1. Measuring Carcinogens in People: Exposures come from a variety of sources

Thousands of natural and man-made chemicals are present in the environment – indoors and out, in air, food, water and consumer products. Most commercially used chemicals have never been adequately assessed for safety and most have not been biomonitored for their presence in people. Under the broken and outdated federal Toxic Substances Control Act only about 7 percent of the approximately 3,000 high volume chemicals (used in excess of a million pounds a year) have been tested for safety.

The gold standard for assessing exposure to chemical carcinogens is biomonitoring – the measurement of chemicals or their metabolites in blood, urine, breast milk, hair or other human samples.Biomonitoring is vital for accurate determination and tracking of exposures. An inventory of carcinogens measured in people would provide a knowledge base for researchers and a tool for policy-makers and regulators to assess and reduce exposures. This is especially important in light of the conclusions of the 2008-2009 report of the President’s Cancer Panel:

The Panel was particularly concerned to find that the true burden of environmentally induced cancer has been grossly underestimated. With nearly 80,000 chemicals on the market in the United States, many of which are used by millions of Americans in their daily lives and are un- or understudied and largely unregulated, exposure to potential environmental carcinogens is widespread. . . . [T]he public remains unaware of many common environmental carcinogens. . . . Most also are unaware that children are far more vulnerable to environmental toxins and radiation than adults.4

A comprehensive review by EWG of the scientific literature revealed a stunning number of carcinogens—up to 420* – that have been detected in people through biomonitoring studies. The carcinogens detected include both natural and man-made chemicals that come from a wide range of sources, including: industrial processes, commercial products, pesticides and naturally occurring materials. Table 1 provides examples of the types of carcinogens detected and their sources (the full list of carcinogens detected in people can be found in Appendices A & B).

Biomonitoring studies are a window into the amount of exposure, but do not address the source or route of exposure. Grouping the carcinogens detected in the human body into categories based on primary use can help us better understand these factors.

