Occurrence, Fate, Human Exposure, and Toxicity of Commercial Photoinitiators

Photoinitiators (PIs) are a family of anthropogenic chemicalsusedin polymerization systems that generate active substances to initiatepolymerization reactions under certain radiations. Although polymerizationis considered a green method, its wide application in various commercialproducts, such as UV-curable inks, paints, and varnishes, has ledto ubiquitous environmental issues caused by PIs. In this study, wepresent an overview of the current knowledge on the environmentaloccurrence, human exposure, and toxicity of PIs and provide suggestionsfor future research based on numerous available studies. The residualconcentrations of PIs in commercial products, such as food packagingmaterials, are at microgram per gram levels. The migration of PIsfrom food packaging materials to foodstuffs has been confirmed bymore than 100 reports of food contamination caused by PIs. Furthermore,more than 20 PIs have been detected in water, sediment, sewage sludge,and indoor dust collected from Asia, the United States, and Europe.Human internal exposure was also confirmed by the detection of PIsin serum. In addition, PIs were present in human breast milk, indicatingthat breastfeeding is an exposure pathway for infants. Among the mostavailable studies, benzophenone is the dominant congener detectedin the environment and humans. Toxicity studies of PIs reveal multipletoxic end points, such as carcinogenicity and endocrine-disruptingeffects. Future investigations should focus on synergistic/antagonistictoxicity effects caused by PIs coexposure and metabolism/transformationpathways of newly identified PIs. Furthermore, future research shouldaim to develop greener PIs with high efficiency, lowmigration, and low toxicity.

Automated summary

Photoinitiators (PIs) are anthropogenic chemicals used in polymerization systems to initiate polymerization reactions. Their wide application in commercial products has led to environmental issues. This study reviews the occurrence, human exposure, and toxicity of PIs and suggests future research directions. PIs have been found in commercial products, water, sediment, sewage sludge, indoor dust, serum, and breast milk. Benzophenone is the most detected congener. PIs have toxic effects, such as carcinogenicity and endocrine disruption. Future research should focus on coexposure effects, metabolism/transformation pathways, and the development of greener PIs.