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Comparative description of PFAA developmental toxicity: An update
Citation:
U.S. EPA, C. LAU, K. DAS, J. R. THIBODEAUX, B. E. GREY, AND J. M. ROGERS. Comparative description of PFAA developmental toxicity: An update. Presented at PFAA Days, RTP, NC, June 03 - 04, 2008.
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Presentation
Description:
The perfluoroalkyl acids (PFAAs) are a family of fluorocarbons consisting of a perfluorinated carbon tail (typically 4-12 carbons in length) and an acidic functional moiety, usually carboxylate or sulfonate. These compounds have excellent surface tension reducing properties and have numerous industrial and consumer applications. The rates of PFAA elimination and their body burden accumulation appear to be dependent on carbon-chain length, functional moieties, and animal species. For instance, in rodents, the serum half-life for the C-8 compounds perfluorooctane sulfonate (PFOS) was estimated as 7 days (rats) and perflurorooctanoate (PFOA) as 17-19 days (mice), but that for the C-4 compound perfluorobutyrate (PFBA) was only 2-17 hours (rats and mice). Correspondingly, a slightly longer half-life for the C-9 compound perfluorononanoate (PFNA), than that of PFOA has been reported in the rat. When laboratory rodents were exposed to some PFAAs during pregnancy, adverse developmental effects were noted. Generally, in utero exposure to PFAAs did not produce anatomical defects, except at high doses where maternal toxicity was observed. However, newborn rats and mice exposed to PFOS showed labored breathing and died within hours to days, in a dose-dependent manner. Neonatal mortality was also observed in mice exaosed to PFOA, but the rate of loss was less abrupt than that seen with PFOS, with deathreported as late as 3-5 postnatal days of age. Deficits of growth and development were evident in the neonates exposed to lower doses of the chemical Preliminary results from a recent study indicated that mouse neonates exposed to PFNA displayed a similar pattern of mortality as that seen with PFOA. However, pup loss was much more gradual, with pups dying until weaning at postnatal day 24. Significant growth deficits and developmental delays were noted among survivors, and significant increases in liver weight were observed up to 6 weeks postnatally. In contrast to the C-8 and C-9 compounds, in utero exposure to PFBA did not lead to any neonatal death or growth deficits, although slight developmental delay and transient liver enlargement were seen in the pups. Thus, developmental toxicity of PFAAs appears to be correlated to the carbon-chain length (with a potency ranking of PFNA > PFOA > PFOS >> PFBA), and is, to a large extent, related to the rate of elimination of the chemical. This abstract does not necessarily reflect US EPA policy.