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Local application to mouse skin as a carcinogen specific test system for non-volatile nitroso compounds
Abstract:
Using the epicutaneous test as an experimental model for detecting carcinogenicity, 3 doses each of nitrosomethylurea (NMU), nitrosonornicotine (NNN) and nitrosocarbaryl (NC) were administered to the skin of 65 female CFLP mice/group. To compare the carcinogenic potency of the nitroso compounds, benzo[a]pyrene (BaP) was taken as reference substance. Dose-response relationships were obtained for NMU and NC as well as for BaP. NNN exhibited only a weak carcinogenic effect in the dose range from 12.5 micrograms to 200 micrograms tested in the skin painting model. It showed, however, no dose dependent activity. After probit analysis of the results, the carcinogenic potencies of the nitroso compounds investigated in this system rank as follows: NC, 0.18; NMU, 0.04; NNN, 0.008 (BaP, 1.00).
Insights
This study compared the carcinogenicity of three nitroso compounds in mice using a skin test. Nitrosocarbaryl (NC) was found to be the most potent carcinogen among those tested, followed by nitrosomethylurea (NMU) and nitrosonornicotine (NNN).
Area of Science:
- Toxicology
- Carcinogenesis Research
- Dermatology
Background:
- Epicutaneous testing is a valuable experimental model for assessing chemical carcinogenicity.
- Nitroso compounds are a class of chemicals known for their potential carcinogenic properties.
- Understanding the relative carcinogenic potency of different nitroso compounds is crucial for risk assessment.
Purpose of the Study:
- To evaluate and compare the carcinogenic potency of nitrosomethylurea (NMU), nitrosonornicotine (NNN), and nitrosocarbaryl (NC) using an epicutaneous mouse model.
- To establish dose-response relationships for these nitroso compounds.
- To use benzo[a]pyrene (BaP) as a reference substance for comparative carcinogenicity.
Main Methods:
- Female CFLP mice were subjected to epicutaneous administration of three doses of NMU, NNN, and NC.
- Benzo[a]pyrene (BaP) was used as a reference carcinogen.
- Probit analysis was employed to determine dose-response relationships and compare carcinogenic potencies.
Main Results:
- Dose-response relationships were established for NMU, NC, and BaP.
- NNN demonstrated a weak carcinogenic effect but lacked dose-dependent activity within the tested range.
- The ranking of carcinogenic potencies in this skin painting model was NC (0.18) > NMU (0.04) > NNN (0.008), with BaP as the reference (1.00).
Conclusions:
- Nitrosocarbaryl (NC) exhibits the highest carcinogenic potency among the tested nitroso compounds in the epicutaneous mouse model.
- Nitrosomethylurea (NMU) and nitrosonornicotine (NNN) show lower carcinogenic potencies, with NNN being the weakest.
- The epicutaneous test model effectively differentiates the carcinogenic potential of various nitroso compounds.