The war of words over possible chemical warfare in Southeast Asia and Afghanistan will probably extensive for quite some time, despite last week's claim by a Harvard professor that so-called "yellow rain" is nothing more than bee feces.
The announcement by Harvard's Matthew S. Meselson, Cabot Professor of Natural Sciences, and Thomas D. Seeley, a Yale biology professor, seems likely only to fuel further the debate over U.S. government charges that the Soviet Union and its allies are waging chemical warfare in Laos, Cambodia, and Afghanistan.
Meselson and Seeley dropped their bee bombshell at a Harvard press conference last week, following a ten-day trip to Thailand in which they observed bee defecation flights and said they were caught in a five-minute shower of bee feces.
The scientists said that these observations confirmed their hypothesis--first advanced at a scientific conference last May--that a natural explanation exists for yellow rain.
But the announcement scarcely was out before the government and other scientists leapt to denounce the findings and stand by their own conclusions that the Soviets are up to mischief.
One scientist even insinuated that Meselson has a professional are to grind over the yellow rain issue, alleging that Meselson is acting "not as a scientist, but as a politician."
Meselson, an expert on chemical warfare was one of the principal architects of the 1972 Biological Weapons Convention the international agreement outlawing biochemical weapons.
The bitter acrimony over the issue stems from the high political stakes involved.
Some experts feel that if scientists can conclusively prove that the Soviet Union is involved with chemical warfare, it will call into question the reliability of arms control agreements and increase pressure for the United States to develop chemical weapons--long considered unusually cruel.
Neither side on the increasingly polemical yellow rain dispute has been able to produce incontrovertible scientific evidence, and each has relied on what explanation seems most plausible for reports of yellow substances falling from the sky.
The government and its supporters base their conclusions on evidence ranging from persistent refugee reports of chemical warfare and intelligence interceptions of radio communications, to the discovery of a Soviet gas mask in Afghanistan containing illegal trieothecene mycotoxins.
The government also has collected laboratory samples of leaves, rocks, blood and urine from alleged attack sites. These contain what some academic exports say are levels of mycotoxins in excess of what occurs naturally in Asia.
"There is a substantial body of evidence collected from other means and methods," said one State Department official, who labeled Meselson's hypothesis "pure speculation."