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     

Statistical study of the correlation between mercury exposure (TWA) and urinary mercury concentrations in chloralkali workers

The present report completes a previous study made on three chloralkali plants that was presented at the 8th International Conference on Occupational Health in the Chemical Industry, Tokyo, 1980, with the final results from five plants located in various regions of Italy. A total of 14,339 measurements of mercury in air and 8,042 determinations of mercury in urine were considered. The total number of workers involved was 275. On the basis of these data, we believe it can be concluded that, as previously reported, a correlation exists between mercury concentrations in the air and in the urine of exposed workers. This correlation is such that for exposures in the order of the present TLV (0.05 mg/m³), the value of the Z ratio (ratio between mean urinary mercury values expressed in mg/l and mean airborne mercury concentrations expressed in mg/m³) is 1.3, while the urinary mercury values vary from 0.051 mg/l to 0.078 mg/l with a mean value of 0.065 mg/l.     

Cytogenetic examination of leucocytes of workers exposed to mercury vapour

Summary Cytogenetic observations have been performed on male subjects occupationally exposed to elemental mercury in a plant where mercury is amalgamated with zinc and in a chloralkali plant [n=22; average level of mercury in urine was 117 g/g creatinine and of mercury in blood 3.1 g/100 ml; mean duration of Hg exposure 4 years (range: 0.3–15.3)]. The exposure to mercury vapour did not result in an increased yield of structural chromosomal aberrations in peripheral blood lymphocytes of the workers. These negative results are in agreement with the findings reported for other eukaryotic systems and confirm that population monitoring based on cytogenetic examination of peripheral blood lymphocytes does not always represent a good indicator of damage to genetic material produced by a chemical.     

Size-dependence of mercury (II) accumulation kinetics in the mosquitofish,Gambusia affinis (Baird and Girard)

Size-dependence of mercury (II) accumulation from water by the mosquitofish,Gambusia affinis was assessed under controlled laboratory conditions. Uptake rates were higher for smaller fish than for larger fish. Mean (±S.D.) uptake rate for mosquitofish exposed to 0.24 g/L of Hg was 0.32 ± 0.15 g/g dry wt/day. Uptake rate constants were similar for the Hg (II) and Hg° as reported elsewhere. Both inorganic species (Hg (II) and Hg°) were accumulated faster than methylmercury. Elimination rate constants averaged 0.530.14 per day (mean ± 1 S.D.). No significant size effects on elimination rate constants were detected. Elimination constants were similar to those reported elsewhere for Hg° elimination but larger than those for methylmercury elimination.     

Excretion kinetics and variability of urinary mercury in workers exposed to mercury vapour

Summary Determinations of mercury in urine were made in samples collected from workers that were: (a) exposed prior to sampling — urine has been sampled over 3 weeks' post-exposure period; (b) currently exposed — sampling on consecutive days of the working week; (c) currently exposed —urine sampled over 24 hrs, during working shift (morning or afternoon) and off work.Mercury excretion in group (a) followed a two-term exponential equation with rate constants of about 0.35 and 0.01 day^–1. Regardless of exposure time pattern in all groups studied, a diurnal variation of urinary concentrations of mercury was observed with a maximum at night and morning hours, and minimal values in the afternoon. The great variability in Hg-concentrations could have been related to the time of day at which the sampling took place, and partly to variation of urine excretion rate, the 2 factors being interrelated. Only a moderate variability in urinary concentrations of mercury was found when the sampling was instituted at a constant time of day, and when the results were standardized for specific gravity of urine.Investigations supported in part by the Polish-American agreement 05-009-2 and 05-003-2 with NIOSH, USA.     

