Parents may want to take a second look at their children's school supplies this season.
The results of lab tests detailed in a report released Tuesday found traces of asbestos, lead and other dangerous chemicals in a number of popular school supplies.
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The US Public Interest Research Group Education Fund tested dozens of typical classroom materials for toxins. While most were nontoxic, some crayons, markers and binders received a failing grade.
Here are some of the products that tested positive for toxic substances:
Playskool crayons (36 count)
This box set, purchased at Dollar Tree, has traces of asbestos, the report found. The chemical can appear in the talc that is used in crayon manufacturing, according to the report.
If ingested or inhaled, asbestos can cause severe damage to a person's health, including lung cancer and mesothelioma.
It is unclear if other versions of the crayons have been affected.
"Product and children's safety are top priorities for Hasbro," the toy company said in a statement to CNN. Hasbro owns the license to the product. "We are conducting a thorough investigation into these claims."
Dollar Tree spokesperson Randy Guiler said the retail chain is "aware of the report and have since reverified that each of the listed products successfully passed inspection and testing."
EXPO dry erase markers with scented ink
The markers, purchased on Amazon, were found to have traces of BTEX, which refers to four chemicals that have been linked to liver, kidney and immune system damage. One of the four chemicals, benzene, is a carcinogen.
It is unclear if unscented versions of the markers also contain traces of BTEX.
In a statement to CNN, EXPO said in part, "We are aware of the report by U.S. Public Interest Research Group and can confirm that our products meet all applicable regulatory and safety standards. Additionally, all EXPO Dry Erase Markers have been examined by an independent, certified toxicologist from Duke University Medical Center and are certified as safe, non-toxic by The Art & Creative Materials Institute, Inc. (ACMI)."
CNN has not yet heard back from Amazon for comment.
The Board Dudes six magnetic dry erase markers
The Board Dudes, another brand of dry erase markers that were also purchased on Amazon, tested positive for traces of BTEX chemicals.
Amazon and Mattel, which owns The Board Dudes' parent company, have not responded to CNN's request for comment.
Jot 1-inch 3-ring binder in blue
This Dollar Tree binder tested positive for traces of phthalates, a group of chemicals used to soften plastics.
According to the report, research suggests the chemicals can cause problems for children, including issues with development, asthma and childhood obesity.
It is unclear if other versions of the binder also contain phthalates.
'Need for constant vigilance'
The organization urged parents to be mindful of the potential presence of toxins when buying school supplies.
"The presence of toxic hazards in school supplies highlights the need for constant vigilance on the part of government agencies and the public to ensure that school supplies containing toxic chemicals are removed from store shelves," the report says.
The report is accompanied by a shopping guide for parents that lists products that tested safe for use.
"We want to give parents and teachers the option to choose school supplies that do not contain toxic chemicals."