Urinary Mercury Levels Research Articles

Occupational exposure to airborne mercury during gold mining operations near El Callao, Venezuela.

The National Institute for Occupational Safety and Health (NIOSH) recently conducted a cross-sectional study during gold mining operations near El Callao, Venezuela. The purpose of the study was to assess mercury exposures and mercury-related microdamage to the kidneys. The study consisted of concurrent occupational hygiene and biological monitoring, and an examination of the processing techniques employed at the different mining facilities. Mercury was used in these facilities to remove gold by forming a mercury-gold amalgam. The gold was purified either by heating the amalgam in the open with a propane torch or by using a small retort. Thirty-eight workers participated in this study. Some participants were employed by a large mining company, while others were considered "informal miners" (self-employed). Mercury exposure was monitored by sampling air from the workers' breathing zones. These full-shift air samples were used to calculate time-weighted average (TWA) mercury exposure concentrations. A questionnaire was administered and a spot urine sample was collected. Each urine sample was analyzed for mercury, creatinine, and N-acetyl-beta-D-glucosaminidase (NAG). The range for the 8-h TWA airborne mercury exposure concentrations was 0.1 to 6,315 micrograms/m3, with a mean of 183 micrograms/m3. Twenty percent of the TWA airborne mercury exposure measurements were above the NIOSH recommended exposure limit (REL) of 50 micrograms/m3, and 26% exceeded the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 25 micrograms/m3. The mean urine mercury concentration was 101 micrograms/g creatinine (microgram/g-Cr), and the data ranged from 2.5 to 912 micrograms/g-Cr. Forty-two percent of the study participants had urine mercury concentrations that exceeded the ACGIH biological exposure index (BEI) of 35 micrograms/g-Cr. Urinary NAG excretion is considered a biological marker of preclinical, nonspecific microdamage to the kidney's proximal tubule cells. The mean urine NAG concentration was 3.6 International Units/g-Cr (IU/g-Cr) with a range of 0.5 to 11.5 IU/g-Cr. Three workers had urine NAG levels in excess of the reference values. Correlation analyses found statistically significant correlations between airborne mercury exposure and urine mercury level (P = 0.01), and between urine mercury level and urine NAG excretion (P = 0.01). In addition, the airborne mercury exposure data and urine mercury data were segregated by job tasks. A Wilcoxon rank sum test revealed significant correlations between tasks and mercury exposure (P = 0.03), and between tasks and urine mercury level (P = 0.02). The tasks with the highest mean airborne mercury exposures were "burning the mercury-gold amalgam" and "gold refining/smelting". Recommendations were provided for improving the retort design to better contain mercury, for ventilation in the gold shops, and for medical surveillance and educational programs.

SENSITIVE DETERMINATION OF URINARY MERCURY(II) BY A BIOLUMINESCENT TRANSGENIC BACTERIA-BASED BIOSENSOR

We used a luminescence-based biosensor to determine mercury in urine samples of subjects with or without dental amalgam restorations. The system utilizes Escherichia coli as a host organism and firefly luciferase luc gene as a reporter under the control of the mercury-inducible promoter from the mer operon from transposon Tn21. The presence of mercury induces the specific gene sequence with consequent synthesis of the luciferase enzyme, and luciferin/luciferase-mediated light output occurs. The method showed a linear relationship between the light signal intensity and the Hg2+ concentration in the range of 1.67 × 10−13–1.67 × 10−7 M with a detection limit of 1.67 × 10−13 M, corresponding to 4.0 × 10−18 mol/tube. The system proved precise, accurate, and highly selective for mercury and methylmercury, with no light emission induced by other heavy metals; the matrix effect caused by urine components was minimal. The analysis of urine specimens showed that urinary mercury levels in subjects with amalgam fillings were slightly significantly higher than those in subjects without amalgam fillings (p < 0.1) and the statistically significant difference improved when creatinine-normalized values were considered (p < 0.05). In summary, from the analytical point of view this luminescent microbial biosensor represents an easy, rapid, and sensitive tool to analyse Hg2+ in biological and environmental samples. Along with the possibility of using 384-well microtitre plates requiring very low reagent volumes, these characterisitcs make the system suitable for the high-throughput screening of Hg2+ on large numbers of specimens. This method could help better clarify the relationship between dental amalgam and urinary mercury excretion by permitting large-scale analysis of many selected groups of subjects, with strict control of all the relevant parameters affecting Hg2+ concentration in urine, such as diet and environmental and occupational exposure.

