1,4-Dioxane – a threat in products?

1,4-Dioxane is not an ingredient in cosmetic and personal care products, it’s an impurity.

The cosmetic and cleaning products industries have focused on decreasing contamination by 1,4-dioxane as much as possible, with great success.

According to the 2022 AICIS assessment,¹ ‘contaminant levels of 1,4-dioxane have declined substantially over time’. For example, the majority of cosmetics now contain 1,4-dioxane levels below 10 parts per million (ppm). In other words, less than 0.001%.

Impurity – why? 1,4-Dioxane is an unavoidable by-product of the ethoxylation reaction, which is used to make many chemicals including some surfactants. Careful control of the reaction conditions and subsequent removal can minimise 1,4-dioxane levels but it cannot be removed completely.

The European Scientific Committee on Consumer Safety (SCCS) estimated the lifetime cancer risk posed by trace 1,4-dioxane levels in cosmetic products.³ (This kind of estimation considers long-term exposure to multiple low-level of a substance.) The SCCS determined that ‘a trace level of 1,4-dioxane in cosmetic products of ≤10 ppm is safe’. 

The United States Environmental Protection Agency (EPA) evaluated the risk to consumers from using surface cleaners, dishwashing products and laundry detergents that contain 1,4-dioxane as a contaminant. It concluded that these uses ‘did not present an unreasonable risk’⁴.

Just because 1,4-dioxane is in a product doesn’t mean it will cause cancer in the amount present.

You need to consider the level of exposure (how much 1,4-dioxane) and how you are exposed (skin contact, inhalation, consumption, injection?). For more on this, see Extra! Extra! Toxic chemicals found in... (Dose matters!)

Going back a while was the headline ‘Toxins found in children’s shampoos’⁵. The kind of headline that causes alarm. And outrage. How DARE they harm our babies! The article went on to report that 1,4-dioxane was in some baby products at approximately one part per million (1 ppm, or 0.0001%). A scary headine, but a very very low amount.

You would need to wash your baby’s hair 620 times a day, every day, to get close to a harmful level of exposure to 1,4-dioxane from baby shampoo, according to the Canadian Health Department.⁶

Simply a media beat-up.

Skin contact is the main way you are exposed to ingredients in cosmetics and personal care products. And many of these products would be rinsed off your skin after a short time.

It’s known that human skin doesn’t absorb much 1,4-dioxane. One study found that only 0.3% of an applied dose of pure 1,4-dioxane penetrated excised human skin when it was allowed to evaporate, and only a little more (3.2%) penetrated when prevented from evaporating⁷.

Skin absorption studies by the US EPA ‘determined that 1,4-dioxane evaporates readily, further diminishing the already small amount available for skin absorption, even in products that remain on the skin for hours’.⁸

1,4-Dioxane is included in Schedule 6 of the national Poison Standard⁹.

How does that protect you? It means cosmetic/personal care products that contain more than 10 ppm 1,4-dioxane need to be labelled with the word ‘POISON’ and have a child-resistant closure.

As you can imagine, this effectively sets a 1,4-dioxane limit of 10 ppm in cosmetics and personal care products, because what brand will want to have to slap a POISON warning and protective cap on its (for example) baby wash? Not great for sales.

AICIS, Australia’s industrial chemicals regulator, assesses chemicals like 1,4-dioxane as required. Like if new information comes to light or an overseas jurisdiction changes its assessment of risk. AICIS considers the public risk from 1,4-dioxane to be suitably managed by the existing controls in Australia.