Beyond Classic Phthalates: Occurrence of Multiple Emerging Phthalate Alternatives and Their Metabolites in Human Milk and Implications for Combined Exposure in Infants

Because of the recognized toxicity and legislative regulation of classic phthalates (PAEs), the manufacture and use of PAE alternatives have rapidly grown. However, lactational exposure to these emerging replacement chemicals remains unknown. In this study, 11 classic PAEs, 14 emerging PAE alternatives, and 24 of their metabolites were comprehensively investigated in human milk from China. Except for nine detectable PAEs, nine of the 14 emerging PAE alternatives, including three (1,4-DEHCH, 1,2-DEHCH, and DEHIP) not reported before in the environment, were first identified and detected in human milk. Total concentrations of nine detectable PAE alternatives were in the range of 0.252-16.1 ng/mL, slightly lower than those of nine detectable PAEs (2.12-34.1 ng/mL). Additionally, 12 of the 24 target metabolites were found in human milk. Total concentrations (4.41-138 ng/mL) of these metabolites were significantly higher than those of their parent compounds. Our findings highlighted the considerable coexistence of PAEs, emerging PAE alternatives, and their metabolites, resulting in a complex cocktail of plasticizers in human milk. Preliminary risk assessment indicated no or minor risk to breast-fed infants, but long-term low-level exposure to the cocktail chemicals is of emerging concern. This is the first identification of multiple emerging PAE alternatives and their metabolites in human milk.

Automated summary

This study comprehensively investigated classic PAEs, emerging PAE alternatives, and their metabolites in human milk from China, revealing the presence of multiple emerging PAE alternatives and their metabolites at relatively high concentrations.