A Cluster of Pediatric Metallic Mercury Exposure Cases Treated with meso-2,3-Dimercaptosuccinic Acid (DMSA)

Nine children and their mother were exposed to vapors of metallic mercury. The source of the exposure appears to have been a 6-oz vial of mercury taken from a neighbor's home. The neighbor reportedly operated a business preparing mercury-filled amulets for practitioners of the Afro-Caribbean religion Santeria. At diagnosis, urinary mercury levels in the children ranged from 61 to 1,213 microg/g creatinine, with a geometric mean of 214.3 microg/m creatinine. All of the children were asymptomatic. To prevent development of neurotoxicity, we treated the children with oral meso-2,3-dimercaptosuccinic acid (DMSA). During chelation, the geometric mean urine level rose initially by 268% to 573.2 microg mercury/g creatinine (p&lt;0.0005). At the 6-week follow-up examination after treatment, the geometric mean urine mercury level had fallen to 102.1 microg/g creatinine, which was 17.8% of the geometric mean level observed during treatment (p&lt;0.0005) and 47.6% of the original baseline level (p&lt;0.001). Thus, oral chelation with DMSA produced a significant mercury diuresis in these children. We observed no adverse side effects of treatment. DMSA appears to be an effective and safe chelating agent for treatment of pediatric overexposure to metallic mercury.

Mercury toxicity due to use of a cosmetic cream.

The Arizona Department of Health Services performed an investigation to determine the health effects associated with the use of a mercury-containing beauty cream. A urine test for mercury was offered to cream users who contacted the Arizona Department of Health Services. Those with urine mercury levels > 20 micrograms/L were offered clinical evaluation. Eighty-nine urine specimens were submitted for testing. Of these, 66 showed an elevated urine mercury level (> 20 micrograms/L), and 55 people were evaluated in clinic. There were no major abnormalities found through physical examination or laboratory testing. Urine mercury levels declined from an initial mean of 170 micrograms/L to 32 micrograms/L at the final test (mean, 139 days later). The high urine mercury levels indicate that the use of this cosmetic cream constitutes a significant exposure. Neuropsychiatric symptoms were frequently reported, but few objective signs were noted.

Transdermal kinetics of a mercurous chloride beauty cream: an in vitro human skin analysis.

Crema de Belleza-Manning is a popular mercurous chloride-containing beauty cream used to smooth and lighten the complexion and treat acne. Hundreds of people in the Southwestern US border states have been identified with elevated (>20 microg/L) urine mercury levels believed to be secondary to using this cream. The kinetic characteristics of percutaneous mercury absorption are incompletely defined. The objective of this study was to determine the transdermal kinetics of two formulations of mercurous chloride from a beauty cream in an in vitro human skin model. A proprietary formulation and an aqueous formulation of the beauty cream were studied using modified Franz diffusion cells. Mercury content in the skin samples and the underlying diffusion buffer was determined using atomic absorption spectrophotometry. A rapid initial increase in mercury content both in the skin and the buffer was noted for both formulations. Mercury concentrations in the aqueous samples were significantly (p < 0.05) higher in both the skin and the diffusion buffer compared to parallel samples containing glycerol. Mercury was readily absorbed through the skin in this in vitro human skin model. The aqueous preparation had a markedly increased rate and extent of mercury absorption relative to the proprietary formulation.

Determination of urinary arsenic, mercury, and selenium in steel production workers.

