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- A carcinogen is a substance that causes cancer (or is believed to cause cancer).
- A carcinogenic material is one that is known to cause cancer.
- The process of forming cancer cells from normal cells or carcinomas is called carcinogenesis.
A known human carcinogen means there is sufficient evidence of a cause and effect relationship between exposure to the material and cancer in humans. Such determination requires evidence from epidemiologic (demographic and statistical), clinical, and/or tissue/cell studies involving humans who were exposed to the substance in question. Obviously, it is unethical to deliberately test potential carcinogens on humans, so "proving" something (in the rigorous scientific sense) to be a carcinogen in humans is a difficult, demanding and lengthy task!
Substances that are reasonably anticipated to be human carcinogens meet any of the following descriptions:|
- There is limited evidence of carcinogenicity from studies in humans. A cause and effect interpretation is credible, but that alternative explanations such as chance, bias, other variables etc. can not be ruled out. Again, science can never prove a hypothesis, only disprove one. Scientific "facts" are established only when a preponderence of the evidence supports a hypothesis and there is 1) no evidence to disprove it and 2) no equally viable (plausible) alternative hypotheses (theories).
- There is sufficient evidence of carcinogenicity from studies in experimental animals (such as mice or rats), which indicates there is an increased incidence of malignant and/or a combination of malignant and benign tumors (1) in multiple species or at multiple tissue sites, or (2) by multiple routes of exposure, or (3) to an unusual degree with regard to incidence, site, or type of tumor, or age at onset.
- There is less than sufficient evidence of carcinogenicity in humans or laboratory animals; however, the substance is structurally related to other materials that are either human carcinogens or reasonably anticipated to
be human carcinogens.
- There is convincing relevant information that the material acts
through mechanisms that are likely to cause cancer in humans.
Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens is the definitive resource on over 2,100 of the most commonly used, transported and regulated chemical substances. Get your copy at Safety Emporium.
A wide variety of information is required to assess carcinogenicity and risks to humans. For example, a substance may cause cancer in laboratory animals, but the mechanism by which this happens may not occur in humans.
OSHA's Hazardous Communications standard 1910.1200 accepts the following sources for establishing that a chemical is a known or potential (reasonably anticipated to be a) human carcinogen:
According to NIOSH's Publication No. 2010-145 (May 2010), past estimates that about 4% of cancer deaths in the U.S. are caused by occupational exposures have underestimated the actual rate. For example, exposures to carcinogens in the workplace may not result in cancer until 15-40 years later.
- National Toxicology Program (NTP), "Annual Report on Carcinogens" (latest edition).
- International Agency for Research on Cancer (IARC) "Monographs" (latest editions), part of the World Health Organization (WHO).
- 29 CFR part 1910, subpart Z, Toxic and Hazardous Substances, Occupational Safety
and Health Administration.
Note: The "Registry of Toxic Effects of Chemical Substances" published by the National Institute for Occupational Safety and Health (NIOSH) indicates whether a chemical has been found by NTP or IARC to be a potential carcinogen. You can download this at the above link in PDF format (3.4 Mb).
- "Carcinogen Risk Assessment (Contemporary Issues in Risk Analysis, Vol 3)", Hardcover, 1988. Estimated price $99.00. Info and/or order .
- "Handbook of Carcinogen Testing", Hardcover, 904 pages, 1995. Estimated price $399.91. Info and/or order.
- "The Biological Basis of Cancer", Paperback, 494 pages, 2006. Estimated price $94.03. Info and/or order.
- "Introduction to the Cellular and Molecular Biology of Cancer, 4th Edition", Paperback, 552 pages, 2005. Estimated price $90.00. Info and/or order.
- "Pick Your Poison: How Our Mad Dash to Chemical Utopia is Making Lab Rats of Us All", Hardcover, 256 pages, 2011. Estimated price $19.97. Info and/or order ILPI recommended.
According to the U.S. OSHA Hazard Communication Standard, 1910.1200(d)(5)(ii), any mixture that has not been tested for carcinogenic properties is considered to be carcinogenic if it contains 0.1% or more of a carcinogenic substance:
"If a mixture has not been tested as a whole to determine whether the mixture is a health hazard, the mixture shall be assumed to present the same health hazards as do the components which comprise one percent (by weight or volume) or greater of the mixture, except that the mixture shall be assumed to present a carcinogenic hazard if it contains a component in concentrations of 0.1 percent or greater which is considered to be a carcinogen under paragraph (d)(4) of this section;"
Use extreme caution when working with carcinogenic (or potentially carcinogenic) materials in the workplace. Be sure to use all proper personal protective equipment (PPE) and to minimize your exposure. Find alternative procedures or materials if possible; while these may cost a little more in up-front costs, the long term savings in disposal costs, litigation etc. usually more than make up for such an expense. Proper engineering controls and adminstrative controls are definitely required when working with carcinogens or potential carcinogens!
Signs, training materials and supplies from Safety Emporium can help ensure a safe and healthy workplace.
See also: carcinoma, clastogen, mutagen, National Toxicology Program (NTP), teratogen.
Additional definitions from Google and OneLook.
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