Coke oven emissions
Coke oven emissions are by-products generated during the heating of bituminous coal in an oxygen-free environment to produce coke, a crucial material in steel manufacturing. This process results in the release of a variety of harmful gases and vapors, including benzene, toluene, and formaldehyde, which are classified as potential carcinogens. Workers in industries that utilize coke, such as steel production and aluminum manufacturing, along with nearby residents, face increased risks of exposure to these toxic emissions. Studies have linked coke oven emissions to several types of cancers, particularly respiratory cancers and skin cancer, as well as cancers of the prostate, bladder, and kidneys. Symptoms associated with these cancers can severely impact quality of life, affecting breathing, digestion, and overall health. Despite the implementation of safety regulations aimed at reducing exposure, challenges remain, such as structural defects in coke ovens that lead to the continued release of these hazardous substances. As a result, coke oven emissions remain a critical public health concern requiring ongoing attention and regulation in affected industries.
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Coke oven emissions
ROC STATUS: Known human carcinogen since 1981
ALSO KNOWN AS: 3,4-benzopyrene, benzanthracene, chrysene, phenanthrene, benzene, toluene, and xylenes
RELATED CANCERS: Respiratory cancers, including tracheal, bronchial, and lung cancers, as well as cancers of the skin, prostate, scrotum, large intestine, pancreas, bladder, and kidneys
DEFINITION: Coke oven emissions are produced when bituminous coals are heated in the absence of oxygen to produce coke, tars, and light oils. Between 70 and 76 percent of the coal is converted to coke; the remainder is emitted in the form of by-products including light oils and gases and vapors of methane, ethane, ethylene, propylene, formaldehyde, ammonia, nitrogen oxides, cadmium, arsenic, and carbon monoxide. Tar acids, naphthalene, creosote, and pyridine are also emitted as coke oven gas tar. These various gases and vapors fall under the category of coke oven emissions and are the source of concern as potential carcinogens.
Exposure routes: Inhalation, dermal contact
Where found: Coke oven emissions occur when coal is processed to produce coke, or when the coke is combusted as fuel for making steel and processing ores, and in the manufacturing of substances such as graphite products.
At risk: Workers in coke oven plants that produce coke from coal, at coal tar plants, and in the aluminum, steel, graphite, electrical, and construction industries are especially at risk. Residents in the immediate vicinity of coke-producing plants and coal tar industries are also at risk of higher-than-normal exposure to vapors and gases.
Etiology and symptoms of associated cancers: Coke oven emissions are related to respiratory cancers that can develop from inhalation or ingestion of toxic substances. These cancers typically interfere with speaking and breathing, and they often affect taste and smell. Skin cancer may result from dermal contact with toxic substances and is characterized by a tumor on or just below the skin surface, which may become red and irritated. Cancers of the prostate, scrotum, pancreas, bladder, kidney, and large intestine can develop if toxic substances are ingested and pass through the blood or urinary system. They may affect urine flow, frequency, and strength or may prevent ejaculation. Pancreatic cancer, kidney cancer, and intestinal cancer can cause extreme abdominal discomfort as well as hinder the digestion and blood-cleansing processes.
History: Coke, or pure carbon, is used as a fuel reductant in the manufacture or synthesis of steel, iron, calcium carbide, graphite, and electrodes. The chemicals given off as coke oven emissions can be used in making plastics, solvents, dyes, drugs, paints, roads, roofing, insulation, pesticides, and sealants.
Coke production in the United States began to decrease around 1950 because of a seemingly strong relationship between exposure to coke oven emissions and cancer rates. A number of studies conducted in the United States, Japan, Sweden, and the United Kingdom have produced significant evidence linking coke oven emissions with increased cancer rates among coke oven workers, especially cancers of the skin, lungs, and prostate. One study that followed 15,818 cohorts over thirty years showed that occupational exposure to coke oven emissions was associated with significant excess mortality from cancer of the respiratory system and of the prostate. Another study found higher rates of lung cancer among topside coke oven workers and among those working near the tops, or lids, of the ovens, where exposure rates were greatest. In 2022, a study by the National Center for Biotechnology Information showed coke emissions overwhelmingly played a role in the prevalence of lung cancer in workers in the manufacturing industry. Additional studies have shown significant links between exposure to coke oven emissions and incidence rates of skin tumors and kidney, large intestine, and pancreatic cancers. All studies have postulated that cancer from coke emissions is an important public health issue.
Because of the studies confirming the relationships between coke oven emissions and cancers, numerous safety regulations are in place, including limitations on exposure levels to coke oven emissions and the use of respirators and protective clothing for coke oven workers. Still, the use of coke as a fuel remains high in certain industries. Alabama, Arkansas, West Virginia, Virginia, and Pennsylvania still produce coking coal. Regulations require that coke oven emissions be collected, but structural defects, including loose-fitting doors and lids on coke ovens and poor engineering controls, result in the continued release of varying amounts of potentially carcinogenic coke oven gases and vapors.
Bibliography
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