Asbestos shouldn't be in crayons, but poses almost no risk, researchers say
Seattle Times medical reporter
With the U.S. Consumer Product Safety Commission (CPSC) expected to release its report on asbestos in crayons by early next week, scientists say the substance shouldn't be used in crayons - but also that the chance of contracting a disease from it is very remote.
Because the tiny fibers are swathed in wax, it's hard to imagine how they could become airborne, inhaled, and cause lung disease, authorities say. And the overwhelming trend of studies suggests there is no cancer risk from swallowing fibers.
"Better to worry about an invasion of aliens from outer space," says Dr. William Robertson, director of the Washington Poison Center and a longtime researcher of toxic substances.
Laboratories of the CPSC are testing crayons for asbestos after the Seattle Post-Intelligencer reported May 23 that a laboratory it hired found asbestos in three brands of crayons: Crayola, Prang and Rose Art.
Last week, it said additional tests found no asbestos in Rose Art crayons and that the company has not used talc in its crayons for at least 15 months, and that Prang had denied having asbestos in its crayons.
ABC News also reported a lab it contracted with had found asbestos in Crayola and Prang. Crayola said an independent lab it hired found no asbestos in its crayons.
Authorities assume the contamination source is talc, which is used to strengthen the materials in crayons.
Asbestos is a known carcinogen when it enters the lungs and also can cause asbestosis, a chronic lung disease that can cause respiratory failure.
In 1989, the federal Environmental Protection Agency banned products containing the substance. But an appeals court rescinded the ban, saying the agency didn't give opponents enough time to be heard and that it failed to consider a less-burdensome alternative.
Experts agree that asbestos should not be used in any products. But if it is bound up in another substance and left undisturbed, it is difficult for it to enter the body, they say. Crayons would be a most unlikely source for transmitting the fibers, several experts said.
David McCumber, senior editor for the Post-Intelligencer, said it's still important for people to know asbestos may be in crayons.
"I don't think anyone would say that any exposure to asbestos by a child would be an acceptable risk," said McCumber.
However, Robertson, University of Washington professor of pediatrics, said, "The potential for it to cause a problem (from crayons) is slim and nil."
Robertson said the only way he could imagine the fibers becoming airborne from a crayon would be through applying intense heat, as with a torch. Simply melting crayons - done in some art projects - would not provide enough heat, he said.
He said a child eating hundreds of crayons over several years probably would have an increased cancer risk so tiny it would not be worth worrying about.
UW scientists examined the risk of cancer from Everett drinking water, supplied by the Sultan River, because it contains "an unusually high concentration" of asbestos. The 1983 study analyzed cancers of the mouth, pharynx, respiratory system, digestive system, bladder and kidneys.
Researchers reported in the journal Environmental Health Perspectives that they had "found no convincing evidence for increased cancer risk from imbibed asbestos."
Other drinking-water studies and studies in which animals were fed asbestos also show no increased cancer.
A group of scientists from the U.S. Department of Health and Human Services in 1987 assessed all available studies concerning ingestion of asbestos and couldn't determine a specific, overall risk of cancer.
"The work group believes that the cancer risk associated with asbestos ingestion should not be perceived as one of the most pressing potential health hazards facing the nation," the group reported in Environmental Health Perspectives.
"However . . . this potential hazard should not be discounted, and ingestion exposure to asbestos should be eliminated whenever possible."
Dr. Michael Morgan, UW professor of environmental health, said the statement amounted to "prudent avoidance" of nailing down the risk. The risk is so small, he said, it probably can't be found in any reasonably sized human study.
"The overwhelming conclusion to me is that ingested asbestos is not a hazard. It's only a hazard if it's inhaled," said Morgan.
Like Robertson, Morgan said it's difficult to envision how asbestos fibers in crayons could find their way to the lungs.
Specks of crayon dust, he said, would likely be too large to get to the lungs and would be coughed up or excreted in mucus. A particle must be smaller than about 10 microns - 10 one-thousandths of a millimeter - to get down into the lung tissue. Such a particle cannot be seen by the naked eye.
Dr. Drew Brodkin, UW associate professor of internal medicine and environmental health, said he still is concerned there might be some potential for inhaling crayon dust - perhaps from a crayon being sharpened or erased from a page.
"It needs to be investigated by industrial-hygiene experts," said Brodkin.
No one knows how many fibers might be inhaled with a puff of crayon dust. And scientists haven't calculated the number would be hazardous to children, who are assumed to be more vulnerable than adults.
But the federal Occupational Safety and Health Administration has calculated that a worker can be exposed to 100,000 asbestos fibers per cubic meter of air for eight hours a day and suffer no ill effects.
This theoretically means that an adult could be safely exposed to 33,000 fibers per cubic meter of air per 24-hour day, says Dr. Dan Luchtel, UW professor of environmental health and an expert on asbestos. Adults breathe an average 10 cubic meters a day; children breathe from three to seven cubic meters a day, depending on their age and activities.
Actually, asbestos fibers are all around us in ambient air.
Luchtel cited studies that found urban-outdoor air contains about 100 fibers per cubic meter of air, meaning the average adult would breathe in about 1,000 fibers a day. He estimated that if 20 percent of those fibers, or 200, actually deposited in the lungs, perhaps 100 would be rapidly cleared and 100 might stay in the deep lung tissue.
Autopsy studies of elderly urban residents have shown millions of fibers embedded in the lungs, Luchtel said.
Luchtel said it would seem highly unlikely that crayons are an asbestos hazard. But he agreed with other experts that products containing asbestos should not be sold.
If talc must be used to bind the materials in crayons, he said, there are mines that produce it without asbestos.
"They shouldn't be introducing asbestos in crayons. It doesn't make sense," he said. "You can avoid the problem in the first place."
Morgan agreed using asbestos-free talc is a relatively easy way to allay concerns about any hazard.
But meanwhile, he said, any small risk that could exist is not sufficient to warrant throwing away a child's crayons or even to justify a recall.
"Forget about this issue," he said, "and worry a lot more if there's a smoker in the house."
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