PFCAs migrating from some packaging linings

Chemicals used in the linings of packaging such as fast-food wrappers and microwave popcorn bags are leaching into foods, adding to human chemical blood contamination, a new study has claimed.

Scientists from the University of Toronto, Canada, said polyfluoroalkyl phosphate esters (PAPs) present in grease-proofing agents in some food contact materials was one source of human exposure to perfluorinated carboxylic acids (PFCAs).

PFCAs are the breakdown products of chemicals used to make non-stick and water-and stain-repellent products ranging from kitchen pans to clothing to food packaging. PFCAs, the best known of which is perfluorooctanoic acid (PFOA), are found in humans globally, said the group.

"We suspected that a major source of human PFCA exposure may be the consumption and metabolism of polyfluoroalkyl phosphate esters (PAPs)," said Jessica D'eon, a graduate student in the university’s department of chemistry.

In the study, rats were exposed to PAPs either orally or by injection and monitored for a three-week period to track the concentrations of the PAPs and PFCA metabolites, including PFOA, in their blood. The team said it had established that humans were exposed to PAPs as part of previous research.

Exposure

The group calculated human PFOA exposure from the PAP metabolism by using PAP concentrations previously observed in human blood along with the PAP and PFCA concentrations observed in the rats.

Professor Scott Mabury, lead researcher, said: "We found the concentrations of PFOA from PAP metabolism to be significant and concluded that the metabolism of PAPs could be a major source of human exposure to PFOA, as well as other PFCAs.”

He added the discovery was important because the ability to limit human chemical exposure hinged on understanding and mapping exposure sources. The professor said that some parties attempted to highlight environmental contamination from previous chemical use as a major cause of human exposure rather than chemicals currently in production.

"In this study we clearly demonstrate that the current use of PAPs in food contact applications does result in human exposure to PFCAs, including PFOA,” said Mabury. “We cannot tell whether PAPs are the sole source of human PFOA exposure or even the most important, but we can say unequivocally that PAPs are a source and the evidence from this study suggests this could be significant."

The findings provided “valuable information” on the use of PAPs in food contact materials to global regulatory bodies which were becoming increasingly interested in monitoring long-term exposure to the chemical, said the Canadian scientists.

European monitoring

The European Food Safety Authority (EFSA) has issued a wide-ranging plea for more data on the presence of perfluoroalkylated substances (PFAS) in foods. Information gathered will be collated, analysed and summarised by EFSA into an intermediate report by January 2011, with a final report scheduled for May 2012.

In February 2008, the body’s CONTAM Panel adopted an opinion on PFOS, PFOA and their salts after looking at several different sources of exposure to the two substances. With regard to PFOS, the Panel established a Tolerable Daily Intake (TDI) of 150ng/kg per body weight (bw) per day. For PFOA, the Panel established a TDI of 1.5µg/kg bw per day, which it said was well above the indicative average and high level human exposure (2 and 6 ng/kg bw respectively).

Earlier this year, the European Commission urged member states to monitor the presence of PFAS in food up until the end of 2011.

Source: University of Toronto