Environment and Breast Cancer: Science Review
Cancer studies: Experimental details
Snyder CA, Goldstein BD, Sellakumar AR, Albert RE. Evidence for hematotoxicity and tumorigenesis in rats exposed to 100 ppm benzene. Am J Ind Med 1984;5(6):429-34.
Notes
One malignant mammary tumor occurred in a a male rat, and no female animals were used. Also used lower levels of benzene than other studies.
One malignant mammary tumor occurred in a a male rat, and no female animals were used. Also used lower levels of benzene than other studies.
Route
Route of chemical administration: dermal, inhalation, gavage (delivery directly into the
stomach), in feed, subcutaneous injection (under the skin), or intraperitoneal injection (into the
cavity that contains the abdominal organs).
inhalation
Doses
Dosage, frequency, and duration of treatment; the sizes of the groups of animals
involved and what age the animals were at the beginning of the study.
100 ppm 6 hr/day, 5 days/wk for life. 40 rats per dose group. Animals were 8 wks old when dosing began.
Mammary tumors, malignant
Development of malignant mammary gland tumors follows the
same format as for benign, as described above.
0/40, 1/40 adenocarcinoma
Comments
This field contains information on the survival rates of the animals and the body
weight trends in order to evaluate whether these factors were likely to have affected the
generation of mammary gland tumors. Mammary gland tumors tend to develop later in an
animal’s life, so studies with lowered survival could mean that animals died before mammary
gland tumors could develop. Decreased weight (perhaps due to toxicity of the chemical) can
decrease the development of tumors. This field may also contain other comments about the
design or outcome of the study.
No difference in body weight. Many animals died from a respiratory infection 448-504 days into the experiment (20 treated, 13 control).
Other tumors
A list of other tumors that developed in the study that were treatment related.
liver, zymbal gland, leukemia
CPDB TD50 (mg/kg-d)
Data excerpted from the CPDB database that is defined as the "dose-rate in
mg/kg body wt/day which, if administered chronically for the standard lifespan of the species,
will halve the probability of remaining tumorless throughout that period". The CPDB
calculated values for all tumor endpoints listed as well as for total tumors. The range of
mammary gland tumors TD50s is provided, as well as an overall range.
Mammary: 634, overall: 93.4-634