Perfluorinated chemicals, which are organic molecules with several fluoride atoms attached to the carbon chain, have had a fair amount of attention from environmental scientists over the past several years, primarily due to their long persistence in the environment. They’ve been used in a large number of consumer products – probably best known for non-stick coatings such as Teflon, but also used in fabric protectors, paper coatings, lubricants, inks, varnishes, cosmetics and more. Due to concerns about their environmental persistence and transport in the environment (they’re now found in the environment worldwide, including in blood and breast milk samples), the major producers began phasing out production of perfluorooctyl materials (perfluorinated chemicals with 8 carbon atoms), which were the most commonly used perfluorinated compounds.After being phased out, concentrations of the two most common perfluorinated compounds, perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) began to decrease in human blood samples. However, even though PFOS stays in human blood for longer than PFOA, the PFOA concentrations were not decreasing at the same rate as PFOS concentrations. Some of the longer-chain perfluorinated compounds have been continuing to increase in concentrations.
A new study by Jessica D’eon and Scott Mabury from the University of Toronto has come up with a possible explanation. They looked at polyfluoroalkyl phosphate esters (PAPs), which are used in paper wrappings for food to greaseproof them – if you get a hamburger at a fast food restaurant, PAPs are probably on the paper wrapping the burger. The study authors administered a mixture of PAPs to rats, collecting a baseline blood sample before dosing and a series of blood, urine and feces samples after. The samples were analyzed for various perfluorinated compounds.
The authors found that many of the PAP compounds were bioavailable, and that they were metabolized into other perfluorinated compounds, including PFOA. They also concluded that even low-level exposure to PAPs could over time lead to significant PFOA exposure, and that exposure to PAPs is likely a significant source of exposure to PFOA and other perfluorinated compounds.
So what does this mean? While there are enough difference between human and rat metabolism to make it difficult to get quantitative results for humans from this experiment, it does provide an indication that PAPs on food wrappers can lead to PFOA and other perfluorinated compounds in human blood, and may explain the trends in blood concentrations.
The presence of these compounds in blood does not necessarily mean they’re causing harm. The data on toxicity of perfluorinated compounds are still a bit more limited than I would like, but generally toxic effects have only been observed so far at doses higher than typical human exposures. However, given the persistence of these compounds, the increasing trends in blood concentrations of higher chain perfluorinated compounds, and the uncertainties about toxicity, this is another good reason to avoid foods in greaseproof paper wrappers (primarily fast food and junk food) – as if we need more reasons.
D’eon, J., & Mabury, S. (2010). Exploring Indirect Sources of Human Exposure to Perfluoroalkyl Carboxylates (PFCAs): Evaluating Uptake, Elimination and Biotransformation of Polyfluoroalkyl Phosphate Esters (PAPs) in the Rat Environmental Health Perspectives DOI: 10.1289/ehp.1002409