Is Agent Orange Still at Large? — Chromatography Investigates

During the Vietnam War, the US military sprayed around 20 million gallons of herbicide to remove forest cover and food crops from their enemy the North Vietnamese and Viet Cong troops. The herbicides were sprayed over Vietnam, Cambodia and Laos between 1961 and 1971 in a programme codenamed Operation Ranch Hand.

The herbicides were meant to remain toxic for only a few days — long enough to do their job of killing anything green — before degrading in the soil. Unfortunately, many of the herbicides were contaminated due in part to the rapid increase in manufacturing during the war years. Agents White, Blue, Purple, Pink and Black were all sprayed across the region. But it was Agent Orange that was used the most and is synonymous with the Vietnam War.

Why was it called Agent Orange?

The herbicide Agent Orange — so named because of the orange stripe on its containers — was made of two active ingredients — 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) — in a 50/50 ratio. Unfortunately, Agent Orange also contained traces of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). TCDD is better known as dioxin and is an unwanted by-product of herbicide production and is one of the most dangerous dioxins known.

Dioxins are classified as human carcinogens by most environmental regulatory bodies, but is commonly found in the environment in low doses as a pollutant from burning waste and car exhausts. But while the active ingredients in Agent Orange degraded in days — dioxin doesn’t, and it is still causing health problems in Vietnam and the surrounding countries.

The aftermath of using chemicals in wars

Unlike 2,4-D and 2,4,5-T, dioxin can survive for much longer both in the environment and in our bodies. Although sunlight can help to break dioxin down in the environment, it still has a half-life of up to three years in soil. If it gets buried or finds its way under the surface, then dioxin could be around for up to 100 years. Many studies have found dioxin in the blood of Vietnamese people in the years following the end of the war. But now, a new study published in the journal Science of the Total Environment reports that dioxin is still being passed from mother to child via breast milk and in utero.

The authors of the paper describe the dioxin hot spots of Vietnam as some of the most polluted areas of on Earth. The study compared 37 mothers from hot spot regions and 47 from non-contaminated regions along with their offspring. Samples of serum, breast milk and saliva were taken and analysed. Breast milk samples were tested using gas chromatography, while liquid chromatography was used for the other samples. Dioxin levels were two to five times higher in the contaminated regions.

The use of chromatography to analyse residues used on plants is discussed in the article, LC-MS/MS and GC-MS/MS Multi Residue Pesticide Analysis in Fruit and Vegetable Extracts on a Single Tandem Quadrupole Mass Spectrometer.