An Epidemiological Study of Mercury Sensitization

Abstract

Mercury sensitization has been historically in question and may be related to recent increases of type I allergic diseases. To clarify the epidemiological factors of mercury sensitization, we investigated factors relating to mercury sensitization in 215 medical students. Their allergic symptoms, family histories and lifestyles were studied by questionnaire. Patch tests were performed with HgCI 2 (0.05% aq.) and NiS0 4 (5% aq.). Anti- Dermatophagoides and anti-Crypfomeria pollen IgE antibodies in sera were also measured. Urinary mercury concentrations were measured in 25 mercury sensitized and 44 non-sensitized subjects (controls). Hair mercury concentrations were also measured in 19 sensitized and 22 non-sensitized subjects. While the positive rate of nickel was 6.0% (13/215), that of mercury was high (13.0%; 28/215). The subjects' individual histories of allergic rhinitis, eczema, urticaria and allergic conjunctivitis were significantly associated with family histories of these conditions ( P < 0.01, P < 0.005 and P < 0.005, respectively), as reported in the literature. However, no allergen- specific antibody positivity or past history of allergic disease was associated with mercury sensitization. Mercury sensitized subjects had experienced eczema caused by cosmetics, shampoos, soaps and haircreams significantly more frequently ( P < 0.05). The history of mercurochrome usage was not associated with mercury sensitization. The number of teeth treated with metals in mercury sensitized subjects was significantly higher than that in the control group (6.8 ± 4.3 vs 4.8 ± 1; P < 0.05). There were significant differences in urinary mercury concentrations (specific gravity adjusted levels) between mercury sensitized subjects and non-sensitized subjects (2.0 ± 0.9 and 1.3 ± 0.6 (xg/L, respectively; P < 0.001). There were also significant differences in hair mercury concentrations between mercury sensitized and non-sensitized subjects (2.0 ± 0.9 and 1.2 ± 0.5 μg/g, respectively; P < 0.01). These results suggest that mercury sensitization is associated with exposure to mercury in the living environment and that skin symptoms are possibly associated as preceding factors.