Evaluation of the estrogenic potency of nonylphenol in non-occupationally exposed humans

In this study, the estrogenic potency of 4-nonylphenol (NP) was estimated and a risk calculation for non-occupationally exposed humans was performed. The daily intake of non-occupationally exposed persons was estimated to be less than 0.16 mg/day. Risk estimates were based on this daily intake and the relative potency of NP to 17β-estradiol. Comparison of this intake with the NOAEL derived from a 90-day subchronic toxicity study in animals, results in a safety factor of about 20 000. A safety margin of 3000 can be derived when comparing the resulting NP blood concentrations (calculated upon pharmacokinetic studies) with 17β-estradiol levels in the blood of adult males. Risk estimations based on the daily intake of NP and the resulting organ concentrations (calculated upon the lipid content) compared with minimal estrogenic cell effect concentrations result in a safety factor in the range of 5000. In addition, the comparison of NP with genistein in human blood indicate a minor importance of nonylphenol. The results of this study show that the non-occupational exposure to NP does not pose an estrogenic health risk to humans.