Epidemiologic Study on the Association between Body Burden Mercury Level and Idiopathic Parkinson's Disease

Abstract

A case-control study was conducted among the multiethnic population of Singapore to test the hypothesis that a high level of body burden mercury is associated with an increased risk of Parkinson''s disease (PD). Selected factors investigated that could contribute to the body burden of mercury included dietary fish intake, ethnic over-the-counter medications, occupational exposures and possession of dental amalgam fillings. Detailed interviews were completed in 54 cases of idiopathic PD and 95 hospital-based controls, matched for age, sex and ethnicity, between July 1985 and July 1987. After adjusting for potential confounding factors, including dietary fish intake, medications, smoking and alcohol consumption, there was clear monotonic dose-response association between PD and blood mercury levels. The odds ratios (OR) and 95% confidence intervals (CI) for the approximate subject tertiles based upon blood mercury levels were 8.5 (CI = 2.2–33.2) and 9.4 (CI = 2.5–35.9), relative to the tertile with lowest blood mercury levels (< 5.8 ng Hg/ml). Similar associations were revealed using scalp hair and urinary mercury levels. However, only the comparisons between the highest and lowest tertiles were statistically different from unity (p < 0.05). When the body burden mercury indicators were mutually adjusted in addition to the four confounding factors, blood and urinary mercury levels showed ORs of 21.00 and 18.65, respectively. These ORs were statistically different from unity (p < 0.05, 2-sided test). After adjustment, scalp hair mercury was shown to be a poor predictor of PD risk.

Neurodegenerative diseases: occupational occurrence and potential risk factors, 1982 through 1991.

“…Finally, the large number of occupations for each cause of death could by chance alone result in some proportionate mortality ratios being statistically significant. 45 The elevated proportionate mortality ratios we observed for presenile dementia in dentists and dental assistants and for Parkinson's disease in dental assistants could be related to mercury exposure. Aluminum has been considered to be a risk factor for Alzheimer's disease because of the finding of a high content of aluminum in neurofibrillary tangles associated with Alzheimer's disease.…”

Genetics, drugs and environmental factors in Parkinson's disease: a case-control study

“…Tanner et al 28 , in a study carried out in China, attributed the low number of cases in that country to the lack of technological development in agriculture. A case-control study conducted with the multiethnic population of Singapore found high levels of mercury in both urine and hair of patients with PD 29 . Recently, Gorell et al 30 found positive results in a group of patients who were in contact with metals for more than 20 years of occupational activity.…”

Epidemiology and etiology of Parkinson’s disease: a review of the evidence

“…One casecontrol study observed no associations for intake of zinc, manganese, or copper [492]. A small case-control study (54 cases) reported higher blood levels of mercury in cases than controls [380], a finding not confirmed in another case-control study [313].…”

“…One early case-control study that measured levels of mercury in blood, urine, and hair reported increased risk of PD in relation to increased mercury levels (OR 9.4, 95% CI 2.5-35.9 for the highest tertile of blood mercury versus the lowest) [380]. An ecologic study reported a correlation between iron industries and PD mortality per county (Spearman rank correlation 0.29, p value 0.008), although there was no correlation between industries using copper and PD mortality [360].…”

“…Although many of the case-control studies reported ORs below unity, the association was nonsignificant in most studies [142,143,293,298,303,309,310,380,407,408,410,413,415,423]. A Swedish study that investigated the relationship of PD with beer, wine, and liquor reported inverse associations for each of these types of alcoholic beverages in univariate analyses.…”