Study of 1,4-dioxane intake in the total diet

1,4-Dioxane is a newly added compound to the water quality standards in Japan that were revised in 2003. In order to estimate the contribution of 1,4-dioxane in drinking water to the total exposure in humans, it is necessary to take into account the quantity of the compound in food. In an earlier study, we measured the intake of 1,4-dioxane in food based on the average consumption of food in the Kanto area.(1)) The total daily intake of 1,4-dioxane was calculated to be 0.440 mu g. In the present study, we investigated the intake of 1,4-dioxane from food by sampling meals from 3 days from 3 homes in 9 prefectures, respectively. 1,4-Dioxane was extracted from 20 g of homogenates of mixed meals using the steam distillation, concentrated by a solid phase cartridge and then measured using gas-chromatography/mass spectrometry. The detection limit of the analysis was 2 mu g/kg. No 1,4-dioxane was detected in 26 samples, while 3 mu g/kg was detected in one sample. In this sample case, the daily intake of the 1,4-dioxane was calculated as 4.5 mu g that represented 0.56% of the total daily intake (TDI) (4.5 mu g/1 16 mu g/kg body weight/day X 50 kg}).