John Wiley & Sons, Ltd.

Use of an avian hepatocyte assay and the avian ToxChip PCR array for testing prioritization of 16 organic flame retardants

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Risk assessors are challenged with the task of providing data for an increasing number of priority chemicals. High‐throughput toxicity screening methods, which permit rapid determination of toxic, molecular and/or biochemical effects of a wide range of chemicals, are essential to help meet this demand. The avian embryonic hepatocyte in vitro screening method has been utilized by our laboratory to assess the effects of a wide range of environmental contaminants on (i) cytotoxicity and (ii) mRNA expression of genes associated with xenobiotic metabolism, the thyroid hormone pathway, lipid metabolism, and growth. Sixteen structurally variable organic flame retardants (OFRs), including tetrabromoethylcyclohexane (TBECH), tris(2‐butoxyethyl) phosphate (TBEP), tricresyl phosphate (TCP), and tris(1,3‐dichloro‐2‐propyl) phosphate (TDCPP), were screened using the in vitro method in this study. Hepatocytes from two avian species, chicken and herring gull, were prepared and species differences in hepatocyte viability were observed for several OFRs. For example, TCP was not cytotoxic in chicken hepatocytes up to the highest concentration tested (300 µM) whereas the LC50 was 31.2 µM in herring gull hepatocytes. Effects on mRNA expression in chicken embryonic hepatocytes were determined using a 3 × 32 custom‐made Avian ToxChip PCR array and were variable among OFRs; TCP, TDCPP and tris(2,3‐dibromopropyl) isocyanurate showed the most significant alterations among the target genes assessed. Overall, this rapid screening method helped prioritize OFRs for further assessment. For example, OFRs that elicited significant effects on cytoxicity and/or mRNA expression represent prime candidates for egg injection studies that determine adverse effects on the whole animal but are more costly from a time, money, and embryo utilization standpoint. Environ Toxicol Chem © 2013 SETAC

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