Nerve Agents or Geopolitical Bee Feces?
In the early to mid 1980s, the United States accused the Soviet Union
of conducting biochemical warfare in several Asian countries.
Scientists found that the claimed biochemical weapons were
actually bee droppings.
The episode became a textbook case in how not to investigate
and publicize suspected geopolitical misbehavior.
The mysterious events had occurred since 1975, but in 1981 the U.S. made
a public accusation of war crimes by the U.S.S.R.
Alexander Haig, the U.S. Secretary of State, made a speech to
the Berlin Press Association on 13 September 1981.
He accused the Soviet Union of supplying deadly fungus-produced poisons
to its Vietnamese and Laotian Communist allies,
and advising and aiding them in deploying it.
And what was more, he said that the USSR was now
using those same biochemical weapons in Afghanistan.
The U.S. allegations of chemical warfare involved
an initial lack of scientific information,
a willing disregard of follow-up investigations,
misleading interviews of supposed victims,
and an unwillingness to back down as the story grew less and less plausible.
The Indochina War and Laos
During the Second Indochina War,
what Americans call the Vietnam War
and Vietnamese call the American War,
the U.S. enlisted Hmong tribes in the mountains of northern Laos
to fight the North Vietnamese military and their Pathet Lao allies.
The Hmong forces were organized under the command of Vang Po,
a tribal chief designated by the CIA as General.
In 1975 the North Vietnamese and Pathet Lao were victorious.
Saigon fell on 30 April 1975.
The U.S. pulled out of Southeast Asia and General Vang Po fled to the U.S.
About 40,000 Vietnamese troops remained in Laos,
which became a tributary state to Vietnam.
Remnants of the U.S.-allied Hmong forces continued fighting
in rugged mountainous regions of Laos.
The Vietnamese Army and the Lao People's Liberation Army launched
a campaign against the Hmong forces.
Thousands of Hmong refugees fled across the Mekong River to
camps in Thailand.
In the summer of 1975, relief workers in refugee camps in Thailand
began passing stories along to western diplomatic staff,
allegations that the Vietnamese-Pathet Lao regime was using
Soviet-supplied chemical weapons against the Hmong.
The reports described attacks against much of northern Laos,
but the most intense attacks were said to be against Phou Bia,
a 2,819-meter peak that is the highest mountain in Laos.
Phou Bia was the main Hmong stronghold, with about
60,000 U.S.-allied Hmong tribesmen taking refuge there.
The reports of chemical attacks increased each year, peaking in 1978-1979.
Almost all of the reports came from Ban Vinai and Nong Khai,
two refugee camps run by former officers of Vang Po's army.
By the end of 1981 they listed 260 incidents supposedly killing
at least 6,500 people.
The Attacks in Laos
The descriptions were consistent.
The attacks occurred on sunny afternoons with gentle wind conditions.
Many were conducted by slow-flying aircraft that dropped bombs or
launched air-to-ground rockets.
The ordnance exploded just above treetop level, emitting a cloud of
colored smoke, colored powder, or an oily liquid.
Other reports described aircraft with crop-dusting spray tanks.
The smoke was described in a wide range of colors: green, red, pink, white,
yellow, blue, and others.
But about 70% of the reports described the agent as an oily yellow liquid.
It fell as large droplets that sounded like rain as it fell on
the ground, vegetation, and roofs, leaving a residue of sticky yellow spots.
The Hmong referred to the material as "Yellow Rain".
The symptoms, as filtered through the refugees' stories under U.S.
government questioning, suggested a wide range of toxic agents possibly
including nerve gas, blistering agents, and tear gases such as CS and CN,
Burning sensation on the skin followed a few hours later with hard
fluid-filled blisters, blood-streaked vomit, eye pain and blurred vision,
headache, dizziness, rapid heartbeat with lowered blood pressure,
severe coughing and breathing difficulty, and diarrhea starting watery
and turning bloody.
Then, for those with greater exposure, heavy bleeding from the gums and nose,
and neurological symptoms including blindness, tremors, and seizures.
However, people at least 100 meters away were unaffected.
The sticky yellow liquid dried in a few hours to a fine powder
that was washed away by rain.
The Attacks Spread
Vietnam invaded Cambodia, then called Democratic Kampuchea,
in 1978 in order to depose its dictator Pol Pot and his murderous
Khmer Rouge regime.
Stories began appearing about Vietnamese forces using artillery
shells filled with poison gas.
The stories expanded to include aircraft dropping bombs and
spraying liquid from tanks.
