Evaluation of the effect of governmental control of human exposure to two phthalates in Japan using a urinary biomarker approach.

In Japan, the use of certain phthalates has been regulated. We analyzed the effectiveness of these measures using an analytical biomarker approach. We measured two phthalate metabolites, mono-n-butyl phthalate (MBP) and mono-2-ethylhexyl phthalate (MEHP) in urine samples from 36 participants using enzymatic deconjugation, offline solid phase extraction, and HPLC-ESI-MS/MS. From the levels measured and individual values of creatinine excretion rate the daily intake was determined and compared to each corresponding tolerable daily intake (TDI). The levels of urinary MBP and MEHP were < 1.8-280 and 0.76-25 microg/l, respectively. The ranges of the estimated daily intake of di-n-butyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEHP) from 35 adult urine samples were 0.22-4.5 and 0.37-7.3 microg/kg/ day, respectively. These values were lower than the corresponding TDIs. After comparing these values to previous exposure assessment data on DEHP in Japan, it could be seen that the DEHP intake dropped over the period from 1998 to 2001. Children were not covered in the present study, so the results may only be applicable to adults, not to the Japanese population at large. Even so, the small number of people in one specific geographic area cannot be considered representative of the adult Japanese population. In addition to MEHP, the secondary metabolites of DEHP, which are more suitable biomarkers should be measured in the future.