High exposure of Chinese mercury mine workers to elemental mercury vapor and increased methylmercury levels in their hair

Objective The aim of this study was to determine the level of exposure of mercury (Hg) miners and smelter workers to elemental mercury (Hg⁰) vapor in China, who work in Hg mines without using protective equipment against Hg⁰ vapor. In addition, the level of methylmercury (MeHg) intake by the workers was estimated from the MeHg concentration in their hair. Methods Urinary total mercury (THg) and hair THg and MeHg concentrations were measured in 26 Hg miners and smelter workers (i.e., exposed group), and 48 unexposed people (unexposed group). Results The exposed group showed high geometric mean THg concentrations in urine (258 ng/ml, 226 μg/g creatinine) and hair (20.0 μg/g). The urinary THg concentration of the smelter workers in particular was extremely high (338 μg/g creatinine in urine). The highest urine THg concentration reached 4577 μg/g creatinine. THg concentrations in urine and hair showed a significant correlation in the exposed group (r=0.62), indicating the adhesion of Hg⁰ vapor to hair. However, no such significant correlation was found in the unexposed group. Hair MeHg concentration in the exposed group (1.97 μg/g) was about threefold higher than that in the unexposed group (0.60 μg/g). Conclusions This study shows that smelter workers in a Chinese Hg mine are exposed to extremely high levels of Hg⁰ vapor, and that Hg miners are exposed to higher levels of MeHg than the unexposed subjects. Further study is needed to determine the cause of the higher hair MeHg concentration in the exposed group.     

Effect of occupational mercury exposure on plasma lysosomal hydrolases

Summary The activities of three plasma lysosomal hydrolases, -galactosidase, -glucuronidase and -N-acetylglucosaminidase, were studied in 20 workers exposed to metallic mercury vapor in a chlorine alkali plant and in 10 nonexposed referents. The urinary excretion and blood levels of mercury were determined on the day of study, and the history of mercury exposure was reviewed from the records of mercury concentrations in urine and blood over periods of up to 133 months. The average levels of -N-acetylglucosaminidase and -glucuronidase were higher in the plasma of exposed workers, but the difference was not significant. No significant positive correlation was seen between lyosomal enzyme activities and cumulative long-term exposure to mercury. It is concluded that measurement of plasma lysosomal hydrolase-activities is not of great value in the biological monitoring of workers exposed to low concentrations of metallic mercury vapor.In line with published data, the concentration of mercury showed a clearcut diurnal variation in nonexposed persons, persons currently exposed and persons with a history of past exposure. The excretion rate of mercury remained constant throughout the day.     

Indoor air mercury concentrations following application of interior latex paint

Mercury vapors are released from paint containing mercury compounds used to prolong the shelf-life of interior latex paint. To determine whether homes recently painted with paint containing mercury had elevated indoor-air mercury concentrations, we studied 37 Ohio homes. Twenty-one homes painted with mercury-containing paint a median of 86 days earlier were compared with 16 homes not recently painted with mercury-containing paint. Paint samples from the exposed homes contained a median of 210 mg Hg/L (range 120–610 mg/L). The median air mercury concentration was higher in the exposed homes (0.3 g/m³; range nondetectable-1.5 g/m³) than in the unexposed homes (nondetectable; range nondetectable-0.3 g/m³, P < 0.0001). Among the exposed homes there were seven in which paint containing <200 mg/L had been applied. In these homes, the median air mercury concentration was 0.2 g/m³ (range nondetectable-1 g/m³). Six (33%) exposed homes had air mercury concentrations >0.5 g/m³, the acceptable indoor concentration recommended by the Agency for Toxic Substances and Disease Registry. Elemental mercury was the form of mercury released into the air. These data demonstrate that potentially hazardous mercury exposure may occur in homes recently painted with paint that contains mercury concentrations <200 mg/L.     

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

Objective: 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. Methods: 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-ß-d-glucosaminidase (NAG). Results: The range for the 8-h TWA airborne mercury exposure concentrations was 0.1 to 6,315?μg/m³, with a mean of 183?μg/m³. Twenty percent of the TWA airborne mercury exposure measurements were above the NIOSH recommended exposure limit (REL) of 50?μg/m³, and 26% exceeded the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 25?μg/m³. The mean urine mercury concentration was 101?μg/g creatinine (μg/g-Cr), and the data ranged from 2.5 to 912?μg/g-Cr. Forty–two percent of the study participants had urine mercury concentrations that exceeded the ACGIH biological exposure index (BEI) of 35?μg/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). Conclusions: 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.     