Table 1: Selected carcinogens measured and detected in the human body

Chemical Detections in NHANESa Associated Cancer(s) Source and Exposure Agency & Classification
Industrial chemicals        
Asbestos (all forms) not tested Strong evidence: lung (including mesothelioma), larynx, ovary; Some evidence: pharynx, stomach, colon & rectum Source/Use insulating material, flooring, brake pads and shoes, roofing, gaskets, cement pipes and sheets, textiles, and natural occurance. Exposure environmental: inhalation and ingestion of particles (breakdown of materials); occupational: inhalation during mining, manufacturing and repair operations. IARC (Known); NTP (Known); EPA (Human carcinogen); CA Prop 65
Benzene 51.40% Strong evidence: leukaemia and/or lymphoma Source/Use component of inks, solvents, gasoline additive, and intermediate chemical (rubber, lubricants, dyes, detergents, pesticides). Exposure environmental: inhalation and some dermal absorption from industrial emissions, fuel, exhaust; occupational: inhalation/dermal exposure to solvents, paint, oil refining and working in manufacturing IARC (Known); NTP (Known); EPA (Known/likely); CA Prop 65
1,3-Butadiene range: >99% ; <1% (N-acetyl-S-(3,4-dihydroxybutyl)-L-cysteine ; N-acetyl-S-(1-hydroxymethyl-2-propenyl)-L-cysteine) Strong evidence: leukaemia and/or lymphoma Source/Use used in production of synthetic rubbers/polymers. Exposure environmental: air (mainly from point sources); occupational: petroleum refining IARC (Known); NTP (Known); EPA (Carcinogenic); CA Prop 65
Polychlorinated biphenyls (PCBs) range: <1%->99% Strong evidence: skin; Some evidence: breast, leukaemia and/or lymphoma, prostate, brain, liver, lung, thyroid, stomach, pancreas, colon & rectum, uterus & ovary Source/Use electrical equipment, hydraulic machinery, fluorescent lighting fixtures, plasticizers, adhesives, flame retardants, caulk, and paints. Exposure environmental: inhalation from dust and breakdown of electrical equipment, haudraulics, and caulking; occupational: mechanical and electrical repair, construction IARC (Known); NTP (Reasonably anticipated); EPA (Likely); CA Prop 65
Chemical Detections in NHANESa Associated Cancer(s) Source and Exposure Agency & Classification
Consumer products        
Alcoholic beverage consumption not tested Strong evidence: breast, liver, colon & rectum, oral cavity, pharynx, oesophagus, nasal cavity & sinuses, larynx; Some evidence: pancreas Source and exposure: alcohol use IARC (Known); NTP (Known); CA Prop 65
Ethylene oxide 59.3% (N-acetyl-S-(2-hydroxyethyl)-L-cysteine) Some evidence: breast, leukaemia and/or lymphoma Source/Use raw material used in manufacture of chemicals for consumer goods. Exposure environmental: minor exposures through tobacco, food, skin-care products; occupational: production of ethylene oxide, use in industrial and hospital sterilization IARC (Known); NTP (Known); CA Prop 65
Perchloroethylene (Tetrachloroethylene) 16.40% Some evidence: leukaemia and/or lymphoma, bladder, kidney, lung, cervix, oesophagus Source/Use dry cleaning, chemical intermediates (production of fluorocarbons), metal cleaning and degreasing. Exposure environmental: air, water, food; occupational: dry cleaning, textiles, metal industry, automotive industry, printing and cleaning IARC (Probable); NTP (Reasonably anticipated); EPA (Likely); CA Prop 65
Polybrominated Biphenyls 87.9% (PBB-153) Some evidence: leukamia and/or lymphoma, digestive system combined (liver, stomach, oesophagus, pancreas) Source/Use flame retardants (primarily). Exposure air, water and soil contamination, food (milk, eggs, meat, fish) IARC (Probable); NTP (Reasonably anticipated); CA Prop 65
Tobacco(smokeless, second-hand, smoking) including: N'-Nitrosonornicotine (NNN) and 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK) 72.9%/70.4% (cotinine/NNAL) Strong evidence: lung, oral cavity, pharynx, oesophagus, kidney, bladder, liver, stomach, colon & rectum, pancreas, nasal cavity & sinuses, larynx, uterine cervix, ovary, leukaemia and/or lymphoma; Some evidence: breast Sources and exposure: smoking and other tobacco use IARC (Known); NTP (Known); CA Prop 65
Chemical Detections in NHANESa Associated Cancer(s) Source and Exposure Agency & Classification
Glyphosate not tested Some evidence: leukaemia and/or lymphoma Sources and exposure: mixing and application as herbicide, possible residue on foods, water and environmental contamination IARC (Probable)
Permethrin 73.4% (3-Phenoxybenzoic acid) Some evidence: leukaemia and/or lymphoma, prostate Sources and exposure: mixing and application as insecticide, possible residue on foods, water and environmental contamination EPA (Likely)
Chemical Detections in NHANESa Associated Cancer(s) Source and Exposure Agency & Classification
Arsenic and inorganic arsenic compounds 96.20% Strong evidence: lung, skin, bladder; Some evidence: liver, prostate, kidney Source/Use natural occurance, pharmaceuticals, wood preservatives, agricultural chemicals, applications in mining, metallurgy, glass, and semiconductor industries. Exposure primarily contaminated food/water, some inhalation, minor occupational exposures IARC (Known); NTP (Known); EPA (Human carcinogen); CA Prop 65
Cadmium and cadmium compounds 77.60% Strong evidence: lung; Some evidence: prostate, kidney Source/Use batteries, plating, stabilizers of plastics, natural occurance. Exposure environmental: ingestion of food, ambient air (minor), contaminated drinking water; occupational: inhalation during cadmium production and refining, alloy production, other smelting/plating industry IARC (Known); NTP (Known); EPA (Probable); CA Prop 65
Chromium hexavalent compounds not tested Strong evidence: lung; Some evidence: nasal cavity & sinuses Source/Use pigment (textile dyes, paint, ink, plastic), corrosion inhibitor, wood preservative, metal/chrome finishing, leather tanning, given off in casting/welding, natural occurance. Exposure environmental: inhalation, contaminated drinking water; occupational: inhalation of dusts, mists, fumes and dermal contact with chromium containing products IARC (Known); NTP (Known); EPA (Known/likely); CA Prop 65
Chemical Detections in NHANESa Associated Cancer(s) Source and Exposure Agency & Classification
Combustion by-products/other by-products        
Bromoform 31.90% Evidence in animals: colon & rectum, liver Source/Use disinfection by-product, used as fluid for mineral ore separation, lab reagent, electronics industry, formerly used as solvent for waxes, greases, oils, fire-resistent chemical. Exposure drinking water disinfected with chlorine, bromine, or bromine compounds, inhalation near factories, in laboratory use, swimming pools EPA (Probable); CA Prop 65
Polycyclic aromatic hydrocarbons (PAHs) 98.8% (1-hydroxypyrene) Some evidence: lung, bladder, kidney, larynx, skin, pancreas, stomach, oesophagus, prostate, leukaemia and/or lymphoma Sources combustion of organic materials. Exposure mainly ambient air pollution, some indoor combustion sources IARC (Known, Probable, Possible); NTP (Reasonable anticipated); CA Prop 65
Chemical Detections in NHANESa Associated Cancer(s) Source and Exposure Agency & Classification
Dichloromethane (Methylene chloride) <1.0% Some evidence: liver, leukaemia and/or lymphoma, cervix, breast, CNS tumors, rectum, lung Source/Use solvent. Exposure environmental: air (indoor may be higher especially from spray painting, aerosol use), contaminated soil, water (minor); occupational: industrial use IARC (Probable); NTP (Reasonably anticipated); EPA (Likely); CA Prop 65
Trichloroethylene 1.60% Strong evidence: kidney; Some evidence: liver, leukaemia and/or lymphoma Source/Use solvent, degreaser, anaesthetic, heat-transfer medium, extraction agent for fats and oils, intermediate to produce chlorofluorocarbons and other chemicals. Exposure occupational: degreasing IARC (Known); NTP (Reasonably anticipated); EPA (Carcinogenic); CA Prop 65
Chemical Detections in NHANESa Associated Cancer(s) Source and Exposure Agency & Classification
Formaldehyde not tested Strong evidence: leukaemia and/or lymphoma, nasopharynx; Some evidence: nasal cavity & sinuses Source/Use production of resins, chemical intermediate, disinfectant/preservative. Exposure environmental: natural occurance, combustion, building materials, tobacco smoke, auto exhaust IARC (Known); NTP (Known); EPA (Probable); CA Prop 65
Nitrate or nitrite (ingested) under conditions that result in endogenous nitrosation 99.7% (nitrate) Some evidence: stomach, bladder, kidney, colon & rectum, brain, lung, pancreas, Source/Use natural occurance in food/water, fertilizer, food perservative. Exposure water and food IARC (Probable)

