During the Vietnam war the US sprayed jungles to defoliate broad leafed plants and make visible places where Vietcong and their supporters would hide. Millions of tons of this mixture of two herbicides (2,4-D and 2,4,5-T) were used over a period of several years. After the war our veterans complained of symptoms and illnesses from exposure to agent orange sprays. The cold war prevented recognition of Vietnam until recently and thus a laboratory of contaminated soil and contaminated villagers was closed off to investigation by the US and its allies. The Vietnamese lacked the resources to carry out effective chemical and medical studies on their own population.
In 1983 I was one of a dozen or so Americans who met in Ho Chi Minh City with about 100 European and other scientists to discuss our work at an International Symposium on Agent Orange. I had studied 2,4-D and 2,4,5-T on fruit flies and found many biological effects. They were alone or in combination lethal at certain doses to the developing flies (as embryos and larvae). They inhibited egg-laying by the fertile females. They forced the larvae to crawl to their death before they were mature enough to undergo metamorphosis. Females (which contain more fat) were more drastically killed at sublethal doses and I would get bottles with almost all males emerging. I did not find mutations, gains or losses of chromosomes, or breakage of chromosomes.
The trip was arranged through the UN by our US representative (as an advisor since he could not formally act on behalf of the US government). I was not impressed by the Vietnamese data on birth defects because they had control values that were unrealistic. But they did have an incredible excess of molar pregnancies, which are implanted sacs lacking an embryo. These appeared among women in the sprayed regions and not among the wives of male veterans who returned to the unsprayed Northern cities and villages. I suspect that the dioxins or agent orange components caused the eggs to extrude a nucleus and when the sperm entered, a molar pregnancy formed. Since the male-only composition of these molar pregnancies appeared in print about two years after the conference, it couldn’t have been faked data based on prior knowledge.
Our veterans, and the Vietnamese, lost an opportunity to study the effects of these compounds in the food chain. Both 2,4-D and 2,4,5-T decay from sunlight and other environmental activities within a few years. Dioxins last longer but it has been more than 25 years since these sprayings took place.
Congress finally pressured the US government to compensate the veterans exposed to these dangerous compounds regardless of the strength of evidence for or against the harmful effects of these compounds. Officially we only recognize a skin disease, chloracne, as caused by agent orange exposure, but many reports of soft tissue cancers, and neurological damage have been dismissed as unproved or consequences of shell shock. When I spoke to veterans groups during the 1980s I was not convinced these men were the alcoholics, drug abusers, and malingerers many of their government critics claimed them to be.