High-dose exposure to inorganic mercury in man can influence the immune system and in rare cases cause immune-related disease. Some experimental animals also react with autoimmunity after low doses of inorganic mercury. Glomerulonephritis and an increased formation of immunoglobulin type E (IgE) are characteristic of these reactions. A recent study of 15-year-old adolescents demonstrated an association between immunoglobulin type A (IgA) and mercury concentration in plasma (P-Hg). There was also an association between allergic disease and IgA levels. The present study included 54 male and 23 female 19-year-old students who were recruited from a cohort that had been previously defined in a survey of allergic disease. Of the students, 39 (51%) had asthma, allergic rhinoconjunctivitis or eczema. Similar amalgam burden and P-Hg levels were observed in students with (n = 39) and without (n = 38) allergic disease (P = 0.48 and P = 0.98, respectively). As expected, IgE levels were significantly higher in the group with allergic disease (P = 0.006), but there was no association between P-Hg and IgE. The P-Hg levels were very low (median 1.50 nmol/l) and correlated significantly (r = 0.31) with the small number of amalgam surfaces (P = 0.007). Thirty-seven students had no amalgam fillings. P-Hg levels did not associate significantly with IgA, but did so with IgG2 (r = 0.33; P = 0.003). No conclusive correlation was observed between IgG2 and amalgam fillings. The findings of this study in 19-year-old subjects differ from earlier data obtained in a sample 4 years younger. The possibility of chance in the association between P-Hg levels and IgG2 must, however, be considered.
Section for Contaminants, Effects and Marine Mammals, Department of Arctic Environment, National Environmental Research Institute, University of Aarhus, Frederiksborgvej, Roskilde, Denmark. csh@dmu.dk
BACKGROUND: In the Arctic, polar bears (Ursus maritimus) bio-accumulate mercury as they prey on polluted ringed seals (Phoca hispida) and bearded seals (Erignathus barbatus). Studies have shown that polar bears from East Greenland are among the most mercury polluted species in the Arctic. It is unknown whether these levels are toxic to liver and kidney tissue. METHODS: We investigated the histopathological impact from anthropogenic long-range transported mercury on East Greenland polar bear liver (n = 59) and kidney (n = 57) tissues. RESULTS: Liver mercury levels ranged from 1.1-35.6 microg/g wet weight and renal levels ranged from 1-50 microg/g wet weight, of which 2 liver values and 9 kidney values were above known toxic threshold level of 30 microg/g wet weight in terrestrial mammals. Evaluated from age-correcting ANCOVA analyses, liver mercury levels were significantly higher in individuals with visible Ito cells (p
Populations of many North American sea ducks are declining. Biomarkers may offer valuable insights regarding the health and fitness of sea ducks in relation to contaminant burdens. In this study we examined body condition, immune function, corticosterone stress response, liver glycogen levels and vitamin A status in relation to tissue concentrations of mercury, selenium and cadmium in female common eiders during the nesting period. The study was conducted in the eastern Canadian arctic during July, 2000. Hepatic mercury, selenium and renal cadmium concentrations ranged 1.5-9.8, 6.5-47.5 and 74-389 microg/g, dry wt, respectively. Mercury concentrations were negatively related to dissection body mass, heart mass and fat mass. Cadmium concentrations were negatively related to mass at capture and dissection mass after controlling for the mercury concentration-dissection mass relationship. Cell-mediated immunity was assessed by the skin swelling reaction to an injection of phytohemagglutinin-P, and was unrelated to metal concentrations. After adjusting the corticosterone concentration to account for the time between capture and sampling, there was a negative relationship between the residual corticosterone concentration and selenium. Liver glycogen concentrations were not significantly related to metal concentrations. Mercury concentrations were positively related to those of hepatic retinol and retinyl palmitate and the ratio of the retinol to retinyl palmitate in liver. They were negatively related to the ratio of plasma to liver retinol. Our findings do not indicate that exposure to metals may have adversely affected the health of these birds. They do, however, suggest that more research is required to elucidate mechanisms by which exposure to these metals could impact body condition.
