Objective: To assess the critical issues concerning the use of urinary inorganic arsenic (iAs), including As3, As5, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), as biomarker of internal dose in order to monitor environmental and occupational exposure to inorganic As, considering the influence of diet and drinking water on excretion of iAs.
Methods: The design protocol stipulated collection of weekly urine samples from 6 male subjects for 5 consecutive months. In all the urine samples, iAs was determined by Hydride Generation-Atomic Absorption Spectrophotometry (HG-AAS). In the subjects with iAs higher than 35 microg/L, Biological Exposure Index (BEI) proposed by the American Conference of Governmental Industrial Hygienists (ACGIH), urinary arsenic speciation was performed by HPLC-ICP-MS. Exposure to airborne As was evaluated monthly using personal environmental samplers worn for 8 hours. Throughout the study, the participants filled out a daily food diary, also detailing types of water drunk.
Result: Exposure to airborne As was invariably below the limit of detection, equal to 1 ng/m3. A total of 77 urine samples were collected. iAs was always detectable and was higher in 7 urine samples, obtained from 5 of the 6 subjects examined, than the BEI. Among foods with a high As content, the intake of seafood and fish within 72 hours before providing the sample seems to be the principal source of the iAs concentrations, while the intake of rice or drinking water showed no influence on this biological marker. Instead, drinking wine within 24 hours before urine sample collection can cause a significant increase in the excretion of iAs.
Conclusions: In populations that eat large amounts of fish and seafood, the use of iAs to monitor occupational and environmental exposure to inorganic As seems to present some problems, and urinary As speciation may be essential at least in cases with As measurements above the biological limit values. In any case, a diet sheet reporting all foods eaten within 3 days of urine collection seems to be an indispensable tool to ensure a correct interpretation of the results.