The fumes and dust of trace elements and their compounds are very toxic and have been related to an increase in the incidence of diseases. Occupational exposure to toxic metals and metalloids can be determined by means of workplace air measurements and biological monitoring. The aim of our investigation was to determine the concentrations of As, Hg, and Se in urine samples under routine clinical laboratory conditions. To assess the reliability of these methods, critical factors such as detection limit(s), calibration range(s), cost, accuracy, and precision were studied. The method was employed for the quantitative determination of arsenic, mercury, and selenium in urine samples from steel production and quality control workers and healthy unexposed controls. After pretreatment with acids, the samples were digested by means of a microwave oven. Arsenic was determined by hydride atomic absorption spectrometry and mercury was determined by cold vapor atomic absorption spectrometry, whereas selenium was determined by a graphite furnace atomic absorption spectrometry. The results indicate those urinary arsenic, mercury, and selenium levels of the exposed workers are significantly higher than those of the controls. The possibility that these elements are involved in the etiology of diseases is discussed and recommendations are made to improve workplace ventilation and industrial hygiene practices.

Multiple sclerosis, dental caries and fillings: a case-control study

To investigate the association between multiple sclerosis, dental caries, amalgam fillings, body mercury and lead. Matched case-control study. Leicestershire in the years 1989-1990. Thirty-nine females with multiple sclerosis (of recent onset) were matched with 62 controls for age, sex and general practitioner. Home interview of cases and controls within which there was an assessment of the DMFT index and blood and urine mercury and lead levels. The odds of being a MS case increased multiplicatively by 1.09 (95% CI 1.00, 1.18) for every additional unit of DMFT index of dental caries. This represents an odds ratio of 1.213 or a 21% increase in risk of MS in relation to dental caries in this population. There was no difference between cases and controls in the number of amalgam fillings or in body mercury or lead levels. There was a significant correlation between body mercury levels and the number of teeth filled with amalgam (controls: r = +0.430, P = 0.006, cases: r = +0.596, P = 0.001). There was evidence of excess dental caries among MS cases compared with the controls. This finding supports the strong geographical correlation between the two diseases. A further study of this association is recommended.

Neuropsychological and Stress Evaluation of a Residential Mercury Exposure

Residents of a former factory building converted to apartments were exposed to mercury over a 2-year period. The neurobehavioral and emotional health effects of this exposure and subsequent evacuation are presented. Urine mercury levels were measured before (urine1) and 3-10 weeks after evacuation (urine2) of the building, when neurobehavioral and psychological measures were also completed. Performance on neurobehavioral and psychologic measures were compared between subjects above and below the median for urine1 (&gt;=19 microg/g creatinine) and were correlated with urine1 mercury levels. The high urine mercury group made more errors on a test of fine motor function and 84% of the residents reported clinically significant elevations in somatic and psychologic symptoms. Although subclinical tremor from mercury exposure may have affected subtle hand-eye coordination, other tests of motor function were not affected. Therefore, the observation of reduced hand-eye coordination may be due to chance. Significant levels of psychosocial stress were more closely associated with the evacuation necessitated by mercury exposure rather than a direct effect of mercury exposure.

Presence of Micronuclei in Lymphocytes of Mercury Exposed Workers

This work was supported by grants from the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq).

Pustular eruption following acute mercury exposure

Pustular eruptions are often overlooked complications of mercury exposure. A 35-year-old woman with a history of contact dermatitis to Mercurochrome® in childhood presented with generalized erythema with a symmetrical reinforcement in the flexures 2 days after exposure to a broken mercury thermometer. She was febrile with no other clinical or biological signs. Blood and urinary mercury levels were within normal range. Histology of a pustular lesion of the thigh showed eczematiform and pustular changes. Patch tests evidenced sensitization to several mercury derivatives, but not to other allergens from the ICDRG standard battery, except for nickel. This case report further illustrates that inhalation of mercury vapour can result in systemic contact dermatitis, sometimes called baboon syndrome or acute generalized exanthematous pustulosis. Copyright © 1999 by John Wiley & Sons, Ltd.

Button battery impaction in nasal cavity.

A button battery inserted in the nose of children is an unusual foreign body which is capable of causing extensive tissue damage, resulting from electrical and chemical burns. We report a case of button battery in the nose of a 4-year-old boy presenting with unilateral nasal discharge, and necrosis in the septum and turbinate of the right nasal cavity. Mercury level in concentrated urine was within normal limit. Microscopic examination disclosed extensive liquefaction necrosis with calcification and fibrosis. Numerous dark brown to black granules were noted in the elastic and collagen fibers and interstitium. Dark-field examination of the section revealed brilliantly refractile granules. Polarized microscopy failed to show the granules. Most brown pigments reacted to prussian blue. Tissue mercury analysis yielded a mercury content of 8.01 ppm. We report this case to emphasize the hazards of button battery impaction and to draw attention to the significance of the problem through histopathologic examination.

