methyl mercury, exposure guidelines based on oral methyl mercury in adults may not be accurate for risk assessments in children who receive thimerosal-containing vaccines.

Electrophysiological evidence for impairment of contrast sensitivity in mercury vapor occupational intoxication

Contrast sensitivity (CS) was evaluated in 41 former workers from a lamp manufacturing plant who were on disability retirement due to exposure to mercury and 14 age-matched controls. The CS was measured monocularly using the sweep visual evoked potential (sVEP) paradigm at 6 spatial frequencies (0.2, 0.8, 2.0, 4.0, 15.0, and 30 cpd). Statistical difference ( p<0.05) was found between the controls and the patient right and left eyes for 2.0 and 4.0 cpd. According the results in those spatial frequencies the eyes were classified in best and worst. Statistical differences were found between the controls and the best eyes for 2.0 and 4.0 cpd and for 0.8, 2.0, and 4.0 cpd for their worst eyes. No correlation was found between CS results and the time of exposure (mean=8.9 yr±4.1), time away from the mercury source (mean=6.0 yr±3.9), urinary mercury level at the time of work (mean=40.6 μg/g±36.3) or with the mercury level at the CS measurement time (mean=1.6 μg/g±1.1). We show the first evidence of a permanent impairment in CS measured objectively with the sVEP. Our data complement the previous psychophysical works reporting a diffuse impairment in the CS function showing a CS reduction in the low to middle spatial frequencies. In conclusion, non-reversible CS impairment was found in occupational exposure to mercury vapor. We suggest that CS measurement should be included in studies of the mercury effects of occupational exposure.

Arthroscopic treatment of knee joint injury for intraarticular mercury from a broken thermometer

Intraarticular injection of metallic mercury (Hg) such as those found in thermometers is very rare. According to available data in literature, an arthroscopic presentation and treatment of knee injury that had intraarticular elementary mercury seems not to have been published yet. We report a first case of arthroscopically treated chronic right knee synovitis after accidental intraarticular mercury infusion by a broken thermometer in an 11-year-old boy. Mercury levels in blood and urine were slightly increased, but no systemic mercury intoxication developed. Inflamed synovia as well as synovia with incorporated metal particles was excised. A histological analysis of macroscopically inflamed synovia revealed an unspecific inflammation reaction. The symptoms gradually subsided and the knee regained full function. However, all the metal particles were not successfully removed from the injured knee; therefore a careful follow-up of the patient was provided. It seems that arthroscopic excision and lavage could be suitable treatments for knee injury, infused with elementary mercury, and toxic knee synovitis.

Mercury Intoxication: Lack of Correlation Between Symptoms and Levels

The incidence of mercury intoxication has decreased considerably because of stricter public health regulations. However, it has not been completely eliminated and should be considered in a child with unexplained tachycardia, hypertension, mood changes, weight loss, and acrodynia. Mercury intoxication can be difficult to differentiate from pheochromocytoma and Kawasaki's disease. Here, the authors report the case of an 8-year-old boy with history of mercury exposure, signs and symptoms suggestive of mercury intoxication, and good response to chelation therapy, but with only mild increase in urinary mercury levels. This case highlights the fact that urinary mercury levels do not necessarily correlate with the severity of clinical signs and symptoms of mercury intoxication.

국내 초등학생의 체내 총수은 농도 및 노출요인 조사

Mercury contamination and its health effects have become major concern of environmental health study in Korea. Mercury exposure of some group were investigated to get the accurate data for policy making and study. About 2,000 children at 26 elementary schools participated in this survey to evaluate the exposure levels and to investigate main exposure source of mercury. Analysis of mercury levels in the whole blood and urine samples were conducted and questionnaire survey was done about the factors influencing exposures simultaneously. Mercury exposure levels of domestic children were N.D. to 17.26 ppb in blood, 0.17 to <TEX>$21.67{\mu}g/g$</TEX>-creatinine in urine. The mean(arithmetic) levels are 2.42 ppb in blood and <TEX>$2.53{\mu}g/g$</TEX>-creatinine in urine. Both of them were below the recommendation levels of US EPA and German CHBM I <TEX>$5.8{\mu}g/l$</TEX> and <TEX>$5{\mu}g/l$</TEX> in blood, <TEX>$5{\mu}g/g$</TEX>-creatinine of German CHBM I in urine. But 1%, 0.51% of levels in blood exceed the level of CHBM I and US EPA, 8%, 0.85% of children were over the level of CHBM I and CHBM II in urine. Multi-valuable regression analysis showed that the existence of road near the residence in addition to the preference for fish have significance with blood mercury exposure level of domestic children. The existence of factory near the house and the experience of dental amalgam treatment had statistical relations with urine mercury level.

