Daily inorganic arsenic intake of the Japanese estimated by a probabilistic approach.

OBJECTIVE: The objective was to estimate the inorganic arsenic (iAs) intake of the general Japanese adult population by a probabilistic approach.

METHODS: Bioaccessible iAs concentrations in rice (n=56) and hijiki (n=32), the two food items that are the major iAs sources for the Japanese, were measured by liquid chromatography-ICP mass spectrometry. The concentration in cooked rice was estimated from the measured concentration in a raw rice sample while taking into consideration the loss of iAs during cooking. The iAs concentration in hijiki was measured using soaked hijiki samples. The daily consumption of cooked rice and soaked hijiki was taken from published data. The distribution profile of daily iAs intake was estimated by multiplying the bioaccesible iAs concentration in cooked rice and soaked hijiki samples by the amount of these samples consumed daily, which were randomly extracted according to the respective distributions. This process was repeated 10,000 times.

RESULTS: The distribution profiles of iAs concentration in rice and hijiki were normal and log-normal, respectively, and those of the amount of cooked rice and soaked hijiki consumed were beta and log-normal, respectively. The daily bioaccessible iAs intake values were estimated to be 19 and 59 μg/day at 50 and 95 percentile. At 50 percentile iAs intake, the contributions from rice and hijiki were estimated to be equal, whereas the contribution from hijiki increased with the estimated total daily iAs intake.

CONCLUSIONS: The iAs intakes of Japanese subjects estimated in previous duplicated portion studies were fairly consistent with the present estimation. Moreover, it was confirmed that the cancer risk derived from dietary iAs intake of the general Japanese population was not negligible.