a Most recent available data varies for each carcinogen

Carcinogenic chemicals identified by the following authoritative agencies:

International Agency for Research on Cancer, U.S. National Toxicology Program U.S., EPA, California’s Office of Environmental Health Hazard Assessment –Proposition 65

Industrial chemicals

Industrial chemicals are used in the production of plastics, rubber and other polymers, and electrical components; in dyes, pigments, resins, solvents and adhesives; and as intermediates in the production of other industrial chemicals. Asbestos is used in insulating and fire resistant materials. Most contact with industrial chemicals comes on the job, although anyone can be exposed through contaminated air and drinking water - and to some degree from contaminated soil and food.

Cancers associated with exposure to industrial chemicals include leukemia, lymphomas, and cancers of the bladder, lung, liver, kidney, colon, rectum, pancreas, prostate and breast.

Commercial and consumer products

Around one-third of all cancers in the U.S. are caused by tobacco or alcohol. No single agent is a bigger cause of preventable cancer than tobacco - yet tobacco and alcohol are not the only commercially used chemicals associated with cancer.

Many products we routinely use contain carcinogenic chemicals, including flame retardants in furniture and other items; dry cleaning chemicals; styrene in plastics; nonstick, waterproof and grease-resistant chemicals in cookware, clothing and food wrappers; other chemicals in paints and hair coloring; and flavoring and fragrance ingredients.

Associated cancers: Tobacco and alcohol – lung and other respiratory cancers, oral cancers, breast, bladder and pancreas. Tobacco – kidney, liver, stomach and cervical cancer. Other chemicals – kidney, leukemia and/or lymphoma, liver, bladder, stomach, testis, pancreas and ovary.


Many pesticides have been identified as carcinogenic to some degree. People are exposed during mixing and application, pesticide drift from fields and residues on food. These exposures are not just a concern near farms. They can also occur from home use, contamination of food and drinking water, products containing wood preservatives and even some clothing.

Associated cancers: prostate, lung, liver, lymphomas and leukemias, bladder and possibly breast cancer.

Heavy Metals/Alloys

Metal molecules can bind to DNA and cause mutations. Many industrial workers come into contact with carcinogenic heavy metals and alloys, such as lead, nickel and arsenic. The public can also be exposed to trace amounts of heavy metals in food and water and even contaminated air and soil.

Associated cancers: cancers of the lung, bladder and skin and associations with liver, prostate and kidney cancers

Combustion and other by-products

Sources of combustion by-products, particularly polycyclic aromatic hydrocarbons or PAHs, include engine exhaust and air emissions from industrial facilities, power plants, and hazardous waste incinerators. Other by-products are produced when chlorine or other drinking water disinfectants react with organic solids, and when meat is cooked at high temperatures and charred.

Associated cancers: multiple cancer sites including lung, kidney, bladder, skin, stomach, prostate and non-Hodgkin lymphoma.


Solvents are used in adhesives, in the production of pesticides and the manufacture of plastics, polymers and personal care products. Most exposures to carcinogenic solvents come in occupational settings. Exposures to the public are mostly from air contamination, especially the indoor use of paint, degreasers or some aerosols.

Associated cancers: liver, kidney and breast

* A high-end estimate. Some chemicals are measured by metabolites, or breakdown products, rather than the parent compound. Metabolites are not always specific to a single chemical and instead indicate exposure to any or all of their parent compounds. Adducts, which are the products of a chemical or its metabolite binding to DNA or protein in the body, are also sometimes measured. Our investigation did not include chemicals used primarily as medications.