Mercury Exposure in Young Children Living in New York City

Residential exposure to vapor from current or previous cultural use of mercury could harm children living in rental (apartment) homes. That concern prompted the following agencies to conduct a study to assess pediatric mercury exposure in New York City communities by measuring urine mercury levels: New York City Department of Health and Mental Hygiene's (NYCDOHMH) Bureau of Environmental Surveillance and Policy, New York State Department of Health/Center for Environmental Health (NYSDOHCEH), Wadsworth Center's Biomonitoring Program/Trace Elements Laboratory (WC-TEL), and Centers for Disease Control and Prevention (CDC). A previous study indicated that people could obtain mercury for ritualistic use from botanicas located in Brooklyn, Manhattan, and the Bronx. Working closely with local community partners, we concentrated our recruiting efforts through health clinics located in potentially affected neighborhoods. We developed posters to advertise the study, conducted active outreach through local partners, and, as compensation for participation in the study, we offered a food gift certificate redeemable at a local grocer. We collected 460 urine specimens and analyzed them for total mercury. Overall, geometric mean urine total mercury was 0.31 microg mercury/l urine. One sample was 24 microg mercury/l urine, which exceeded the (20 microg mercury/l urine) NYSDOH Heavy Metal Registry reporting threshold for urine mercury exposure. Geometric mean urine mercury levels were uniformly low and did not differ by neighborhood or with any clinical significance by children's ethnicity. Few parents reported the presence of mercury at home, in a charm, or other item (e.g., skin-lightening creams and soaps), and we found no association between these potential sources of exposure and a child's urinary mercury levels. All pediatric mercury levels measured in this study were well below a level considered to be of medical concern. This study found neither self-reported nor measured evidence of significant mercury use or exposure among participating children. Because some participants were aware of the possibility that they could acquire and use mercury for cultural or ritualistic purposes, community education about the health hazards of mercury should continue.

Mercury exposures and symptoms in smelting workers of artisanal mercury mines in Wuchuan, Guizhou, China

Mercury exposures to smelting workers of artisanal mercury mines in Wuchuan, Guizhou, China were evaluated by urine and hair mercury survey. The mean urinary mercury (U-Hg), hair total mercury (T-Hg), and hair methyl mercury (Me-Hg) for smelting workers was 1060 μg/g creatinine (μg/g Cr), 69.3 and 2.32 μg/g, respectively. The results were significantly higher than that of control group, which is 1.30 μg/g Cr, 0.78 and 0.65 μg/g, correspondingly. The average urinary β2-microglobulin ( β2-MG) was 248 μg/g Cr for the exposed group contrasting to 73.5 μg/g Cr for the control group and the data showed a serious adverse effect on renal system for the smelting workers. The workers were exposed to mercury vapor through inhalation, and the exposure route of Me-Hg may be through intake of polluted diet. The results indicate that age, alcohol drinking, and smoking are not crucial factors controlling the urine and hair mercury levels for the exposed and the control group. Clinical symptoms including finger and eyelid tremor, gingivitis, and typical dark-line on gums were observed in six workers. This study indicated that the smelting workers in Wuchuan were seriously exposed to mercury vapor.

Blood and urine mercury levels in adult amalgam patients of a randomized controlled trial: Interaction of Hg species in erythrocytes

