Evaluation of the toxicological risk in animals following the ingestion of cheese obtained from milk with added formaldehyde

The epidemiological evidence concerning the carcinogenicity of formaldehyde (FA) to man provides no proof of causal relationship between previous exposure and the occurrence of malignant neoplasma. The use of FA as an antimicrobial agent in food has caused concern mainly because of the lack of toxicological data about oral FA toxicity and because of the potential hazard caused by the stable reaction compounds between FA and food proteins. The aim of the present work was to study the absorption fate and excretion of the complex H14CHO-milk protein in mice and rats. Unlabelled FA and C14-FA were added to milk to obtain a final concentration of 35-40 ppm. Groups of rats and mice were given the 14C-cheese obtained; 2.2 g (18 μCi) and 0.5 g (4.0 μCi), respectively, and were killed at different times. Blood, liver, gastrointestinal tract, kidney, lungs, spleen, testes, muscle, and adipose tissue were removed; urine and faeces were collected from the metabolic chambers. Within 16-32 h after the administration, when radioactivity was almost completely excreted in the faeces and urine (65-70%), 25-30% of radioactivity was exhaled as CO2 in both species. The radioactivity profile of blood indicated a maximum content corresponding to 0.008% and 0.3% of the dose per milliliter of blood for rats and mice, respectively. No concentration of the 14C-activity occurred in any of the tissues of either species. Although a study is in progress on the identification of radioactivity associated with the catabolites of 14C-cheese, very likely represented by methylated aminoacids, the present opinion is that no hazard would result from the ingestion of cheese produced with such concentrations of formaldehyde.