Assessment of exposure to inorganic arsenic by determining the arsenic species excreted in urine.

Urinary concentrations of inorganic arsenic metabolites (AsIII, AsV, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA)) and occupational exposure to arsenic were measured in 24 copper smelter and arsenic trioxide refinery workers during a study period consisting of 2 pairs of work days and the 6 (partly 4) days off between them. The correlations between the time-weighted average (TWA) concentrations of arsenic in air (0.8-45 micrograms/m3) and the concentrations of arsenic species in urine 0, 0-8, 8-16 and 16-20 h after the exposure were calculated. The best correlation (r = 0.78, P = 0.0001) was found for the sum of AsIII and AsV concentration in urine collected between 0 and 8 h after the exposure. The DMA concentrations at any time in urine correlated only poorly to the exposure. A reason for this was obviously an increased urinary excretion of DMA due to the ingestion of DMA in the diet. An 8-h TWA exposure of 10 micrograms As/m3 was calculated to lead to an inorganic arsenic concentration of 5 micrograms/l in urine.