Parts of the population are permanently exposed to low levels of Hg° and Hg(II) from dental amalgam. It was the aim (1) to investigate the internal exposure to amalgam-related mercury from the kinetics of inorganic Hg in plasma and erythrocytes after amalgam removal, and (2) to estimate the amalgam-related absorbed dose. Dietary coexposure was monitored by determination of blood organic-Hg. Postremoval steady-state Hg concentrations were measured for 18 months. Eighty-two patients had been randomized into three groups: (A) removal of the fillings; (B) removal and non-specific detoxification, and (C) a health promotion program without removal. After amalgam removal, inorganic Hg dropped rapidly in plasma and red cells, stabilizing at 27% of preremoval levels after 60 days. Concentrations of organic Hg in plasma remained unchanged, indicating no change in dietary uptake of organic Hg. The concentration of organic Hg in red cells of group A was in the early postremoval phase lower and in the late postremoval phase higher than the preremoval control ( p<0.01 for low-high difference). A protracted increase in organic Hg was also found in red cells of group B after 60 days. Thus, the effect of removal on organic Hg levels in the combined group A+B was compared with the values of group C in a linear mixed effects (LME) model which showed a significant increase with time in group A+B ( p=0.028). In all groups, time profiles of urinary concentration and excretion of total-Hg were very similar to those of inorganic-Hg levels in plasma. From extrapolations of blood and urine data it was estimated that the amalgam-related inhalation and ingestion of Hg species were within the limits proposed by WHO, ATSDR and EPA. The integrated daily Hg dose absorbed from amalgam was estimated up to 3μg for an average number of fillings and at 7.4 for a high amalgam load. Conclusions This is the first study on adult amalgam patients which continuously monitored the postremoval decline of inorganic Hg and the coexposure from dietary organic Hg in a randomized-controlled-trial design. The integrated daily dose of 7.4 μg absorbed from a high amalgam load is well below the tolerable dose of 30 μg (WHO, 1990). The unexpected postremoval increase in erythrocyte organic Hg, which is associated with the depletion of cellular inorganic Hg, might result from binding of organic Hg to cellular sites previously occupied by inorganic Hg.

Levels of Lead, Cadmium, and Mercury in Blood and Urine of the Czech Schoolchildren

Levels of Lead, Cadmium, and Mercury in Blood and Urine of the Czech Schoolchildren

Elemental Mercury Releases Attributed to Antiques—New York, 2000-2006

Metallic (i.e., elemental) mercury, a heavy, silvery odorless liquid, is in common household products such as thermostats and thermometers. Lesser-known household sources of elemental mercury include certain antique or vintage items such as clocks, barometers, mirrors, and lamps. Over time, the mercury in these items can leak, particularly as seals age or when the items are damaged, dropped, or moved improperly. Vacuuming a mercury spill or vaporization from spill-contaminated surfaces such as carpets, floors, furniture, mops, or brooms can increase levels of mercury in the air, especially in enclosed spaces. Environmental sampling conducted after releases of elemental mercury have indicated substantial air concentrations that were associated with increases in blood and urine mercury levels among exposed persons. In 1990, the Agency for Toxic Substances and Disease Registry (ATSDR) created the Hazardous Substances Emergency Events Surveillance (HSEES) system, a multistate health department surveillance system designed to help reduce morbidity and mortality associated with hazardous substance events. This report describes antique-related mercury releases reported to HSEES, all of which occurred in New York state during 2000-2006. Although none of these spills resulted in symptoms or acute health effects, they required remediation to prevent future mercury exposure. The findings underscore the need for caution when handling antiques containing elemental mercury and the need for proper remediation of spills.

Baboon syndrome induced by mercury – first case report in China

A case of mercury-induced baboon syndrome was reported. A 31-year-old woman presented with itching papules and vesicles in the right axilla, which extended to the left axilla, arms, fossa poplitea, buttocks, and groin. A mercury thermometer was broken 2 days before exanthema. Patch testing to ammoniated mercury, mercury, mercuric chloride, and mercurochrome were positive. Blood and urine mercury level was marginally normal, yet showed a descending trend over time.

Mercury intoxication in a 2-year-old girl: a diagnostic challenge for the physician

A 2-year-old girl presented with hypertension, anorexia and vomiting, restlessness, insomnia and acrodynia. Her blood pressure upon arrival was 145/98 mmHg. Ultrasound of the abdomen, CT scan of chest, abdomen and pelvis, and echocardiogram, were normal. Urinary levels of catecholamines were elevated, urine level of mercury was found to be high (33.2 microg/g creatinine), although blood level was normal (>0.5 microg/dl, reference value 0-4 microg/dl). Following a 1-month course of oral treatment with dimercaptosuccinic acid (DMSA) the child's symptoms and signs resolved, and urinary mercury and catecholamines levels normalized. Mercury intoxication should be suspected in a patient with severe hypertension, personality changes and acrodynia. Normal blood levels of mercury do not exclude this diagnosis, and catecholamine levels may serve as a surrogate marker for confirmation of the diagnosis and to evaluate response to treatment.

