Environment and Breast Cancer: Science Review
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Major use
We assigned each chemical into one of the following groups based on its major
sources and uses: industrial chemicals, chlorinated solvents, products of combustion,
pesticides, dyes, radiation and drinking water disinfection, pharmaceuticals, hormones, natural
products, and research chemicals.
Hormone
Found in consumer products
"Likely" indicates that the chemical is contained in consumer
products or traces of the chemical are present in products, including food and water, resulting
in likely exposure for the general population. For some chemicals marked as "likely," consumer
product uses have been discontinued, and this will be indicated in the "Use in Consumer
Products" field.
Not likely
Food additive in US
Chemicals are classified as "Listed" or "Not listed" in the Everything
Added to Food in the United States database developed by the US Food and Drug
Administration.(22)
Not listed
California Proposition 65
Chemicals are labeled "Listed" or "Not listed" based on the Proposition 65 list of chemicals updated on May 27, 2005. Listed chemicals are "chemicals known by the State of
California to cause cancer or reproductive toxicity"(19).
Not listed
Air pollutant
Chemicals classified as "Likely" air pollutants are those likely to be found in
indoor or outdoor air, including products of combustion and industrial chemicals that may offgas
from consumer products, leading to human exposure.
Not likely
Current High Production Volume chemical
Chemicals are classified "Yes" or "No," based on
2002 production volume information submitted to the US EPA: "Yes" for >1 million pounds
produced; "No" for < 1 million pounds produced. Some past production volumes are
referenced, where appropriate, in the HPV comment column (20). In addition, Scorecard.org is
referenced and noted in the HPV comment column when it was inconsistent with current
production volume information obtained from US EPA (21).
No
Production volume information
Production volume information is from the US EPA database
on non-confidential production volume information submitted by companies for chemicals
under the 1986-2002 Inventory Update Rule (IUR) using the most updated (2002) values (20).
The Inventory Update Rule requires the submission of basic production data every four years
on chemical substances manufactured (including imported) for commercial purposes in
amounts of 25,000 pounds or more at a single site. Out of over 80,000 chemicals on the TSCA
Chemical Substances Inventory, reports are required for approximately 9,000 substances. For
those substances with annual volumes of 300,000 lbs or more per site, reporters also submit
chemical processing and use information.
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General population exposure
This field includes information describing pathways of exposure
for the general population obtained from a variety of sources including: IARC Monographs (9),
NTP 11th ROC on Carcinogens (4), NTP Study Reports and Abstracts (3), Hazardous Substance
Database (10), and other sources located through use of the Google search engine.
The primary routes of potential human exposure to norethisterone are ingestion, dermal contact, and inhalation. When used as an oral contraceptive, it is usually given in a dose of 0.5 to 2.0 mg daily in combination with mestranol or ethinylestradiol. It is also used continuously at a daily dose of 0.35 mg in the so-called contraceptive “mini-pill”. In its other medicinal uses, norethisterone is given in daily doses ranging from 10 to 30 mg (11th ROC).
Use in consumer products
Summaries of chemical use in consumer products were developed
from information found in US EPA SRD (11), NLM HPD (12), and Scorecard (12). Major uses
were taken from IARC Monographs (9), NTP 11th ROC (4), NTP Study Reports (3), HSDB (10),
and PAN Pesticides Database (13). If a chemical could not be found in these sources, we
searched ToxNet (14), PubChem (15), and The Merck Index (16), and conducted searches by both
name and CAS No. using Google.
No consumer products listed in SRD, HPD, or Scorecard. Norethisterone, an orally active progestin, has been used in small amounts in human medicine since 1957 to treat conditions such as amenorrhea, dysfunctional uterine bleeding, endometriosis, premenstrual tension, and dysmenorrhea. Since 1962, the most common use in the United States has been as the progestin in progestin-estrogen combination oral contraceptives. Norethisterone has been used in the treatment of inoperable malignant neoplasms of the breast or as an adjunct to surgery or radiotherapy. Norethisterone is also used as an intermediate in the commercial synthesis of norethisterone acetate and possibly in the synthesis of ethynodiol diacetate (11th ROC).
Occupational exposure to women
We extracted the total number of potentially exposed workers and the
number of potentially exposed female workers from the National Occupational Exposure
Survey (NOES) 1981-1983; we listed specific industry classifications if >5,000 women were
potentially exposed in that industry. Note: NOES does not include farm workers.
Not listed in NOES. Potential occupational exposure may occur through inhalation or dermal contact for workers involved in the manufacture, formulation, packaging, or administration of norethisterone (11th ROC).
US EPA cancer classification
The US EPA Weight of Evidence Characterization of the
chemical’s carcinogenic potential is listed: Group A: Carcinogenic to humans; Group B:
Probably carcinogenic to humans. Group C: Possibly carcinogenic to humans. Group D: Not
classifiable as to human carcinogenicity. Group E: Evidence of non-carcinogenicity for
humans. NA: Not evaluated by US EPA (17).
NA
NIOSH Pocket Guide - potential carcinogen?
This field indicates whether NIOSH identifies the chemical as a potential
carcinogen for workers (yes/no) (24).
NA
Risk assessments not reviewed for this chemical