Environment and Breast Cancer: Science Review

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).

Mostly rat or mouse, though some studies use hamster or monkeys.

F for female, M for male.

Strain information for the animal species used in the study.

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.

How long the animals were observed after the chemical was no longer being administered and before death of the animals.

Development of malignant mammary gland tumors follows the same format as for benign, as described above.

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.

A list of other tumors that developed in the study that were treatment related.

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.