What is ethylene oxide?
Related cancers: Leukemia, stomach, lymphatic, pancreatic, and brain cancers
Definition: Ethylene oxide is a flammable, colorless gas at temperatures above 51.3 degrees Fahrenheit. It is a three-atom ring made of two carbon atoms and one oxygen atom. Each of the two carbon atoms is bonded to two hydrogen atoms.
Exposure routes: Inhalation, ingestion, skin contact
Where found: Fumigation of foodstuffs, sterilization of hospital instruments, and various synthetic chemical operations
At risk: Workers in the detergent, fungicide, and synthetic chemical fields, especially those related to ethylene glycol manufacture
Etiology and symptoms of associated cancers: The high reactivity of ethylene oxide is shown by ring opening and the introduction of new carbon groups at reactive sites in deoxyribonucleic acid (DNA). This type of reaction takes place largely at a nitrogen atom of guanosine. Such modified nucleic acid fragments have been observed in mice and are most prevalent in the liver, kidney, spleen, and testis. A variety of mutations and reverse mutations have also been found. Gene mutations and heritable translocations are common.
History: Ethylene oxide has been produced in large quantities in the United States since 1921. Annual production ranges between 2.6 million and 3.4 million metric tons. According to the US National Toxicology Program's 13th Report on Carcinogens (2014), peak production in the United States reached over 4 million metric tons in 1999. The 13th ROC also reports that ethylene oxide is one of the top twenty-five chemicals produced in the United States in terms of production volume. Well over half of the production is consumed in the synthesis of the antifreeze, ethylene glycol.
Five studies of workers exposed to ethylene oxide, beginning in the mid-1980s, showed that exposure produces statistically significant excess tumor appearance. There are difficulties in the interpretation of each of these studies, but a causal relationship between the compound and tumor production is likely. Animal studies involving rats, mice, and hamsters clearly show its carcinogenicity.
Federal regulations exist for the control of ethylene oxide. The Department of Transportation (DOT) lists the chemical as hazardous and requires special marking, labeling, and transporting precautions. The Environmental Protection Agency (EPA) requires that the manufacture of ethylene oxide meet provisions for the control of volatile organic compounds (VOCs). Also, under the Clean Air Act, the compound is listed as one of thirty-three hazardous air pollutants that present the greatest threat to public health, and the EPA requires that as little as ten pounds of the substance must be reported. The Occupational Safety and Health Administration (OSHA) has set the permissible exposure limit at one part per million for an eight hour time weighted average with a five parts per million excursion level.
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