Toxicological evaluation in rats and mice of the ingestion of a cheese made from milk with added formaldehyde

Meeting report: summary of IARC monographs on formaldehyde, 2-butoxyethanol, and 1-tert-butoxy-2-propanol

An international, interdisciplinary working group of expert scientists met in June 2004 to develop IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans (IARC Monographs) on formaldehyde, 2-butoxyethanol, and 1-tert-butoxy-2-propanol. Each IARC Monograph includes a critical review of the pertinent scientific literature and an evaluation of an agent's potential to cause cancer in humans. After a thorough discussion of the epidemiologic, experimental, and other relevant data, the working group concluded that formaldehyde is carcinogenic to humans, based on sufficient evidence in humans and in experimental animals. In the epidemiologic studies, there was sufficient evidence that formaldehyde causes nasopharyngeal cancer, "strong but not sufficient" evidence of leukemia, and limited evidence of sinonasal cancer. The working group also concluded that 2-butoxyethanol and 1-tert-butoxy-2-propanol are not classifiable as to their carcinogenicity to humans, each having limited evidence in experimental animals and inadequate evidence in humans. These three evaluations and the supporting data will be published as Volume 88 of the IARC Monographs.

Multiple intragastric treatment versus continuous administration via the diet. Comparative pharmacokinetics of abecarnil in mouse

1. Abecarnil was administered to female mice at doses of 5, 50 and 150 mg/kg per day for 4 weeks either intragastrically once a day or was offered continuously via the diet. 2. On days 1, 7, 14 and 28 plasma level profiles (0-24 h) were determined in identical groups of animals. Additionally, faecal excretion of abecarnil and distribution in brain, liver and kidney was measured. 3. Drug administration via the diet was characterized by: (a) a circadian rhythm of concentrations with highs at night and lows during the day; (b) a dose-proportional increase in AUC and mean plasma levels; (c) slight accumulation in the plasma after the two higher doses. 4. Intragastric treatment resulted in: (a) clearly distinguishable absorption and disposition phases in the plasma with prominent peaks; (b) slight accumulation at the two higher doses; (c) dose-proportionality for the 50 and 150 mg/kg doses. 5. Drug load after the two routes of administration was different resulting in four times higher peak plasma levels and in double AUC values after intragastric administration than after the diet.

Oral toxicity of formaldehyde and its derivatives

Formaldehyde (FA) has been commercially produced since the early 1900s. Its widespread use in a variety of applications is known to result in appreciable exposure of workers and of a section of the general population. Formaldehyde is a normal metabolite in mammalian systems. It occurs in air as a product of the natural photooxidation of automobile exhaust, combustion processes, incinerators; formaldehyde has been found in municipal and industrial effluents and is present in food either naturally (fruits and vegetables, in the order of parts per million), or as a result of its use as a food additive. The use of FA and its derivative, hexamethylenetetramine (HMT), which gradually decomposes to FA under acidic conditions as antimicrobial agents in food, raises questions about their potential chronic oral toxicity. Furthermore, since FA is a very reactive compound and reacts with different macromolecules such as proteins and nucleic acids, the safety evaluation of FA as a cheese additive must take into account the toxicity of the reaction products between FA and milk components. Biochemical aspects, acute and short-term toxicity studies including mutagenicity, multigeneration, and reproduction studies, long-term carcinogenicity studies after oral administration of FA and HMT are reviewed in this paper. The results of these studies indicate that repeated oral exposure of a relatively large amount of FA that could overwhelm the normal metabolic capacity of animals to convert FA into formiate, CO2, and water produces histopathological gastric changes. This paper correlates the hazard caused by the exposure to low levels of FA, as far as its carcinogenic potential by oral route is concerned per se or regarding its use as a food additive. Based on the evidence that FA is formed naturally in food and is a normal mammalian metabolite and that a threshold for carcinogenicity exists both after exposure by inhalation and oral administration, it may be deduced that FA is not carcinogenic at low levels of exposure.

Identification of spinacine as the principal reaction product of gamma-casein with formaldehyde in cheese

Formaldehyde is added to milk in the production of grana cheese as an antimicrobial agent. In order to study the fate of the formaldehyde, a grana cheese preparation was made using 14C-labelled formaldehyde. The 14C-activity in the cheese was found to be mainly associated with the caseins, but it was not uniformly distributed among the different fractions (alpha s, beta- and gamma-caseins). gamma-Casein, separated by electrophoresis, was the most reactive component showing the highest specific activity. In the gamma-casein fractions, 99% of 14C-activity was associated with the basic amino acids. The only radioactive reaction product present in the gamma-casein fraction was identified by HPTLC and by an amino acid analyser to be spinacine, a condensation product of formaldehyde and histidine. Using the same method, other unknown radioactive products, of much less relevance, were detected in the total casein hydrolysate.