Urinary mercury excretion and body weight on workers exposed to mercury vapour

Summary From the 5-year record of health checks including urinary mercury levels and body weights on 33 workers exposed to mercury vapour in a tungsten rod manufacturing factory, the relationships between the level of urinary mercury and the body weight, and between the change of urinary mercury levels and that of body weights, were analysed. Except for the workers with the short period of exposure, on whom no significant correlation was found, correlations between the changes; urinary mercury and body weight, were much stronger than those between the levels. In contrast to the significant negative correlations in the mentioned relationships on the workers with the long period of continuous exposure at atmospheric concentrations below 0.2 mg/m³, there was significant positive correlations on the workers with occasional, short-period exposures at much lower concentrations of mercury. The importance of analysis on the change of exposure and its relation to the effect was emphasized, and possible effects of mercury to the regulation of body weight was discussed.     

Study of preclinical changes in workers exposed to inorganic mercury in chloralkali plants

Summary The aim of the present work was to clarify the question of preclinical changes of Hg intoxication (micromercurialism) in man. The study to detect these disorders was performed on 39 chloralkali plant workers who had been exposed to mercury for more than 7 years. The ambient air, urine and blood values of the last few years were determined in extensive measurements by various methods and related to one another. The average ambient air concentrations were clearly below the currently applicable threshold limit value (German MAK) of 0.1 mg/m³. For the purpose of clarifying the mentioned question of preclinical changes of intoxication, the exposed persons were subjected to psychomotor-function examinations and compared with a group of nonexposed persons. The blood pressure and pulse frequency values of both groups were also determined and compared with one another. No significant differences between the two groups of persons examined were detectable.Presented at the 18th Congress of the Deutsche Gesellschaft für Arbeitsmedizin in Frankfurt, 24th May 1978     

Estimation of mercury dose by a novel quantitation of elemental and inorganic species released from amalgam

Amalgam fillings constitute, after food, the main source of exposure to mercury for the general population. An evaluation of potential health risks has to be based on the dose of mercury released from the fillings. This dose is estimated by a new procedure of mercury speciation which elutes the released elemental and inorganic mercury with solvents of different polarity (paraffin and saline). In vitro tests with spherical amalgam pellets have shown that mercury release into the solvents is linearily correlated to time and amalgam surface area. Doses estimated in volunteers by this method average 4.5 g/day (range 0.3–13.9), as compared to a dose of 3.4 g/day (range 0.1–11.8) measured conventionally in the oral air. The aforementioned dose, combined with the nearly equal mercury uptake from food, is below the acceptable daily intake of 40 g for all forms of mercury.German patent nr. 4323072     

Human co-exposure to mercury vapor and methylmercury in artisanal mercury mining areas, Guizhou, China

Mercury (Hg) concentrations were determined in human urine and hair samples from Gouxi (GX, n=25) and Laowuchang (LWC, n=18), Tongren, Guizhou, China, to evaluate human exposure from artisanal Hg mining. Geometric means of urinary Hg (U-Hg) were 216 and 560 μg g⁻¹ Creatinine (μg g⁻¹ Cr) for artisanal mining workers from GX and LWC, respectively, and clinical symptoms (finger tremor) were observed in three workers. The means of hair Me-Hg concentrations were 4.26 μg g⁻¹ (1.87-10.6 μg g⁻¹) and 4.55 μg g⁻¹ (2.29-9.55 μg g⁻¹) for the population in GX and LWC, respectively. Significant relationship was found between estimated rice Me-Hg intake and hair Me-Hg levels (r=0.73, p<0.001). Co-exposure to Hg vapor and Me-Hg may pose health risks for the study population.     

Post-mortem findings and clinical signs of dimethyl mercury poisoning in man

Summary A lethal dimethyl mercury poisoning was described in a 28-year-old chemist who had prepared 6000 g of this compound in the laboratory. Numbness and tingling of the lips, hands, and feet developed, as well as ataxia, disturbance of speech, concentric constriction of the visual fields, and signs of upper motor neurone lesion. There was no damage to peripheral nerves either in clinical or EMG examination. The spontaneous daily Hg excretion in urine was 124 to 142 g Hg/day. The amount of eliminated mercury was not changed by administration of dimercaptopropanole nor by peritoneal dialysis. Penicillamine, administered at 750 mg/day, increased excretion to 535 g Hg/day, but with no noticeable clinical effect. Total mercury levels (in g Hg/g wet weight) were found in various organs as fallows: brain 13.2 to 14.2, kidney 25.6, liver 26.8, spleen 5.4, and muscle 4.67. On post-mortem examination, symmetrical lesions in the cerebral cortex were found, particulary in the calcarine area. In the cerebellar cortex there was primarily a loss of Purkinje cells. The brain stem and anterior horns of the spinal cord also showed a moderate degree of damage.     

