CAN HUMANS METABOLIZE ARSENIC COMPOUNDS TO ARSENOBETAINE

Arsenic compounds were determined in 21 urine samples collected from a male volunteer, The volunteer was exposed to arsenic through either c onsumption of codfish or inhalation of small amounts of (CH3)(3)As pre sent in the laboratory air, The arsenic compounds in the urine were se parated and quantified with an HPLC-ICP-MS system equipped with a hydr aulic high-pressure nebulizer. This method has a determination limit o f 0.5 mu g As dm(-3) urine. To eliminate the influence of the density of the urine, creatinine was determined and all concentrations of arse nic compounds were expressed in mu g As g(-1) creatinine, The concentr ations of arsenite, arsenate and methylarsonic acid in the urine were not influenced by the consumption of seafood, Exposure to trimethylars ine doubled the concentration of arsenate and increased the concentrat ion of methylarsonic acid drastically (0.5 to 5 mu g As g(-1) creatini ne), The concentration of dimethylarsinic acid was elevated after the first consumption of fish (2.8 to 4.3 mu g As g(-1) creatinine), after the second consumption of fish (4.9 to 26.5 mu g As g(-)1 creatinine) and after exposure to trimethylarsine (2.9 to 9.6 mu g As g(-1) creat inine), As expected, the concentration of arsenobetaine in the urine i ncreased 30- to 50-fold after the first consumption of codfish, Surpri singly, the concentration of arsenobetaine also increased after exposu re to trimethylarsine, from a background of approximately 1 mu g As g( -1) creatinine up to 33.1 mu g As g(-1) creatinine. Arsenobetaine was detected in all the urine samples investigated, The arsenobetaine in t he urine not ascribable to consumed seafood could come from food items of terrestrial origin that-unknown to us-contain arsenobetaine. The p ossibility that the human body is capable of metabolizing trimethylars ine to arsenobetaine must be considered. (C) 1997 by John Wiley & Sons , Ltd.