Anthrax scares, which often trigger hugely expensive emergency responses by police, fire and public-health officials, are fast becoming a favored tactic for those with scores to settle or grudges to act out. And while some of the 100-plus hoaxes in the last year seem to be no more than disturbing variations on the old-fashioned bomb threat, incidents like the one in Kansas City are believed to be part of a concerted effort to disrupt patient services at abortion clinics and women’s health centers all across the country. According to Eleanor Smeal of the Feminist Majority Foundation, dozens of anthrax hoaxes have been reported since last October–35 of them in a five-day span between Feb. 18 and Feb. 22. Many of the letters were mailed from Lexington, Ky., and the FBI says its field office in Louisville is investigating. Typically, the hoaxes consisted of an envelope containing the warning that whoever opened the envelope had just been exposed to anthrax, a virulent livestock disease that can be used as a germ weapon. In the Kansas City case, the envelope appeared to be a piece of junk mail from a medical-supply company. Inside was a stained sheet of paper bearing a computer-generated skull and crossbones and a sarcastic threat: “Anthrax. Have a nice death.”

The specter of bioterrorism forces law-enforcement officials to take such nonsense very seriously. The Feds are currently working on secret guidelines to help local authorities separate genuine threats from hoaxes, but one big step is simply avoiding panic. Though anthrax is deadly, it isn’t easy to transform the spores into a usable weapon, and antibiotics are highly effective treatment for those who are exposed to it. Still, everyone involved in the recent hoaxes understands that the threat, however unlikely, could be real. Debi Jackson, who owns a women’s clinic in Cincinnati, got one of the “have a nice death” letters on Feb. 18. “I was 99 percent sure it wasn’t anthrax, but I thought, ‘What if we were the first one where it’s real?’ " Jackson said. She, too, called 911, triggering a biohazard emergency. When it was over, she and her staff had to close the clinic for four days to clean up the mess. “For the cost of a stamp and an envelope and a dirty piece of paper,” said Jackson, “somebody can shut me down.”

The FBI so far has no suspects in any of the abortion-clinic incidents, but it is prepared to play hardball with any anthrax hoaxer. In many cases, however, the threats appear to have no political motive at all. In Indianapolis, authorities have tallied 17 anthrax threats since October, but the targets include three high schools, an elementary school and a television station. In Los Angeles, the FBI has recorded 40 anthrax threats since October, including one against a bankruptcy court and another against a hospital. But in the L.A. area, at least, the fad appears to have run its course–perhaps because of publicity surrounding the arrests of two men charged in separate, apparently nonpolitical anthrax hoaxes. Under a new federal law, says FBI spokesman Ramiro Escudero, anyone convicted of threatening to use a weapon of mass destruction, such as anthrax, can get life in prison.

For abortion clinics and their supporters, the spate of anthrax hoaxes poses a tactical dilemma, since speaking out against this politicized form of malicious mischief may encourage copycat crimes. Galen Sherwin, president of the New York City NOW chapter, says many clinic operators “don’t want to draw attention to themselves because they’re under siege”–but insists silence isn’t the answer. “We don’t want to encourage copycats, sure,” Sherwin says. “But keeping quiet about clinic harassment hasn’t stopped the violence from escalating.” She may be right. Bombings and sniper attacks have already forced abortion clinics to adopt stringent security precautions: the anthrax threats are just the latest wrinkle. In Kansas City, the worker who opens Planned Parenthood’s mail now wears rubber gloves and a surgical mask.