Formic acid occurs in a variety of plants and fruits, mammalian tissues, and insect venoms.
In addition, in vitro genetic toxicity studies were performed with Salmonella typhimurium, with or without metabolic activation. Formic acid was not mutagenic in this assay. Microscopic lesions in the respiratory and olfactory epithelia occurred in rats and mice exposed to 62.5 ppm and higher concentrations, with the severity related to the exposure concentration. The lesions consisted of squamous metaplasia, necrosis, and inflammation. Exposures had minimal or no effects on coagulation times, blood pH and electrolytes, or on concentrations and activities of urine analytes in rats during the 2-week studies.