In its latest assessment, which can be read here, the European Food and Safety Authority (EFSA) stated that furans and its related compounds 2- and 3-methylfurans pose a higher risk to infants—the most exposed group—via consumption of these foods.
Mean concentrations ranging from 20 to 57 micrograms per kilogram (μg/kg) were found in ready-to-eat meals for infants and young children as well as salads, soy sauce, bread and rolls, raw pasta and breakfast cereals.
What are furans?
Furans form from naturally occurring substances present in food, including vitamin C, carbohydrates, amino acids, unsaturated fatty acids and carotenoids.
Like furan, 2-Methylfuran and 3-methylfuran also form during specific cooking/processing conditions and are likely to undergo a similar metabolic fate.
These conditions determine how much furan is formed and lost (mainly via evaporation), and how much is present when food is consumed.
Mean dietary exposures calculated for infants ranged from 0.14 to 0.99 μg/kg body weight (bw) per day.
According to EFSA, furan exposure could be reduced through different preparation methods.
“Our opinion describes how cooking practices could reduce dietary exposure to furan and methylfurans, bearing in mind that consumers are exposed to them in a variety of foods,” explained Dr Helle Knutsen, chair of the expert Panel on Contaminants in the Food Chain.
“For example the volatility of furan, re-heating ready-to-eat meals for infants and young children in a hot water bath without a lid may reduce their exposure by about 15-30%.
The EFSA assessment also found for adults, elderly and very elderly, the highest mean exposure—driven by coffee and toast consumption—was approximately 3.3 μg/kg bw per day
“Different preparation methods for coffee result in different losses of furan concentrations,” said Dr Knutsen.
“The losses in boiled/Turkish coffee are 3 to 4 times greater than in filter coffee and espresso.
“The level of furan in toast increases with toasting time and with the degree of browning, albeit toast is a less important contributor to overall furan exposure.”
Data from commercial organisations and governments found the highest concentrations of furan were found in whole roasted coffee beans, with a mean value of 4,579 micrograms per kilogram (μg/kg).
High mean concentrations of furan were also found in ground roasted coffee (2,361 μg/kg), unspecified coffee solids (2,186 μg/kg), coffee imitates for brewing (1,922 μg/kg), instant coffee powder (310 μg/kg) and instant coffee imitates (127 μg/kg).
“Based on animal studies we concluded that liver damage and liver cancer are the most critical health effects,” said Dr Knutsen.
“How furan might cause cancer in animals is not fully understood. Since the panel could not rule out that this may be due to a direct interaction with DNA, we were not able to set a safe level – the tolerable daily intake. Instead we calculated a ‘margin of exposure’.
Margin of exposure
The margin of exposure (MOE) of a substance is defined as the ratio of its no-observed-adverse-effect level to its theoretical, predicted, or estimated dose or concentration of human intake.
Here, the CONTAM Panel used as a reference point a benchmark dose lower confidence limit for a benchmark response of 10% of 0.064 mg/kg bw per day for the incidence of cholangiofibrosis in a rat.
“The calculated MOEs indicate a health concern,” EFSA summarised. “This conclusion was supported by the calculated MOEs for the neoplastic effects.”
In the absence of human data, EFSA called for additional data on the occurrence of methylfurans in food and changes to furan and methylfurans concentrations during the stages of coffee preparation for all coffee types.
In addition, studies in vivo on the effect of furan on the genome were required to clarify the carcinogenic MoA as well as the toxicity, including the genotoxic properties, of methylfurans.