The back-to-school shopping season is underway and parents across New Jersey have started to purchase new items for their children.

But the U.S. Public Interest Group says that some school items may contain dangerous chemicals and should be avoided.

The group says that it tested a variety of school items like markers, binders and crayons.

Trace amounts of asbestos were found in Playskool crayons sold at Dollar Tree. Asbestos can cause lung cancer and mesothelioma.

Lead was discovered in recently recalled children's water bottles. Base Brands Children's Reduce Hydro Pro Furry Friends bottles have since been removed from inventory at Costco and L.L. Bean.

And benzene was found in Board Dudes brand markers. Benzene is a known carcinogen linked to leukemia and disruptions in sexual reproduction and liver, kidney and immune system function.

U.S. PIRG suggests that parents should look for certain labels on product when going back-to-school shopping. Items with an AP label lets consumers know that the products are nontoxic. Consumers should also look for a manufacturer's "children's product certificate" on the product, which assures parents that the product has been tested in a third-party laboratory.