Cm. Skisak et al., CHRONIC AND INITIATION PROMOTION SKIN BIOASSAYS OF PETROLEUM REFINERYSTREAMS/, Environmental health perspectives, 102(1), 1994, pp. 82-87
Nine refinery streams were tested in both chronic and initiation/promo
tion (I/P) skin bioassays. In the chronic bioassay, groups of 50 C3H/H
eJ mice received twice weekly applications of 50 mu l of test article
for at least 2 years. In the initiation phase of the I/P bioassay, gro
ups of CD-1 mice received an initiating dose of 50 mu l of test articl
e for 5 consecutive days, followed by promotion with 50 mu l of phorbo
l-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
mu l of 7,12-dimethylbenzanthracene (0.1%) w/v in acetone) or acetone
, followed by promotion promotion with 50 mu l of test article twice w
eekly for 25 weeks. The most volatile of the streams, sweetened naphth
a, and the least volatile, vacuum residuum, were noncarcinogenic in bo
th assays. Middle distillates, with a boiling range of 150 degrees-370
degrees C, demonstrated carcinogenic activity in the chronic biossay
and acted as promoters but not-initiators in the bioassay. Untreated m
ineral 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 A highly solvent-refined
mineral stream lacked initiating activity. These, results indicate tha
t the I/P bioassay, which takes 6 months to complete, may be a good qu
alitative predictor of the results of a chronic bioassay, at least for
petroleum streams. Furthermore, the I/P bioassay provide insight into
possible mechanisms of tumor development.