A U.S. Army medical team went to Thailand in October 1979 and interviewed
Hmong refugees who reported surviving Yellow Rain attacks.
Of course these would be among the least affected, as they not only
had survived but then had taken a multi-week trek through the mountains
to reach Thailand.
Over half of them described symptoms that could not be attributed to
any known chemical warfare agents.
Pellagra (a vitamin deficiency), hemorrhagic dengue fever,
and severe malaria seemed to be the correct diagnoses.
Then, in December 1979, the U.S.S.R. invaded Afghanistan.
The mujahedin and Afghan civilians began reporting Soviet
chemical attacks in several parts of the country, attacks launched
from helicopters and fixed-wing aircraft, artillery, and mines.
A Dutch photojournalist reported a Soviet Mi-24 helicopter dropping
canisters that emitted a yellow cloud that left sticky yellow powder
on the ground.
Villagers and the journalist developed skin lesions that resembled
some of the reports by Hmong refugees.
U.S. President Jimmy Carter's administration sent formal diplomatic
protests to the governments of Laos, Vietnam, and the Soviet Union
in 1979, and a second formal protest to the Soviet Union in early 1980.
All three governments denied using chemical weapons, so in August 1980
the Carter administration published a 125-page document containing
declassified intelligence reports and assembled press accounts.
Maybe It's a Fungus
The U.S. chemical warfare experts remained baffled by the reports.
The symptoms reported by Hmong and Cambodian refugees did not match
the effects of any known agents.
Samples of Yellow Rain were analyzed at the U.S. Army's
Chemical Research and Development Center in Aberdeen, Maryland.
In July 1981, a toxicologist at the Armed Forces Medical Intelligence Center
at Fort Detrick, Maryland, noticed a similarity between the reported symptoms
and the effects of trichothecene mycotoxins,
a family of natural poisons produced by several species of molds that
grow on grains.
Trichothecenes are a large family of non-protein toxins.
You could extract them from fungal cultures using organic solvents,
yielding an oily yellow-brown liquid.
Trichothecenes are produced by several species of Fusarium,
These fungi grow on barley, wheat, oats, and other grains.
T-2 trichothecene mycotoxin
fit the stories, at least as far as the reported symptoms
and appearance of the agent.
Low levels cause forms of the wide array of reported symptoms,
and a 35 milligram oral dose can kill a 70-kilogram human.
It can cause these effects by being inhaled, ingested, or absorbed
through the skin.
Medical science began figuring out trichothecene poisoning in the early 1900s,
after some large fatal outbreaks in Russia.
About 100,000 people, 10% of the local population,
died in the Orenburg District of the Soviet Union in the 1940s.
World War II had delayed the grain harvest, food was scarce,
and people ate bread made from grain that had been left in fields
under the snow through the winter.
The grain was contaminated with Fusarium mold and T-2 mycotoxin.
Finally, a Look at Actual "Yellow Rain"
Finally, later in 1981, the U.S. government obtained a fresh sample
of Yellow Rain.
This was collected on a battlefield in Cambodia within 24 hours
of the reported attack.
Three trichothecene mycotoxins were found in the sample.
Also in 1981, Hmong refugees gave an ABC News documentary crew a sample
of yellow powder they said they had scraped off foliage in Laos.
That sample also contained some trichothecene mycotoxins.
In 1981 through 1983, the u.s. government analyzed blood, urine, and
tissue samples from 20 people who reported being victims of chemical
attacks in Southest Asia.
Trace amounts of trichothecene mycotoxins showed up.
A Leap To Conclusions?
The U.S. government had only very limited background information.
"Mold on stored grain in Southeast Asia" had never been a pressing topic.
The assumption was, "We have never looked for these fungi or their
toxins in Southeast Asia, and so we have never seen them,
and so they must not exist."
The U.S. intelligence community connected the supposedly anomalous
trace levels of trichothecene in the samples with the Soviet grain
contamination of the 1940s.
Vietnam and Laos lacked the technology to mass-produce these toxins.
So, obviously, Soviet research into mycotoxin poisoning
had led to weapons development, and the Soviets very likely field-tested
the weapons during the civil war in Yemen in 1963-1967 before providing
them to the Vietnamese Army and the Lao People's Liberation Army.
This was the conclusion of Special National Intelligence Estimate (or SNIE)
published in February 1982.
The following month, the U.S. State Department published a special
report on Yellow Rain for Congress and the United Nations.
This was an unclassified version of the SNIE.
All the accused governments denied any chemical warfare activity.
