A consumer group is warning shoppers after its tests allegedly found the potential dangerous mineral in Playskool Crayons

Playskool Crayons

Parents are being cautioned that their children’s crayons could contain asbestos.

A consumer group is warning shoppers after its tests allegedly found the potential dangerous mineral in Playskool Crayons.

A green Playskool Crayon, purchased in a 36-count pack at Dollar Tree, tested positive for tremolite, a type of asbestos, according to the U.S. Public Interest Research Group Education Fund.

The fund tested the crayon as part of its Safer School Supplies Shopping Guide.

“The good news is that when we were testing three years ago, all sorts of brands came back with asbestos,” U.S. Public Interest Research Group toxics director Kara Cook-Schultz told CBS News. “Now it’s just this one.”

However, a Dollar Tree spokesman told PEOPLE in a statement that the company tested its products and they passed all safety and legal standards.

“The safety of our customers and associates is our top priority. Our Company utilizes a very stringent and independent testing program to ensure our supplies products meet or exceed all safety and legal standards. We are aware of the report and have since re-verified that each of the listed products successfully passed inspection and testing,” the emailed statement read.

Hasbro, which owns Playskool Crayons, said they are investigating the reports of asbestos.

“Product and children’s safety are top priorities for Hasbro. We are conducting a thorough investigation into these claims, including working with Leap Year, the licensee of the product,” said Hasbro’s July Duffy, SVP of Global Communications, in a statement to PEOPLE.

A spokesperson for Leap Year Publishing said “there is nothing more important” than the safety of its products

“All of our products, including the Playskool-branded green crayon mentioned by PIRG, are thoroughly tested by independent labs to meet or exceed all CPSC and Federal Standards for Safety,” John Sorenson, Vice President of Marketing, said.

“We are currently re-verifying that they are safe and free of any asbestos, as well as requesting a review of PIRG’s testing methods.”

According to Melanie Benesh, the Legislative Attorney for the Environmental Working Group, it is “very unlikely” that manufacturers “are actually intentionally adding asbestos to their crayons. More likely, there is another ingredient that they use that grows or is mined in places where asbestos also tends to be found and it contaminates the product.”

Benesh hopes to see the federal government, namely the EPA, take steps to address asbestos — as the chemical is not currently banned by the government.

“This is one of the areas where we really need the government to step in and impose stronger regulation, particularly with regards to asbestos,” Benesh said.