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Yellow Rain

by A. Maureen Rouhi
January 28, 2013 | A version of this story appeared in Volume 91, Issue 4

To celebrate C&EN’s 90th anniversary, one Editor’s Page each month will examine material from C&EN Archives. Hyperlinks in this editorial lead to C&EN Archives content that is freely downloadable for one month.

“For years, and from faraway places have come reports of death and sickness from the skies. The tales from ruggedly independent and mostly illiterate mountain people of Laos, Kampuchea, and Afghanistan tell of aircraft-, rocket-, and artillery-delivered clouds of yellowish material that killed rapidly and grotesquely those directly hit. … Survivors often told tales of mysterious yellow rainlike spots on or near their villages ... associated with death and illnesses.”

Thus begins Lois R. Ember’s “Yellow Rain,” the C&EN story that painstakingly dismantled the U.S. charge that the Soviet Union was using fungal toxins in chemical warfare in the early 1980s (C&EN, Jan. 9, 1984, page 8). The U.S. case was based on physical evidence, medical evidence, and accounts of refugees. In “Yellow Rain,” Ember methodically examines the science behind the evidence and concludes that the U.S. “has badly botched the science needed to prove its case for toxin warfare.”

The U.S. allegation of Soviet use of chemical warfare unfolded during the Cold War. In the aftermath of the Vietnam War, Soviet-backed forces clashed with groups resisting communist regimes in Laos and Cambodia. The Soviet Union’s invasion of Afghanistan in 1979 further heightened tensions between the rival superpowers.

The U.S. first publicly charged the Soviet Union in a speech by then-secretary of state Alexander M. Haig on Sept. 13, 1981. Ember quotes from the speech: “For some time now, the international community has been alarmed by continuing reports that the Soviet Union and its allies have been using lethal chemical weapons in Laos, Kampuchea, and Afghanistan. … We now have physical evidence from Southeast Asia which has been analyzed and found to contain abnormally high levels of three potent mycotoxins—poisonous substances not indigenous to the region and which are highly toxic to man and animals.”

If the allegation were true, the Soviet Union would have been in violation of treaties prohibiting the use of chemical and biological weapons in war, Ember reports earlier. The implication “was strong enough to trigger a vehement denial from the Soviet Union” (C&EN, Sept. 21, 1981, page 7).

It was Michael Heylin, then-C&EN editor, who insisted on an investigative piece about yellow rain, Ember says. The story “was my whole life for three months,” she recalls. Interviewing scores of sources in different time zones, she kept going, she says, because “I wanted an answer, and I’m tenacious, and I had to get something that satisfied me, so I kept digging.”

“The coverage of other media didn’t hang together. Scientifically, it made no sense,” Heylin says. “The Wall Street Journal was … spreading what I considered misinformation on a topic that we were capable of examining ourselves.” Ember “did a hell of a job,” Heylin says. “It paid off enormously.”

“Yellow Rain” may have caused the U.S. to tone down its rhetoric against the Soviet Union, Heylin writes in an editorial (C&EN, Feb. 27, 1984, page 5). The Wall Street Journal, he continues, “devoted an unusually long editorial to answering C&EN with a cleverly crafted concoction of innuendo, red-baiting, and uncharacteristically inept journalism.”

“The New York Times was very positive,” Ember says. “Because the Times picked it up, the story went viral around the country. The magazine got its name spread around quite well.”

For “Yellow Rain,” Ember received the 1984 Science-in-Society Award from the National Association of Science Writers and the 1984 George Polk Award for special-interest reporting. The citation on the latter award states in part: “Her remarkable 27-page account … demonstrated that the State Department had been so anxious to reach its conclusions that it violated basic scientific principles and in so doing wounded its own case. Her story led to a re-evaluation of the evidence by many, including some of the nation’s most prestigious journals.”

So what is yellow rain? Find out in C&EN Archives at

Views expressed on this page are those of the author and not necessarily those of ACS.


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