Chapter 3A: Phthalates: Biomarkers and Human Biomonitoring

A qualitative and quantitative assessment of the general population's exposure to phthalates is important because phthalates are reproductive toxicants (endocrine disruptors) and exposure is known to be ubiquitous. Human biomonitoring (HBM) is an ideal tool to assess exposure to phthalates because HBM determines internal exposures by measuring specific metabolites in urine. These metabolites are not prone to external contamination, a problem that is inevitable when analyzing phthalates in environmental media. Furthermore, metabolites in urine represent an integral measure of exposure from all sources and routes possible. In this way, HBM can also estimate exposures from sources that are difficult to evaluate quantitatively (such as dermal exposures or exposures from mouthing) or from sources that are altogether unknown. Therefore, especially in the case of phthalates, HBM has opened a new and alternative approach to an integral exposure and risk assessment of phthalates. We present a comprehensive review on HBM of phthalates, including basic data on human metabolism with a discussion on the choice of biomarkers most suitable for HBM, a compilation of data on urinary phthalate metabolite levels from numerous HBM studies, approaches to extrapolate from urinary metabolite levels to the phthalate dose taken up (daily intakes), a critical risk assessment comparing HBM-derived daily phthalate intakes with health benchmarks and limit values, and a consideration of the cumulative exposure to phthalates with concepts such as the cumulative tolerable daily intake (TDI_cum) and the hazard index (HI).