The International Agency for Research on Cancer (IARC) isinternationally recognized for evaluation of compounds, complex mixtures with acarcinogenic potential. For the current state of the science of classificationand evaluation see Annexure 2. The IARCevaluations rank the compounds and complex mixtures into five groups. Selectexamples of workplace carcinogens are enlisted below:
· Group 1: Carcinogenic to humans, which are based mainly on studies inhumans. This group comprised 28 definite occupational carcinogens, includingasbestos, crystalline silica, wood dust, arsenic and arsenic compounds,beryllium, cadmium and cadmium compounds, hexavalent chromium compounds, nickelcompounds, benzene, vinyl chloride monomer, 4-aminobiphenyl, benzidine,2-naphthylamine, ethylene oxide, 1,3-butadiene (recently reclassified to Group1, cf. below), and coal tars and pitches.
· Group 2A: Probably carcinogenic to humans, which are based on sufficientevidences from animal studies. This group comprised 27 probably occupationalcarcinogens, including benzo[a]pyrene, tetrachloroethylene, trichloroethylene,acrylamide, epichlorohydrin, benzidine-based dyes, diethyl sulphate, andformaldehyde.
· Group 2B: Possibly carcinogenic to humans, which are based on a combinationof effects in humans, animals and other evidences. This group comprised morethan 100 occupational exposures, including antimony trioxide, cobalt and cobaltcompounds, lead and inorganic lead compounds, naphthalene, acrylonitrile, ethylacrylate, isoprene, styrene, toluene diisocyanate, acetaldehyde, acetamide,chloroform, 1,2-dichloroethane, dichloromethane, some aromatic amine dyes, someazo dyes (including trypan blue), butylated hydroxyanisole (BHA), catechol,1,4-dioxane, and hydrazine.
· Group 3: Not classifiable as to its carcinogenicity to humans due tolimitations in the data set.
· Group 4: Probably not carcinogenic to humans, which are based on acombination of effects in epidemiologic and animal studies together with otherevidences.
For moredetails on classifications and the various categories and examples ofcarcinogenic compounds see article in Annexure 3. The summary andoverall evaluations by IARC are available from the home web of the InternationalProgramme on Chemical Safety [http://www.inchem.org/pages/cicads.htmland
http://www.inchem.org/pages/icsc.htmlDf]. Another comprehensive list with documentations ofcarcinogenic compounds is available from the U.S. Department of Health andHuman Services through the home web of the National ToxicologyProgram[http://ntp.niehs.nih.gov/ntp/roc/toc11.htm].The list is published biennially and distinguishes between compounds ‘‘known tobe human carcinogens”, which is based on epidemiological studies, and compounds‘‘reasonably anticipated to be human carcinogens”, which is based on humanand/or animal studies as well as on other relevant data. The lists are usefulas a first choice of information about potential carcinogenic effects.