Bisphenol A (BPA) is frequently detected in food stuffs and has come under attack because of its endocrine disrupting effects. In response, many manufacturers have replaced BPA with other bisphenol analogues in their products. Yet, estrogenic activity has also been reported for bisphenol analogues other than BPA (Viñas and Watson 2013; Cabaton et al. 2009, Grignard et al. 2012). However, few studies have evaluated the presence of those bisphenol analogues in food. In a new study published November 25, 2013 in the peer-reviewed scientific journal Food Additives & Contaminants: Part A researchers from the State University of New York, Albany, U.S. investigated the contamination of Chinese food products with bisphenol analogues (Liao and Kannan 2013). The researchers found BPA to remain the most important bisphenol contaminant, with canned foods and beverages containing particularly high levels of BPA. Liao and Kannan observed that the presence of other bisphenol analogues was food packaging type dependent and only contributed 5% to overall bisphenol contamination.
Methods. Chunyang Liao and Kurunthachalam Kannan analysed 289 food samples collected from 9 cities in China for the following 8 bisphenol analogues: BPA (80-05-7), Bisphenol AF (BPAF (1478-61-1), bisphenol B (BPB, 77-40-7), bisphenol F (BPF, 620-92-8), bisphenol S (BPS, 80-09-1), bisphenol AP (BPAP; 1571-75-1), bisphenol P (BPP; 2167-51-3) and bisphenol Z (BPZ; 843-55-0). The food stuffs were classified under 13 categories, including cereal products, meat products, fish, eggs, dairy products, bean products, fruit and vegetables. While solid foods were homogenized, freeze-dried, weighed and extracted, cooking oil samples did not undergo the freeze-drying process and beverage samples were not homogenized, but instead evaporated to near dryness. All samples were analyzed using high-performance liquid chromatography – tandem mass spectrometry (HPLC-MS/MS). The limits of quantification were 0.01 ng/g weight/weight for BPA, BPAF, BPAP, and BPS, 0.025 ng/g w/w for BPB and BPP, and 0.05 ng/g ww for BPF and BPZ.
Results. Liao and Kannan detected bisphenol analogues in 78% of food samples. BPA was the most frequently detected contaminant (60.9% of samples), followed by BPF and BPS, which were detected in around 20% of samples. In a similar study previously carried out by Liao and Kannan in the US, the researchers observed BPA to contribute 20% less to overall bisphenol levels (42%, Liao and Kannan 2013). BPA levels were particularly high in canned foods, which dominated mean BPA values per food category. This resulted in the beverage category having the highest mean BPA levels. The highest individual measurement was taken from a spiced salt sample, which contained 299 ng BPA/g. Further, baked bread contained notable BPA concentrations. BPF was measured at the highest levels in vegetables and fish/seafood. The highest levels of total bisphenols in foodstuffs ranged from <LOQ to 671 ng/g (mean 9.35 ng/g), but notably bisphenols other than BPA contributed less than 5% to overall levels. The researchers did not find significant differences between food categories and cities. They concluded that different bisphenol analogues were used for different food packaging types, but BPA and BPF, as well as BPAF and BPS were used for similar materials. BPA concentrations in cans were 2-4 times higher than in foods packaged in plastics. They found levels in beverages, cooking oils, cereals, and fish 1-2 orders of magnitude higher than those reported in previous studies. Liao and Kannan estimated dietary BPA intake in Chinese adults to amount to 489 ng/kg bw/day, a factor of 3 lower than European estimates (EFSA estimates exposure to be 1500 ng/kg bw/day). Currently, EFSA proposes an estimated dietary exposure of 132 ng/kg bw/ day (EFSA, 2013). However, Liao and Kannan point out that in China, food ingestion varies widely among the population, complicating any good estimate of average dietary exposure.
EFSA (July 25, 2013). “Food is main source of BPA for consumers, thermal paper also potentially significant.”
Liao, C. and Kannan, K. (2013). “A survey of bisphenol A and other bisphenol analogues in foodstuffs from nine cities in China.” Food Additives & Contaminants: Part A (published online on November 21, 2013).
Liao, C. and Kannan, K. (2013). “Concentrations and Profiles of Bisphenol A and Other Bisphenol Analogues in Foodstuffs from the United States and Their Implications for Human Exposure.“Journal of Agricultural and Food Chemistry 61, 19, 4655-4662.
Viñas, R. and Watson, C. (2013). “Bisphenol S disrupts estradiol induced non-genomic signaling in a rat pituitary cell line: effects on cell functions”. Environmental Health Perspectives (published online January 17, 2013).
Cabaton, N. et al. (2009). “Genotoxic and endocrine activities of bis(hydroxyphenyl)methane (bisphenol F) and its derivatives in the HepG2 cell line.” Toxicology 255, 1–2, 8, 15–24.
Grignard, E. et al. (2012). “Weak estrogenic transcriptional activities of Bisphenol A and Bisphenol S.” Toxicology in Vitro 26, 5, 727–731.