Investigation of the amount of transdermal exposure of newborn babies to phthalates in paper diapers and certification of the safety of paper diapers

A risk assessment study of seven phthalates in paper diapers for newborn babies produced in Japan was performed. The diapers were purchased and the contents of the seven phthalates were determined and estimated amounts of exposure were calculated based on the eluted rate into artificial medium of urine or sweat, average weight of infants, and frequency of use. Di-2-ethylhexyl phthalate and di-n-butyl phthalate were detected in the topsheets and determined to be 0.6 μg/g and 0.2 μg/g, respectively. The daily estimated exposure volume was calculated to be in the range of 1.86 × 10−10-2.98 × 10−6 mg/kg/day as follows: content of seven phthalates in the topsheet (0.1-1 μg/g) × eluted rate of phthalates into artificial sweat (0.0006-2.4%) × weight of the topsheet of a diaper (1.5 g) × the number of diapers used per day (12 sheets) × skin absorption rate (0.005-0.1)/average body weight (2.9 kg). For hazard assessment, we used 0.2-300 mg/kg/day for the seven phthalates based on the data available at international agencies. The margin of exposure to the seven phthalates was 6.71 × 104-1.99 × 1011, indicating that the risk of exposure to phthalates from the diapers produced in Japan was negligible.