By GREG GORDON

Minneapolis-St. Paul Star Tribune

WASHINGTON -- Aspartame, the popular artificial sweetener sold most often as NutraSweet, is a leading suspect in an upsurge of deadly brain tumors in the United States, researchers at Washington University in St. Louis have concluded.

Their analysis of National Cancer Institute data, to be published this week in the Journal of Neuropathology and Experimental Neurology, found that the number of brain tumors jumped by 10 percent in 1984, a year after the Food and Drug Administration (FDA) approved the sweetener for widespread use in food and soft drinks. Similar increases in brain tumors occurred in Europe, the researchers said.

The U.S. increase -- about 1,310 cases per year -- was marked by rising diagnoses of the same type of highly malignant tumor found in laboratory rats in an aspartame study in the 1970s, the scientists said.

Dr. John Olney, lead author of the paper, is a noted neuropathologist and psychiatrist who has challenged aspartame's safety since the 1970s.

``Compared to other environmental factors, aspartame appears to be a promising candidate for explaining the surge in brain tumors in the mid-1980s,''

Olney and three colleagues said, emphasizing that they were not asserting a causal link but rather urging further research here and abroad.

The FDA and aspartame's top manufacturer disputed the paper's hypothesis.

Dr. Michael Friedman, the FDA's deputy commissioner for operations, said there are ``serious methodological questions about Dr. Olney's conclusions.''

Neither epidemiologists at the National Cancer Institute nor the FDA's own scientists who reviewed the data ``find even a weak association between aspartame and brain tumor incidence in the United States,'' he said, saying no further study is needed.

A spokesman for the Illinois-based NutraSweet Kelco Co., which sells close to $1 billion of aspartame annually, said the researchers ``manipulated the data to make their point.''

``Aspartame is likely the most tested food additive in history,'' the company said. ``There is no evidence that aspartame is a carcinogen, let alone that it causes brain tumors.''

The firm, a unit of the Monsanto Corp., sells aspartame as the tabletop sweetener Equal, and supplies it for a smorgasbord of products, including soft drinks, Crystal Lite, puddings, gelatins and chewing gum, for use by more than 100 million people worldwide.

While a highly profitable product, aspartame has been enmeshed in controversy ever since the Chicago-based G.D. Searle & Co. won FDA approval -- first in 1981, for use in dry foods, and then in 1983, for soft drinks and other foods. At the time, Donald Rumsfeld, now chairman of Bob Dole's presidential campaign, was G.D. Searle's chairman.

Thousands of consumers have filed adverse-reaction reports with the FDA blaming NutraSweet for migraine headaches, vision problems, epileptic seizures and other maladies -- links the company says have never been clinically proved.

While the vast majority of industry-sponsored studies have said aspartame causes no health problems, a number of independent studies have raised serious questions.

Cancer concerns date back two decades. In the mid-1970s, 12 of 320 aspartame-fed rats in a company-sponsored study developed brain tumors, compared with none in a control group. The company provided other research to discount that finding, but in 1986, FDA commissioner Alexander Schmidt told a Senate Committee that Searle's research could ``at best be characterized as sloppy'' and that its scientists had made decisions that ``tended to minimize the chances of discovering toxicity.''

In 1981, acting on a petition from Olney and consumer attorney James Turner, an FDA Public Board of Inquiry voted unanimously to keep aspartame off the market because of concerns about brain tumors. But shortly after assuming the FDA commissioner's job that year, Arthur Hull Hayes Jr. overruled the board and approved NutraSweet for limited use, citing a late-arriving study sponsored by Searle's Japanese partner; that study's statistical validity also has been questioned.

Olney, who recently was elected to the Institute of Medicine, an affiliate of the National Academy of Sciences, established himself as a pioneer in the field of food additive research in the 1970s. His discovery that monosodium glutamate killed nerve cells in immature animals caused the food industry to remove MSG from baby food.