# The Mostly Overlooked Legacy of Agent Blue in the Vietnam War
The Vietnam War’s lasting legacy of ecological and human destruction is frequently linked to the extensive deployment of Agent Orange, a herbicidal chemical weapon that has garnered over $400 million in remediation efforts thus far. However, less attention has been given to the effects of another chemical weapon from the “rainbow herbicide” arsenal—**Agent Blue**, an organoarsenic-based defoliant that caused a different but equally nefarious type of environmental damage. While it may not be as notorious as its dioxin-laden counterpart, studies indicate that Agent Blue’s long-term effects—especially arsenic contamination in groundwater—are emerging as dangerously widespread.
This article examines the origins, usage, and ongoing repercussions of Agent Blue during the Vietnam War, underscoring recent research that highlights its neglected toxic legacy.
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## **What Was Agent Blue?**
Agent Blue consisted of a blend of organoarsenic substances, mainly **cacodylic acid** and **sodium cacodylate**. Its main purpose was to eliminate narrow-leaf vegetation, such as rice crops, grasses, and bamboo. In contrast to Agent Orange, which was a mixture of two synthetic herbicides (2,4-D and the now-prohibited 2,4,5-T), Agent Blue specifically focused on food denial, intentionally targeting rice paddies to disrupt the food supply for North Vietnamese forces.
As it decomposes, cacodylic acid releases **arsenic**, a heavy metal harmful to both humans and the environment. Arsenic is highly soluble in water, promoting its leaching into groundwater and surface water sources—presenting long-term hazards that extend far beyond the war era.
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## **Agent Blue and the Vietnam War**
Chemical herbicides, including Agent Blue, were essential to the U.S. military’s tactics during the conflict. These herbicides were part of the so-called “rainbow herbicides,” so named for the colored stripes painted on their storage containers. The U.S. military started utilizing Agent Blue in South Vietnam’s Mekong Delta region as early as the early 1960s, with its application escalating in the years leading up to the official onset of the Vietnam War in 1965.
While the **U.S. Air Force concentrated on Agent Orange**—defoliating jungles to remove cover for North Vietnamese troops—the **South Vietnamese government and military partners utilized Agent Blue as part of a “food denial” strategy.** This involved extensive spraying over rice paddies to annihilate the enemy’s food supply while simultaneously pushing rural populations into controlled hamlets, undermining food self-sufficiency for both factions.
This tactic starkly contrasts with the Geneva Conventions, which ban the use of chemical weapons to starve civilian populations in wartime. Bryan Higgins, a veteran from the Vietnam War and geography scholar, points out, “If the U.S. military or government were involved in food denial operations, that would have been a significant political issue subject to scrutiny by the United Nations and the World Court.” The weight of such ethical and legal dilemmas further highlights the deeply controversial nature of Agent Blue’s application.
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## **Agent Blue’s Ongoing Impact**
Years after the war, evidence of Agent Blue’s enduring legacy has emerged in findings from researchers like Dr. **Ken Olson**, a soil scientist at the University of Illinois Urbana–Champaign. Olson’s research illustrates how arsenic from Agent Blue continues to infiltrate South Vietnam’s ecosystem, particularly within the Mekong Delta.
### **Arsenic Contamination in Groundwater**
Groundwater in the Mekong Delta, extending into areas of Cambodia and Vietnam, now demonstrates alarming levels of **arsenic contamination**, with concentrations often surpassing the World Health Organization’s advised limit of 10 parts per billion (ppb). In some instances, levels exceed 50 ppb, rendering the water unsafe for human use.
The situation is particularly critical due to substantial groundwater extraction through around **700,000 tube wells** established throughout the region since 1975. These wells frequently draw water rich in arsenic, whether from natural sources or remaining Agent Blue contamination. Once in the soil, arsenic tends to bond with clay particles or organic matter, only to be later displaced and reintroduced into water systems.
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### **Health Consequences**
Arsenic poisoning is notoriously difficult to identify and treat, as its symptoms are often vague, vary among individuals, and may take years or even decades to manifest. Chronic arsenic exposure is linked to a range of severe health issues, including:
– **Skin ailments:** Darkening, pigmentation changes, and keratosis.
– **Cancers:** Increased risk of skin, lung, kidney, and bladder cancers.
– **Cardiovascular and nervous system disorders.**
– **Reproductive and developmental complications.**
Olson underscores that the arsenic pollution of water has created a