Activatable mutagens

On the other hand, direct acting mutagens such as nitro-substi-tuted polycyclic aromatic hydrocarbons have been detected in diesel exhaust emissions and may be responsible for a major portion of the mutagenic activity. However, in view of the presence of a variety of detoxification enzymes in human cells, the distinction between direct acting and activatable mutagens may not be justified for the assessment of health hazards. 

Vithayathil et reported that an enhanced rate of mutation by microsomes in Salmonella strain TA 1538 results from the presence of 2-5 ppm of microsome-activatable mutagens in bacterial nutrient broths containing beef extract. Since it is known that strain TA 1538 responds, apparently exclusively, to organic compounds capable of including frameshift mutations, it can be concluded that the active materials present in nutrient broth are also of this type. Vithayathil et ai suggest that hitherto undetected presumptive carcinogens may be present in food preparations derived from beef, at a concentration... 

Stark and co-workers (1985) reported that irradiation of a 0.1 mM solution of 1-nitropyrene in 2-propanol with light from 320 to 418 nm changes its absorption spectrum and concurrently results in almost total loss of its direct ( —S9) or activatable ( + S9) mutagen activity in the Ames Salmonella assay. 

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