What if the Cure is Also a Cause?

A NIOSH Alert , left, issued last March warned health care workers of risks from contact with chemo drugs. The drugs are usually administered to patients intravenously, right. (Cdc.gov)

And a housekeeper who dumps the contents of a bedpan into a toilet might not realize that the waste is toxic. "Sometimes, 80 percent of the active ingredient [in a drug] goes right through the patient's system," said Borwegen, who also served on the NIOSH work group.

An Emerging Risk

Chemotherapy -- the use of potent drugs to kill cancerous cells -- is more than 60 years old. The first such drugs were nitrogen mustards, originally developed as chemical warfare agents. Modern chemotherapy drugs are so strong, by necessity, that they can cause secondary cancers in patients; to a healthy person, they're poison.

For decades, experts say, most health care workers were oblivious to the risks posed to them by these and other drugs, which attack good cells as well as bad.

By the 1970s, NIOSH says in its alert, "the carcinogenicity of several [chemotherapy] drugs in animals was well established. Likewise, a number of researchers during this period linked the therapeutic use of [certain drugs] in humans to subsequent leukemia and other cancers. Many in health care began to question whether occupational exposure to these agents was hazardous."

Little was done, however, to control exposures. Eleven of 12 studies in the 1980s and '90s, for example, detected cyclophosphamide in the urine of health care workers.

"Even at the big institutions we've looked at, there's contamination," said Connor, who was involved in about 20 exposure studies during the two decades he spent at the University of Texas School of Public Health in Houston. "We think some of the clinics might be worse because they don't take good precautions."

As a rule, European countries have moved more aggressively than the United States, requiring hospitals to monitor employees and keep even minuscule amounts of the drugs from being spilled or aerosolized.

"In Holland, we've seen a decline in contamination. Most workers don't have [drugs] in their urine anymore," Paul Sessink, a chemist in the Netherlands who runs a consulting firm called Exposure Control, said in a telephone interview.

The International Agency for Research on Cancer -- part of the World Health Organization -- lists nine chemotherapy drugs and two "combinational therapies" as known human carcinogens. Another nine drugs are listed as "probable" and 10 as "possible" carcinogens.

U.S. authorities have no way to accurately estimate how much harm has been caused by the careless handling of these drugs. Cancer often takes decades to emerge. A case of leukemia diagnosed in a nurse or pharmacist today might be the product of workplace exposures in the 1970s or '80s. But in many instances, the connection between work and disease is never made.