Effects of oxygen concentrations on release of mercury from sediments and accumulation byCeratophyllum demersum andAnodonta grandis

The effects of different oxygen concentrations on the release of mercury from sediments and its subsequent accumulation by the plant,Ceratophyllum demersum, and the clam,Anodonta grandis, were investigated. Clams and plants were subjected to three treatments which were designated as control, treatment 1 and treatment 2. Two of the control replicates had normal oxygen concentrations (x=6.4–6.6 mg.L^–1) while the third had reduced concentration (x=1.8 mg.L^–1)- Oxygen concentrations in treatment 1 were reduced (¯x 1.3–2.0 mg.L^–1) for all three replicates. The three replicates in treatment 2 had normal oxygen concentrations (x=6.7–7.2 mg.L^–1). Mercury was added to the sediments in treatments 1 and 2. The resulting measured mean total mercury concentrations ((g.g^–1 dry weight) in the sediments of the replicates were 0.05–0.09 (controls), 4.42–7.28 (treatment 1) and 3.92–5.90 (treatment 2). The mercury concentration in water ranged between 0.10 g.L^–1 to 0.20 g.L^–1 for the six week period that the clams and plants were exposed to one of the three treatments. The total mercury concentrations in water were significantly lower in controls than in treatment 2. In plants, the mercury concentration was significantly higher in deoxygenated treatment 1 as compared to oxygenated treatment 2 and in controls. No significant difference in mercury concentration occurred between control and treatment 2 plants. Clams in treatments 1 and 2 contained significantly more mercury compared to the controls. Mercury concentrations in treatment 1 clams were also significantly higher than in treatment 2 clams. The mercury concentration in water, plants and clams was not significantly different in oxygenated and deoxygenated controls.     

Search for anti-laminin antibodies in the serum of workers exposed to cadmium,mercury vapour or lead

Summary Anti-laminin antibodies were sought for in the serum of workers exposed to mercury vapour (Hg, n = 58), lead (Pb, n = 38) or cadmium (Cd, n = 47). Thirty-one workers removed from Cd exposure for an average of eight years were also examined. Compared with control workers matched for age and socio-economic status, the prevalence of circulating anti-laminin antibodies was not increased in workers exposed to Hg (mean duration of exposure: 7.9 years and mean urinary excretion of Hg: 72 g/g creatinine) nor in those exposed to Pb (mean duration of exposure: 10.6 years and mean Pb levels in blood: 535 g/l). In contrast, anti-laminin antibodies were significantly more prevalent in Cd-exposed workers whose urinary Cd exceeded 20 g/g creatinine. This observation was made in both currently exposed workers and in workers removed from Cd exposure (mean duration of exposure: 9.4 and 24.6 years and mean urinary Cd: 7.8 and 13.4 g/g creatinine respectively). These autoantibodies were found in Cd workers with normal renal function as well as in those with increased proteinuria.     

Phthalic acid excretion as an indicator of exposure to phthalic anhydride in the work atmosphere

Summary The concentration of phthalic acid was determined in the urine of nine subjects occupationally exposed to phthalic anhydride. For the determination, the urine samples were acidified, extracted with dimethyl ether, esterified with boron trifluoride/methanol and measured by electron capture gas chromatography. Environmental air samples were collected in Tenax tubes, eluted with methyl-t-butyl ether and assayed by electron capture gas chromatography. Significant correlations were found between the concentration in urine samples (range: 0.3–14.0 mol/mmol creatinine), collected at different times of the day, and the time-weighed average atmospheric concentrations (range: 0.03–10.5 mg/m³). No conjugation of phthalic acid in the urine was observed. The detection limit for urine samples (10 ml) was 0.05 mol/l) and that for air samples 0.4 g/m³. The method has potential for biological monitoring of workers exposed to phthalic anhydride. It was found that at atmospheric anhydride concentrations of about 30% of the hygienic reference value (6 mg/m³). which is applied in many market economies, a body-burden was caused which was not eliminated overnight.     

