Developmental neurotoxicity of organophosphate flame retardants (OPFRs): risks to human health and ecosystems.

Abstract

Organophosphate flame retardants (OPFRs), widely used as primary alternatives to banned brominated flame retardants, have been extensively applied across various industries worldwide. In recent years, OPFRs have increasingly emerged as significant environmental pollutants and have been shown to possess potential developmental neurotoxicity. This review systematically synthesizes current research on their environmental distribution, bioaccumulation, and neurodevelopmental effects. Studies indicate OPFRs are widely detected in air, water, soil, and organisms, demonstrating high environmental persistence and mobility. Humans are exposed through inhalation, ingestion, and dermal absorption, with infants and young children at higher risk due to frequent hand-to-mouth behavior and prolonged indoor exposure. Epidemiological studies suggest that prenatal exposure to OPFRs may be associated with low birth weight, behavioral abnormalities, and cognitive deficits, with evidence of sex-specific susceptibility. Experimental studies using model organisms, such as zebrafish and rodents, have further elucidated the potential mechanisms underlying OPFR-induced developmental neurotoxicity. Chemicals such as TDCPP, TPhP, and TCEP have been found to disrupt neural cell proliferation and differentiation, dysregulate gene expression, induce neuroinflammation, increase oxidative stress, and impair endocrine homeostasis. Despite significant progress in understanding the toxicity of OPFRs, critical scientific challenges remain unresolved. For example, the long-term effects of low-dose OPFR exposure on the nervous system are not yet fully understood. Furthermore, there is a lack of systematic analysis regarding the combined effects of multiple pollutants. Therefore, a deeper understanding of the toxicological mechanisms of OPFRs is essential to provide a stronger scientific foundation for the formulation of evidence-based environmental and public health policies.