Environment and Breast Cancer: Science Review

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CAS RN 78-79-5

Cancer studies: Mammary gland tumors
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Originating list
The list(s) or database(s) in which the chemical was identified as showing an increase in mammary gland tumors. CPDB: Carcinogenic Potency Database, IARC: International Agency for Research on Chemicals Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man summaries, NTP TR: National Toxicology Program (NTP) Technical Reports, NTP 11ROC: NTP 11th Report on Carcinogens, CCRIS: Chemical Carcinogenesis Research Information Service.
IARC Monographs, National Toxicology Program studies, Chemical Carcinogenesis Research Information System
Mammary gland tumor summary
A summary of findings related to mammary gland tumors, most often excerpted from IARC Monographs or the NTP 11th ROC, and, in some cases, supplemented by our evaluation of individual studies and reviews, is available for the priority chemicals and 67 others.
NTP 11th ROC: Inhalation exposure of rats to isoprene vapors induced increased incidence of neoplasms of the mammary gland. Common sites of neoplasm induction by isoprene and butadiene include the mammary gland in rats.
Citations to review sources and individual studies reporting mammary gland tumors are listed below.
Source Type
International Agency for Research on Cancer, Monographs on the evaluation of carcinogenic risk of chemicals to man.VOL.: 71 (1999) (p. 1015) Isoprene.
In one adequate study with rats, increased incidences were observed for benign neoplasms in the mammary gland in males and females: NTP (1997).
Carcinogenic Potency Database 2005. Gold LS ST, Manley NB, Garfinkel GB, Ames BN. Summary Table by Chemical of Carcinogenicity Results in CPDB on 1485 Chemicals. 2005
One of one study does not report mammary tumors (Placke 1996).
National Toxicology Program 11th Report on Carcinogens. Isoprene
Inhalation of rats to isoprene vapors induced increased incidences of neoplasms of the mammary gland (IARC 1999). Other studies showed tumor formation at multiple sites in multiple experimental animals, which may or may not include mammary tumors: -NTP 1995,1999, Melnick 1994, Placke 1996.
National Toxicology Program TX31, 1995
Primary Literature
Just a 2 week and 13 week assay- no cancer endpoints. However: "These inhalation studies showed that isoprene caused toxic effects in the testis of rats and at multiple organ sites in mice. In F344/N rats, exposure to 7,000 ppm isoprene for 6 months caused an increase in the incidence of testicular interstitial cell hyperplasia, and after 6 months of recovery there was a marginally increased incidence of benign testicular adenomas that may have been related to isoprene administration"
Melnick RL, Sills RC, Roycroft JH, Chou BJ, Ragan HA, Miller RA. Isoprene, an endogenous hydrocarbon and industrial chemical, induces multiple organ neoplasia in rodents after 26 weeks of inhalation exposure. Cancer Res 1994;54(20):5333-9.
Primary Literature
A study referenced in the NTP 11th ROC that reports tumors "at multiple sites."
National Toxicology Program Technical Report 486, 1999
Primary Literature
Placke ME, Griffis L, Bird M, Bus J, Persing RL, Cox LA, Jr. Chronic inhalation oncogenicity study of isoprene in B6C3F1 mice. Toxicology 1996;113(1-3):253-62.
Primary Literature
A study referenced in the NTP 11th ROC that reports tumors "at multiple sites." Also listed by CPDB.