overnment restrictions that caused a sharp decrease in the manufacture and use of 2,4,5-T. Since 1983, the use of 2,4,5-T has been prohibited in the United States.
Many other countries also have ended its use. Of additional concern is a contaminant called dioxin (2,3,7,8,-tetrachlorodibenzo-p-dioxin, or TCDD), which often forms when 2,4,5-t is manufactured. Of the approximately 75 chemicals in the dioxin family, TCDD is the most toxic. It can cause chlorance, a skin disease, and is suspected to cause some kinds of cancer.
The TCDD level in agent orange varied from 0.02 to 54 micrograms per gram of 2,4,5-T. (Cancer 1996)
Agent Orange was purchases by the Defense Department to defoliate enemy territory and destroy enemy crops in Vietnam. It was a 50-50 mixture of herbicides 2,4-D and 2,4,5-T.
All of the 2,4,5-T contained dioxin because all of it was made for trichlorophenol cannot be produced without some dioxin being carried along as a by-product.(Gough 1986)
There are three occupational groups of people, who may be at risk in exposure to Agent Orange. Who work in manufacturing trichclorophenol can be expressed to dioxin through ?explosions? or ?runaway reactions? or ?events.? When an explosions occurs, the chemicals in the reaction vessels are forced into the workrooms, exposing everyone to fumes, liquids and solid particles containing dioxin.
?Formulators? are workers whose job it is to mix pesticides with other chemicals to make the pesticide easier to apply or ?Stickier? so that it will work better. Agent Orange formulators mixed 2,4,5-T containing dioxin with the other closely related herbicide 2,4-D. The last occupational group to risk exposure to dioxin are ?applicators? who spray to otherwise disseminate Agent Orange, 2,4,5-T or other dioxin contaminated pesticides in the environment. In this country, applicators sprayed 2,4,5-T in forests, croplands, and pastures to control broad-leaf plants.
The most famous applicators in history are pilots, air crews, and ground crews of the Air Force’s ?Operation Rich Hand? who sprayed millions of pounds of Agent Orange in Vietnam.(Gough 1986)
People can also be environmentally exposed to dioxin. Anyone who is near an area sprayed with 2,4,5-T or Agent Orange, risks exposure to dioxin. Environmentally exposed persons received large doses of dioxin.
A large but unknown fraction of the 2.8 million Vietnam veterans were exposed to Agent Orange, and considering the amounts of 2,4,5-T used in this country, other thousands or millions have to be exposed here. (Gough 1986)
Some environmental exposures are more risky than incidental exposure to sprayings. When trichlorophenol is produced, ?still bottoms,? thick viscous dioxin containing materials, accumulate in the reaction vessels.
Periodic cleaning out of still bottoms exposes workers to high concentration of dioxin. In addition, still bottoms themselves present a disposal problem.(Gough 1986)
High-temperature incineration of still bottoms or any other waste can completely destroy dioxin, eliminating any risk, but other disposal techniques leave substantial exposure risks. Before society became aware that chemical waste posed potential threats to human health, it was an accepted practice to discard chemical residues, including still bottoms, in waste dumps.
Neither the safe disposal method, incineration, nor the unsafe one, dumping, generates any revenue for the company that has still bottoms to dispose of, on the contrary, both cost money. (Gough 1986)
An alternative to a manufacturer directly disposing of its wastes was to pay other businesses to haul them off and dispose of them. Sinclair Lewis said of all the Chicago stockyards that they sell everything of the pig but the squeal, and business has to look for sealable items and services. With entrepreneurial spirit, some haulers found a market for still bottoms, which are dense and oily.
When mixed with other oily materials, still bottoms were sold and sprayed on dirt roads and the unpaved, ungrassed areas to suppress dust. This inventive manufacture for still bottoms introduced untold amounts of dioxin into the environment. (Gough 1986)
The environmental Protection Agency (EPA) estimates that 80-90% of all dioxin ever made in chemical plants ended up in still bottoms. The EPA refuses to estimate the amount of dioxin that was made by manufacturers and provides no information about how much dioxin was in still bottoms or how much of the still bottoms was disposed of by incineration or dumping or used in dust suppression.
We do know, however, that still bottoms have wrought havoc. To eliminate exposure to dioxin, the federal government bought Times Beach, Missouri, because the chemical had been sprayed on roads throughout the town as part of a dust suppression program. The Canadian government estimates that over 100 pounds of dioxin lie buried in the Love Canal and more that two tons in Hyde Park Dump near Niagara Falls, New York. No one can deny that these are huge amounts; they can be compared to the total of 368 pounds of dioxin sprayed in Vietnam over a six year period.
Unfortunately, we cannot estimate the magnitude of the remaining dioxin waste problem, because there is no record of the amounts of dioxin sprayed for dust suppression or buried in every dump. (Gough 1986)
Three problems plague efforts to understand dioxin’s risk for humans: uncertainty about what dioxin does to human health, uncertainty about who was exposed to dioxin, uncertainty about how much of it anyone was exposed to. Were a person to be standing under an airplane, or beside a truck spraying 2,4,5-T or Agent Orange, he or she would certainly be exposed. Since sunlight degrades dioxin, a person walking through a field the day after it was sprayed, would not be in a substantial risk.
Farmers, forestry workers, and Vietnam veterans exposed to chlorophenoxy herbicides have been studied to see whether they had a higher incidence of cancer than would be expected. The results of these studies have been conflicting and inconclusive. In 1984, Congress mandated that studies be conducted to determine whether service in Vietnam could be related to adverse health effects. In one study, focused specifically on the health effects f exposure to Agent Orange in Vietnam; and a third study looked at the increased risk, if any, the Vietnam veterans would develop any six specific kinds of cancer.
In March 1990, the Centers for Disease Control and Prevention (CDC) released the results of the last of its studies. The investigators reported a 50-percent higher incidence of non-Hodgkin’s lymphoma (NHL), a cancer of the immune system among the Vietnam veterans than among veterans who did not serve in Vietnam. However, the studies could not show that this increased incidence is related to exposure to Agent Orange. Navy veterans who served on vessels off the coast of Vietnam tended to have a higher rate of NHL than did veterans based on land, and veterans who served in other regions of Heaviest Agent Orange use tended to have a somewhat lower incidence than veterans had an increased incidence than veterans who served in other regions of Vietnam.
The CDC could not determine why the Navy veterans had an increased incidence of NHL. No increased incidence was found for the other five cancers in the study( soft tissue and other sarcomas, Hodgkin’s disease, and nasal, nasopharyngeal, and liver cancers.