What is a chemical carcinogen?

uAny discrete chemical compound which has been shown to cause cancer in human or animal studies.

uHundreds of individual compounds have been shown to induce cancers.  Many thousands of additional
compounds are “suspect” carcinogens.

uMany are commonly used in laboratory operations, shops and factories.

u NTP; IARC - carcinogen classification based on rodent tests.

                            How is chemical carcinogenicity determined?

u  Epidemiological studies determine the relationship between a cancer suspect chemical and a human
population over a long period of time.

u  Animal studies directly induce cancer in test animals using a large sample of animals, usually of
two or more species with varying dose and time parameters. 

u  Experiments with animals are based on the premise that chemicals that produce cancer in animals
will have similar effects on human cells.  Most known human carcinogens produce cancer in
experimental animals.

                                  What materials are carcinogens?

uAsbestos

uCertain chemicals

uCoal tars and coke oven emissions

uNatural products (progesterone, safrole)

uTobacco smoke

uIonizing radiation

uUltraviolet radiation

                                 Examples of chemical carcinogens?

u  Epoxides:                 Ethylene oxide        Propylene oxide

u  Organohalogen comp.:   Vinyl chloride          Carbon tetrachloride  Chloroform      
Hexachlorobenzene  Trichloroethylene

u  Hydrazines:

    Hydrazine (and salts)    1,2-Dimethylhydrazine

                                 Human carcinogens - environmental:

•            Aflatoxins

•            Asbestos

•            Benzene

•            Cadmium

•            Coal tar

•            Second hand smoke

•            Creosote

•            DDT

•            Polycyclic aromatic hydrocarbons

•            Radon

•            Solar Radiation

                         What factors influence the development of cancer?

uDose--amount and length of exposure.  The lower the dose the least likely you are to develop cancer
or related diseases.

uEnvironmental or “lifestyle” factors.

      uCigarette smoking (co-carcinogen)

      uAlcohol consumption (co-carcinogen)

      uDiet--high fat consumption, natural antioxidants

      uGeographic location--industrial areas, UV light

      uTherapeutic drugs--some are known carcinogens

      uInherited conditions