title: Weight of the evidence on the human carcinogenicity of 2,4-D.
abstract: The phenoxy herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) is widely used to control the growth of weeds and broadleaf plants. We convened a panel of 13 scientists to weigh the evidence on the human carcinogenicity of 2,4-D. The panel based its findings on a review of the toxicological and epidemiological literature on 2,4-D and related phenoxy herbicides. The toxicological data do not provide a strong basis for predicting that 2,4-D is a human carcinogen. Although a cause-effect relationship is far from being established, the epidemiological evidence for an association between exposure to 2,4-D and non-Hodgkin's lymphoma is suggestive and requires further investigation. There is little evidence of an association between use of 2,4-D and soft-tissue sarcoma or Hodgkin's disease, and no evidence of an association between 2,4-D use and any other form of cancer. Scientists on the panel were asked to categorize 2,4-D as a "known," "probable," "possible," or "unlikely" carcinogen or as a noncarcinogen in humans. The predominant opinion among the panel members was that the weight of the evidence indicates that it is possible that exposure to 2,4-D can cause cancer in humans, although not all of the panelists believed the possibility was equally likely: one thought the possibility was strong, leaning toward probable, and five thought the possibility was remote, leaning toward unlikely. Two panelists believed it unlikely that 2,4-D can cause cancer in humans.
authors.affiliation: Center for Risk Analysis, Harvard School of Public Health, Boston, MA 02115.
authors.forename: M A
authors.initials: MA
authors.lastname: Ibrahim
authors.forename: G G
authors.initials: GG
authors.lastname: Bond
authors.forename: T A
authors.initials: TA
authors.lastname: Burke
authors.forename: P
authors.initials: P
authors.lastname: Cole
authors.forename: F N
authors.initials: FN
authors.lastname: Dost
authors.forename: P E
authors.initials: PE
authors.lastname: Enterline
authors.forename: M
authors.initials: M
authors.lastname: Gough
authors.forename: R S
authors.initials: RS
authors.lastname: Greenberg
authors.forename: W E
authors.initials: WE
authors.lastname: Halperin
authors.forename: E
authors.initials: E
authors.lastname: McConnell
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000009:adverse effects* / Q000493:pharmacokinetics / Q000633:toxicity; D000818:Animals; D015197:Carcinogenicity Tests; D016022:Case-Control Studies; D015331:Cohort Studies; D004781:Environmental Exposure; D006801:Humans; D008228:Lymphoma, Non-Hodgkin / Q000139:chemically induced / Q000453:epidemiology; D008297:Male; D009152:Mutagenicity Tests; D009369:Neoplasms / Q000139:chemically induced* / Q000453:epidemiology; D009784:Occupational Diseases / Q000139:chemically induced / Q000453:epidemiology; D010573:Pesticide Residues / Q000009:adverse effects; D051381:Rats; D012306:Risk
chemical_list: D010573:Pesticide Residues; D015084:2,4-Dichlorophenoxyacetic Acid