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Inactivity of two noble metals as carcinogens
Abstract:
Silver and gold were evaluated for potential carcinogenicity by suspending fine (-300 mesh) powders in trioctanoin and injecting these intramuscularly in Fischer-344 rats. As a positive control, cadmium powder was tested; the vehicle alone served as the negative control. Under the conditions of these experiments, no tumors appeared at the site of injection in the silver-treated animals. Vehicle control (trioctanoin) and gold-treated groups each developed a single fibrosarcoma. In contrast, 60% of the cadmium-treated rats developed fibrosarcomas at the injection site. The mean survival time for the cadmium injected group was 16.5 months, whereas for all other groups it was approximately 23.5 months. It is concluded that the noble metals, silver and gold, are not carcinogenic under the conditions reported here.
Insights
This study found that silver and gold nanoparticles are not carcinogenic in rats. Cadmium exposure, however, led to a high incidence of tumors, indicating its carcinogenic potential.
Area of Science:
- Toxicology
- Nanomaterials Science
- Oncology
Background:
- Silver and gold nanoparticles (NPs) are increasingly used in various applications.
- Assessing the long-term safety and potential carcinogenicity of nanomaterials is crucial.
- Previous studies on metal NP toxicity have yielded varied results.
Purpose of the Study:
- To evaluate the carcinogenic potential of silver (Ag) and gold (Au) nanoparticles.
- To compare the effects of Ag and Au NPs with a known carcinogen (cadmium) and a vehicle control.
Main Methods:
- Fine powders of Ag, Au, and cadmium (Cd) were suspended in trioctanoin.
- These suspensions were administered via intramuscular injection to Fischer-344 rats.
- Trioctanoin alone served as the negative control.
Main Results:
- No tumors were observed at the injection site in the silver-treated group.
- A single fibrosarcoma developed in the gold-treated group and the vehicle control group.
- In contrast, 60% of cadmium-treated rats developed fibrosarcomas, with a significantly shorter mean survival time.
Conclusions:
- Under the experimental conditions, silver and gold nanoparticles demonstrated no significant carcinogenic effects.
- Cadmium exposure confirmed its potent carcinogenicity in this rat model.
- Noble metals like silver and gold appear to be non-carcinogenic in this specific in vivo assay.