Chemical once used in degreasing, dry cleaning classified as carcinogenic

November 06, 2012
Trichloroethylene (TCE), a chemical that was often used as a degreaser and in dry cleaning, has been reclassified from a cancer “hazard” to “carcinogenic to humans” during an evaluation by 18 international scientists, including Ivan Rusyn, MD, PhD.

Dr. Ivan Rusyn

Dr. Ivan Rusyn

Rusyn is professor of environmental sciences and engineering at the Gillings School of Global Public Health at The University of North Carolina in Chapel Hill and deputy director of UNC’s Superfund Research Program (SRP). The SRP is a network of university grants, including at UNC, designed to seek solutions associated with hazardous waste sites in the U.S. The program is funded by the National Institute of Environmental Health Sciences, one of the National Institutes of Health, in coordination with the U.S. Environmental Protection Agency (EPA).

Rusyn chaired a subgroup of scientists who focused on mechanistic evidence. Mechanistic data are those resulting from or related to a process that involves physical, rather than biological or chemical change.

The scientists convened at the World Health Organization’s International Agency for Research on Cancer (IARC) in Lyon, France. During an eight-day meeting in October, the group evaluated evidence and reached conclusions about the potential of several chlorinated solvents, including TCE, to cause cancer in humans.

“TCE was widely used for degreasing metal parts and in dry cleaning and is still used in chlorinated chemical production,” Rusyn said. “It is one of the most pervasive environmental contaminants and, despite numerous studies over the past 50 years, the conclusion that it is a ‘known human carcinogen’ has only just been reached.”

The scientists’ assessments will be published as volume 106 of the IARC Monographs. A summary of the evaluations was published Oct. 26 in Lancet Oncology.

TCE and other chemicals evaluated by IARC-affiliated expert scientists have been a subject of intensive research in human epidemiological and animal toxicology studies, as well as in cells, bacteria and other systems.

However, making decisions based on numerous and sometimes conflicting results is a challenging task.

“Mechanistic data like those generated through fundamental toxicology research in programs such as the SRP is absolutely invaluable,” Rusyn said. “Understanding whether a chemical causes DNA damage or other adverse effects in experimental systems and, perhaps, in human cells or tissues, can provide evidence necessary to sort through scarce epidemiological studies and provide mechanistic plausibility for the observed cancer findings in animal studies.”

Rusyn said that while the group’s evaluation, now included in the World Health Organization’s guidance to the international community, is only one step toward recognizing the human health hazards of environmental pollutants, the work to mitigate human risks from such exposures must continue.

Government agencies around the world will take this guidance into consideration when making decisions about cleaning polluted sites and regulating industrial processes and practices, he said.

“Translating the results of our studies to the affected communities and individuals is a challenge, but it is a necessary step to demonstrate the value of basic research, whether for a community in our backyard or one on the other side of the world,” Rusyn said.


UNC Gillings School of Global Public Health contact: David Pesci, director of communications, (919) 962-2600 or