Urinary cadmium and N-acetyl-beta-D-glucosaminidase excretion of inhabitants living in a cadmium-polluted area.

Urinary cadmium (Cd), N-acetyl-beta-D-glucosaminidase (NAG), and creatinine levels were determined for 400 inhabitants living in Cd-polluted districts of Annaka City in Gunma Prefecture, Japan. The Cd pollution was mainly due to falling dust from a zinc smelter factory according to seasonal winds. The Cd-polluted areas were divided into five administrative districts around the factory. The geometric mean of the urinary Cd level of the inhabitants in the five districts, Nodono, Iwai, Ooya, Nakajyuku, and Itahana, were 2.95, 2.66, 2.45, 1.97, and 1.67 micrograms/g creatinine, respectively. The geometric means for Nodono and Iwai are statistically larger than that for Itahana (P less than 0.01). These results were well explained by the wind direction and proximity to the factory. In addition, a two-way analysis of variance on the urinary Cd level was made using place of residence and smoking habits. The effect was mainly due to the place of residence, and no interactions were found. There were statistically significant differences in NAG excretion among the five groups, but no difference could be found between two groups using a multiple comparison. Pearson's correlation coefficient between the logarithm of urinary Cd content and that of NAG was 0.203, but statistically significant (r = 0.462 without creatinine correction; P less than 0.01). The present results indicate the association of urinary Cd and NAG levels in a Cd-exposed population whose geometric mean of urinary Cd content is about 2 micrograms/g creatinine. We recommend a continuous survey of the minimum health effects of the Cd pollution using urinary levels of Cd and protein including NAG.