The Human Health Impact of Agent Orange


There are many ways for Dioxin, the toxic contaminant in Agent Orange, to wreak havoc on the human body.

Even while Dioxin is a heavily studied toxic substance, its full impacts on human health are still not well known. Dioxin’s impacts on human health have either been studied through epidemiological studies of exposed human populations or through animal studies. Neither type of study is considered conclusive or dispositive, as human studies’ sample sizes are too small, and animal studies results are difficult to extrapolate into human contexts.

Yet the chemical companies knew as early as the 1940s that 2,4,5-T caused Chloracne in workers exposed to it; and by 1965, the companies determined that it was the Dioxin contaminant in 2,4,5-T that was causing Chloracne. A 1969 study found that 2,4,5-T was teratogenic, deforming fetuses in laboratory rats and subsequent studies later confirmed that the causal agent was Dioxin.

Animal studies first showed that, in all animal species studied, Dioxin was an endocrine disrupting chemical that impacted the immune, endocrine, reproductive, gastrointestinal, skin, cardiovascular and nervous systems of animals.

Studies on exposed populations including chemical workers, veterans of the war in Viet Nam, residents near chemical factory accidents, found that Dioxin exposure resulted in an increase in the risk of developing numerous types of cancer, cardiovascular disease, and Type 2 Diabetes.

In 1997, based on animal and human epidemiological data, the International Agency for Research on Cancer (IARC) of the World Health Organization declared Dioxin a “known human carcinogen.”

“There is no doubt that during and after the war, many Vietnamese absorbed this very toxic material [dioxin]. It is our belief from toxicological research and epidemiological studies from many countries that this dioxin probably resulted in significant health effects in Vietnam.”

– Arnold Schecter and John Constable

As part of the Agent Orange Act of 1991 the Institute of Medicine–now the National Academy of Science, Engineering and Medicine–was charged with reviewing the scientific studies on Dioxin, as well as the individual herbicides used by the U.S. during the Vietnam war. Over the years, the list of conditions that were found to either have sufficient evidence of association or limited/suggested evidence of association to Dioxin and/or the herbicides used in Vietnam, has increased. In their latest and last Veterans and Agent Orange: Update 11 (2018), the Academy lists 20 conditions as having some level of association.

To date, the U.S. Department of Veterans Affairs uses this list to determine the conditions that qualify for disability benefits. Currently, all but stroke is on the list of presumptive diseases covered by VA benefits.

Since the late 1960s, Vietnamese scientists have been conducting epidemiological research on Dioxin exposure. They found that veterans who served in the south, as compared to those who served elsewhere, had increased rates of cancer, nerve, digestive, skin, and respiratory disorders. Among the cancers found were throat cancer, acute/chronic leukemia, Hodgkin’s lymphoma and non-Hodgkin’s lymphoma, prostate cancer, lung cancer, soft tissue sarcoma and liver cancer. But the international scientific community has cast doubt on many of these research findings for their lack of peer review.

There are still a lot of open questions about how Dioxin impacts human health, especially when it comes to reproductive outcomes and birth defects. Recent animal studies on how Dioxin has epigenetic impacts and how Dioxin affects how genes are expressed, may eventually answer some of these open questions.

“We knew it was poison, so we washed our food in the stream. But the stream was poisoned, too.”

– Mrs. Hong, Vietnamese breast cancer sufferer, “The Last Ghost of War,” 2007

Stills from “The Last Ghost of War” by Janet Gardner (2008). More information.

Clips from “The Last Ghost of War” by Janet Gardner (2008). More information.