Methyl salicylate

Carcinogenicity

Description of key information

No full carcinogenicity study according to current guidelines is available. Assessment of the carcinogenic potential of MeS has been made based on chronic studies on MeS itself, plus a screening carcinogenicity study on SA and data on carcinogenic potential of sodium salicylate (NaS) and Acetylsalicylic acid (ASA).

Key value for chemical safety assessment

Carcinogenicity: via oral route

Endpoint conclusion

Dose descriptor:

NOAEL

50 mg/kg bw/day

Justification for classification or non-classification

Not carcinogenic according to EU and GHS (UN/EU) criteria.

Based on chronic toxicity studies in rats and dogs and on absence of carcinogenicity in a screening study on SA.

Additional information

The evaluation of the carcinogenic potential of MeS was included in 2 -year studies on the chronic toxicity of MeS by the oral route in rats and dogs (Webb and Hansen, 1963). In the rat, at 0, 0.1%, 0.5%, 1.0% or 2.0% MeS in diet, the only tumors described were pituitary tumours. Similar incidences of benign pituitary tumours were reported in controls and treated rats. Malignant pituitary tumours were reported in 3 rats at 0.5% but none at 1% MeS in diet. No tumors were reported in dogs fed MeS in capsule form at doses of 0, 50, 150 or 350 mg/kg/bw/day for 2 years.

In a non-standard carcinogenicity study (Stoner et al., 1973), MeS was tested by the intraperitoneal route in the A/He strain of mouse, a strain susceptible to carcinogen-induced lung tumorigenesis. In the low-dose group, 2/15 (13%) males and 1/15 (6%) females developed lung tumors while in the high-dose group, 1/15 males (6%) and 5/15 (33%) females developed lung tumors. In comparison, 22/80 (28%) male and 16/80 (20%) female control mice developed "spontaneous" lung tumors. MeS was reported as negative for pulmonary tumour response in this assay.

In Chang et al. (1983), the cocarcinogenic potential of acetylsalicylic acid on gastric tumors induced by N-Nitroso-N-methylnitroguanidine in rats was studied. No gastro-intestinal tumors were found with rats treated only with acetylsalicylic acid twice a week for 18 months.

In a screening test for carcinogenic hazard of SA (Uhmeda. 1957), rats were fed with salicylic acid or injected with sodium salicylate in solution. None of the animals treated with salicylic acid developed tumors in any organ in the course of the experiment. No marked change in internal organs was found in the rats treated with sodium salicylate under the conditions of this experiment.

MeS has been studied for anti-carcinogenic potential in several older assays (Strong, 1932 and Boyland and Huntsman-Mawson, 1938). A number of epidemiological studies have claimed that low doses of aspirin (ASA) are effective in preventing colorectal cancer.  The most detailed scientific evaluation on the efficacy of aspirin (ASA) as a colorectal cancer chemopreventive has been conducted by a Working Group of experts convened by the International Agency for Research on Cancer (IARC). This Working Group (IARC, 1997) considered that the strength of scientific evidence that aspirin prevents colorectal cancer in humans was limited.[p1] 

 

Taken together, the data on these salicylates suggest that salicylic acid would have no carcinogenic potential.

 

 [p1]IARC Handbooks of Cancer Prevention. Volume 1 - Non-steroidal anti-inflammatory drugs. International Agency for Research on Cancer, , 1997.