Large stacks of 55-gallon drums filled with Agent Orange.

An estimated 19 million gallons of Agent Orange, an herbicide used to kill the trees and foliage used for cover by guerrilla warriors during the Vietnam War, were sprayed across an area of jungle about the size of Massachusetts from 1962 to 1971. Levels of the active chemical in the defoliant, dioxin, were found in the blood of the Vietnamese as early as 1970. The latest studies have shown those blood levels have decreased a hundred-fold in the years since.

But dioxin is still being passed from mother to child, both in utero and through breast milk, according to a new study in the journal Science of the Total Environment.

The “hotspots” show a lingering contamination within the very blood of the population, conclude the authors, from various institutions in both Japan and Vietnam.

“Dioxin hotspots in the South of Vietnam are (some) of the most severely polluted regions in the world,” said Teruhiko Kido, the lead author, from Kanazawa University in Japan. “Decades of industrial development and chemicals released during the Vietnam War have led to high levels of dioxins in the soil and atmosphere and people are absorbing these chemicals from the food they eat and the air they breathe.”

The scientists looked at two sites: a “hotspot” known as Bien Hoa, an industrial city where the U.S. stored approximately 50 percent of its Agent Orange stockpile; and a rural area known as Kim Bang in the northern part of the country that did not have major dioxin exposure.

The mothers – 37 from the hotspot and 47 from the non-contaminated region – and their newborn children were assessed by serum, breast milk, and saliva samples.

The breast milk dioxin levels were assessed by gas chromatography/high-resolution mass spectrometry. The other fluids were measured by liquid chromatography/tandem mass spectrometry, they report.

Dioxin levels were two to five times greater in the contaminated regions.

Since dioxin is an endocrine-disrupting chemical, various hormones were tested in the mother-child pairs. Only the levels of salivary dehydroepiandrosterone (DHEA) were found to be significantly elevated.

But those levels were up to three times higher in the babies form the hotspots. And previous research has shown that DHEA is a hormone essential to differentiate between male and female characteristics. Disruptions can cause health problems and disfigurement, the researchers explain.

The current study will continue until the children are the age of 10, the scientists add in their paper.

The Vietnamese in parts of the country have continued to be plagued by the health specters of Agent Orange, but American serve members were also affected. Some 3 million Vietnamese were exposed to the chemical during the conflict, but so were a good proportion of the 2.8 million Americans who went to Vietnam up until the 1975 withdrawal. The U.S. has sent tens of millions of dollars to the Communist nation to clean up the hotspots of contamination. In the meantime, the U.S. has still not finished cleaning up domestic places of dioxin production and storage, like the Passaic River in New Jersey.