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“Yellow Rain” by Lois Ember


Ember, Lois R. “Yellow Rain.” Chemical and Engineering News 62 (9 Jan. 1984). 8-34. Print.

In her article, Ember analyzes U.S. government claims that the Soviet Union supplied chemical weapons in the form of yellow rain to communist forces in Laos, who then used them as part of a genocide campaign against the Hmong. Her analysis is a good counterpoint to Grant Evans’ The Yellow Rainmakers, which examines the yellow rain controversy through a political lens, and Sterling Seagrave’s Yellow Rain, which examines the controversy through a historical lens. As appropriate for the publication in which her article appears, Ember examines the controversy through a scientific lens. She includes all known evidence, regardless of which side of the debate it seems to support, but makes it clear early in the article that her focus is the U.S. government’s persistent refusals to accept any scientific evidence contradicting its claims that yellow rain was a Soviet military weapon. She concludes that yellow rain was indeed a trichothecene mycotoxin produced by Fusarium fungi, as every other source I’ve encountered agrees, but contends tricothecene occurred naturally in Southeast Asia and was ingested by Hmong already in a fragile physical and psychological condition from having to flee for their lives.

She outlines the U.S. government’s evidence first and acknowledges that several officials purport to have classified information proving beyond doubt that yellow rain was a Soviet weapon. It is common knowledge worldwide that the Soviet Union has studied mycotoxins—including potential military applications—for a century or more, after large portions of its population died from eating infested grain. The Soviets increased suspicion of their involvement with yellow rain in Laos when they exerted “influence [that] kept the UN team of experts from investigating yellow rain allegations first hand in Laos” (26).

After outlining the government’s evidence, Ember highlights its gaps, inconsistencies, and flaws. Like Evans, she points to inconsistencies among witness testimony. She cites several specific examples of such inconsistencies, the most problematic of which are presented by “star witness” Ger Pao Pha, whose “story varies substantially over time, and from interview to interview” (29). She explains that among the changes to his story are the method of delivery for yellow rain, the number of people killed by it, how he survived the attack, and whether his only surviving relative was a son or daughter (30).

The most significant problem with the government’s accusations is the evidence itself. Ember explains that “no munition has been retrieved that tests positive for toxins,” despite witness reports that “shells, grenades, rockets, and canisters have been reported to be the delivery systems for early [yellow rain] attacks in Laos” (25). No chain of evidence can be verified for yellow rain samples taken from Laos, Kampuchea, and Afghanistan—all places where yellow rain is purported to have been used—and sent to laboratories for analysis. In some cases, the government can’t name or even generally describe the person(s) who collected the samples or pinpoint the locations from which they were taken. No one knows the exact route the samples took to arrive at labs where they were tested, so their authenticity can’t be guaranteed, and contamination can’t be ruled out. The arrival of every sample to testing laboratories was also at least several weeks—and in some cases months—after having been discovered, and results from experiments to determine how quickly mycotoxins degrade in the environment, are metabolized, and are excreted from the body vary widely in their results. Nearly every laboratory arrived at different results as to whether or not trichothecene (or any mycotoxins) are present in the samples, whether any found to be present are of natural or synthetic origin, or the concentrations in which any found to be present appear. Ember quotes several government officials who scoff at science as further support for her claim that the government turns a blind eye to anything that doesn’t further its charges. Even in the face of evidence provided by government agencies, such as the Army’s Chemical Systems Laboratory, which “ha[d] not identified a single toxin in any of the myriad samples [of yellow rain] tested,” the U.S. government continued accusations first made public by Secretary of State Alexander M. Haig in a September 13, 1981 speech in West Germany, that the Soviet Union violated the 1972 Biological Weapons Convention provisions by employing yellow rain in Laos.

Another complication to scientific analysis of mycotoxins are contradictory claims among scientists as to whether or not they exist naturally in Southeast Asia. Although a few scientists claim they do not, most agree that they do and that they are often found in crops exposed to damp environments, including those where the Hmong lived, grew their food, and raised their animals.

One alternate theory Ember examines is that yellow rain is a mycotoxin occurring naturally and transmitted via bee feces. Scientists worldwide have known since the 1920s that honeybees, which are found in large numbers in Laos and other parts of Southeast Asia, conduct “cleansing flights” every spring, the time in which most claims of yellow rain were reported. Bees exit the hive after spending the winter in it without defecating (to keep the hive clean); they fly straight up as a group and defecate during a period of 10-20 minutes. Their defecation takes the form of a yellow mist and dries to a yellow powder, both of which match descriptions of yellow rain. The bees’ ascension begins from such heights that people on the ground wouldn’t identify them as the source of the yellow mist. Mostly harmless, bee feces can be harmful to humans in large quantities, but more importantly, scientists claim it can serve as a medium for mycotoxins. This, they assert, explains the presence of pollen and bee hair found in every sample of yellow rain taken from Laos. Scientists suggest that “at the same time people [the Hmong] are eating moldy food and getting sick, the bees swarm and defecate. Because the two events are happening together, the people relate illness to yellow spots. Then on top of this float rumors of chemical warfare” (24). Thus, reports of yellow rain are born.

A second alternate theory is that the Hmong were sickened by U.S. application of defoliants and herbicides to poppy fields in Laos. The Hmong were among the most prolific poppy farmers in the region, and “the Hmong reported deaths from these aerial sprayings,” which took place in 1973-1974, a decade before official reports of yellow rain surfaced (30). The Hmong described “these decade-old sprayings as ‘yellow poisons’ or ‘yellow rain’” (30). Because the Hmong in Laos had only an oral (not written) language and relied on storytelling to relate their history, these older stories about yellow rain became part of the culture and influenced their perceptions of physical illness related to the yellow mist of bee feces later on.

The last category of evidence Ember uses to discredit U.S. government claims is logical reasoning. She and other scientists ask why the Soviets would use a toxin that has to be applied in huge quantities and is more likely to sicken than kill people when other chemical/biological agents are known to kill people quickly and effectively in far smaller amounts. More to the point, she states, “There are less exotic and equally effective terror weapons that violate no treaties”; why, she asks, wouldn’t the Soviets have used them? (26). Proponents of the yellow rain theory, however, argue that using mycotoxins would attract less attention from the international community, would be more difficult for investigators to detect, and would still cause the Hmong to abandon villages located in areas highly-sought areas of Laos. Most of the mycotoxins in Hmong villagers’ blood and urine samples came from gastrointestinal tissue rather than respiratory tissue, indicating the toxins were ingested rather than inhaled. That seems to support theories that the Hmong suffered mycotoxins existing in nature and their food supply rather than dropped from planes.

Ember’s doubts about U.S. government claims are compelling, as is her analysis of evidence. The article is too long and too technical to assign in its entirety for ENGL 2330 Hmong American Literature, but depending on time constraints, I may include a brief excerpt. The excerpt would be part of the yellow rain unit culminating in the Yellow Rain Essay assignment.


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