Risks for public health related to the presence of furan and methylfurans in food

The European Commission asked EFSA for a scientific evaluation on the risk to human health of the presence of furan and methylfurans (2-methylfuran, 3-methylfuran and 2,5-dimethylfuran) in food. They are formed in foods during thermal processing and can co-occur. Furans are produced from several precursors such as ascorbic acid, amino acids, carbohydrates, unsaturated fatty acids and carotenoids, and are found in a variety of foods including coffee and canned and jarred foods. Regarding furan occurrence, 17,056 analytical results were used in the evaluation. No occurrence data were received on methylfurans. The highest exposures to furan were estimated for infants, mainly from ready-to-eat meals. Grains and grain-based products contribute most for toddlers, other children and adolescents. In adults, elderly and very elderly, coffee is the main contributor to dietary exposure. Furan is absorbed from the gastrointestinal tract and is found in highest amounts in the liver. It has a short half-life and is metabolised by cytochrome P450 2E1 (CYP2E1) to the reactive metabolite, cis-but-2-ene-1,4-dialdehyde (BDA). BDA can bind covalently to amino acids, proteins and DNA. Furan is hepatotoxic in rats and mice with cholangiofibrosis in rats and hepatocellular adenomas/carcinomas in mice being the most prominent effects. There is limited evidence of chromosomal damage in vivo and a lack of understanding of the underlying mechanism. Clear evidence for indirect mechanisms involved in carcinogenesis include oxidative stress, gene expression alterations, epigenetic changes, inflammation and increased cell proliferation. The CONTAM Panel used a margin of exposure (MOE) approach for the risk characterisation using as a reference point a benchmark dose lower confidence limit for a benchmark response of 10% of 0.064 mg/kg body weight (bw) per day for the incidence of cholangiofibrosis in the rat. The calculated MOEs indicate a health concern. This conclusion was supported by the calculated MOEs for the neoplastic effects.

Physiological modeling of age-specific changes in the pharmacokinetics of organic chemicals in children

Age-specific changes in the pharmacokinetics of chemicals are primarily due to differences in physiological and biochemical factors. For integrating the available information on the age-dependent changes in the physiological and biochemical factors, and for evaluating their combined influence on the pharmacokinetics of chemicals, physiologically based pharmacokinetic (PBPK) models are potentially useful. The objectives of this study were, therefore, (1) to assemble information on age-specific differences in physiological parameters such as alveolar ventilation rate, cardiac output, tissue volumes, tissue blood flow rates, and tissue composition for children of various age groups, and (2) to incorporate these data within a PBPK model for simulating the inhalation pharmacokinetics of a highly metabolized, volatile organic chemical (furan) in children of specific age groups (6, 10, and 14 yr old). The age-specific data on various physiological parameters were assembled following a review of the relevant literature and the hepatic metabolism rate of furan was set equal to the liver blood flow rate in adults and children. The blood:air and tissue:blood partition coefficients were calculated using molecular structure information along with the data on the blood and tissue composition (lipid and water contents) in children and adults. The PBPK model was used to simulate the pharmacokinetics of furan in adults and children (6, 10, and 14 yr old) exposed continuously for 30 h to 1 microgram/L of this chemical in inhaled air. The model simulations suggest that, for the same exposure conditions, the blood concentration of furan is likely to be greater in children by a factor of 1.5 (at steady state) than in adults, and the maximal factor of adult-children differences in liver concentration of furan metabolite is about 1.25. The PBPK model framework developed in this study should be useful for predicting the adult-children differences in internal dose of chemicals for risk assessment applications.