Exposure assessment of a mercury spill in a Nevada school—2004

Background. Although mercury is toxic, few studies have measured exposure in children who handled elemental mercury briefly. In 2004, a student spilled approximately 60 milliliters of mercury at a Nevada school. Within 12 hours, all students were removed from the source of exposure. We conducted an exposure assessment at the school. Methods. We administered questionnaires and obtained urine samples from students. Using two-sample t-tests, we compared urine mercury levels from students who self-reported exposure to mercury levels of other students. Results. Two-hundred students participated, including 55/62 (89%) who were decontaminated. The students' geometric mean urine mercury level was 0.36 μg/L (95% confidence interval 0.32–0.40 μg/L). The student who brought the mercury to school was the only one to have an elevated urine mercury level (11.4 μg/L). Conclusion. Despite environmental contamination, mercury exposure may have been minimized because of rapid identification of the elemental mercury spill and decontamination.

Exposure assessment of young children living in Chicago communities with historic reports of ritualistic use of mercury

Objective. According to a 1997 finding, mercury was available for sale in several Chicago communities for use in spiritual or medicinal practice. Mercury used this way may impact the health of children. The Chicago Department of Public Health (CDPH) and the Centers for Disease Control and Prevention conducted a study to 1) quantify mercury exposure in biological specimens collected from a pediatric clinic or home visit in selected neighborhoods in Chicago, and 2) investigate possible sources of mercury exposure in homes. Methods. An exposure assessment study design was chosen to determine whether children living in Chicago communities that historically sold mercury were exposed to mercury vapor. We enrolled and collected biological samples from 306 children aged 2–10 years. In addition, we enrolled 42 children during a door-to-door survey of community residents. All the urine samples were analyzed for elemental or inorganic mercury. We also analyzed 43 blood samples to assess dietary mercury. Results. Overall geometric mean urine mercury was 0.26μg/L. Urine mercury levels did not differ among the three clinics or between the various participant groups. We did not find any association between ritualistic mercury use and exposure to mercury. Conclusions. Although pediatric mercury exposure does not appear to be problematic among our study population, mercury remains a potential health threat as long as it is readily available in communities. Healthcare providers should be aware of the potential for mercury exposure. Physicians and patients may call the National Poison Control Centers (1-800-222-1222) for information about diagnosis, testing, and treatment for all types of exposures, including exposure to mercury. Professionals are available 24 hours a day.

Community Mercury Levels in the Vicinity of Peri-Urban Waste Disposal Sites and Fossil Fuel Burning Operations

Abstract Introduction A study was conducted as a result of concern about mercury absorption amongst residents of a peri-urban area in Cape Town, South Africa, in close proximity to waste disposal sites and an industrial area. Study methods The study compared urine mercury concentrations in a random sample of adult residents and children in both the formal and informal housing settlements of the “exposure” area ( n = 90) and a control area ( n = 90). A short questionnaire elicited demographic, lifestyle and medical details and possible occupational, household and environmental mercury exposures. Results The two samples were comparable with respect to background and potential confounding variables. The prevalence of urinary mercury levels ≥ the WHO reference range in the exposure area was also higher than that in the control area (13% vs. 0%). The median urinary mercury concentrations in both study areas were below the World Health Organisation (WHO) reference level of 5.0 μg/g creatinine. The median level in the exposure area was slightly, but statistically significantly, higher than in the control area (1.1 vs. 0.25 μg/g creatinine), and the excess persisted after controlling for known possible mercury exposures. Conclusions This is to our knowledge the first study of community inorganic mercury absorption in a developing country setting, and where airborne mercury was the exposure of concern. It was concluded that the health risk associated with the urinary mercury levels of residents in the exposure area was very low. However, low level environmental exposure in the area of concern could not be excluded.

Mercury Exposures in Informal Gold Miners and Relatives in Southern Peru

Subjects working in or living near informal gold mining and processing in southern Peru were studied to determine mercury exposures from two tasks: amalgamation and amalgam smelting. The authors collected 17 airborne and 41 urinary mercury levels. The mean urinary levels were 728 (range: 321-1662) and 113 (45-197) microg/L for working in smelters and living near smelters, respectively. A third group working in amalgamation had a mean 18 microg/L (range 8-37). People living in the mining town but with no mining activities had 8 microg/L (5-10), while a control group outside the town had 4 microg/L (2-6). Mean airborne mercury exposure was 2423 microg/m3 (range 530-4430) during smelting, 30.5 microg/m3 (12-55) during amalgamation, and 12 microg/m3 (3-23) in the mining town. Smelters are highly contaminated with mercury, as are the people living around smelters.