When botanist George Washington Carver proposed 300 new uses for the peanut, he couldn't have foreseen enriched cocoa, Kung Pao chicken and pine-cone bird feeders.
Today, scientists say the ubiquity of peanuts has contributed to a surprising upswing in allergic reactions that can kill -- symptoms that can escalate from itching and wheezing to outright choking.
The peanut is so powerful an allergen that some people can't tolerate any food that has shared the same counter top with a peanut butter sandwich. In restaurants, people question chefs to make sure that dishes as innocent as filet mignon are untainted.
"A man died a year and a half ago -- his egg roll had been glued shut with peanut butter," said Anne Munoz-Furlong, founder of the Food Allergy Network, a consumer group based in Fairfax, Va.
Two Massachusetts schools and an entire school district in London, Ontario, have banned peanuts from cafeterias. Elsewhere, other schools have taken lesser steps. The McDonogh School in Owings Mills, for instance, is keeping peanuts out of its prepared lunches and desserts.
Allergic children are learning to scrutinize the ingredients on snack food packages before daring to take a bite.
"No matter where he goes, he has to read labels," said Julie Finkelstein of Owings Mills, whose son Andrew, 8, attends McDonogh. "Peanuts may be the 10th or 15th ingredient. It's something he has to think about all the time."
Food allergists, led by Dr. Hugh A. Sampson of the Johns Hopkins Medical Institutions, are trying to answer perplexing questions about the peanut, a legume that grows underground. For instance, what are the specific proteins that make some people sick? The answer could lead to a cure -- even to a genetically engineered peanut that's as benign as lettuce.
Another puzzle is the recent rise in cases. Peanuts have been a staple of the American diet for much of the 20th century, but only in the last decade have they become a common health problem among youngsters.
Scientists also want to know why children outgrow allergies to eggs and cow's milk by the time they are 3, but rarely lose their sensitivity to peanuts. They also wonder why other legumes, such as peas and beans, rarely cause life-threatening reactions.
Just as mysterious is the peanut's potency: Some people can't even tolerate its aroma.
"Sean has trouble sitting next to anybody eating peanut butter," said Heidie Augustino of Gaithersburg, whose 6-year-old son has multiple allergies but reacts most intensely to peanuts. "The smell permeates. He's had episodes where his eyes swell up and become very itchy."
Doctors aren't required to report food allergies, and nobody has done a large study to document the prevalance of peanut reactions. So the peanut's rising toll is largely anecdotal, based on the experiences of pediatricians, allergists and emergency-room physicians who are sure they are seeing more peanut reactions than ever.
Sampson has seen an increase among children treated at his Hopkins clinic for severe, allergic skin rashes. Peanuts were blamed in 16 percent of the rashes between 1981 and 1984, and in 31 percent between 1991 and 1994.
Why is this happening?
Sampson's theory is that parents are feeding their children peanut butter at an earlier age than ever. Children who are exposed to a potential food allergen before age 3 are more likely to become hypersensitive than those who are exposed later.
"We look at it as a period of vulnerability when the immune system hasn't totally developed to where it can see these foreign proteins, recognize they are safe and not react against them," he said.
Sampson recommends that parents withhold peanuts from children under 3 who fall into two risk groups: youngsters with asthma or with family histories of peanut sensitivity.
No matter what a person's age, the peanut's versatility makes it hard to avoid.
"Restaurants are the biggest problem," said Munoz-Furlong of the Food Allergy Network. "Some use peanut butter to thicken brown gravy. One fortifies hot cocoa with a dollop of peanut butter."
She recommends that allergic patrons avoid Chinese restaurants altogether. The nut flavors many dishes, and its residue can linger in woks that are used and reused throughout the day.
Most peanut oils are safe, says Sampson, because manufacturers eliminate everything from the raw peanut but the oil itself. Not so pure are the new "extruded oils" that are used in fancy potato chips and other products.
Peanut reactions can be frightening -- and unforgettable.
Sitting in a high chair, Andrew Finkelstein was gumming a peanut butter sandwich when his eyes swelled and his face erupted in hives. He was 9 months old.
Immediately, his mother called the pediatrician, who told her to try an antihistamine and cold compresses. But the reaction intensified, and she phoned again. "He asked me if Andrew was having trouble breathing, and when I stopped to listen, I noticed he was wheezing."