Exploring indirect sources of human exposure to perfluoroalkyl carboxylates (PFCAs): evaluating uptake, elimination, and biotransformation of polyfluoroalkyl phosphate esters (PAPs) in the rat.
BACKGROUND
Perfluorinated carboxylic acids (PFCAs) are ubiquitous in human sera worldwide. Biotransformation of the polyfluoroalkyl phosphate esters (PAPs) is a possible source of PFCA exposure, because PAPs are used in food-contact paper packaging and have been observed in human sera.


OBJECTIVE
We determined pharmacokinetic parameters for the PAP monoesters (monoPAPs) and PAP diesters (diPAPs), as well as biotransformation yields to the PFCAs, using a rat model.


METHODS
The animals were dosed intravenously or by oral gavage with a mixture of 4:2, 6:2, 8:2, and 10:2 monoPAP or diPAP chain lengths. Concentrations of the PAPs and PFCAs, as well as metabolic intermediates and phase II metabolites, were monitored over time in blood, urine, and feces.


RESULTS
The diPAPs were bioavailable, with bioavailability decreasing as the chain length increased from 4 to 10 perfluorinated carbons. The monoPAPs were not absorbed from the gut; however, we found evidence to suggest phosphate-ester cleavage within the gut contents. We observed biotransformation to the PFCAs for both monoPAP and diPAP congeners.


CONCLUSIONS
Using experimentally derived biotransformation yields, perfluorooctanoic acid (PFOA) sera concentrations were predicted from the biotransformation of 8:2 diPAP at concentrations observed in human serum. Because of the long human serum half-life of PFOA, biotransformation of diPAP even with low-level exposure could over time result in significant exposure to PFOA. Although humans are exposed directly to PFCAs in food and dust, the pharmacokinetic parameters determined here suggest that PAP exposure should be considered a significant indirect source of human PFCA contamination.
Department of Chemistry, University of Toronto, Ontario, Canada.
Jessica C
JC
D'eon
Scott A
SA
Mabury
D000818:Animals; D001711:Biotransformation; D004781:Environmental Exposure / Q000032:analysis*; D004785:Environmental Pollutants / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D004952:Esters / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D005243:Feces / Q000737:chemistry; D005466:Fluorocarbons / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D006801:Humans; D008297:Male; D010710:Phosphates / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D051381:Rats; D017207:Rats, Sprague-Dawley
D004785:Environmental Pollutants; D004952:Esters; D005466:Fluorocarbons; D010710:Phosphates