The European Food Safety Authority has recommended that the generally toxic chemical formaldehyde can be safely fed to chickens as a fattener, as long as dosage limits are respected.

Its Scientific Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) said that chickens were healthy when fed formaldehyde at up to 660 mg per kg of feed. Formaldehyde is already authorised in the European Union (EU) for use in skimmed milk for piglets up to the age of six months and within silage for all livestock.

Regarding chickens however, EFSA concluded there "was little margin for error (over dosage) before adverse effects were apparent".