The company behind the popular Brazilian Blowout hair-straightening treatments will have to warn hairstylists that two of its most popular products can expose users to formaldehyde gas, according to the terms of a settlement with the California attorney general.

GIB, based in North Hollywood, had advertised its products as "formaldehyde free," according to the office of Atty. Gen. Kamala D. Harris, which announced the settlement Monday.

The state sued GIB in 2010, charging that significant levels of formaldehyde gas were emitted by the products in testing.

Under terms of the settlement, the products have to say on labels that the solutions "will expose you to formaldehyde [gas], a chemical known to the state of California to cause cancer."

Lynda Gledhill, a spokeswoman for the attorney general's office, said the warning will remind hairstylists to take precautions when handling the products.

"This is a consumer product safety issue," Gledhill said. "People need to be able to trust the products that they use."

A statement from GIB called the settlement "a fair and equitable resolution."

"The labeling and marketing and advertising changes agreed to in the settlement have already been in place for months," the statement said.

According to a survey released by the Environmental Working Group in April 2011, 28 out of 41 top salons offered Brazilian Blowout treatments, which became popular after it became known that several celebrities had had the treatments.

Some salon owners have joined class-action lawsuits against GIB. But hairdresser Janelle Hernandez, 35, who works at Via Romi Salon in Atwater Village, has not and she continues to offer the treatments.

"My clients love it and I believe in it," Hernandez said. "It's been really, really great for my business."