Asbestos, once a common building material, has surfaced in an unexpected place: children's crayons. As The Washington Post reports, tests revealed that Playskool-brand crayons sold at Dollar Tree, Amazon, and DollarDays.com contained trace amounts of the toxic substance.

Asbestos is a carcinogen that can be harmful when inhaled. In 1989, the EPA introduced the Asbestos Ban and Phase Out Rule in light of reports that exposure to the material was linked to deadly illnesses, including lung cancer and mesothelioma. Though asbestos is heavily regulated in the U.S. today, it isn't outlawed completely.

Its presence in crayons was identified through tests conducted by the U.S. PIRG Education Fund. As part of the fund's campaign for safe back-to-school products, it also found phthalates in Jot-brand blue three-ring binders and benzene in Board Dudes-brand dry-erase markers. (The report notes that the Consumer Product Safety Commission has already recalled two brands of water bottles, GSI Outdoors Kids insulated water bottles and Base Brands Reduce Hydro Pro Furry Friends water bottles, for the presence of lead.)

Hasbro, Playskool's parent company, and Leap Year Publishing, which manufactures the crayons, say they are investigating the test results. In the meantime, parents looking to purchase asbestos-free school supplies before September can find PIRG's safe shopping guide here [PDF].

[h/t The Washington Post]