Sulfur exposure refers to events in which a human, other animal, or plant is exposed to the element sulfur or one of its compounds. The compound of primary health interest is sulfur dioxide (SO2). The element's name is spelled sulphur in Europe and many other parts of the world.
Sulfur occurs naturally in locations where molten rock and its by-products are carried to Earth's surface, as around the rim of a volcano or adjacent to geysers and hot springs. Very large reserves of natural sulfur may also occur in domes similar to veins of coal beneath the Earth's surface. At one time, these domes were mined by a procedure known as the Frasch process in which steam and hot water were pumped into a vein of sulfur and the molten element forced to the surface. The sulfur thus produced was very pure, but the cost of the technology eventually became greater than that of other methods for the production of sulfur, and is no longer used to any great extent today.
Compounds of sulfur, particularly sulfur dioxide and hydrogen sulfide, typically occur in combination with elemental sulfur in the natural world. Very large amounts of sulfur dioxide and sulfur trioxide are now produced by industrial activities. (Environmental scientists often refer to the two gases together as “oxides of sulfur.”) The largest single source of sulfur dioxide produced by human activity (about three-fourths of all the gas thus released into the atmosphere) comes from fossil-fuel-burning power plants. Coal, oil, and natural gas all contain small amounts of elemental sulfur and sulfur compounds. When these fuels are burned in an industrial process, the sulfur is converted primarily to sulfur dioxide, which then tends to escape into the atmosphere through emission systems. An additional 20 percent of all sulfur dioxide produced by human actions comes from a variety of industrial processes. The extraction of metals from their ores and the combustion of high sulfur fuels by locomotives, large ships, and non-road equipment account for the remaining fraction of sulfur dioxide produced by human activity.
Elemental sulfur is also released into the environment as a result of human activity, primarily as a pesticide. Sulfur has been used for this purpose for at least two millennia, and it continues to be popular for use with certain types of crops and certain types of pests. For example, sulfur sprays are used on a number of commercial fruit and vegetable crops to control the growth of ticks, mites, and other arachnids.
Elemental sulfur is thought to have few significant acute or chronic health effects on humans. Inhalation of sulfur dust may cause a burning sensation and cough, followed by a sore throat, while a deposit of sulfur dust on the skin may produce redness and burning. Sulfur dust in the eyes may result in a burning sensation, pain or discomfort, and short-term blurred vision, while ingestion of the dust can cause intestinal upset and distress. All of these symptoms disappear fairly readily, however, when exposure to sulfur dust ends.
The U.S. Environmental Protection Agency (EPA) has established standards for safe exposure to sulfur dioxide. The primary standard is for an exposure of no more than 75 ppb over a period of one hour, while the secondary standard is for an exposure to no more than 500 ppb over a three hour period, no more than once a year. The primary standard is designed to protect all Americans against deleterious health effects of sulfur dioxide, including those with special health problems and the elderly. The secondary standard is designed to protect individuals against all possible effects of the gas on all aspects of the environment, including damage to plants, other animals, physical structures, and atmospheric visibility.
Blood tests are available for providing a differential diagnosis for sulfur dioxide poisoning, but signs and symptoms, along with recent patient history of possible exposure to the gas, are usually adequate to obtain a diagnosis for the condition.
Primary treatment for all cases of sulfur exposure is removal of the patient from exposure to the gas, providing access to clean air as quickly as possible. Skin irritation can best be dealt with by thorough washing of the exposed area with soap and water. Ingestion of the gas typically requires no special treatment, although rehydration and electrolyte supplementation may be needed in the most severe cases.
The primary method for avoiding health problems associated with sulfur dioxide exposure is to restrict to the extent possible one's exposure to the gas. This precaution is not a problem for most people since ambient sulfur dioxide concentrations are so low. Individuals who work at locations where sulfur dioxide concentrations may be higher than average may require specialized protective equipment, such as a full-face mask, gloves, clothing that covers as much of their bodies as possible, and respirators or plant equipment that removes sulfur dioxide from the work atmosphere.
As noted above, health problems arising out of exposure to sulfur dioxide generally clear up when a person is removed to a source of clean air. Large-scale release of sulfur dioxide may required specialized medical treatment, but should also result in relatively rapid recovery.
See also Asthma ; Mercury .
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Environmental Protection Agency (EPA), Ariel Rios Bldg., 1200 Pensylvania Ave. NW, Washington, DC, 20460, (202) 272–0167, http://publicaccess.supportportal.com/ics/support/ticketnewwizard.asp?style=classic , http://www.epa.gov/ .
David E. Newton, EdD