Could dry shampoo give you cancer? We asked a cosmetic chemist

Three cans of this hair product are sold every second - but testing has revealed it could contain a chemical linked to cancer. Do the claims about health risks stack up? A cosmetic chemist weighs in.

Dry shampoo has become the bogeyman of hair products, after multiple class actions, product recalls and concerning lab tests. Is it warranted? Source: SBS

An independent lab in the US made waves last November when it claimed some popular dry shampoos contain cancer-causing chemicals.

To prove it, the Valisure lab released results showing one in seven of the products it tested had “high levels” of benzene – a known carcinogen.

One of the named brands was Batiste, which markets itself as “Australia’s no.1 dry shampoo brand”. Three cans of Batiste dry shampoo are sold every second worldwide, News Corp reports.

Outraged consumers turned on Batiste. The parent company settled a class action for US$2.5 million ($3.8 million), agreeing in August to refund customers who had bought the products.

Batiste is one of the most popular brands of dry shampoo, marketing itself as "Australia's no.1 dry shampoo brand". Source: Getty / Michael Bezjian

The Feed has contacted Church and Dwight, Batiste’s parent company, for comment, but hadn't received a response at the time of writing.

Dry shampoo is a common hair product that’s sprayed into hair to absorb dirt and oil. It prolongs the time you can go before washing your hair, making it a convenient option for busy people. It was first commercially produced in the 1940s.

Sandra (not her real name), a busy working mum, uses dry shampoo weekly.

“Washing and styling my hair takes two to three hours I don’t have midweek. It cuts into dinner/lunch making, work, helping kids with homework,” she said.

She’s now looking into alternatives.

“Hopefully the damage hasn’t been done for my health already.”

Big companies such as Unilever and Procter & Gamble have issued voluntary recalls, after discovering benzene in their own dry shampoos.

But should we be ditching dry shampoo?

Can dry shampoo cause cancer?

The culprit is benzene – a common chemical that’s also found in petrol, cigarette smoke and crude oil. It’s known to increase the risk of blood cancers, such as leukaemia.

In Australia, the Therapeutic Goods Administration (TGA) doesn’t regulate cosmetics - but it does restrict benzene levels in sunscreen to two parts per million.

Valisure’s test results showed some dry shampoos were over 10 times this level.

Michelle Wong is a Sydney-based cosmetic chemist and science communicator, who's known online as Lab Muffin Beauty Science.

Michelle Wong is a certified cosmetic chemist and science communicator. Source: Supplied

She’s previously worked with benzene in research labs – and believes the health risks of dry shampoo are exaggerated.

“Benzene is everywhere,” she told The Feed.

“The numbers in the products were in the low parts per million…it is probably equivalent to the exposure you get for breathing in the city for half a day.”

Benzene isn’t intentionally added to dry shampoo. It’s used in the manufacturing process of other ingredients like the propellant (the gas that helps you spray the shampoo) or the solvent, but can end up contaminating the actual product.

Benzene is an extremely common chemical - the word for "petrol" is derived from "benzene" in countries such as Germany and Iran. Credit: Jakob-Schlothane

Wong said most examples of benzene-related cancer are people who work in industries that use large quantities of the chemical – not the trace amounts found in cosmetics.

“If you are worried, you can always use it in a well-ventilated place, which you probably should be doing anyway, because inhaling things is generally not great for you,” she said.

Doubts cast over independent lab

Dry shampoo isn’t the only product Valisure is targeting – the lab has also brought attention to benzene in hand sanitiser, sunscreen and deodorant.

“They kind of have a history of overestimating the amount of contaminants they find in products,” Wong said.

The US regulator, the Food and Drug Administration (FDA), has raised concerns over the lab’s scientific methods.

Dry shampoo is a convenient way to absorb oil from hair, for people who wash their hair less frequently. Credit: Karolina Grabowska

After an inspection of the lab, the FDA wrote a letter to Valisure saying it “failed to provide any supportive evidence or reports that your methods have been validated, verified, or suitable for use”.

The FDA also wrote a peer-reviewed paper claiming Valisure used a flawed test method that “led to over-reporting”, after the lab found a carcinogen in the diabetes drug metformin.

Online misinformation is causing health scares

Wong said consumers are often misled by online content creators who spread misinformation about the risks of cosmetic products.

“When we hear that something that we use in everyday life is causing long-term health problems, it kind of hooks into our emotions,” she said.

“It’s a strategy that's used to a lot to great effect on places like TikTok. It's a really good way of getting videos to go viral.”

She encourages people to do their research and listen to reliable experts before deciding to dump a product.

“I get really upset when I see people throwing all their products out … environmentally and financially, it just stresses me out,” she said.

“Just put it to the side, look deeper into it, and then at least you can rescue your product instead of just chucking them in the bin.”