A DECADE AGO, the Native American Graves Protection and Repatriation Act (NAGPRA) cleared the way for Indian tribes to recover cultural artifacts and human remains from museum collections. After a lengthy Native American lobbying effort, spearheaded in large part by the Hopi, George Bush finally signed the bill in 1990. Under the terms of the legislation, federally funded institutions are required to provide summaries of their collections and release items of cultural and religious significance to tribes that request their return. NAGPRA seemed to be a monumental victory for Native Americans. However, its unforeseen consequences have created a serious health threat: Hundreds of artifacts have been contaminated with arsenic, mercury, and other toxins applied by museums themselves.

Leigh Kuwanwisiwma, director of the Hopi tribe's Cultural Preservation Office, first learned about the poisoning in 1995. He was at Harvard's Peabody Museum arranging for the repatriation of three Hopi artifacts known as Katsina Friends. During discussions with Peabody officials, he discovered the unfathomable: The Friends had been poisoned to prevent insect decay. To the Hopi, these objects are much more than mere assemblages of leather and feathers, yarn and paint. "In Hopi," explains Kuwanwisiwma, "these objects have life and spirit. [They] are just like your son, your mother. It's part of our living human community that has been contaminated with poison."

By the time Kuwanwisiwma learned about the poisons, the Hopi had already repatriated some sixty objects and returned them to their owners on the reservation, who performed reconsecration ceremonies to welcome the sacred items back to their homeland. Many of the items were restored with new feathers and paint. Most ominously, many artifacts had already been worn and used in ceremonies, stored in clan houses, and even brought into underground, poorly ventilated religious chambers called kivas.

MUSEUMS APPLIED pesticides to organic materials from the mid-nineteenth century until the 1970s. Mercury and arsenic were the most common pesticides employed, but other chemicals that are now banned for use as pesticides were also applied, including carbon tetrachloride and ethylene dichloride, which are both classified by the EPA as probable carcinogens. The thinking was that contaminated artifacts would be forever safely ensconced in glass. But that all changed when NAGPRA became a federal law a decade ago. Tribes like the Hopi, the Hoopa of Southern California, and the Seneca Nation of New York are all bringing artifacts back to use them in ceremonies. This has taken museums by surprise and presented a whole host of public-health concerns. And it has underscored a fundamental disparity between museums that have treated these artifacts as relics needing to be preserved at all cost and tribes, especially the Hopi, who see these objects as living, sacred beings.

The fact that some artifacts are well over two hundred years old and still exist in museum collections is testament to how well these contaminants have worked. But the residues that these poisons left behind pose serious, and in some cases severe, health risks to Indian tribes. A few years ago, the Hopi tried to repatriate artifacts from a collection in Santa Fe's School of American Research. "One item," says Kuwanwisiwma, "was found to have three hundred to four hundred times the accepted level of arsenic. It is so hazardous that the Arizona Poison Control Center simply told the Hopi tribe, 'Please never ask for it back.'" Lucas Namoki, a Hopi tribal member who works for the Indian Health Service, doesn't understand why collectors didn't tell the Hopi people that they had applied chemicals to their artifacts. He considers this just another example of the lack of communication between the Hopi and non-Indians.

Arsenic and mercury, both used well before their health and environmental risks were fully understood, are of most concern to tribes. They "affect a wide variety of target organs," explains Kathy Makos, an industrial hygienist at the Smithsonian Institution. "The predominant symptoms of acute arsenic poisoning include severe gastrointestinal and central nervous system problems, while long-term overexposure could lead to lung or skin cancer. Exposure to inorganic mercury primarily targets the nervous system and kidneys." Making matters worse, it could be a number of years after someone is exposed to a pesticide residue before the symptoms of chronic poisonings are seen.

Makos is quick to point out that while a serious concern, with proper tribal education and close communication between museums and tribes, the risk posed by pesticide contamination should be easily controlled. "It's not the fact so much that you have a serious hazardous pesticide on an object," she says, "as much as how is that object going to be handled, where is the contact, what is it going to mean to that person's short term or long term health? That's a classic public health evaluation." In other words, if tribes know what pesticides are present on an object and in what quantity, they can manage the risks involved with handling that object. But for the most part they haven't been able to do this, because museums often don't have accurate records of what has been applied to collections.