(FORTUNE Magazine) – WHEN A WOMAN from Peekskill, New York, died in early February after taking Tylenol capsules that had been laced with cyanide, the commercial reverberations resounded beyond the executive offices of Johnson & Johnson, makers of Tylenol, and even beyond the pharmaceutical industry. There were tremors as well in the $475-billion-a-year U.S. food business, which may be even more vulnerable than over-the-counter drug makers to product tampering. By coincidence, safety seals have lately begun appearing around Skippy peanut butter jar lids, for example, and Heinz has started introducing button tops on ketchup bottles. The tops have a depression in the center that pops up audibly when a container is opened for the first time, breaking the vacuum seal. Gerber Products, beset by a rash of largely unsubstantiated complaints about glass fragments in baby food jars, took the offensive and denounced its critics as a ''lynch mob.'' The industry faces a painful dilemma. Its managers want to reassure consumers about product safety, but -- like drug company executives -- they fear that public statements could inspire hoaxers, attract copycat complaints, or goad a tamperer into action. Says Sanford Miller, director of the Food and Drug Administration center for food safety, ''It is an extraordinarily delicate issue. There is always the danger that you'll give some kook ideas.'' Since 1982, when Tylenol capsules containing cyanide killed seven people in and around Chicago, food companies have stepped up their efforts to safeguard products. Most food processors have concluded that improving product safety outweighs any possible negative impact on sales of ''tamper evident'' packaging, the industry term for safety seals and jar tops that show whether they have been broken or opened. ''The food industry became frantic after Tylenol, fearful that it would be next,'' says John Carroll, executive vice president of the Closure Manufacturers Association, a trade group. To meet demand for more secure seals, his industry turns out plastic wrappers, shrink seals around lids, and pop-up caps for vacuum-packed jars. ''I'd say our business has grown 60% to 70% since 1982,'' says Vincent Keegan, marketing director of Continental Can's White Cap division in Northbrook, Illinois, a leading maker of button-top caps. They are now used for fruit juices as well as spaghetti and barbecue sauces. Last year about 70% of the roughly 7.5 billion lids on containers of vacuum-packed foods had pop- up buttons. For mayonnaise and peanut butter, which are not vacuum-packed, processors have started using plastic safety bands to secure the tops of containers. The food industry has some advantages over the pharmaceutical business. Food is harder to contaminate fatally than capsules, which people swallow without tasting, and it is not easily poisoned without affecting its taste, smell, color, or appearance. ''People know what food should look or taste like,'' says James Tillotson, technical research and development director of Ocean Spray Cranberries in Plymouth, Massachusetts. INDUSTRY AND government officials concede that even the fanciest seals and lids aren't tamper-proof. ''You'll never protect yourself entirely against tampering,'' says the FDA's Miller, ''but you can make it more difficult.'' As for fresh fruit, vegetables, bread, and milk, even strenuous supervision cannot prevent what Johnson & Johnson Chairman James Burke calls ''an act of terrorism.'' Admittedly nervous about the potential for mischief, many food industry executives opted for secrecy. ''Most supermarkets that received tampering threats over the past three years never reported them to us,'' says Miller. ''All of a sudden, we've started getting reports of this food and that food being contaminated.'' Most of the complaints the FDA investigates turn out to be phony. The FDA's most publicized case since the latest Tylenol scare involves Gerber Products of Fremont, Michigan, which has used tamper-evident button-top lids on baby % food jars for more than 20 years. In recent weeks, consumers in 30 states reported finding glass fragments in more than 250 Gerber jars, and many grocery stores quickly removed Gerber products from their shelves. Nevertheless, after opening and inspecting some 40,000 sealed jars of Gerber baby food, the FDA found only ''harmless'' glass specks no bigger than grains of sand in nine of them. ''Gerber happens to be a very good company,'' says Miller. ''Their plants are state-of-the-art. They use filters and all sorts of screening devices as the stuff goes along the line. Yet apparently some customers go through a store and buy four