Related Experiment Videos
Modulation of N-nitrosodiethylamine-induced hamster lung tumors by ozone
H Witschi1, D W Wilson, C G Plopper
1Institute of Toxicology and Environmental Health, School of Veterinary Medicine, University of California, Davis 95616.
Abstract:
Male Syrian Golden hamsters were treated with subcutaneous injections of N-nitrosodiethylamine (DEN), 20 mg/kg, twice a week for 24 weeks. Half the animals were kept in filtered air and the other half was exposed continuously to an atmosphere of 0.8 ppm of ozone. After 6 months, no more DEN injections were given and all animals were kept in air until termination of the experiment at 7 months. It was found that the animals kept in ozone developed half as many peripheral lung tumors as did the animals kept in air; however, the difference was not statistically significant. Tumors of the trachea, bronchi, nasal cavity and liver developed with the same incidence whether the animals were exposed to ozone or not. It was concluded that ozone, an agent known to produce cell proliferation in the respiratory tract, does not enhance the development of tumors in the peripheral lung or in the nasal cavity of hamsters.
Insights
Ozone exposure did not increase cancer risk in hamsters treated with N-nitrosodiethylamine (DEN). This study found no significant difference in tumor development in animals exposed to ozone versus filtered air.
Area of Science:
- Toxicology
- Environmental Health
- Carcinogenesis
Background:
- Ozone is a respiratory irritant known to cause cell proliferation.
- N-nitrosodiethylamine (DEN) is a chemical carcinogen used to induce tumors.
- The potential synergistic effects of environmental pollutants and carcinogens on cancer development require investigation.
Purpose of the Study:
- To investigate whether continuous exposure to 0.8 ppm ozone enhances tumor development in hamsters treated with N-nitrosodiethylamine (DEN).
- To assess the impact of ozone on peripheral lung tumors, as well as tumors in the trachea, bronchi, nasal cavity, and liver.
Main Methods:
- Male Syrian Golden hamsters were administered subcutaneous injections of DEN (20 mg/kg) twice weekly for 24 weeks.
- Animals were divided into two groups: one group exposed to filtered air, and the other to continuous 0.8 ppm ozone.
- Tumor incidence was evaluated 7 months post-initiation of DEN treatment.
Main Results:
- Animals exposed to ozone developed approximately half the number of peripheral lung tumors compared to the control group, though this difference was not statistically significant.
- No significant differences in tumor incidence were observed in the trachea, bronchi, nasal cavity, or liver between ozone-exposed and control groups.
- Ozone exposure did not appear to promote or inhibit DEN-induced carcinogenesis in the studied respiratory and liver tissues.
Conclusions:
- Continuous exposure to 0.8 ppm ozone does not enhance the development of N-nitrosodiethylamine-induced tumors in the peripheral lung or nasal cavity of Syrian Golden hamsters.
- The findings suggest that, under these experimental conditions, ozone does not act as a co-carcinogen for DEN-induced cancers in the respiratory tract.
- Further research may be warranted to explore potential effects of ozone at different concentrations or in combination with other carcinogens.