The potential use of diisononyl phthalate metabolites hair as biomarkers to assess long-term exposure demonstrated by a rat model

•DINP metabolites were generated by in vitro liver enzyme incubation for mass and retention time matching.•Demonstrated that the eight DINP metabolites reported previously were detected in hair samples.•Profiles of the eight DINP metabolites were different in urine and hair samples.•Dose-response relationship was observed for using DINP metabolites in hair as exposure biomarkers.•Dose-response saturation was less pronounced in hair than in urine samples.

Diisononyl phthalate (DINP) is a widely used industrial plasticizer. People come into contact with this chemical by using plastic products made with it. Human health can be adversely affected by long-term DINP exposure. However, because the body rapidly excretes DINP metabolites, the use of single-point urine analysis to assess long-term exposure may produce inconsistent results in epidemiologic studies. Hair analysis has a useful place in biomonitoring, particularly in estimating long-term or historical exposure for some chemicals. Several studies have reported using hair analysis to assess the concentrations of heavy metals, drugs and organic pollutants in humans. As a biomarker, DINP metabolites were measured in rat hair in animal experiments to evaluated long-term exposure to DINP. In addition, we evaluated the correlation between the levels of DINP metabolites in hair and in urine. The levels of DINP metabolites in rat hair were significantly higher in the exposure group, relative to the control group (p < 0.05). DINP metabolites had a positive correlation with increasing administered dose. Significant positive correlations for MINP, MOINP and MHINP were found between hair and urine (r = 0.86, r = 0.79 and r = 0.74, respectively, p < 0.05). Several metabolites in urine showed earlier saturation than in hair. In this report, we detected eight metabolites in hair and demonstrate that hair analysis has potential applications in the assessment of long-term exposure to DINP.