Food intake is assumed to be the major source of PFAS exposure for humans [1, 2]. The European Food Safety Authority (EFSA) has set a tolerable daily intake of 150 ng PFOS/kg body weight and 1500 ng PFOA/kg body weight in 2008 . In 2012 EFSA performed a dietary intake estimation based on 54,195 analytical results obtained for 7,560 food samples reported by European member states . The conclusion was that the high frequency of non-quantifiable results (< LOQ) prevented calculation of a more realistic dietary exposure.
Several different analytical method protocols based on LC-MS/MS methodology, were developed in the course of the project in order to provide significant analytical performance improvements (e.g. detection limits, matrix effects reduction) that allows analysts to determine PFAS in food items at the pg/g level. In addition, LC- and GC-High Resolution MS methods were tested for the determination of PFAS and several types of precursors (e.g. FTOHs, PAPs) and applied successfully to food samples.
The consortium has initiated the production of two Certified Reference Materials (CRM), viz. a fish homogenate and a drinking water material that contain certified levels of certain PFAS. The certification process is under way and will be terminated in 2013. The CRMs will be available commercially from the IRMM in Geel, Belgium.
A standardized selection of food items, sampling procedures and analytical methods was identified in order to assess the occurrence of the common set of PFAS in the European diet through European wide surveys. These surveys have identified major sources of PFC exposure via food in a uniform manner, enabling the comparability of data through Europe. The prioritization of type and number of food items collected in the survey was based on an extensive evaluation of national consumption data from eight different European countries. The survey design was such that four distinct regions in Europe (Norway, Czech Republic, Belgium and Italy) with different dietary habits representing the northern, eastern, central and southern parts of Europe, respectively, have been identified, together with 14 food categories. The first survey focused on single (non composite food) samples with specific items selected for each food category. The second focused on a comparison of market basket and cauldron studies with data on individual food items, and also assessed levels of PFAS in certain hot spot areas in Europe. The results of the surveys show that some food categories, viz. seafood, fish, bovine liver, pork and bovine meat and hen eggs appear to be more highly contaminated with PFAS than other items. Most elevated levels so far were found in food items from Belgium, indicating the influence of industrial production sites of PFAS. Different PFCA patterns can be found in the four sampling locations, with Norway showing a higher abundance of long-chained PFCAs in the food categories analysed.
Raw food items contain higher concentrations of PFAS than the processed or cooked food products in most cases. In general, the levels in raw food, unprepared composites samples, warm meal cauldrons, and composite food prepared with non-stick cookware are not a matter of concern. Elevated PFAS levels could be found in almost all selected hotspots.
For tracking of the origins of PFAS in dietary items several laboratory and field experiments were conducted in the project. A conventional dairy farm with a herd of milk cows served to perform a mass balance study of PFAS using bulk flow data of water, feed, milk, etc., needed for mass balance calculation. Relatively low biotransfer factors of PFCAs and PFOS were observed in meat and milk from dairy cows. However, the increased enrichment of PFOS and long-chain PFCAs in liver indicates that consumption of offal food from dairy cows will result in a higher human exposure.
In controlled greenhouse experiments vegetables were grown and exposed to different solutions of PFAS. Results from these experiments show that PFAAs are taken up by plants and that relatively high concentrations occur in the roots of the plants especially of long-chained PFAAs. Short chain PFAS are translocated to leaves. Uptake factors derived from the field cultivation experiments with spiked soils showed lower accumulation factors than from the greenhouse experiments, but a similar accumulation pattern among the PFAS analogues: concentrations of short chain PFAS were highest in the vegetative parts of all plants.
Carry-Over Rates of PFAS from feed to fillet in farmed fish have been estimated in the range of 0.06 to 0.6 %. The regular consumption of farmed fish would lower the PFOS intake about 10 times with respect to wild fish consumption.
Groundwater bodies may become contaminated by PFAS from different sources. Groundwater bodies originating from either river water or rainwater show distinctly different patterns of relative abundances of PFAS. Field measurements revealed that landfills can be an important source of PFAS to the groundwater. The presence of PFAS in drinking water depends on the technologies used in different treatment plants. Drinking water prepared by treatment which does not include GAC filtration or reverse osmosis will generally contain higher PFAS levels, in particular when surface waters, bank infiltrated waters or phreatic groundwater is used as source water. Other processes used in producing drinking water, e.g. coagulation, rapid sand filtration, dune passage, aeration, rapid sand filtration, ozonation, pellet softening, and slow sand filtration are not effectively removing PFAS from contaminated source waters.
Several food contact materials (FCM) such as baking papers, sandwich papers and butter wraps have been found to be a potential source of migration of organic fluorine compounds into food. In the project screening methods were developed and these methods detected PAPs and S-PAPs as well as PTFE in these FCM. FTOH were detected in almost every F positive FCM, maximum PFCA levels were in the upper ppb range, however, they were not detectable in a series of FCM.
The PFAAs intake estimates made by the PERFOOD project are background exposures in the selected Belgian, Italian, Czech, and Norwegian regions. In the general population, the resulting Margin of Safety (MOS) for PFOS (TDI = 150 ng/kg bw per day), as the most sensitive contaminant, amounted to > 300 and >100 in adults and children, respectively, for mean consumption; In children as high consumers (95P), the lowest MOS was 72. For PFOA, the estimated intake was far below the TDI of 1.500 ng/kg (BW) per day in all regions considered. Regional-based intake patterns can be recognized, on the basis of both the different food consumption habits, and of a different occurrence in selected food items. Potential high overexposure with respect to the PFOS TDI have been predicted in some of the hot spot areas considered, where the local food of animal origin represents the main source of exposure. Considering the different bioaccumulation features of PFOS and PFOA, the intake estimates from toxicokinetics modelling appear in good agreement with that from the systematic PERFOOD assessment. In the estimates, the uncertainties related to the potential contribution from dust and food-packaging materials appear negligible. The design of the food surveys within PERFOOD did not allow for a complete representativity of the food sampling. The presence of potentially hidden small but diffuse hot spots area can result in exposures above the TDIs. The results of the PERFOOD assessments, including the sensitivity analysis performed, allow one to identify threshold values for the contamination of most consumed food items, water included, that can be translated into geo-referenced risk management options.
1. Trudel, D., et al., Estimating Consumer Exposure to PFOS and PFOA. Risk Analysis, 2008. 28(2): p. 251-269.
2. Vestergren, R., Human exposure to perfluoroalkyl acids, in Department of Applied Environmental Science. 2011, Stockholm University.
3. EFSA, Perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and their salts. J Eur Food Saf Auth 2008;653:1-31. J. EFSA, 2008. 653: p. 1-31.
4. EFSA, Perfluoroalkylated substances in food: occurrence and dietary exposure. J. EFSA, 2012. 10(6): p. 2743 [55pp].