“The only major Rainbow herbicide used throughout all 10 years of the Vietnam War was Agent Blue. One-third of Agent Blue was transported from Marinette, Wisconsin and Menominee, Michigan (Figures 4-7) via Menominee River, Green Bay, Lake Michigan [2] and the St. Lawrence Seaway to the 551th Ordinance Storage Depot in Da Nang and the other two-thirds went to the 20th Ordinance Storage Depot in Saigon. Agent Blue was used primarily on grain and cereal crops [3] [4]. Agent Blue was aerially sprayed (Figure 8) [5] on rice seedlings and plants to kill the crop and seed in preparation of areas for crop burning [6]. Burning of dried crop residues likely released volatilized toxic As4O6 or as fine particulate material ( 2.5) in smoke into the atmosphere [7]. Thus, the U.S. and Republic of Vietnam military personnel and Vietnamese civilians stationed or living in the Mekong Delta and Central Highlands were exposed to airborne As-containing materials.”
https://www.scirp.org/journal/paperinformation.aspx?paperid=104568
The U.S. Agency for Toxic Substances and Disease Registry suggests arsenic cannot be destroyed once added to the environment [1]. During the Vietnam War, Agent Blue [(CH3)2As OOH] the arsenic based herbicide, was used to desiccate rice plants before maturity. Spraying and dropping of Agent Blue into rice paddies added massive quantities of water-soluble arsenic to the soil root zone and the surface water of the Mekong Delta (Figure 1) rice paddies (Figure 2) and to mangrove forests. The United States and South Vietnamese militaries significantly added to the As load (1,132,400 kg As) in Mekong Delta and the Central Highlands environments as a result of the application of the Agent Blue herbicide. For the last 60 years, highly varying levels of trace amounts of arsenic have been ingested and bioaccumulated by Vietnamese living in the Mekong Delta or Central Highlands from contaminated food and drinking water (Figure 3). Two water soluble arsenical species, arsenite (+3 oxidation state) and arsenate (+5 oxidation state) are the most abundant in surface water, the soil, and groundwater. The fate of arsenic in the South Vietnam environment included: reacting with and being retained by the solid mineral phase of the soil, volatilized to the atmosphere as gaseous arsine from manufacturing or industrial transformations, as arsenic laden smoke and ash particulates from rice plant residue burning, leached from the root zone (soil) and into the groundwater and taken up by rice plant roots from surface water, accumulated in plant residues and returned to the soil, or stored in the grain.
The only major Rainbow herbicide used throughout all 10 years of the Vietnam War was Agent Blue. One-third of Agent Blue was transported from Marinette, Wisconsin and Menominee, Michigan (Figures 4-7) via Menominee River, Green Bay, Lake Michigan [2] and the St. Lawrence Seaway to the 551th Ordinance Storage Depot in Da Nang and the other two-thirds went to the 20th Ordinance Storage Depot in Saigon. Agent Blue was used primarily on grain and cereal crops [3] [4]. Agent Blue was aerially sprayed (Figure 8) [5] on rice seedlings and plants to kill the crop and seed in preparation of areas for crop burning [6]. Burning of dried crop residues likely released volatilized toxic As4O6 or as fine particulate material ( 2.5) in smoke into the atmosphere [7]. Thus, the U.S. and Republic of Vietnam military personnel and Vietnamese civilians stationed or living in the Mekong Delta and Central Highlands were exposed to airborne As-containing materials.
Water soluble arsenic leached from the rice paddies into the soil root zone after frequent applications of Agent Blue by the U.S. and Republic of Vietnam militaries from 1961 to 1971. After the Vietnam War, vast amount of natural and manufactured arsenic rich groundwater was pumped from more than 100,000 private shallow tube wells onto the land surface to irrigate the rice paddies, fill shrimp ponds and to meet the drinking water needs of the 15 million people living in the Mekong Delta and along the Mekong River (Figure 1). Thus, during the last 60 years, the Vietnamese people living on the Mekong Delta have continued to ingest and bioaccumulated arsenic (from war contamination and natural sources) via their drinking water and food supply. The primary objective of this paper is to determine and describe the environmental impact and fate of Agent Blue, containing 1,132,400 kg of As in the arsenic based herbicide, which was applied from 1961 to 1971 to 400,000 ha of land in South Vietnam by the United States and Republic of Vietnam militaries.
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See also [url]https://www.ncbi.nlm.nih.gov/books/NBK236351/[/url]
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