Biomonitoring equivalents for di-isononyl phthalate (DINP)

Biomonitoring Equivalents (BEs) are defined as the concentration or range of concentrations of a chemical or its metabolite in a biological medium (blood, urine, or other medium) that is consistent with an existing health-based exposure guideline such as a reference dose (RfD) or tolerable daily intake (TDI). BE values can be used as a screening tool for the evaluation of population-based biomonitoring data in the context of existing risk assessments. This study reviews available health based risk assessments and exposure guidance values for di-isononyl phthalate (DINP) from Health Canada, the United States Consumer Product Safety Commission (US CPSC), and the European Food Safety Authority (EFSA). Controlled dosing data reporting the urinary excretion fractions of major DINP metabolites following administration of labeled DINP are reviewed, and BE values corresponding to the available exposure guidance values are derived assuming chronic, steady-state intake and excretion at those exposure values. The BE values range from 1500 to 3600μg/L (1900-4600μg/g creatinine) based on the sum of three oxidative metabolites. Sources of uncertainty relating to both the basis for the BE values and their use in evaluation of biomonitoring data, including the transience of the biomarkers relative to exposure frequency, are discussed. The BE values derived here can be used as screening tools for evaluation of population biomonitoring data for DINP in the context of existing risk assessments and can assist in prioritization of the potential need for additional risk assessment efforts for DINP relative to other chemicals.