Simple direct method for the determination of total mercury levels in blood and urine and nitric acid digests of fish by inductively coupled plasma mass spectrometry

A simple direct method was developed to determine Hg by ICP-MS in diluted urine, diluted blood and HNO3 digests of fish. Wash-out times of <130 s for Hg concentrations ≤30 µg l–1 were achieved by complexing Hg with (NH4)2H2EDTA and the presence of ammonia. A novel disinfection procedure for urine and blood utilised dilution with a virucidal agent, Virkon. Virkon precipitated blood proteins, requiring subsequent dissolution using tetramethylammonium hydroxide. More than 85% of internal QC results were within ±1 µg l–1 of their target values for blood and >80% within 5% for urine. There was successful participation in three QA schemes for urine and one for blood. NIST Albacore Tuna gave 95% recovery of the target, 0.95 µg g–1, and good precision, 0.90±0.01 µg g–1 (n=3). The method did not discriminate between inorganic and organic Hg. Detection limits for Hg, using 3σ at or near the blank level, were 0.13 µg l–1 in blood, 0.27 µg l–1 in urine and 0.004 µg g–1 in fish. The developed methods were used to analyse samples collected from four sites in the Tapajos Valley of Brazil in an EC funded study of exposure to Hg as a result of gold mining. All but one of the subjects (n=106) had Hg levels in either blood or urine that exceeded the upper 95% limits for non-exposed subjects, 55% had blood Hg levels above the 95% limit in industrial workers (19 µg l–1) and 17% exceeded the urine Hg limit at which industrial workers should be removed from exposure (50 µg l–1). Subjects living in a fishing village, Jacareacanga, 100 km from mining activities, had significantly higher blood Hg levels (mean 81 µg l–1) than the other three groups (p<0.004), presumed to be related to fish consumption. Fish Hg levels were similar to those found in other polluted areas, mean 0.379 mg kg–1 (n=52). The EC study provided the strongest evidence to date in 1991 that Hg in fish in the Amazon basin posed much more of a general health problem than Hg vapour since it affected a larger proportion of the population than just the gold miners, ancillary workers and traders. The methods were also used in the routine clinical analysis of blood and urine samples within the UK National Health Service. Investigations included a case of acute mercury poisoning in a 28-month-old boy who had swallowed a battery who had an initial blood Hg of 394 nmol l–1 and urine Hg of 16 nmol mmol–1 creatinine. He was successfully treated with the chelating agent British Anti-Lewisite.

Biological Monitoring of Inorganic Mercury in Workers in a Fluorescent Lamp Plant

Biological Monitoring of Inorganic Mercury in Workers in a Fluorescent Lamp Plant. Masako Iden, et al. Matsushita Electronics Corp., Okayama Factory—The level of mercury in urine is measured as an exposure monitoring of mercury, and the activity of urinary N‐acetyl‐β‐D‐glucosaminidase (NAG) is used as an index of adverse effects of mercury on human kidneys. Here we examined the validity of these procedures by comparing the urinary total mercury (U‐Hg) level and NAG activity in both 75 male workers exposed to inorganic mercury and age‐matched unexposed male workers in a fluorescent lamp plant. To investigate factors affecting the levels of U‐Hg, 12 items were selected in relation to oral intake and excretion of mercury: consumption of 1) soft drink, 2) coffee or tea, 3) milk and 4) alcohol; 5) habit of drinking tap water at the work place; frequency of 6) eating fish and 7) alcohol intake; 8) smoking; 9) use of dental amalgam; 10) eating of home grown rice; 11) exercise habit and 12) age. The U‐Hg level and NAG activity were adjusted by creatinine levels. Personal exposure levels of inorganic mercury in air (A‐Hg) and the U‐Hg level correlated well (p&lt; 0.001) in the exposed group but neither the exposed nor unexposed group showed a correlation between the U‐Hg level and NAG activity. Although the mean level of U‐Hg in the exposed group was higher than that in the unexposed (p&lt; 0.001), no difference was observed in the mean level of NAG activity. A multiple regression analysis followed by a one‐way ANOVA revealed that only the frequency of eating fish per week contributed to increase the level of U‐Hg. The results suggest that oral intake of mercury from fish is a possible confounding factor in the exposure monitoring of inorganic mercury in the work place.

