Weight of the evidence on the human carcinogenicity of 2,4-D.

Environmental health perspectives (1991-12-01)
M A Ibrahim, G G Bond, T A Burke, P Cole, F N Dost, P E Enterline, M Gough, R S Greenberg, W E Halperin, E McConnell
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.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
2,4-Dichlorophenoxyacetic acid, ≥95%, crystalline
Supelco
2,4-D, PESTANAL®, analytical standard
Sigma-Aldrich
2,4-Dichlorophenoxyacetic acid, 97%
Supelco
2,4-D, certified reference material, TraceCERT®
Supelco
2,4-D, PESTANAL®, analytical standard
Supelco
2,4-D solution, certified reference material, 5000 μg/mL in acetonitrile