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Carcinogenic and co-carcinogenic studies of thiram on mouse skin
Y Shukla1, S M Baqar, N K Mehrotra
1Laboratory of Environmental Carcinogenesis, Industrial Toxicology Research Centre, Lucknow, India.
Abstract:
Thiram (tetramethyl thiuram disulfide), a carbamate fungicide, is used in the rubber processing industry as an accelerator and vulcanizing agent. Previous studies evaluated the tumorigenic potential of thiram in rodents, but failed to provide conclusive results. In the present study the tumorigenic potential of thiram was evaluated in Swiss albino mice by a two-stage initiation-promotion protocol and a long-term in vivo bioassay for carcinogenicity. Results revealed that following tumour initiation with thiram and promotion with 12-O-tetradecanoyl phorbol 13-acetate, skin tumours developed, mostly at the site of treatment (dorsal skin) in single and multiple dose-initiated animals. Similarly, papillomatous growths were observed on the dorsal skin of the mice initiated with a single subcarcinogenic dose of dimethylbenzanthracene and promoted with thiram. Thiram failed to provoke tumorigenesis when tested as a complete carcinogen for up to 52 wk and thereafter the study was terminated due to increased mortality. It is concluded that thiram has both tumour initiating and tumour-promoting potential in both sexes of Swiss albino mice following topical exposure at the tested dose level.
Insights
Thiram, a rubber industry chemical, shows potential for initiating and promoting skin tumors in mice. Further research is needed to understand its carcinogenic effects in humans.
Area of Science:
- Toxicology
- Carcinogenesis
- Dermatology
Background:
- Thiram (tetramethyl thiuram disulfide) is a carbamate fungicide used in rubber processing.
- Previous studies on thiram's tumorigenic potential in rodents yielded inconclusive results.
Purpose of the Study:
- To evaluate the tumor-initiating and tumor-promoting potential of thiram in Swiss albino mice.
- To assess the carcinogenicity of thiram using a two-stage initiation-promotion protocol and a long-term in vivo bioassay.
Main Methods:
- Swiss albino mice were subjected to a two-stage initiation-promotion protocol.
- Thiram was used as an initiator with 12-O-tetradecanoyl phorbol 13-acetate as a promoter, and vice versa.
- A long-term in vivo bioassay was conducted to assess carcinogenicity.
Main Results:
- Thiram demonstrated both tumor-initiating and tumor-promoting effects on the dorsal skin of mice.
- Skin tumors and papillomatous growths were observed following thiram treatment.
- Thiram did not act as a complete carcinogen, and high mortality was observed in long-term studies.
Conclusions:
- Thiram possesses both tumor-initiating and tumor-promoting capabilities in Swiss albino mice upon topical exposure.
- The findings suggest a carcinogenic risk associated with thiram exposure.