According to the Soviet Union, the trichothecene mycotoxins were the
fault of the U.S. government.
U.S. forces had defoliated large areas of Vietnam with napalm and
strong herbicides, and then planted those areas with elephant grass.
That fast-growing grass provided fertile grounds for mycotoxin-producing fungi.
Their spores then blew into Laos and Cambodia on the prevailing winds.
Several countries carried out independent investigations.
Canada, Britain, and France were the only ones to back up the U.S. charges,
while Australia, Denmark, Israel, Norway, Sweden, Thailand, West Germany,
and others (including China and South Africa) found nothing to back up the U.S.
In 1982, a scientist at the U.K.'s
Chemical and Biological Defence Establishment at Porton Down
exampled samples of Yellow Rain to see what it was
as opposed as looking for evidence to support existing theories.
That's how actual science is done.
The Yellow Rain samples were mostly pollen.
A honeybee coated with pollen.
(Not actually a biochemical weapon)
The U.S. Army's Chemical Research and Development Center at
Edgewood Arsenal, Maryland, looked at their collection of Yellow Rain samples.
Yellow Rain is mostly pollen.
A U.S. State Department press briefing announced that pollen grains,
being 10 to 20 microns in size, were appropriately sized to serve as
carriers for toxins as they could enter and lodge within the mucous
membranes of the bronchi in victims' lungs.
Peter Ashton, a botanist from Harvard University,
observed that the pollen making up the Yellow Rain samples
was from plant species indigenous to Southeast Asia.
Thomas Seeley, an entomologist from Yale University,
said that the descriptions of sticky yellow spots on leaves
sounded like bee droppings.
Joan Nowicke, a pollen expert from the Smithsonian Institution,
examined samples of leaves with splotches of Yellow Rain
under a scanning electron microscope.
The shape, size, color, texture, and pollen content of the spots
were almost identical to
Southeast Asian honeybee droppings.
The pollen grains in the Yellow Rain spots were too densely concentrated
to have been blown in by the wind.
Beyond being unlikely to blow in the wind, it would take a large
amount of energy to aerosolize and disperse it.
The spots contained pollen from up to twenty plant families
common to Southeast Asia.
No two spots had the same pollen composition.
Adjacent spots on the same leaf had different pollen makeup.
A single fluid tank or artillery shell could not have dispersed these.
So, at this point the theory of chemical weaponry required the Soviet Union
to export several tons of pollen each year from Southeast Asia.
The agent was produced in batches and then deployed so the original
pollen sources were kept separated.
The pollen grains were hollow, as if they had been consumed,
digested, and excreted by bees.
All that was left were the indigestible exterior shells of the grains.
Now the theory of Soviet chemical warfare required that those tons of
carefully separated pollen had to be digested.
Thomas Seeley, the entomologist from Yale University,
had seen swarms of tens of thousands of Southeast Asian honeybees
flying high above the ground and simultaneously defecating
showers of pollen-rich feces.
This wasn't news to science and public health.
In September 1976, in northern Jaingsu Province, China,
villagers had reported what they called Yellow Rain.
The villagers were worried that it was a serious threat to their health.
Investigators found that the material was
pollen-rich bee feces.
Seeley led a field trip to Thailand in March 1984.
He was joined by Matthew Meselson, a professor of biochemistry and
chemical weapons expert at Harvard University,
Meselson had initiated the search for non-military explanations of Yellow Rain.
Pongthep Akratanakul, a Thai bee specialist, also joined the expedition.
They observed large swarms of local honeybees on group "defecation flights".
These produced showers of feces, lasting several minutes and
covering an area of a half a hectare or more with hundreds of thousands
of sticky yellow spots.
The defecating swarms were very difficult to see as they flew 15 meters
or more above the ground at speeds of about 30 kph.
The Military Explanation Becomes More and More Strained
Trichothecenes cause permanent damage to the cornea.
But while some refugees mentioned temporary blurred vision or blindness,
actual eye damage was almost never reported.
Refugees from Cambodia frequently reported Yellow Rain attacks delivered
by rocket and artillery fire, bombs, and mines.
The Vietnamese Army and Pathet Lao forces had used non-lethal harassing
agents including tear gas, colored smoke, and herbicides.
But no munition or shell or bomb fragment recovered from the battlefields was
ever found to be contaminated with mycotoxins or any other biochemical agent.
Anthropologists looked at the records of the refugee reports.
The anthropologists said that the reports had spread through the refugee camps
by "mass suggestion"
and the stories had been embellished through repetition.