Mercury exposure from dental amalgam fillings: absorbed dose and the potential for adverse health effects.

This review examines the question of whether adverse health effects are attributable to amalgam-derived mercury. The issue of absorbed dose of mercury from amalgam is addressed first. The use of intra-oral Hg vapor measurements to estimate daily uptake must take into account the differences between the collection volume and flow rate of the measuring instrument and the inspiratory volume and flow rate of air through the mouth during inhalation of a single breath. Failure to account for these differences will result in substantial overestimation of the absorbed dose. Other factors that must be considered when making estimates of Hg uptake from amalgam include the accurate measurement of baseline (unstimulated) mercury release rates and the greater stimulation of Hg release afforded by chewing gum relative to ordinary food. The measured levels of amalgam-derived mercury in brain, blood, and urine are shown to be consistent with low absorbed doses (1-3 micrograms/day). Published relationships between the number of amalgam surfaces and urine levels are used to estimate the number of amalgam surfaces that would be required to produce the 30 micrograms/g creatinine urine mercury level stated by WHO to be associated with the most subtle, pre-clinical effects in the most sensitive individuals. From 450 to 530 amalgam surfaces would be required to produce the 30 micrograms/g creatinine urine mercury level for people without any excessive gum-chewing habits. The potential for adverse health effects and for improvement in health following amalgam removal is also addressed. Finally, the issue of whether any material can ever be completely exonerated of claims of producing adverse health effects is considered.

Mercury levels in plasma and urine after removal of all amalgam restorations: The effect of using rubber dams

Objective The aim of the present study was to determine whether removal of all amalgam restorations might significantly affect mercury levels in plasma and urine and whether the use of rubber dams might reduce patient exposure to mercury during amalgam removal. Methods All amalgam restorations were removed from 18 subjects during a single treatment session in which a rubber dam was used and from 10 subjects when a rubber dam was not used. All amalgam restorations were removed by the same dentist using high-speed cutting, water coolant, and high-volume evacuation. The levels of mercury in plasma and urine were analyzed both before and during the subsequent twelve months after amalgam removal. In order to determine whether removal of all amalgam restorations might cause an exposure large enough to significantly increase the mercury levels in two indicator media for mercury exposure, i.e., plasma and urine, and to determine if the removal might cause a significant decrease in the mercury levels found over time, the one-tailed, paired Students' t-test was used. For each individual, the pre-removal levels were compared with both the levels found in plasma on d 1 and in urine on d 10, and also with the levels found 1 y after removal. Furthermore, in order to examine whether the use of rubber dams had any effect on the mercury levels found after removal, the changes in the mercury levels found were compared between the groups using the Wilcoxon-Mann-Whitney rank sum test. Results After removal of all amalgam restorations, only the non-rubber dam group showed significant increases in the mercury levels found in plasma (p=0.012) and urine (p=0.037). However, one year later, the mercury levels in plasma and urine had sunk significantly below the pre-removal levels for both groups. When the changes in the mercury levels found were compared between the groups, the non-rubber dam group showed a significantly higher increase of mercury in plasma than the rubber dam group the day after removal (p=0.0010). Compared to the pre-removal mercury levels in plasma and urine, the levels found 1 y after removal of all amalgam restorations were on average 52 t 23% (range 4 – 89%) lower in plasma and 76 f 21 % (range 20 – 94%) lower in urine. Significance The study showed that dental amalgam had a statistically significant impact on the mercury levels found in plasma and urine in the patients tested, and that the use of a rubber dam during removal of all amalgam restorations significantly reduced the peak of mercury in plasma following removal.

B lymphocytes in mercury-exposed workers.

