Ecological and human health risk of aryl-phosphate flame retardants (APFRs): Sources, distribution, and toxicity

Aryl-phosphate flame retardants (APFRs), a subcategory of organophosphate flame retardants (OPFRs), are present in a diverse range of materials including plastic, and foam products, furniture, and electronic waste. Despite their widespread use, research on the toxicity of APFRs remains limited. In order to clarify more clearly the environmental and health risks caused by APFRs, this review provides a comprehensive overview of the occurrence and toxicity of four environmental APFRs: triphenyl phosphate (TPHP), 2-ethylhexyl diphenyl phosphate (EHDPP), isobutyl diphenyl phosphate (IDPP), and diphenyl phosphate (DPHP). Regarding the toxicity of APFRs, it seems that EHDPP and TPHP act in different ways in the intestine, but both cause disorders of lipid metabolism in the liver. On the contrary, the toxic effects of EHDPP and IDPP in the liver may be similar, but the specific mechanisms require further study. At the same time, DPHP, as the main biotransformation of APFRs, should receive more attention for its toxicity. Prioritizing the investigation of in vivo transformation products, particularly DPHP and enhancing the study of APFRs' biodegradation are crucial to comprehensively assess the toxicity of APFRs.