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Swedish Researchers Link Ethylene Oxide to Cancer

March 27, 1986

CHICAGO (AP) _ Workers exposed to a chemical used for sterilizing medical equipment face higher cancer risks, say Swedish researchers who found that some workers faced 10 times the risk of getting two forms of the disease.

The study of 733 Swedish workers at three plants, reported in Friday’s Journal of the American Medical Association, is the first to link ethylene oxide to cancer risks in humans, the researchers said.

Previous studies have linked the agent to plant and animal mutations, they said.

Thousands of U.S. health-care workers are exposed to ethylene oxide each year, but ″to use this study here in the United States would be like comparing apples and oranges,″ said Clarence Daley, director of the American Hospital Association’s American Society for Hospital Service Personnel.

In Sweden, the chemical frequently is mixed with methyl formate and formaldehyde, ″two known carcinogens,″ Daley said.

He also cited strict U.S. regulations that ″are achievable, reasonable and acceptable to protect health care workers.″

But Dr. Christer Hogstedt, principal researcher in the Swedish study, said the findings are applicable to any workers exposed to ethylene oxide and should serve as a warning to restrict its use.

While other chemicals were used at two of the plants studied, ″ethylene oxide is the only chemical in common in the three plants,″ Hogstedt said, ″all adding up to a very strong case against ethylene oxide.″

He also said he knew of no definitive studies finding methyl formate or formaldehyde to be carcinogens.

Hogstedt, of the National Board of Occupational Safety and Health in Solna, Sweden, worked with Dr. Leif Aringer and associate Annika Gustavsson in the study of workers from three plants where ethylene oxide was made or used to sterilize hospital equipment.

At the first plant, where the agent was used for sterilizing, researchers found three workers out of 60 had developed leukemia in 1977.

″The expected number according to the national average was less than two- tenths,″ Hogstedt said in a telephone interview Thursday from Sweden.

Those findings led to follow-up studies at two plants where ethylene oxide is manufactured. Researchers found unusually high cancer rates among workers there as well, Hogstedt said.

Among 733 workers exposed to the chemical at the three plants, eight cases of leukemia were found, compared to an expected 0.8 cases, and six cases of stomach cancer were found, compared to an expected 0.65, he said.

The findings were based on personnel records and data from Sweden’s National Cancer Registry from 1977 to 1982. All the workers studied had been exposed to ethylene oxide for at least eight years during the 1960s and 1970s.

The amount of ethylene oxide in the air at the plants ranged from an average of about 5 parts per million to 25 parts per million, over an eight- hour period, Hogstedt said.

Findings from the initial study led the Swedish government in 1983 to set maximum allowable levels of ethylene oxide at 1 part per million for new plants and 5 parts per million for old ones, he said.

U.S. regulations in effect since January 1985 set the maximum allowable level of ethylene oxide in the workplace at 1 part per million over eight hours, said Daley.

The agent is used at up to 85 percent of U.S. hospitals, he said, but he labeled the Swedish findings inconclusive and said they should not alarm U.S. workers.

Researchers at the National Institutes for Occupational Safety and Health in Cincinnati are studying the effects of ethylene oxide, he said, and their findings may be more applicable to workers in this country.