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Carcinogenicity

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Description of key information

Read across: potassium formate (1:2); CAS 20642 -05 -1
OECD guideline studies (No. 453) with rats and mice: NOAEL for carcinogenicity: 2000 mg/kg bw/d (highest tested dose)

Key value for chemical safety assessment

Additional information

Read across: potassium formate (1:2); CAS 20642 -05 -1

In a combined toxicity/carcinogenicity study that was equivalent to OECD guideline No. 453 and conducted und GLP conditions, the oral administration of potassium diformate (1:2) to rats (50/sex/dose) at dose levels of 50, 400, and 2000 mg/kg bw/day was well tolerated including the top dose without effects on clinical condition or survival. Depression of food consumption and body weight with sequel was observed in rats at 2000 mg/kg bw/day. The NOAEL for systemic toxicity was 400 mg potassium diformate/kg bw/day. Adaptive hyperplastic changes in the stomach and the gastro-intestinal tract were seen in rats at 400 and, to a higher extend, at 2000 mg/kg bw/day. The NOEL was 50 mg potassium diformate/kg bw/day for these effects.

There was no evidence of a tumorigenic effect in the stomach or any other tissue, i.e. the NOAEL for carcinogenic effects was 2000 mg potassium diformate/kg bw/day.

In a combined toxicity/carcinogenicity study that was equivalent to an OECD guideline No. 453 and conducted under GLP conditions, the dietary administration of potassium formate (1:2) to the mouse at 50, 400 and  2000 mg/kg bw and day for 80 weeks was well tolerated and did not adversely affect clinical conditions or survival, or the pattern or incidence of neoplastic lesions at any dose level. Treatment related changes were limited to high dose males and included minor disturbances of body weight (overall body weight gain reduced by 15%, level of statistical significance not reached) and food consumption (up to 5% increased), and an increased incidence of limiting ridge hyperplasia in the forestomach. The incidence and nature of tumours was not affected by the test substance, i.e. the test substance was not carcinogenic.

The NOAEL for local effects and systemic toxicity was 400 mg potassium diformate/kg bw and day in male mice. The systemic NOAEL was 2000 mg potassium diformate/kg bw/day in female mice. The NOAEL for carcinogenicity was 2000 mg potassium diformate/kg bw/day in both sexes.

Justification for classification or non-classification

There was no evidence of a tumorigenic effect in OECD guideline studies (No. 453) with potassium formate (read across).

Taking into account the lack of genotoxic effects, it is concluded that carcinogenicity should not be an endpoint of concern.