Environment and Breast Cancer: Science Review

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.

"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.

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)

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).

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.

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).

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.

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.

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.

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.

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).

Any Silent Spring Institute notes on treatment of mammary tumors in US EPA risk assessment.

This field indicates whether NIOSH identifies the chemical as a potential carcinogen for workers (yes/no) (24).

Lists target organs from animal cancer bioassays (24).

For 11 chemicals that are of particular interest because of recent regulatory attention, we identified and summarized risk assessment materials developed by a wide range of agencies and groups. We specifically searched for documents by the following organizations: California EPA Office of Health Hazard Assessment, Health Canada, IARC, International Program on Chemical Safety (IPCS), World Health Organization, RIVM (Dutch chemical standards agency), Toxicology Excellence for Risk Assessment ITER database and Peer Consultation documents, and by searching PubMed, ToxLine, the National Library of Medicine, and Google for documents related to “risk assessment” and the CAS No. or chemical name.