We have investigated the number of B lymphocytes in mercury-exposed workers. The study group consisted of 33 workers from a mercury-producing plant, mean age 27 years and a mean exposure period 19 months. At the time of testing and for the three previous months, the exposed persons had urinary mercury levels below the currently accepted limit of 50 micrograms g creatinine. A significant reduction in the number of B lymphocytes was observed in the mercury-exposed individuals. We found no correlation between B lymphocytes changes and urinary mercury concentrations, length of exposure or age of the workers.

Subcutaneous Metallic Mercury Injection

The case of a patient who injected 10 cc of metallic mercury subcutaneously into his left forearm through multiple punctures in an attempt at suicide is presented. Diagnosis was made by plain radiography of his left forearm, which exhibited redness, edema, and tenderness on the third day postinjection. Early excision of all affected subcutaneous tissues including metallic mercury deposits was performed on the fifth day postinjection. Blood and urine mercury levels that were initially found in high levels decreased dramatically to normal ranges after the excision and remained unchanged at the follow-up period of 6 months. No renal or hepatic functional impairment was encountered. The patient was free of toxic symptoms and mercury embolism. The local, aseptic lytic property of metallic mercury, which could cause severe damage to vital structures, was observed perioperatively. Early diagnosis and early, massive excision of mercury deposits in affected tissues is the important treatment modality in these rare cases.

The future of dental amalgam: a review of the literature. Part 5: Mercury in the urine, blood and body organs from amalgam fillings.

This is the fifth article in a series of seven on the future of dental amalgam. This covers the studies of mercury distribution to the blood, body organs and the fetus and its excretion in the urine and faeces of humans and experimental animals. It firstly describes the clinical studies comparing the blood and urine mercury levels in patients with and without amalgam fillings and goes on to consider attempts which have been made to calculate tolerable mercury thresholds for the urine. It secondly describes the studies on the body distribution of mercury from amalgam restorations in experimental animals and human cadavers. It finally describes the studies of mercury distribution to the fetus during pregnancy and includes both studies of experimental animals and human clinical studies. The factors affecting the accuracy of these calculations and the relevance of these results is also extensively discussed.

Follow-up of mercury levels in fish, human hair and urine in the Madeira and Tapajós basins, Amazon, Brazil

Informal economy of gold mining has contaminated some important river basins in Amazon. Follow-up studies on critical compartments showed some areas with high Hg levels in fish as well as in human hair samples. Average Hg in piscivorous fish in the Madeira river itself was 846 ppb (N=284) with a maximum of 3921 ppb. Mercury in fish from non polluted areas in this basin shows high variability, even for single species. A seasonal variation in Hg content was observed, with higher values at the end of the dry season. In the upper Tapajos basin comparable values were found for fish but with a definite decreasing trend downstream. Average value for piscivorous fish in the whole Tapajos basin is 482 ppb (N=122) with a maximum value of 3770 ppb. Hair Hg was higher in fishing villages in the Tapajos (average: 17 ppm; with N=432 and maximum value of 176 ppm) than in the Madeira (average: 9 ppm; N=169; maximum 71 ppm), and data from some areas of the Tapajos suggest a decrease with time. Mercury was much higher in urine of goldshop workers in Santarem (low Tapajos) than in Alta Floresta (high Tapajos) and show a decreasing trend in both cases, probably related to the significant decline in gold mining activities during the study period (1986-1994).

Biological monitoring for mercury within a community with soil and fish contamination.

To assess the impact of elevated levels of inorganic mercury in soil and dust and organic mercury in fish, biological monitoring was conducted among Native Americans living next to an inactive mercury mine in Clear Lake, California. Of resident tribal members, 46% (n = 56) participated in biomonitoring. Urine mercury levels are equivalent to background, indicating that soil and dust exposures among study participants are not substantial. The average blood organic mercury level among study participants is 15.6 +/- 8.8 micrograms/l (n = 44), which is higher than levels reported by others among those who do not consume fish (2 micrograms/l). Consistent with results from other studies, a correlation between fish consumption and blood organic mercury is observed (p = 0.03). The margin between observed and established adverse effect levels for adults is examined for blood organic mercury and found to be less than 10-fold for 20% of the study population. Protective public health efforts for the study population and other similarly exposed populations, notably those who consume commercial fish products, are considered.