It's back-to-school season, which means it's also back-to-school shopping season for parents across the country.

While we fret about getting the right calculator or math set, most parents aren't concerned they could be buying toxic school supplies for their young children.

But a watchdog group says that's just the case, and they're warning parents which supplies to avoid.

Toxic Ingredients In School Supplies

Each year, the U.S. Public Interest Research Group conducts random tests on school supplies.

The consumer protection group got some scary results back this year, including on tests of brand name items from nationwide discount chains.

The group purchased 27 items and sent them to an independent lab, where many of them tested positive for carcinogens and toxic substances.

It's worth noting that many of the substances found were usually detected in small, trace amounts.

In fact, it's actual legal for some school supplies to contain harmful ingredients like asbestos. Despite the fact that experts warn children should not be exposed to it.

PIRG worries that most parents have no idea what's lurking in their family's shool supplies.

Toxins, Carcinogens, And More

Here are some of the most distressing findings from this year's test by U.S. PIRG:

• A 36-pack of Playskool crayons purchased from Dollar Tree tested positive for tremolite, a form of asbestos. Asbestos is a fibrous mineral that can cause cancer and mesothelioma if it's inhaled.
• A Jot brand three-ring binder purchased from Dollar Tree tested positive for phthalates, a kind of plastic softener linked to cases of asthma, obesity, attention deficit disorders, and lowered IQ scores in children.
• Two water bottles made by Base Brands tested positive for lead, a neurotoxic chemical poisonous to almost every organ in the body. These water bottles have since been recalled.
• The Board Dudes brand dry-erase markers, sold on Amazon.com, tested positive for benzene, a probable carcinogen that is believed to damage reproductive organs, the liver, kidneys, and immune system.

In past years, the Center for Health, Environment & Justice ordered their own study of children's lunch boxes and bags.

In one of their tests, a Disney Princess lunch bag tested positive for phthalates. If the bag had been a children's toy, the level of phthalates would have been 29 times the federal limit on that substance.

A Dora the Explorer backpack tested positive for phthalates at 69 times the allowable limit.

How can I keep my children safe?

While the news is pretty scary, U.S. PIRG says it's easy to avoid buying harmful products.

The group recommends looking for the Art and Creative Materials Institute's "AP" label on products. This tag means they have been certified nontoxic.

A product's label will also say if it met the Consumer Product Safety Comission's guidelines in third-party laboratory testing.

"Based on our testing, we know that most manufacturers make safe school supplies," said Kara Cook-Schultz, U.S. PIRG's education fund toxics director.

"We're calling on the makers of unsafe products to get rid of toxic chemicals and protect American schoolchildren."

U.S. PIRG has put out their own helpful shopping safety guide. You can also read the full report on their website.

Be careful to check for safety tags on your back-to-school products!

[H/T: KTVU, WTOP, Duluth News Tribune]