Certain crayons and other kids toys sold in popular chains such as Toys R US, Dollar Tree, Amazon, and Party City have tested positive for asbestos.

The Environmental Working Group Action Fund hired a private lab through a sister group and found 4 out of 28 boxes of crayons tested positive for asbestos, and is calling for regulatory and policy changes,  according to CNN.

The microscopic asbestos fibers breathed into the lungs has been linked to mesothelioma, lung disease and lung cancer. The exposure to asbestos happens as soon as the asbestos-containing material is released and the particles become airborne.

Besides the crayons, the lab found traces in black fingerprint powder in The Edu Science Deluxe Forensics toy Lab Kit from  ToysRUs.com, as well as white finger print powder included in  the Intelligence Secret Spy kit sold on Amazon.

Dr. Jerry Paulson, the former chairman of the American Academy of Pediatrics’ Council on Environmental Health, was particularly concerned about the powered products, according to the report.

“Powders make this material much more available to the lung, where asbestos does its damage,” Paulson said.

The EWG Action Fund purchased the products, either through chain stores in the San Francisco bay area or online between Fabruary and May of this year, and had them tested at The Scientific Analytical Institute in Greensboro, North Carolina.

The retailers involved indicated they would take the issue seriously and investigate. In a released statement, Toys In R Us spokeswoman Kathleen Waugh indicated said  “The safety of our customers is, and always has been, our highest priority…At this time, we are reviewing the referenced report, along with supplier test reports, to ensure full compliance to our strict safety standards.”