The yellowish color of the supposed agent was about the only real consistency
across the refugess' stories.
The details of the attacks and the reported medical symptoms varied widely.
U.S. government officials had claimed that the collected interviews
presented a consistent narrative, but that was not true at all.
A team of U.S. State and Defense
Department officials tracked down and interviewed some of the Hmong refugees
who had been interviewed back in 1979-1981.
Their descriptions in 1983-1985 agreed very little to none at all
with what they had said in 1979-1981.
The stories told by refugees in 1979-1981, and worked into the U.S.
reports and public accusations, had claimed that over 200 attacks
had occurred around Phou Bia.
However, in 1983-1985 the U.S. investigators interviewed a
Hmong resistance leader who had spent eight years at Phou Bia
including the period in question.
He said that he had never seen a chemical attack, and said that
any descriptions of chemical attacks were just rumors.
The U.S. State and Defense Department investigators finally
concluded that the Hmong refugees were not reliable witnesses.
Hmong activists had coerced some of the refugees into telling some
stories that they later denied.
Grant Evans, a sociologist from Australia who also analyzed the Hmong
reports, reported that the Hmong were "prone to rumor and confabulation".
Their testimony was also filled with reports of magic, like the tree
that had acted like a giant magnet during a battle, attracting enemy
rifle fire and artillery shells away from the Hmong forces.
The U.S. government representatives in the initial interviews
had violated several basic rules of how to do meaningful surveys.
First, they let Hmong military leaders pre-select refugees to be
questioned, excluding those who would not tell the desired story.
The U.S. interviewers made their interests known in advance,
they asked leading questions, and they did not randomly select refugees
from the same villages to cross-check and verify reports.
The surveys assumed that, of course, chemical attacks had happened.
The only real questions were about the precise details of the attacks
Back to the Laboratory
In 1982, laboratories in several countries analyzed carefully collected
Yellow Rain samples, attempting to verify the initial reports of
Scientists at the U.S. Army Chemical Systems Laboratory in Aberdeen, Maryland,
at the U.K.'s Chemical and Biological Defence Establishment at Porton Down,
and at French and Swedish defense laboratories all failed to detect
any trichothecenes in the sample.
They concluded that the original supposed detections were false-positive errors.
These new tests, using newly available better technology, did not support
the earlier conclusions.
Also in 1982, Canadian Defence Force scientists detected measurable
trichothecene mycotoxins in the blood of Thai civilians who had
not claimed to be victims of Yellow Rain chemical attacks.
So much for the U.S. claim that trichothecene-producing Fusarium
fungi was not indigenous to Southeast Asia.
A 1994 assessment by three scientists at the U.S. Army's Edgewood
Research, Development, and Engineering Center in Aberdeen, Maryland, reported:
The investigation of the "Yellow Rain" allegations is a prime example
of how not to conduct an investigation of allegations of
No samples were obtained from the alleged attack sites,
witnesses were rated as unreliable, and the allegation was released
prematurely, for maximum political effect, when the evidence was
weak, unconfirmed, and based on classified sources not
releasable to the public.
U.S. government officials continued to claim that there was compelling
secret evidence that, unfortunately, they could not reveal.
In 1986 the Stockholm International Peace Research Institute concluded:
Officials of the U.S. Administration have now taken to saying more
emphatically than before that there exists secret intelligence which
supports the charges of past toxic warfare in Laos, Kampuchea
and Afghanistan, intelligence which is too sensitive to disclose publicly.
It would be wrong to pay any attention to statements of this kind.
Matters of international law must be judged on the basis of evidence presented.
Still, The Mystery Continues
It is possible that the Vietnamese and Pathet Lao military employed
some chemical agent unseen before or after.
In four incidents between late 1968 and early 1969 North Vietnamese
or Viet Cong forces used non-lethal chemical agents against U.S. personnel.
A U.S. Joint Chiefs of Staff memorandum reported "The agent (or agents)
appears capable of producing greater physical incapacitation than agents
presently used by the U.S. ....
No known chemical agent will cause the combination of effects reported."
But the Yellow Rain certainly seems to have been bee feces.
U.S. troops suffered from mycotoxosis-like symptoms in 1991 during
the Persian Gulf War, after an Iraqi missile detonated in a U.S. military
camp in Saudi Arabia.
However, like the supposed supporting evidence for Soviet activity
in the 1970s, much of the information remains classified.
for speculation on Iraq's possible military use of T-2 mycotoxin.
The International Toilet Seat Trade