A former employee of a large aerospace company telephoned the Deseret News with concerns about the use of methylene chloride in that business. It's a solvent widely used in industry to degrease metal and strip paint.
Sometimes, as workers assemble parts and clean off epoxy resins using methylene chloride, they wear a charcoal-activated air filter, he said. But the filter data sticker says it can't protect against this solvent.In this company's production process, rolls of material are cut and glued together on glass-topped tables. "Even though there are other ways to clean the tables, the common use is to use this methylene chloride to clean the tables off," he said.
"They buy it in 55-gallon drums." Gallon and half-gallon containers are then used, with people dumping solvent on rags to clean material. He was concerned, because the solvent has been known to cause cancer in laboratory animals.
Frank Kane, an Office of Safety and Health Administration spokesman in Washington, said a proposed new rule on methylene chloride is expected to be issued early this fall, changing the permissible exposure levels.
If anyone is concerned about worker exposure to chemicals, he can call the local area office of OSHA and file a complaint. If the office decides the complaint is justified, it can hold a safety inspection.
"They usually are without advance notice," Kane said. The office in Salt Lake City can be reached at 524-5080.
Arthur Gass, OSHA's project officer for methylene chloride, also in Washington, said the solvent is widely used in industry. Also, many minor uses are known, such as in hair sprays used by cosmetologists not the type of hair spray available over the counter.
"Methylene chloride is being removed from the hair spray business and being replaced by other products, chemical substitutes," he said.
Since around the turn of the century, methylene chloride has been known to produce effects like loss of awareness and irritability. It was once used in France as an anesthetic for labor and delivery of babies, but was dropped because it was irritating.
The solvent is known to produce carbon monoxide at the cellular level, an effect something like smoking a pack of cigarettes a day.
In 1985, the National Toxicology Project found that methylene chloride can produce cancer of the liver, lungs and some breast cancers among mice and rats. Industry experts contend this doesn't mean any cancer can be produced in humans.
Of more concern, OSHA has learned that in confined spaces methylene chloride "is quite deadly." From one to five Americans die every year because of exposure to the solvent fumes, working in confined spaces, sometimes even within the official standard.
Gass says that "people are either misusing it or don't have enough ventilation. New workers who are less trained, less conscious of the hazards involved, get into trouble using it."
People have died in transferring the solvent from tank to tank, using hoses that allowed some to escape.
In South Carolina two years ago, workers were stripping paint from an electric plant floor. A depression on the floor allowed solvent to accumulate. Three workers were killed and several others hospitalized.
At high exposure levels, methylene chloride can damage the brain's speech centers. Gass said 141 cases of acute effects are known, though they aren't permanent.
A physician in Cincinnati said workers have fainted while cleaning cars' plastic parts with the solvent. They may be knocked out from a few hours to a day, then awake with speech disorders finding the talk of others to be garbled, having speech defects themselves.
After one or two years of speech therapy, they have 95 percent of their speech capacity. "So there is some loss of awareness and there is some effect on tracts of the brain that are concerned with speech and language," he said.
If a worker were to pass out beside some dangerous machinery, he could be killed in an industrial accident.
So OSHA now is looking at the carcinogenicity data to see if industry is correct in saying that mouse data is not in this case a suitable model for man.
The exposure standards for methylene chloride were set in 1971. They are 500 parts per million, with a ceiling of 1,000 ppm, and a short-term exposure limit (15 minutes within a two-hour period) of 2,000 parts per million.
The National Institute of Occupational Safety and Health, which by statute advises OSHA, once recommended that the new standard should be 75 parts per million, period. Now it is saying that in light of the mouse cancer data, exposure should be as low as feasible.
Methylene chloride is an example of the pernicious danger from industrial chemicals. As more becomes known about it, researchers discover their earlier assumptions of safety were wrong.