Purpose: Aristolochic acid can cause urothelial carcinoma. Herbal remedies containing aristolochic acids were previously categorized as proven group 1 human carcinogens by the WHO cancer agency, the International Agency for Research on Cancer. However, the health effect on workers exposed to aristolochic acid is unclear. Fangchi, a representative herb containing aristolochic acid, is commonly used in the Chinese herbal medicine industry. We determined whether workers exposed to fangchi are at increased risk for urothelial carcinoma. Materials and Methods: We designed a case-control study based in a national representative cohort of Chinese herbalists. This study analyzed 6,564 Chinese herbalists employed between 1985 and 1998. All incident cases of urothelial carcinoma that occurred between 1988 and 2001 were defined as the case group. Controls were selected from the baseline cohort in a randomized manner. A total of 24 cases and 140 controls were included in analysis. Information about fangchi exposure was obtained in a questionnaire survey administered in 2002. Results: Processing, selling or dispensing herbs containing fangchi significantly increased the risk of urothelial carcinoma (HR 2.4, 95% CI 1.1-5.3, p = 0.03). This relationship was independent of cigarette smoking or potential arsenic exposure from drinking water from deep wells. Conclusions: Exposure to the Chinese herbal drug fangchi increases the risk of urothelial carcinoma in herbalists. Appropriate medical monitoring is warranted for workers who have similar exposure.
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