OBJECTIVES: To study the carcinogenicity of inorganic mercury in humans. METHODS: We studied the mortality from cancer among 6784 male and 265 female workers of four mercury mines and mills in Spain, Slovenia, Italy and the Ukraine. Workers were employed between the beginning of the century and 1990; the follow-up period lasted from the 1950s to the 1990s. We compared the mortality of the workers with national reference rates. RESULTS: Among men, there was no overall excess cancer mortality; an increase was observed in mortality from lung cancer (standardized mortality ratio [SMR] 1.19, 95 percent confidence interval [CI] 1.03-1.38) and liver cancer (SMR 1.64, CI 1.18-2.22). The increase in lung cancer risk was restricted to workers from Slovenia and the Ukraine: no relationship was found with duration of employment or estimated mercu ry exposure. The increase in liver cancer risk was present both among miners and millers and was stronger in workers from Italy and Slovenia: there was a trend with estimated cumulative exposure but not with duration of employment, and the excess was not present in a parallel analysis of cancer incidence among workers from Slovenia. No increase was observed for other types of cancer, including brain and kidney tumours. Among female workers (Ukraine only), three deaths occurred from ovarian cancer, likely representing an excess. CONCLUSIONS: Exposure to inorganic mercury in mines and mills does not seem strongly associated with cancer risk, with the possible exception of liver cancer; the increase in lung cancer may be explained by co-exposure to crystalline silica and radon.
Light microscopy and immunocytochemistry have been used to study the tissue reaction to non-irritant concentrations of mercury painted onto the oral mucosa of genetically mercury-sensitive BN rats. Low-dose skin injections of HgCl2 in BN rats result in an autoimmune syndrome, including also a spontaneous migration of T lymphocytes into the oral mucosa. Our results show that such infiltrates confer an increased degree of reactivity (contact stomatitis) to HgCl2 painted onto the BN (Hg) rat oral mucosa. In contrast, results were negative in the LEW rat strain, which is also resistant to development of autoimmunity to skin-injected mercury. The possible involvement of mucosal mercury-loaded macrophages is discussed. The results are also discussed with respect to possible etiologic and pathogenetic mechanisms involved in the development of dental material (amalgam)-associated lichenoid lesions of human oral mucosa.
Increasing knowledge about the risk of toxic effects caused by anthropogenic mercury accumulation in ecosystems has resulted in a growing pressure for reduction of the discharge of mercury waste. Consequently, the mercury waste problems of dental clinics have been given increased attention, and restrictions on handling and discharge of contaminated waste have been established in several countries. Major amalgam particles from trituration surplus of those produced during the carving and burnishing of new amalgam restorations are generally collected in coarse filters and sold for refinement. Minor amalgam particles released by production of new fillings or by removal of old restorations partly sediment in tubes and drains. The remaining particles are carried with the waste water stream to the local purifying plant. In Scandinavia, the industrial discharge of mercury-contaminated waste water has been reduced to a minimum. According to recent investigations, dental clinics appear to be responsible for the major amount of mercury collected in the sludge generated in purifying plants. If threshold values for heavy metal content, including mercury, are exceeded, the sludge is not allowed to be recycled as fertilizer. Installation of an approved amalgam-separating apparatus in dental clinics is now mandatory in several countries--for example, Switzerland, Germany, Sweden, and Denmark. Approval of amalgam separators is based on national testing programs, including clinical or laboratory tests demanding 95-99% separating efficiency.
Chronic exposure to inorganic mercury can cause kidney injury. Evidence gained from occupational medicine indicates that individuals who are exposed to only environmental sources, including amalgam tooth fillings, are at very little risk. Animal experiments, however, have revealed glomerular lesions of immunologic origin after low-dose exposure to inorganic mercury. In this study, the association between the number of amalgam tooth surfaces, urinary mercury, and proteinuria was explored in a sample of 48 randomly selected, apparently healthy male students who were 17-22 y of age. Presence of any of the following proteins in two separate urine samples was considered to be potentially indicative of any tubular and/or glomerular lesion: albumin, alpha-1-microglobulin (HC-protein), kappa and lambda light chains, and N-acetyl-beta-D-glucosaminidase. No significant relationship was found between any of the proteins and amalgam or urinary mercury. The results of this study did not suggest that amalgam fillings cause kidney dysfunction in humans.
