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Metadata Record <br /> <br />Page 1 of 2 <br />1. REVIEW OF THE EPIDEMIOLOGICAL AND OTHER DATA ON POTENTIAL <br />CARCINOGENICITY OF 2,4D BY THE SAB/SAP JOINT COMMITTEE <br />2. EPA-SAB-EHC-94005 <br />3. ABSTRACT: In August 1980, the EPA requved oncogenicity testing of 2,4-D (2,4- <br />dichlorophenoxyacetic acid. EPA reviewed the resuhs of those studies completed to date (some <br />of which reported an association of phenoxy herbicides, including 2,4D, and non-Hodgkin's <br />lymphoma (NHL)) and requested that a joint ComIItittee of the Science Advisory Board and the <br />Scientific Advisory Panel review the epidenriologic studies and other available relevant data. A <br />joint Committee was formed, and met in Arlington, Virginia on April 1-2, 1993 to review <br />humaa/canine epidemiological studies and animal toxicology studies re possible human <br />carcinogenicity and mutagenicity. <br />Epidemiologic cohort studies have generally shown no increased risk of cancer, albeit that all of <br />the populations for which specific exposure to 2,4-D have been identified were small, and the <br />follow-up period usually short. Some case-control studies have shown a risk ofNon-Hodgkin's <br />Lymphoma (NHL) in association with farming but many of these studies did not control for <br />exposure to other agents in addition to 2,4,D. The Committee concluded that cun:ent studies <br />cannot distinguish whether observed risks reported aze due to the use of 2,4,D. The single canine <br />epidemiologic study suggested that pet dogs may be at risk from exposure to 2,4,D or to areas <br />treated by a lawn care service. Although this study is supportive of a finding of carcinogenicity, <br />there aze questions about its applicability to human carcinogenicity because of poor information <br />on exposure and possible non-comparability between canine and human lymphomas. Toxicology <br />studies show that rats (but not other animal species tested) may develop astrocytomas from <br />exposure to 2,4,D, but this outcome has not been reported in the human studies. An ongoing rat <br />study at higher doses will clarify whether this finding is treatment-related or not. Tests of 2,4-D <br />have not shown any mutagenic changes under experimental situations. <br />The Committee concludes that the data aze not sufficient to find that there is a cause and effect <br />relationship between the exposure to 2,4,D and NHL. Because there is some evidence that NHL <br />occurs in excess in populations that are h7cely to have been exposed to 2,4,D, there should be <br />continued eYa+*+;~ation of the issue through fiuther studies. Other data gaps exist, and decision- <br />making on 2,4D would benefit from completion of rodent studies previously requested by EPA, <br />particularly further animal cazcinogenicity studies that test 2,4-D jointly with other substances <br />that might reflect the human exposure situation; a replication of the dog epidemiology study; <br />additional case/control studies, with cazefiil attention to exposures; additional human cohort <br />studies designed to assess both relative risk of NHL and the comparative risk of all mortality; <br />and additional follow up and analysis of worker cohorts involved in the production of 2,4D. <br />KEYWORDS: 2,4,D; 2,4-dichlorophenoxyacetic acid; carcinogenicity; astrocytoma; Non- <br />Hodgkin's Lymphoma (NHL); farming; canine epidemiology <br />4. Documents the Science Advisory Boazds review of this topic, and the report to the <br />Administrator. <br />5. Science Advisory Board (1400F) <br />6. April 1-2, 1993 <br />7. NA <br />8a. Science Advisory Board (1400), U.S. EPA, 401 M St. SW, Washington DC 20460 (202) <br />http://www.epa.gov/docs/SAB-Reports/24D/metadata.txt.html 11/15/98 <br />