FROM ANAHEIM
Interest in Chernobyl high at nuclear session It was inescapable: Chernobyl was again and again on the minds and lips of scientists attending the Division of Nuclear Chemistry & Technology's symposium on the chemistry of severe nuclear plant accidents. That was true even though the four-day symposium began taking shape long before the Soviet disaster burst into the world's consciousness. In fact, most of the 50-odd papers presented didn't deal specifically with the type of graphite-moderated reactor that exploded in the Ukraine. Nevertheless, interest in the details of the Chernobyl accident and its aftermath was h i g h . Several speakers at the symposium had conferred with Soviet nuclear scientists at an International Atomic Energy Agency (IAEA) meeting in Vienna in late August. The events leading up to the chemical explosion were detailed by Michael W. Jankowski, a senior IAEA officer. According to Soviet estimates, he said, the explosion released about 12 million curies of radiation on the first day. This value, however, is subject to great uncertainties. Jankowski also noted that the Soviets planned to finish entombing the damaged reactor later this month. The data on the accident, gathered by the Soviets but so far largely unprocessed, include a number of chemical curiosities. For instance, the amount of cesium and neptunium released appear to be remarkably similar despite their very different volatilities, says chemist Dana A. Powers of Sandia National Laboratories. Also, the fission-product composition of some of the particles released from the destroyed reactor are quite u n u s u a l , giving chemists further reason to scratch their heads. Although the Soviets have been forthcoming with information, the complex chemical events that took place at Chernobyl remain unclear. According to Jankowksi, scientists are still uncertain what role hydrogen may have played in the explo-
sion. They now believe the graphite blocks holding the fuel rods caught fire after the explosion allowed air to enter the reactor. In a related development, John W. Gofman, professor emeritus of medical physics at the University of California, Berkeley, created a bit of a stir by predicting, elsewhere at the ACS meeting, that the Soviet accident could result in more than 1 million cancer cases worldwide, half of them fatal. Most other scientists consulted at the ACS meeting believe Gofman's staggering prediction is way off base. Soviet scientists have estimated that 5000 to 24,000 Soviet citizens eventually could die from cancer as a result of exposure to Chernobyl fallout. D
FROM ANAHEIM
Manganese lack may lead to osteoporosis Lack of manganese in the diet may lead to osteoporosis. Moreover, many U.S. women may not be getting enough manganese. And the calcium supplements that are currently in vogue may make the problem even worse. Those were among the findings presented at a Division of Agricultural & Food Chemistry symposium on the bioavailability of manganese. Biologist Paul Saltman, University of California, San Diego, related that about six years ago he was asked to consult in the case of basketball star Bill Walton. At that time Saltman says, Walton was eating "a bizarre" macrobiotic diet. He also was having problems with broken bones that wouldn't heal. Tests showed that Walton's serum manganese level was zero. " T h e guy h a d an osteoporosislike disease," Saltman says. Fortunately, diet changes and mineral supplements brought speedy improvement. Interest p i q u e d , Saltman embarked on experiments with rats. Packets of bone powder were implanted under the skin to stimulate growth of the cells that break down bone and the cells that promote bone formation. With rats fed manganese-deficient diets, the rate of
bone breakdown was slowed. But the rate of bone rebuilding was slowed even more. The net result was loss of bone mass. Meanwhile, Belgian orthopedists were compiling data showing that the average serum manganese level of p o s t m e n o p a u s a l osteoporotic women was only 25% that of agematched normal women. Saltman says the two studies provide concrete evidence that manganese plays a key role in bone development. According to University of Nebraska nutritionist Constance Kies, the estimated safe and adequate level of dietary manganese is 2.5 to 5 mg per day. But the estimate may be too low. Furthermore, surveys suggest that U.S. women eat, on average, far less than even the estimated safe dose. "Bioavailability" complicates the situation. Plant foods like wheat bran, tea, and spinach are rich in manganese. But, Kies says, the manganese is contained in forms that render it almost completely nonabsorbable in the gut. Meat doesn't contain so much manganese, but what it does contain is better absorbed. Both scientists stress that people shouldn't, as Saltman puts it, "rush out and superdose on manganese." They agree that the best approach probably is to eat a varied diet, one that includes meat. But people who are dieting to lose weight, or who are vegetarians for whatever reason, might consider taking a vitamin-mineral supplement that includes trace amounts of manganese. D
FROM ANAHEIM
ACS meeting is well attended Last week's 192nd national meeting of the American Chemical Society attracted more than 11,000 attendees to sunny Anaheim, Calif. Among the hundreds of technical presentations at the meeting, one highlight was the presidential plenary session on communicating science. The session, chaired by ACS president George C. Pimentel, brought togethSeptember 15, 1986 C&EN
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