The European Food Safety Authority’s (EFSA’s) recently updated risk assessment of sulfur dioxide and sulfites concludes that dietary intakes of sulfites may be a food safety concern. EFSA also found evidence of adverse health effects on the central nervous system such as a delayed response of nerve cells to stimuli, which is an early sign of nervous system dysfunction. However, gaps in toxicity data meant the extent of certain adverse health effects could not be confirmed.

Sulfites are naturally occurring, and are also added as preservatives and antioxidants to a range of foods, such as dried fruit and vegetables, potato-based products, beer and malt beverages, wine, and fruit juices. Sulfites may also be used to halt fermentation during the winemaking process.

The last reevaluation of sulfur dioxide-sulfites was conducted in 2016, at which time, there existed several uncertainties and limitations in the available data. The 2016 assessment decided that the group acceptable daily intake (ADI) was adequate, but should be considered temporary while more data were generated. Since 2016, little information has been generated to address the data shortcomings.

In the present assessment, the available toxicity data was insufficient for EFSA to derive an ADI level, which is a threshold below which daily intake is known to be safe. Instead, the agency calculated margins of exposure (MOE), which defines whether current intakes are likely to be harmful, considering dietary intakes and the dose associated with neurotoxic effects in animal tests.

The MOE is a ratio between the lowest estimated dose at which an adverse effect is observed and the level of exposure to the substance. In the case of sulfites, a ratio below 80 could indicate a safety concern. The MOEs EFSA calculated indicate that estimated intakes for consumers potentially exceed what would be considered safe, by up to 12.5 percent for children aged 3–10, and up to 60 percent for adults.