Styrene
Styrene is classified by IARC as 'probably carcinogenic to humans' (Group 2A) and listed in the National Toxicology Program 15th Report on Carcinogens as 'reasonably anticipated to be a human carcinogen.' FDA permits residual styrene in food-contact polystyrene under 21 CFR 177.1640 with migration limits.
What it is
Styrene is a vinyl aromatic monomer used to make polystyrene plastics; it can migrate at trace levels from polystyrene packaging into foods.
Not a food ingredient; a contaminant from packaging.
Why it's flagged
- Carcinogenicity (IARC 2A; NTP RoC reasonably anticipated)
- Migration from packaging
What regulators actually say
"Styrene is reasonably anticipated to be a human carcinogen based on limited evidence of carcinogenicity from studies in humans, sufficient evidence of carcinogenicity from studies in experimental animals, and supporting data on mechanisms of carcinogenesis."
"Polystyrene basic polymers... shall not exceed... residual styrene monomer."
Regulatory status
United States — FDA
Permitted as residual monomer in polystyrene food-contact materials per 21 CFR 177.1640
European Union — EFSA
EFSA has evaluated styrene in food-contact materials
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