UT-H Study Looking at Health Care Workers' Risks From Exposure to Cytotoxic Drugs

Cancer chemotherapy drugs may pose a health threat to hospital personnel not directly involved with the preparation and administering of the extremely toxic drugs as well as to those who actually do work with them, says Thomas H. Connor, Ph.D., associate professor of environmental sciences and occupational health at The University of Texas-Houston School of Public Health.

Dr. Connor was the principal investigator for a study looking at surface contamination from cytotoxic drugs - he first American/Canadian investigation assessing such health risks. The results appeared in a recent issue of the American Journal of Health-System Pharmacy. Recent European studies also have shown that measurable levels of environmental contamination are present in the health care setting.

Environmental contamination with cytotoxic agents (substances having a toxic effect on cells) was detected in six cancer centers - three in the United States and three in Canada. Wipe samples were collected from the pharmacy preparation areas as well as ambulatory care areas to measure the levels of contamination with cyclophosphamide, 5-fluorouacil and ifosfamide, just three of the few dozen agents typically used to treat cancer.

"Each center prepared an average of over 30,000 (range 2,000 to 109,000) cytotoxic doses annually," says Dr. Connor. "All used class II biological safety cabinets and in four of the six sites, the cabinets were designed to exhaust back into the pharmacy area via a second HEPA (high efficiency particulate air) filter. If the protective measures used had eliminated contamination, then nothing would have been detected," he says.

Even though the centers followed the recommended guidelines, surface contamination was common. Sites sampled included the work surface, airfoil and bottom grill of the biological safety cabinets, the floor in front of the cabinets and other areas inside and outside the preparation room. In the ambulatory care areas, samples were taken from chairs, tables, worktops and floor areas. Seventy-five percent of all the pharmacy areas and 65 percent of all the drug administration areas showed contamination. "Surprisingly," says Dr. Connor, "some of the low usage areas had relatively high levels of contamination."

Occupational exposure to cytotoxics was first recognized as a potential hazard to health care workers in the 1970s. The Occupational Safety and Health Administration (OSHA) issued guidelines for the handling of antineoplastic and other hazardous agents in 1986 and revised them in 1995. Although OSHA guidelines are the most widely recognized, other organizations have also published similar guidelines.

The unknowns are high, he says. "We don't know the extent of the human exposure or the biological significance of exposure to single agents or combinations of agents. Although a number of these agents are known to cause cancer in patients treated with them, reproductive effects might be evident long before carcinogenic effects," he says.

The bottom line? "There has been too much reliance on biological safety cabinets. The significant contamination that our study revealed points up that guidelines for these drugs will have to be revised."

Roger W. Anderson, Dr.P.H., head, division of pharmacy at The University of Texas M. D. Anderson Cancer Center, was the other Houston author of the study.

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©2006 Texas Medical Center

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