Aristolochic Acid Exposure via Dermal Contact or Inhalation of Herbal Powders: Evidence of Occupational Exposure in Herbalists with Urothelial Cancer

Emerging evidence showing urothelial cancer in herbalists is linked to aristolochic acid (AA) exposure; however, the exposure pathway remains unclear. Here, we show that dermal contact and inhalation of fine powders of AA-containing herbs are significant occupational AA exposure pathways for herbalists. We initiated the study by quantifying the amount of AA in the AA-containing powder deposited on gloves and face masks worn by the operators of an AA-containing herb grinding machine. Then, we measured the kinetics of dermal absorption and dissolution of AA from fine powders of AA-containing herbs into artificial sweat and surrogate lung fluid. Lastly, we quantified the mutagenic AA-DNA adduct levels formed in the kidneys of mice exposed to AA-containing fine powders through dermal contact. Our findings highlight an urgent occupational risk that should demand implementation of safety standards for herbalists exposed to AA-containing fine powders.