[An epidemiological study of factors relating to mercury sensitization]

We investigated factors relating to mercury sensitization in 156 medical students (mean age 22.7 +/- 2.4, mean +/- S.D., male 113, female 43). Their allergic symptoms, lifestyles and family histories were studied by questionnaire. Patch tests were performed on them with HgCl2 (0.05%aq.), NiSO4 (5%aq.), PPD (2%pet.) and urushiol (0.01%pet.). Anti-dermatophagoides and anti-cryptomeria pollen IgE antibodies in serum were also measured. While the positive rates of urushiol, nickel and PPD were 11.1%, 5.1% and 2.6%, respectively, that of mercury was as high as 12.8%. Each allergen specific antibody positivity and past histories of allergic diseases were not associated with mercury sensitization (by the chi-square test). Mercury sensitized students had significantly more frequently experienced eczema caused by cosmetics, shampoos, soaps and haircreams (by the chi-square test, p < 0.005). They also had significantly more teeth treated with metals compared to the controls (one-tailed t-test, p < 0.05). And their urinary mercury concentrations were significantly higher than those of the controls (one-tailed t-test, p < 0.05). These findings suggest that mercury sensitization is associated with exposure to mercury in the living environment.