Chemicals found in junk food wrappers and microwave popcorn bags are migrating into food and into the people who consume them, say scientists at the University of Toronto.
The scientists conducted a study on perfluorinated carboxylic acids (PFCAs), the breakdown products of chemicals used to make non-stick and water- and stain-repellant products such as food packaging.
The scientists found that PFCAs, the best known of which is perfluorooctanoic acid (PFOA), are found in humans all around the world.
A major source of human PFCA exposure may be through the consumption and metabolism of polyfluoroalkyl phosphate esters or PAPs, say the scientists.
And PAPs are often applied as greaseproofing agents to paper food contact packaging such as fast food wrappers and microwave popcorn bags.
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 scientists had already established human exposure to PAPs in a previous study. Researchers used the PAP concentrations previously observed in human blood together with the PAP and PFCA concentrations observed in the rats to calculate human PFOA exposure from PAP metabolism.
What they found was 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.
The scientists add that the discovery is significant because the aim is to control human chemical exposure, which is possible if scientists can understand the source of the exposure.
In addition, some scientists have tried to locate the blame for human exposure on environmental contamination that resulted from past chemical use rather than the chemicals that are currently in production.
This study, say the scientists, clearly demonstrates that the current use of PAPs in food contact applications does result in human exposure to PFCAs, including PFOA.
The scientists cannot tell whether PAPs are the sole source of human PFOA exposure or even the most important, but they say unequivocally that PAPs are a source and the evidence from this study suggests this could be significant.
Regulatory interest in human exposure to PAPs has been growing.
Governments in Canada, the U.S. and Europe have signaled their intentions to begin extensive and longer-term monitoring programs for these chemicals.
The results of this investigation provide valuable additional information to such regulatory bodies to inform policy regarding the use of PAPs in food contact applications.