The 1,4-Dioxane Problem: Why Regulations Are Tightening
In part one, we discussed how ethylene oxide is an important base chemical for producing a wide range of chemical intermediates and formulation ingredients. As with most chemical reactions, there is a potential for the formation of byproducts. When two molecules of ethylene oxide react with each other during the ethoxylation process instead of with the intended reagent, they form a six-membered ring called 1,4-dioxane. This unwanted byproduct has become one of the personal care industry’s most pressing concerns.
The Hazard
1,4-Dioxane carries some concerning classifications. The National Toxicology Program calls it “reasonably anticipated to be a human carcinogen,” while the International Agency for Research on Cancer classifies it as “possibly carcinogenic to humans” based on animal studies. Beyond cancer concerns, it’s known to affect multiple organs including the liver, kidneys, and central nervous system.
Unlike ethylene oxide, which breaks down quickly outside of neutral pH conditions, 1,4-dioxane is moderately persistent in the environment. Improper handling of dioxane and dioxane-contaminated chemicals has resulted in high groundwater levels in some areas of the country which persist long after the initial contamination.
The Regulatory Patchwork
Regulations vary wildly depending on where you are. The European Union’s Scientific Committee on Consumer Safety recommended a 10 ppm limit in 2015. ASEAN countries implemented 10 ppm limits by 2023.
At the end of 2019 New York State’s Governor signed into law the nation’s strictest rules. For cosmetics (leave-on products), the limit is 10 ppm. For personal care products (rinse-off items like shampoos and body washes), it’s now just 1 ppm. That’s incredibly tight—and the law includes provisions to potentially make limits even stricter if technology allows.
The Industry Response
The personal care industry has been proactive in reducing dioxane exposure and household products are now not far behind. Surveys conducted before the NY State law took effect showed that about 65% of cosmetic products already contained less than 1 ppm of dioxane, and 84% were below 5 ppm. Manufacturers had been working hard to reduce contamination levels, but the newest regulations are pushing the industry toward eliminating ethoxylates altogether. In parts 3 and 4 we’ll examine the technologies being used to accomplish that.
