Agent Orange: Encyclopedia II - Agent Orange - Description

Agent Orange - Description

Agent Orange is a roughly 1:1 mixture of the two phenoxy herbicides in ester form, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). These herbicides were developed during the 1940s by independent teams in England and the United States for use in controlling broad-leaf plants. Phenoxy agents work by mimicking a plant growth hormone, indoleacetic acid (IAA). When sprayed on broad-leaf plants they induce rapid, uncontrolled growth, eventually killing it. When sprayed on crops such as wheat or corn, it selectively killed just the broad-leaf plants in a field, the weeds, leaving the crops relatively uneffected. First introduced in 1946, these herbicides were in widespread use in agriculture by the middle of the 1950s.

It was later learned that a dioxin, 2,3,7,8-tetrachlorodibenzo-para-dioxin (TCDD), is produced as a side effect of the manufacture of 2,4,5-T, and was thus present in any of the herbicides that used it. The National Toxicology Program has classified TCDD to be a known human carcinogen, frequently associated with soft-tissue sarcoma, Non-Hodgkin lymphoma, Hodgkin disease and chronic lymphocytic leukemia (CLL). 2,4,5-T has since been banned for use in the US and many other countries.

The herbicide 2,4-D does not contain dioxin, and remains one of the most used herbicides in the world today.

Diseases sufficiently associated to dioxin are chloracne, soft tissue sarcomas, Hodgkins disease, and non- Hodgkins lymphoma. Diseases with limited evidence of an association with Agent Orange are respiratory cancers, prostate cancer, multiple myeloma, Porphyria cutanea tarda (a type of skin disease), acute and subacute transient peripheral neuropathy, spina bifida, Type 2 diabetes, and acute myelogenous leukemia found only in the second or third generation. Diseases with inadequate or insufficent evidence of an association are hepatobiliary cancers, nasal or nasophargyngeal cancers, bone cancer, female reproductive cancers, renal cancer, testicular cancer, leukemia, spontaneous aborption, birth defects, neontal or infant death and stillbirths, low birth weight, childhood cancers, abnormal sperm parameters, cognitive neuropsychiatric disorders, ataxia, perpheral nervous system disorders, circulatory disorders, respiratory disorders, skin cancers, urinary and bladder cancer. Diseases with limited or suggestive evidence of no association are gastrointestinal tumors such as stomach cancer, pancreatie cancer, colon cancer, and rectal cancer, and brain tumors.

Adapted from the Wikipedia article "Description", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki