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Description
Per- and polyfluoroalkyl substances (PFAS) are chemicals resistant to degradation. While such features are desirable in consumer and industrial products, some PFAS, including perfluorooctanoic acid (PFOA), are toxic and bioaccumulate. Hexafluoropropylene oxide dimer acid (HFPO-DA), an emerging PFAS developed to replace PFOA, has not been extensively studied. To evaluate the potential toxicity of HFPO-DA with a cost- and time-efficient approach, we exposed C. elegans larvae to 4×10-9–4 g/L HFPO-DA in liquid media and measured developmental, behavioral, locomotor, and transcriptional effects at various exposure levels. After 48 hours of 1.5–4 g/L HFPO-DA exposure, acute developmental toxicity was observed as developmental delay; significantly delayed (p < 0.05) progeny production was observed in worms exposed to 2–4 g/L HFPO-DA. After 48 hours of 4×10-9–0.4 g/L exposure, no significant behavioral or locomotor effect was observed. At 48-hour, statistically significant differential gene expression was identified in all fourteen HFPO-DA exposure groups 48-hour ranging from 1.25×10-5 to 4 g/L, except for 6.25×10-5 g/L. Among 10298 genes analyzed, 2624 differentially expressed genes (DEGs) were identified in the developmentally delayed 4 g/L group only, and 78 genes were differentially expressed in at least one of the thirteen groups testing 1.25×10-5–2 g/L HFPO-DA exposures. Genes encoding for detoxification enzymes such as cytochrome P450 and UDP glucuronosyltransferases are upregulated in 0.25–4 g/L acute exposure groups. Statistically significant gene expression changes were also observed in lower exposure level groups, though these DEGs did not share biological functions except for six ribosomal protein-coding genes. While our transcriptional data is inconclusive to infer mechanisms of toxicity, the detection of significant gene expression differences at 1.25×10-5 g/L, the lowest concentration tested for transcriptional changes, calls for further targeted analyses of low-dose HFPO-DA exposure effects.
