If you use dry shampoo to keep your hair fresh between wash days, you may want to check the brand.

A number of dry shampoos have been voluntarily recalled over high levels of a cancer-causing chemical, benzene, which has been linked to leukemia and other blood disorders, according to the Food and Drug Administration.

But a class-action lawsuit says Unilever, the company that makes the products, knew about the chemical long before the recall. 

“It’s always been known that this is a dangerous drug,” said Dr. June McKoy, professor of medicine at Northwestern University School of Medicine. “I cannot believe that Unilever can say that they were not aware of it. They knew, or should have known, because the public knows benzine at this point is dangerous.”

Benzine is a popular chemical, McKoy said, found in gas, shampoos, pesticides and in the workplace. 

“We know that what benzene does, it can get into the bone marrow, the soft portion of the bones, where blood cells are made and they can actually change the genetic makeup of the bone marrow,” she said.

Changing the DNA makeup is what can lead to leukemia. 

The lawsuit claims that Unilever knew about the harms of benzene since November 2021, after an independent laboratory submitted a petition to the FDA. 

However, the company did not warn consumers or pull products out of sale until Oct. 18, 2022, when they released a statement issuing a voluntary recall, according to the lawsuit. 

“Failure to warn. Failure to actually pull the product from the market early enough exposed people who would normally not have been exposed from that period of time when they claimed that they were made aware of it, placed those people in harm,” McKoy said. 

McKoy suggests that individuals who used the recalled products should stop using them, and get tested to ensure proper red and white blood cell counts, as well as platelets. 

However, she recommends that individuals keep the products as proof. 

“I would actually pack those products and keep them because you might need take those as proof that you were using these particular products to an attorney who might be handling your case,” she said.