Identification and Toxicity Prediction of Biotransformation Molecules of Organophosphate Flame Retardants by Microbial Reactions in a Wastewater Treatment Plant.

Yeowool Choi,Sang Don Kim

doi:10.3390/ijms22105376

Abstract

Organophosphate flame retardants (OPFRs) are substances added to plastics, textiles, and furniture, and are used as alternatives to brominated flame retardants. As the use of OPFRs increases in the manufacturing industry, the concentration in the aquatic environment is also increasing. In this study, OPFRs introduced into a wastewater treatment plant (WWTP) were identified, and the toxicity of biotransformation molecules generated by the biological reaction was predicted. Tris(2-butoxyethyl) phosphate, tris(2-butoxyethyl) phosphate, and triphenyl phosphate were selected as research analytes. Chemicals were analyzed using high-resolution mass spectrometry, and toxicity was predicted according to the structure. As a result, tris(1-chloro-2-propyl) phosphate showed the highest concentration, and the removal rate of OPFRs in the WWTP was 0–57%. A total of 15 biotransformation products were produced by microorganisms in the WWTP. Most of the biotransformation products were predicted to be less toxic than the parent compound, but some were highly toxic. These biotransformation products, as well as OPFRs, could flow into the water from the WWTP and affect the aquatic ecosystem.

Highlights

Organophosphate flame retardants (OPFRs) are substances applied when manufacturing plastics and fibers, and their production is gradually increasing due to the regulation of brominated flame retardants used in the past [1,2]
The concentration of OPFRs (TBEP, tris(1-chloro-2-propyl) phosphate (TCPP), and TPHP) and the removal rate of organic pollutants were identified according to the wastewater treatment process
tris(2-butoxyethyl) phosphate (TBEP) was found to have the highest concentration, and TCPP was not eliminated by the biological reaction of the wastewater treatment plants (WWTPs)

Summary

Introduction

Organophosphate flame retardants (OPFRs) are substances applied when manufacturing plastics and fibers, and their production is gradually increasing due to the regulation of brominated flame retardants used in the past [1,2]. OPFRs are likely to be eluted in water as they are added without chemical bonding in the product [4]. Research on OPFRs has been conducted with a focus on surface water and wastewater treatment plants (WWTPs). The total concentration of OPFRs was 877 ng/L (28.3–16,000 ng/L) in Lake Shihwa, South Korea. An OPFR concentration of 164–627 ng/L was detected near the WWTP runoff. The main OPFRs detected were tris(2-butoxyethyl) phosphate (TBEP), triethyl phosphate, and tris(2-chloroethyl) phosphate [5]. In Beijing’s surface water, an average concentration of 14 kinds of OPFRs was

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Conclusion