Dioxin: Environmental thalidomide

I recently came across an article I wrote 20 years ago following a trip to Vietnam and I was surprised how much I had forgotten, and how much is now generally forgotten, about the horrors of the ‘American War’, as the gentle people of Vietnam call it.

My focus for the article was chemical/biological weapons and was prompted at the time by the hypocritical and moral indignation of international political leaders as the world learned of a chemical weapons attack by the Syrian government on its own people.

Toxic chemicals have been in the arsenals of armies for millennia. Whereas chemical and biological weapons are less acceptable today, you have to ask is there ever a good, proper or humane way to kill our enemies? Are the typhoid-infected cow carcasses hurled across the battlements in the Middle Ages, the mustard gas engulfing the First World War trenches or the Sarin gas of Saddam Hussein’s genocide any more grotesque than the ‘Shock and Awe’ carpet bombing of towns and cities? These technical achievements are all designed to deliver the upper hand in any chaotic theatre of war irrespective of their collateral consequences.

Vietnam, 50 years after the end of hostilities with America, carries the burden of chemicals poured over the county by the US. It remains a stain on our humanity and, even though it is still a problem, we have too easily forgotten it (if we ever accepted it).

I recently returned to this vibrant and exciting country and I wanted to be reminded of what had happened all those years ago. I arrived at Tan Son Nhat Airport in Ho Chi Minh City (Saigon) and then flew the next morning mid-way up the long thin country to Da Nang before transferring to Hoi An by bus. Da Nang has a population of more than one million and is pleasantly located near the seven-mile China Beach, where in the late 1960s and early 1970s American GIs took their R&R.

The Vietnam conflict was a brutal war which dispatched millions — including two million civilians who died between 1965 to 1975. At that time, Da Nang was home to the B52 bombers who rained ordnance onto the mountains, cities, plains, and people. Indeed, Da Nang, and a threat to its military base there, was the reason why America entered the war between the North and South — making it much bloodier and more wicked.

Today, luxury beach resorts are springing-up all along the white sands that link Da Nang and Hoi An. My hotel faced the most beautiful emerald sea backed by an azure sky. Visible out at sea were the rocky Cham islands, home to the sea sparrows that build valuable nests harvested for food. The nests are thankfully, however, still safe from over-exploitation as this is a major naval base for the Republic of Vietnam, which is one of the world’s few remaining Communist states. Sipping a cocktail at the beachfront bar, it was easy to forget that collectivism remains the politics of this nation.

I took the short taxi ride to the four streets that run parallel to the Thu Bon River and make up the town of Hoi An, a UNESCO World Heritage Site. These 200-year-old streets of merchant houses and Chinese meeting halls have remained unchanged since Hoi An was the main trading port of Vietnam. The first missionaries came to the country through this port but that missionary zeal ended when the last Americans flew out of Saigon in their helicopters in 1975. Although they are free to practise any religion now,, the population remain secretive of official religious designation, and for obvious reasons.

I finally arrived back in Saigon to pay a visit to the War Remnants Museum. On the surface, the museum appears to be a kitsch, poorly-curated series of rooms within a modern square building. The exhibits, mostly sepia photographs taken by different photo journalists, seem nothing more than blatant communist propaganda, yet very soon I am absorbed into the brutality inflicted on, and the horrors suffered by, this mild and gentle people.

The Vietcong were hardly angels, but the exhibits unmask America’s hypocrisy. As a child of the 1960s, I watched this jungle war on TV — set to become a check on American arrogance for the past 50 years. I came to the museum to learn more about Agent Orange. I was quickly engrossed in the facts and figures on the use of defoliants and the legacy of the poison.

The chemicals used to remove the forest canopy were called the rainbow herbicides: A half-dozen formulations identified by names — Agent Pink, Agent White, etc — after the colours used to mark the holding barrels. Agent Orange was a 50-50 blend of two commercially available herbicides; 2,4-dichlorophenoxyacetic acid, and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). The defoliants were believed to be harmless to humans and US troops typically handled them without wearing protective gear.

By the late 1960s, however, lab experiments showed that 2,4,5-T could cause abnormalities and stillbirths in mice, and there were reports of human birth defects in sprayed areas of Vietnam. Later, it became clear that the herbicide manufacturing process introduced a particularly toxic dioxin, known as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), into Agent Orange and other herbicides. Four years before the war ended, the US abandoned its decade-long spraying campaign amid mounting international condemnation and safety concerns.

What I had not realised was that dioxin is an unavoidable contaminant in the manufacture of 2,4,5-T, the synthetic plant hormone mixed in equal parts with 2,4 D to make Agent Orange. So, Agent Orange was not the issue; rather, the problem was poor temperature controls during its manufacture by Dow Chemicals and other American industrial giants in the US. This manufacturing sloppiness caused levels of dioxin as high as 60ppm and when you then spray 90,000 litres of this stuff over a country, it’s not surprising that you get toxic effects.

Today, there is broad consensus that dioxin poses serious health risks to those directly exposed, including Vietnamese citizens. The consensus comes from efforts by the US government to assess how exposure affected the health of US veterans. In 1992, the Department of Veterans Affairs asked the Institute of Medicine, now part of the US National Academies of Sciences, Engineering, and Medicine (NASEM), to review the scientific literature and provide updates every two years. The last of those reports appeared in 2018 and identified 19 cancers and other conditions with “sufficient” or “suggestive” evidence of an association with exposure to the herbicides. Vietnamese investigators separately produced a similar list.

What remains disputed, however, is the intergenerational impact in areas heavily contaminated with dioxin, with ongoing claims that birth defects continue to occur.

Dioxin has staying power. It can survive up to three years in soil exposed to sunlight. If leaked into river or pond sediment, it can have a half-life of more than 100 years — more than enough time to be picked up by aquatic and land animals that people eat. People can also inhale contaminated dust and absorb dioxin through the skin. Once in the human body, dioxin can lodge in fatty tissue and have a half-life of seven-to-11 years. It can also contaminate breast milk and be passed on to breastfeeding babies.

Since the 1970s, numerous animal studies have found that foetuses exposed to dioxin can exhibit a wide range of birth defects and developmental problems, thereby suggesting an impact on human foetuses is biologically plausible. In 2003, an American five-year study to analyse dioxin levels in the blood of 300 Vietnamese mothers of babies with birth defects was approved, using 300 mothers of healthy infants as controls. In 2005, the study was cancelled after failing to agree on research protocols with Vietnam’s Ministry of Health.

The next year, the Vietnamese published a meta-analysis of 22 studies, that suggested mothers exposed to Agent Orange were twice as likely to have children with birth defects. But that conclusion, reported in the International Journal of Epidemiology, proved controversial based on poor methodology, including reliance on observational studies.

This is where science comes up against politics both in Vietnam and in the US. If exposure to dioxin is linked to current birth defects, the US might be expected to pay reparations. Conversely, if no link is found, this might prove embarrassing to the Vietnamese government, which has long highlighted birth defects as Agent Orange’s most prominent harm.

It was a surprise to learn that the British first used Agent Orange during the Malayan Emergency in the late 1950s, but it was the Americans who industrialised it in Operation Ranch Hand from 1965 to 1970. What was most striking was that the personal cost is still evident in the cripples who beg on the busy, noisy, hot streets of Saigon. Agent Orange was not a chemical weapon in the conventional sense, but it was “environmental thalidomide” 50 years ago and may still be causing teratogenicity in the Vietnamese population today.

It must never be used as a weapon of war again.