CBW IN SOUTH ASIA ("YELLOW RAIN")

• Document Type: FOIA
• Collection: FOIA Collection
• Document Number (FOIA) /ESDN (CREST): 06158162
• Release Decision: RIPPUB
• Original Classification: U
• Document Page Count: 9
• Document Creation Date: December 28, 2022
• Document Release Date: September 26, 2017
• Case Number: F-2012-01432
• Publication Date: September 14, 1989

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MEMORANDUM FOR: Deputy Director of Central Intelligence
FROM: Robert L. Foord
Director of Scientific and Weapons Research
SUBJECT: CBW in Southeast Asia ("Yellow Rain")
1. Action: No action required, for your background
use only.-7
2. Based on a wide variety of information, collected
since 1975 from all sources, the Intelligence Community
concluded in 1981 that the Soviet Union had supplied lethal
chemical and toxin weapons to its allies in Laos and
Cambodia and assisted in their use from 1976 through 1982.
The Intelligence Community judged that trichothecene toxins
were only one of several chemical/biological agents in use;
however, only trichothecene toxins were identified by sample
analysis. As a result, the subject of toxins as Soviet-
supplied warfare agents received a great deal more attention
than the overall finding that chemical/biological agents
were used -- probably because the use of these toxins in
warfare is clearly prohibited under the Biological Weapons
Convention.
3. In late 1981 the US Government in a public
declaration raised the probability that the trichothecene
class of mycotoxins was being used in Southeast Asia and
accused the Soviets of giving the toxins to Laotian and
Vietnamese forces for use against H'Mong tribesmen and
resistance fighters. This declaration was keyed to the
first sample analysis that showed the presence of
trichothecene toxins. In February 1982, the Intelligence
Community published a comprehensive compilation of the data
and our analysis. Subsequently the use of trichothecene
toxins was widely publicized by the US Department of State
in unclassified versions of the Intelligence Community
report and by numerous magazine and newspaper articles and
other news media.
4. Professor Matthew Meselson of Harvard University
was a leading critic of the US finding that trichothecene
toxins were used as warfare agents and were supplied by the
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SUBJECT: CBW in Southeast Asia ("Yellow Rain")
Soviets. He has for the past several years criticized the
methodology and conclusions of the US regarding its charges
of chemical and toxin warfare in Southeast Asia. Professor
Meselson was a technical representative and negotiator for
the 1972 Biological Weapons Convention with the Soviets, and
argued at the time that strict verification provisions were
unnecessary; that it would be obvious if biological agents
were being used. Use of mycotoxins (and other agents) in
Southeast Asia has shown this to be incorrect. Dr. Meselson
has responded by attempting to prove that the US
Government's case on "Yellow Rain" is wrong, thus preserving
the credibility of his earlier position. (Dr. Meselson also
tried to show that the US did not have a case for accusing
the Soviets of treaty violations in the Sverdlovsk/anthrax
accident.)
5. Dr. Meselson proposed his now widely publicized bee
feces theory which is presumably based on the media term
"yellow rain" and the fact that bee pollen was present in
two of the five environmental samples containing
trichothecene toxins.
6. We and other agencies in the Government have not
accepted the bee feces theory because:
- Bee droppings do not contain the man-made
chemicals found in many yellow spot samples
collected by intelligence sources from sites of
attack identified by multiple sources.
- Showers of bee feces are not known to produce any
illness in man or animals, but other chemical
substances collected in Southeast Asia from
attack sites have been reported to cause disease
in both.
- The original leaf and stem sample in which
trichothecene toxins were found did not have any
of the yellow spots characteristic of "Yellow
Rain."
- Bee droppings are not only yellow as Dr. Meselson
claims, but are mixed in color--from whitish to
brown and do not affect vegetation. In contrast,
the chemical spots observed in Southeast Asia and
associated with chemical/biological warfare
attacks did injure vegetation.
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SUBJECT: CBW in Southeast Asia ("Yellow Rain")
7. Dr. Meselson spent some time in Thailand in
attempting to prove the validity of the "bee feces" theory.
He reported that during a trip to northern Thailand he and a
colleague, Dr. T. Seely, had "good fortune" when they
experienced a bee feces shower. . While this incident
corroborates a well known fact that wild honey bees
occasionally go on massive cleansing flights, it does
nothing to associate trichothecene toxins with the bee
feces. Dr. Meselson experienced no ill effects from their
contact with the substance they encountered in Thailand.
Dr. Meselson did not report on finding any trichothecene
toxins or other possible toxic agents in samples he
collected and analyzed.
8. In addition to his bee feces theory, Dr. Meselson
suggested two other possible reasons that the US Government
was mistaken in the assessment of trichothecene use.
- That because there are so few positive results
and they come mostly from one laboratory, simple
lab error can ex lain the appearance of
trichothecenes.
- A natural occurrence of trichothecene toxins in
Southeast Asia may explain some of the positive
identification in the samples.
Both of these suppositions are clearly invalid for the
following reasons:
- Dr. Meselson was correct in stating that positive
results came mostly from one lab... funds were
not available for duplicate analysis.
Trichothecene toxins, however, were identified by
three highly qualified and respected scientists
associated with three different universities in
the US.
- While natural producers (fungi species) of
trichothecene toxins do exist in Southeast Asia
(as they do almost everywhere in the world), we
do not know of any naturally occurring diseases
due to these toxins in the natural environment.
Trichothecene toxins were only found in
environmental samples taken from alleged chemical
attack sites. Environmental control samples
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SUBJECT: CBW in Southeast Asia ("Yellow Rain")
taken from ecologically similar non-attack sites
tested negative for these toxins. Biomedical
specimens taken from 26 alleged victims of
chemical attacks showed the presence of
trichothecenes. Control specimens taken from
individuals consuming the same food sources as
the victims but who had not experienced a
chemical attack have all been negative for
trichothecenes. The particular toxins that were
identified in laboratory analysis of
environmental and human tissue samples do not
appear naturally in these combinations and
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Robert L. Foord
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SUBJECT: CBW in Southeast Asia ("Yellow Rain")
Distribution:
1 - Addressee
1 Executive Registry
1 - DDI
1 - ADDI
1 - DDI Registry
1 - OSWR Chrono
(14 September 89)
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