SAN FRANCISCO (WPVI) --If you're already working on your kids' Halloween costumes, here's something to consider - the thick makeup or face paint you might use to complete the look could have more in it than you bargained for.
A new study by CalPIRG and the Breast Cancer Fund looked at 187 cosmetics and face paints marketed for kids and Halloween.
"At least 50 percent of them had at least one chemical of concern in that," said Breast Cancer Fund Director of Science Sharima Rasanayagam.
Sometimes they're long and cryptic ingredient names like DMDM Hydantoin.
Rasanayagam says that's, "A preservative that releases tiny amounts of formaldehyde over time to help stop bacterial growth in the production, but formaldehyde is a carcinogen."
Or in the case of petrolatum, they say it's not the ingredient, but what comes with it.
"It can be contaminated with PAHs, which is a carcinogen that you also find in diesel exhaust," she said.
The groups say they found the ingredients across all brands, even the high-end ones.
"Labeled hypoallergenic, non-toxic and FDA approved. But those terms mean absolutely nothing because there are no legal standards," said mother and author Stacy Malkan.
But the study authors say just as concerning to them is the stuff that's not listed in the ingredients, stuff including heavy metals like lead.
They say the darker the face paint, the higher the levels. And companies aren't required to test them.
"They make these pigments out of things that come out of the ground, and lead is sometimes in the ground," Rasanayagam said.
This is their second study of this type. The first, in 2009, was still on some parents' minds.
"Chloe is gonna be Batman, and Hunter will be Robin," said parent Flora Gibson.
But Gibson says no one's dressing up as the Joker.
"I'm very conscientious of what's going into their bodies," she said.
The groups are lobbying Congress.
"We have a right to know what's in these products," said Malkan. "So that's why we have to change the laws."
The Personal Care Products Council, which speaks for the industry, said their own scientists are looking into the study, but they weren't ready to comment just yet.
UPDATE: On Friday, the Personal Care Products Council, which speaks for the industry, released a statement calling the study "speculative and misleading." The statement goes on to say: "Consumers are often confused by scary sounding claims about chemical risks that may sound science-based, but do not reveal anything about actual risk levels. These ingredients have a long and well documented history of safe use." Click HERE to read the full statement.
For details on this new study, click here.