title: Editor's Highlight: Comparative Toxicity of Organophosphate Flame Retardants and Polybrominated Diphenyl Ethers to Caenorhabditis elegans.
abstract: With the phasing-out of the polybrominated diphenyl ether (PBDE) flame retardants due to concerns regarding their potential developmental toxicity, the use of replacement compounds such as organophosphate flame retardants (OPFRs) has increased. Limited toxicity data are currently available to estimate the potential adverse health effects of the OPFRs. The toxicological effects of 4 brominated flame retardants, including 3 PBDEs and 3,3',5,5'-tetrabromobisphenol A, were compared with 6 aromatic OPFRs and 2 aliphatic OPFRs. The effects of these chemicals were determined using 3 biological endpoints in the nematode Caenorhabditis elegans (feeding, larval development, and reproduction). Because C. elegans development was previously reported to be sensitive to mitochondrial function, results were compared with those from an in vitro mitochondrial membrane permeabilization (MMP) assay. Overall 11 of the 12 flame retardants were active in 1 or more C. elegans biological endpoints, with only tris(2-chloroethyl) phosphate inactive across all endpoints including the in vitro MMP assay. For 2 of the C. elegans endpoints, at least 1 OPFR had similar toxicity to the PBDEs: triphenyl phosphate (TPHP) inhibited larval development at levels comparable to the 3 PBDEs; whereas TPHP and isopropylated phenol phosphate (IPP) affected C. elegans reproduction at levels similar to the PBDE commercial mixture, DE-71. The PBDEs reduced C. elegans feeding at lower concentrations than any OPFR. In addition, 9 of the 11 chemicals that inhibited C. elegans larval development also caused significant mitochondrial toxicity. These results suggest that some of the replacement aromatic OPFRs may have levels of toxicity comparable to PBDEs.
authors: Division of the National Toxicology Program, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, North Carolina.
authors: Mamta
authors: M
authors: Behl
authors: Division of the National Toxicology Program, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, North Carolina.
authors: Julie R
authors: JR
authors: Rice
authors: Social & Scientific Systems, Inc., Durham, North Carolina.
authors: Marjo V
authors: MV
authors: Smith
authors: Social & Scientific Systems, Inc., Durham, North Carolina.
authors: Caroll A
authors: CA
authors: Co
authors: Social & Scientific Systems, Inc., Durham, North Carolina.
authors: Matthew F
authors: MF
authors: Bridge
authors: Division of the National Toxicology Program, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, North Carolina.
authors: Jui-Hua
authors: JH
authors: Hsieh
authors: Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, Kentucky.
authors: Jonathan H
authors: JH
authors: Freedman
authors: Division of the National Toxicology Program, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, North Carolina boydw@niehs.nih.gov.
authors: Windy A
authors: WA
authors: Boyd
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000187:drug effects* / Q000196:embryology / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects; D005247:Feeding Behavior / Q000187:drug effects; D005411:Flame Retardants / Q000633:toxicity*; D055768:Halogenated Diphenyl Ethers / Q000633:toxicity*; D007814:Larva / Q000187:drug effects / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D063065:Organophosphonates / Q000633:toxicity*; D012098:Reproduction / Q000187:drug effects
chemical_list: D005411:Flame Retardants; D055768:Halogenated Diphenyl Ethers; D063065:Organophosphonates
keywords: Caenorhabditis elegans; flame retardants; mitochondrial toxicity.