Studies On The Detection And Migration Of Perfluorooctanoic Acid (PFOA) And Perfluorooctane Sulfonate (PFOS) In The Food-contact Materials

Perfluorinated compounds (PFCs) are viewed as a new type of persistent organic pollutants. Known as C-8s, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are two of PFCs attracting most concerns.PFOA and PFOS have been widely used for decades as processing aid and surfactants in considerable industrial fields even including the manufacturing of non-stick cookware coating and food-contact packaging bags coating. Since both of them have been revealed to have a variety of similar toxicities including fetal development toxicity, reproductive toxicity, neurotoxicity, disordering fat metabolism and potential carcinogenic effects, they are attracting global researcher's growing concerns about the contamination of PFOA and PFOS to the food staffs and bringing potential harm to human health.This research compared and optimized five extraction solvents and five extraction methods. The analysis method of HPLC-MS/MS was also established. The results showed that:methanol is the most efficient solvent in all of methods used in this research. As for the extraction time,2 hours was enough both for extraction methods of ultrasonic with the frequency of 600Hz and reflux and 12 hours was enough for Soxhlet and shaking extraction methods to meet the need of extraction rate of 95% of total PFOA and PFOS residues. Soxhlet method for the extraction of PFOS residue in packaging bags was more efficient and ASE was a better advisable method for the extraction of PFOA residue at the optimized temperature of 100℃.In the meanwhile. it was proved that the detections of PFOA and PFOS varied in different batches of samples, especially for PFOS. Generally, the concentrations of PFOA and PFOS detected in popcorn packaging bags from America and Japan were between 1.49-3.89ng/cm2 and<0.228-2.25ng/cm2 which were higher than the concentrations of samples from China (PFOA:0.498-0.653ng/cm2; PFOS:<0.228-0.668ng/cm2). There was no significant difference for popcorn packaging bags being heated or not by the microwave oven. Besides, popcorns which were heated in bags by the microwave oven were proved to be closely free of contamination by PFOA(only 0.07ng/g) and PFOS(no detected). However, other food-contact materials including sunflower packaging bags and disposable cups were detected of 12.92(±1.25)ng/cm2,8.835(±2.37)ng/cm2 for PFOA and 86.98(±6.47)ng/cm2,30.29(±3.19)ng/cm2 for PFOS respectively. No PFOA and PFOS were detected in the selected non-stick cookware manufactured by six factories.Besides, several simulated food materials were used to test the migrations of PFOA and PFOS from food-contact materials during the process of being heated and stored at different temperatures for different periods. The results showed that:the highest migration concentration of PFOA in popcorn packaging bags happened in the boiling 10% ethanol/water. The rest of simulated foods were detected to be extremely low contaminated by PFOA. Besides, PFOS were not detected in all of the simulants. However, even though not very evident, more migrations of PFOA and PFOS were detected when food simulants were stored at relatively higher temperatures and kept for longer periods.Butter, olive oil and olive oil/emulsion were selected as oily foods, wrapped with packaging bags and heated in microwave oven for 3min. 2.816ng/g (±0.67ng/g) of PFOA was detected in butter. Simulated food materials including water, salty water and soybean oil were heated to boiling in the non-stick cookware and detected at different time. All of the samples were detected free of PFOA and PFOS contamination.Simulated saliva was kept in packaging bags at 37℃for 30min. The results showed that even though PFOA and PFOS were detected, the concentrations were extremely low and proved to be no statistic meaning for the risk assessment of dietary PFCs intake.Lastly, the concentrations of PFCs detected in foods around world were compared and a primary model was established and several suggestions were provided for the risk assessment of dietary intake of PFCs.Conclusions:12h soxhlet extraction coupled with methanol was a better choice for the extraction of PFOS in the packaging bags. Accelerated solvent extraction, whose extraction conditions as follows:pressure,1500psi; temperature,100℃; 3min pre-heating time and 7min static extraction time; cell volume,22ml; flush volume, 60%; purge time:100s; 2cycles, was a better advisable method for the extraction of PFOA in the packaging bags. There was no significant difference for popcorn packaging bags being heated or not by the microwave oven. In addition, popcorns heated in bags by the microwave oven were proved to be closely free of contamination by PFOA and PFOS. No PFOA and PFOS were detected both in the selected non-stick cookware coatings and foods heated with those cookware. In the migration test, even though higher temperatures and prolonged exposure time helped the migration of PFOA and PFOS, the contamination degrees of food simulants were still relatively low. In addition, the migration of PFOA and PFOS into the simulated saliva were extremely low, which meant that it would not make a great effect on the intake risk of PFOA and PFOS by licking the oily residues on the popcorn bags.