different types of Gerber's food and find glass in all of them.'' Miller speculates that glass slivers may sometimes be planted by people seeking damages or publicity. The company, which produces more than 1.3 billion jars of baby food annually and has about 70% of the market, has filed suit to stop a temporary Maryland ban on the sale of its strained peaches that followed a string of complaints about bits of glass. ''We felt the facts did not justify such action,'' says a Gerber spokesman. ''There is no pattern to the complaints, no common lot numbers, no common factor in production lines.'' The wave of baby food complaints was not limited to Gerber products: within days of the first Gerber incident, Beech-Nut customers from California to Long Island started reporting glass particles in baby food jars. One reason Gerber has taken a tough line goes back to a much publicized incident in October 1984, when one or more fruit juice jars in a case of 24 broke during shipment. Fragments of glass that settled around the lids of eight other jars in the case were sucked inside the jars by inrushing air when the vacuum seals were broken as the jars were opened. A month before, Gerber had recalled some strained chicken following a report of contamination with a sliver of glass. All told, Gerber withdrew more than 700,000 jars. ''It was an expensive experience,'' says a spokesman. Gerber's food sales fell 6% for the quarter and the stock price sagged in a month from $27 to $22. Sales recovered within six months, but company officials now think they overreacted. The Gerber case is not the only recent instance of possible or actual tampering. Last August a northern California drugstore chain removed Gatorade soft drink bottles from its shelves after a customer in Santa Clara became ill from a bottle contaminated with urea, an ingredient of urine. California investigators concluded that the tampering occurred after shipment from the bottling plant. Quaker Oats, which makes Gatorade, tackled the unfavorable publicity head-on. The company distributed tapes to San Francisco television stations showing viewers how to tell whether Gatorade's supposedly tamper- evident caps had been fiddled with. The flap quickly subsided. More recently the FBI investigated two incidents in which someone slipped razor blades into packages of hot dogs made by George A. Hormel & Co., the Austin, Minnesota, meat-processing firm that has been involved in a long and bitter strike. ''All evidence indicates that everything occurred outside the plant,'' says Robert J. Thatcher, Hormel's treasurer, who links the sabotage to the strike. ''It's just too much of a coincidence. In 30 years with the company, I can't recall anything like this happening before.'' In 1984 the FBI and the FDA got about 800 reports that purchasers around the U.S. had found pins, needles, and other objects in Girl Scout cookies. The inquiry disclosed no tampering with the cookies at the manufacturing stage. Many complaints were either false or copycat cases where someone wanted publicity. Despite the recent headlines, tampering with food in the U.S. has not been as serious as in Japan, where at least eight people died last year after drinking juice that had been spiked with paraquat, a weedkiller. No one has been charged in the case. And shortly before Saint Valentine's Day last year, extortionists in Japan dosed boxes of chocolates with cyanide; recalls cost candymakers millions. In Britain, a poison hoax by activists protesting the use of animals for tooth decay research forced Mars to replace some candy bars on store shelves in 1984. Since the first Tylenol case, under federal law, tampering with food, drugs, or cosmetics carries maximum penalties of life imprisonment and a $250,000 fine; even a hoax can lead to a five-year prison term. The FBI, which opened more than 100 tampering investigations during the past two years, reports that four federal convictions for tampering with a consumer product have been obtained to date. Sentences have ranged from five years' probation to five years in jail. ''Even when you develop a case,'' says an FBI spokesman, ''it's tough to bring a successful prosecution.'' Getting conclusive evidence is often difficult, and in many cases U.S. Attorneys with more pressing business declined to prosecute. ! Food industry executives and government officials doubt, however, that even a highly publicized tampering conviction would necessarily deter others. ''We've come a long way,'' says Miller of the FDA, ''but the fact is food is practically unprotectable.'' Understandably frustrated managers in the food business prefer to play that down.