Association of past diseases with levels of cadmium and tubular dysfunction markers in urine of adult women in non-polluted areas in Japan.

BACKGROUND AND OBJECTIVES: Whereas information has been accumulating on the association of anemia and other diseases with cadmium (Cd) burden, histories of past diseases of the examinees are often not taken in account when the results of health examination are evaluated for cadmium exposure-related health effects on general populations. The present study was initiated to examine the possible association of previous diseases with Cd exposure parameters, taking advantage of compiled data on adult women.
METHODS: Data were cited from previous publications of this research group on Cd, α1-microglobulin (α1-MG), β2-microglobulin (β2-MG), N-acetyl-β-D-glucosaminidase (NAG) and urine density makers (i.e., creatinine and specific gravity) in the urine of more than 17,000 adult women in non-polluted areas in Japan. Information on previous disease history together with age and smoking habits was obtained by self-administered questionnaires, and 13,031 never-smoking women were selected for the present analyses. To compare the cases with disease history, control cases were randomly selected after stratification by 5 years of age at a ratio of one case to three controls from those with no disease history; summation for all age strata made up the control groups for the disease group in concern. The random sampling to set up control groups was repeated three times in total. The difference between the disease group and control groups was considered valid in cases the difference was statistically significant (p ≦ 0.05), in all three cases after correction (or non-correction) for urine density, and the same results were obtained when compared with the three different control groups.
RESULTS: In the anemia group, Cd-U was higher over corresponding three control groups, although none of α1-MG-U, β2-MG-U or NAG-U showed significant changes. In the diabetes mellitus group, NAG-U was higher than in the controls, but such differences were not observed in Cd-U or β2-MG-U. The elevation in α1-MG-U was not reproducible. In the case of the hypertension group, the elevations in Cd-U, α1-MG-U, and β2-MG-U were observed, but changes in NAG-U could not be confirmed. In the analysis of dose-response relationship, the diabetes mellitus group showed increases in the slope for β2-MG-U and in the intercept for NAG-U. No changes in dose-response relationship were observed in other disease groups as compared with the corresponding control groups.
CONCLUSIONS: Care should be taken in evaluating Cd-related health examination results for those with history of diseases such as hypertension, anemia and diabetes mellitus in particular.