Nine refinery streams were tested in both chronic and initiation/promotion (I/P) skin bioassays. In the chronic bioassay, groups of 50 C3H/HeJ mice received twice weekly applications of 50 microl of test article for at least 2 years. In the initiation phase of the I/P bioassay, groups of CD-1 mice received an initiating dose of 50 microl of test article for 5 consecutive days, followed by promotion with 50 microl of phorbol-12-myristate-13-acetate (0.01% w/v in acetone) for 25 weeks. In the promotion phase of the I/P bioassay, CD-1 mice were initiated with 50 microl of 7,12-dimethylbenzanthracene (0.1% w/v in acetone) or acetone, followed by promotion with 50 microl of test article twice weekly for 25 weeks. The most volatile of the streams, sweetened naphtha, and the least volatile, vacuum residuum, were noncarcinogenic in both assays. Middle distillates, with a boiling range of 150 degrees-370 degreesC, demonstrated carcinogenic activity in the chronic bioassay and acted as promoters but not initiators in the I/P bioassay. Untreated mineral oil streams displayed initiating activity and were carcinogenic in the chronic bioassay, presumably due to the presence of polycyclic aromatic hydrocarbons of requisite size and structure. A highly solvent-refined mineral oil stream lacked initiating activity. These results indicate that the I/P bioassay, which takes 6 months to complete, may be a good qualitative predictor of the results of a chronic bioassay, at least for petroleum streams. Furthermore, the I/P bioassay can provide insight into possible mechanisms of tumor development.Imagesp82-a
This study examined formaldehyde vapor exposures that occurred in the gross anatomy laboratories of a major medical school during a 12-week study period. Formaldehyde samples were collected using personal sampling pumps to draw air through midget impingers containing a 0.1% solution of sodium bisulfite dissolved in deionized water as the absorbing medium. Breathing zone and ambient air samples were collected and analyzed from 8 laboratories on a rotating basis. Analysis was via the chromotropic acid method recommended by the National Institute for Occupational Safety and Health. It was found that 44% of all breathing zone samples were greater than the 1.0 ppm ceiling value for occupational exposure recently recommended by the American Conference of Governmental Industrial Hygienists. Only 11% of ambient air samples were in excess of 1.0 ppm.
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