Cardiovascular reflexes and low long-term exposure to mercury vapour

Summary Subjective symptoms related to autonomic dysfunction and quantitative non invasive tests measuring both sympathetic and parasympathetic functions of the autonomic nervous system were studied among a group of 41 chlorine-alkali workers with low long-term exposure to mercury (Hg') vapour and their matched referents. The test battery included measurements of pulse rate variation in normal and deep breathing, in the Valsalva manoeuvre and in vertical tilt as well as blood pressure responses during standing and isometric work. The exposure time had been 16 years on average, and the mean exposure to Hg vapour was estimated to have been about 30 g/m³ of air. Only a tendency for a subtle reduction of cardiovascular reflex responses and a slight increase of subjective symptoms were seen in the exposed group, but no significant autonomic dysfunction was associated with the low level of exposure.     

Atmospheric distribution and deposition of mercury in the Idrija Hg mine region, Slovenia

The atmospheric distribution and deposition of Hg in the area of the former Idrija Hg-mine, Slovenia, were investigated. Mapping of air Hg⁰ concentrations was performed to assess the spatial distribution and major sources of mercury to the atmosphere in the area. In addition, analyses of mercury speciation in the air over Idrija were performed during a 4-day sampling campaign in September 2006 to better understand the fate and transformation of Hg in the atmosphere of this specific mercury polluted site. The speciation results were then compared to the results of mercury speciation in the wet and throughfall deposition sampled on a precipitation event basis from October 2006 to September 2007. The Hg⁰ concentration in air was mostly below 10 ng m⁻³, with the highest concentration in the area of the former smelter complex exceeding 5000 ng m⁻³. Mercury-bearing airborne particles (TPM) seem to dominate the atmospheric Hg deposition, which revealed noticeable variations between precipitation events (11–76 ng m⁻² day⁻¹), mostly as a function of the amount of precipitation. Hg in precipitation was largely (∼50%) associated with the particulate phase (THg_P). No correlation was found between the THg_P and the dissolved phases (THg_D), suggesting that particulate phase Hg is mostly the result of dry deposition. In the throughfall, significantly higher (2–10 fold) Hg concentrations than in associated event precipitation were observed, mostly due to Hg in the particulate phase (∼70% THg). As shown by SEM/EDXS microscopy, an important amount of mercury in the precipitation and throughfall samples is due to the presence of cinnabar particles as a result of the aeolian erosion of cinnabar-containing surfaces in the area.     

Organic and Inorganic Mercury in Neonatal Rat Brain after Prenatal Exposure to Methylmercury and Mercury Vapor

Background

Many populations are exposed to multiple species of mercury (Hg), predominantly organic Hg as methylmercury (MeHg) from fish, and inorganic Hg as Hg vapor from dental amalgams. Most of our knowledge of the neurotoxicity of Hg is based on research devoted to studying only one form at a time, mostly MeHg.

Objectives

In this study we investigated the effects of prenatal exposure to MeHg and Hg vapor on Hg concentrations in the brain of neonatal rats.

Methods

Female Long-Evans hooded rats were exposed to MeHg (0, 3, 6, or 9 ppm as drinking solution), Hg vapor (0, 300, or 1,000 μg/m³ for 2 hr/day), or the combination of both, from 30 days before breeding through gestational day 18. On postnatal day 4, whole brains were taken from one male and one female from each of four litters in each treatment group to assess organic and inorganic Hg in the brain by cold vapor atomic absorption spectrometry.

Results

Statistical analysis using linear mixed effects models showed that MeHg dose was the primary determinant of both organic and inorganic brain Hg levels. For both outcomes, we also found significant interactions between MeHg and Hg vapor exposure. These interactions were driven by the fact that among animals not exposed to MeHg, animals exposed to Hg vapor had significantly greater organic and inorganic brain Hg levels than did unexposed animals.

Conclusion

This interaction, heretofore not reported, suggests that coexposure to MeHg and Hg vapor at levels relevant to human exposure might elevate neurotoxic risks.