The maximum safe level of propionic acid for poultry is 10 g/kg complete feed, for pigs 30 g/kg complete feed. The corresponding safe concentrations in water for drinking would be 4 and 10 g/L, respectively. Ruminants show a high tolerance to propionic acid. Differences in the safety of propionates and propionic acid are not expected. Propionic acid, sodium propionate and calcium propionate are authorised in the EU for use in food. Ammonium propionate, not authorised as food additive, will essentially share the metabolic pathways of the other propionates. Propionic acid occurs endogenously as a by-product of normal intermediate metabolism and consequently residues in meat, milk or eggs are expected to be negligible. The use of propionic acid and its salts in animal nutrition is therefore considered of no concern for the safety of consumers. Propionic acid and sodium propionate are corrosive to the skin, the eye and mucous membranes; calcium propionate is not classified as an irritant. Propionic acid and its salts are likely not skin sensitisers. In the absence of data, ammonium propionate should be treated as propionic acid. No concerns for the environment are expected from the use of those additives up to the recommend use levels. Propionic acid, sodium, calcium and ammonium propionate have the potential to act as preservatives in feedingstuffs. The efficacy of propionic acid and its salts in water was not demonstrated. The use of propionic acid, sodium and ammonium propionate as silage additives did not result in a better preservation of silage. Improved aerobic stability of silage was not sufficiently demonstrated.