Experimental Study of OH-Initiated Heterogeneous Oxidation of Organophosphate Flame Retardants: Kinetics, Mechanism, and Toxicity
Open Access
- 22 November 2019
- journal article
- research article
- Published by American Chemical Society (ACS) in Environmental Science & Technology
- Vol. 53 (24), 14398-14408
- https://doi.org/10.1021/acs.est.9b05327
Abstract
The environmental risks and health impacts associated with particulate organophosphate flame retardants (OPFRs), which are ubiquitous in the global atmosphere, have not been adequately assessed due to the lack of data on the reaction kinetics, products and toxicity associated with their atmospheric transformations. Here, the importance of such transformations for OPFRs are explored by investigating the reaction kinetics, degradation chemical mechanisms and toxicological evolution of two OPFRs (2-ethylhexyl diphenyl phosphate (EHDP) and diphenyl phosphate (DPhP)) coated on (NH4)2SO4 particles upon heterogeneous OH oxidation. The derived reaction rate constants for the heterogeneous loss of EHDP and DPhP are (1.12±0.22)×10–12 and (2.33±0.14)×10–12 cm3 molecules–1 s–1, respectively. Using recently developed real-time particle chemical composition measurements, particulate products from heterogeneous photooxidation and the associated degradation mechanisms for particulate OPFRs are reported for the first time. Subsequent cytotoxicity analysis of the unreacted and oxidized OPFR particles indicated that the overall particle cytotoxicity was reduced by up to 94% with heterogeneous photooxidation, likely due to a significantly lower cytotoxicity associated with the oxidized OPFR products relative to the parent OPFRs. The present work not only provides guidance for future field sampling for the detection of transformation products of OPFRs, but also strongly supports the ongoing risk assessment of these emerging chemicals and most critically, their products.Keywords
Funding Information
- Chemicals Management Plan
This publication has 61 references indexed in Scilit:
- Co-Existence of Organophosphate Di- and Tri-Esters in House Dust from South China and Midwestern United States: Implications for Human ExposureEnvironmental Science & Technology, 2019
- Are cell phones an indicator of personal exposure to organophosphate flame retardants and plasticizers?Environment International, 2018
- Organophosphate ester (OPEs) flame retardants and plasticizers in air and soil from a highly industrialized city in TurkeyScience of The Total Environment, 2018
- Occurrence and Distribution of Organophosphate Flame Retardants/Plasticizers in Surface Waters, Tap Water, and Rainwater: Implications for Human ExposureEnvironmental Science & Technology, 2018
- Global Atmospheric Concentrations of Brominated and Chlorinated Flame Retardants and Organophosphate EstersEnvironmental Science & Technology, 2018
- Organophosphate Esters in Air, Snow, and Seawater in the North Atlantic and the ArcticEnvironmental Science & Technology, 2017
- Organophosphorus flame retardants and plasticizers: Sources, occurrence, toxicity and human exposureEnvironmental Pollution, 2015
- Priority and emerging flame retardants in rivers: Occurrence in water and sediment, Daphnia magna toxicity and risk assessmentEnvironment International, 2013
- Phosphorus flame retardants: Properties, production, environmental occurrence, toxicity and analysisChemosphere, 2012
- Traffic as a Source of Organophosphorus Flame Retardants and Plasticizers in SnowEnvironmental Science & Technology, 2005