Unilever has brought down more than a dozen of aerosol dry shampoos because the company said that they may contain "elevated levels" of benzene, which is a naturally occurring chemical which can be a carcinogen at high levels of prolonged exposure.

What is Benzene ?

Benzene is a colorless or a light yellow liquid which smells sweet and it is highly flammable, according to the Centers for Disease Control and Prevention. The agency said that it's one of the top 20 chemicals that's used in the US. It's a building block for other chemicals and materials according to the American Chemistry Council.

How does benzene come in your dry shampoo?

Chris Cappa, a professor of environmental engineering St the University of California at Davis, stated butane, which is a petroleum product, it is a common propellant in spray cans. And if the refinement process of butane "isn't very good," then one can end up with gas that contains other components from the crude oil like benzene. “That gas is where, most likely, this benzene is coming from,” Cappa said.

“If you want to limit the potential exposure to things like benzene from contaminated spray cans, then you can make different choices about the products that you use,” he said.

Now is benzene harmful to us ?

By breathing, digesting or otherwise absorbing benzene for long periods of time could lead to serious health issues like cancers like leukemia and other kind of blood disorders, according to the Food and Drug Administration.

It can also slow down the amount of red blood cells which is produced by the bone marrow, leading to anemia, says CDC. It could also damage the body's immune system by changing the blood levels of antibodies. People who breath high levels of benzene could become drowsy, dizzy and confused and could have headaches, irregular heartbeat and tremors.

Sources - https://www.washingtonpost.com/wellness/2022/10/25/benzene-dry-shampoo-recall-unilever/