What Is 1,4-Dioxane? – Limiting Use in Consumer Products

Posted On: April 21, 2020

Consumers want to buy detergents, household cleaners, and personal care products formulated with ingredients which are:

  • produced to be in an environmentally-friendly method
  • safe for use in our households and communities
  • obtained using sustainable (i.e. carbon neutral) techniques

After meeting these critical objectives and important criteria, these ingredients must be effective and affordable for the consumer.

Surfactants are the main components of those household cleaning products. In the past decades, surfactants have replaced ineffective soaps and harmful solvents. Nonionic surfactants are very important ingredients of such household cleaners and personal care products, due to their efficiency at very low concentrations, their compatibility with water hardness, lack of residual deposits, and with several members of the chemical family exhibiting low eye and skin irritation.

As far as hydrocarbon efficiency goes (the ability to do the job asked by the consumer with the least number of hydrocarbons), nonionic surfactants perform extremely well. When nonionic surfactants and their derivatives are replaced by less effective surfactants, consumers immediately realize the difference in the product’s performance. For example, grease spots are not removed, floors remain greasy after mopping, and shampoos do not have the strength to clean oily residue from one’s hair.

The main class of these nonionic surfactants is ethoxylated molecules, which are cost-efficient, generally safe, and biodegradable. However, the synthesis of ethoxylates and some of their derivatives (such as alkyl ether sulfates) carries and/or generates small amounts of a by-product, namely 1,4-dioxane.

This by-product, 1,4-dioxane, is known to be a potentially hazardous substance. Therefore, it is worthwhile to understand what this by-product is, how it is formed, its potential harm, and ultimately the measures that surfactants manufacturers must take to reduce and/or remove it from ethoxylated products and their derivatives.

What Is 1,4-Dioxane and How Is it Formed?

In its pure form, 1,4-dioxane is an oxygenated organic compound that can be used as a solvent due to its high boiling point and miscibility with water.

While there are several ways to intentionally create 1,4-dioxane (as it is a fantastic solvent in the laboratory), its undesired formation can occur during the synthesis of ethylene oxide and ethoxylated surfactants. In these surfactants, 1,4-dioxane can be formed as a by-product during the ethoxylation process (in high amounts under acid-catalyzed conditions), in post-ethoxylation reactions (e.g., sulfation or phosphation) or even in certain post-ethoxylation storage conditions.

One of the most common sources of 1,4-dioxane is as a by-product of the ethoxylation reaction. The 1,4-dioxane molecule is formed when 2 moles of ethylene oxide (EO) react with one another to form the cyclic adduct.

Moreover, 1,4-dioxane can be formed in post-polymerization conditions, in which the ultimate and penultimate poly(ethylene oxide) units essentially ‘back-bite’ on the polymer, thus releasing the cyclic by-product (1,4-dioxane). This reaction, to form 1,4-dioxane, referred to as the polymer-adduct, is particularly prevalent in sulfation reactions to convert alcohol ethoxylates into alcohol ether sulfates (e.g., sodium lauryl ether sulfate, a.k.a. SLES).

Regardless if the 1,4-dioxane forms as the monomer- or the polymer-adduct, high amounts 1,4-dioxane in ethoxylated materials can be hazardous, which is why manufacturers take measures to control its formation in both the monomer- and polymer-adduct formation sequences.

What Is the Harm of 1,4-Dioxane?

Well, being miscible with water makes 1,4-dioxane ever-present in our world. As an example, according to the Environmental Protection Agency (EPA), 1,4-dioxane has been found in groundwater sites throughout the United States. However, the EPA suggests there is a minimal health risk when the amount of 1,4-dioxane contamination is below 35 ppb in drinking water.

Target concentrations of 1,4-dioxane in water vary by state, with some states adopting values lower than 35 ppb. This contaminant may also be found in the atmosphere; however, in air, it is readily subjected to photooxidation with an expected half-life of 1-3 days.

1,4-dioxane is not only found in wastewater, soil, and the atmosphere, but it can also be a contaminant that may be present in trace amounts in many consumer goods, including paint strippers, dyes, greases, antifreeze, as well as cosmetics, personal care, and home cleaning products.

Please note that 1,4-dioxane is not intentionally added to many of these products!  Instead, as mentioned above, 1,4-dioxane forms as a by-product during the manufacturing process of certain ethoxylated ingredients. These raw material ingredients are then used as foaming agents, emulsifiers, and cleaning aids in many consumer products.

1,4-dioxane has a variety of adverse health effects and is considered a likely human carcinogen by the EPA (EPA IRIS 2013) and The U.S. Department of Health and Human Services (DHHS 2011).

Recent Changes in the Regulatory Arena Concerning 1,4-Dioxane

New York State recently adopted a law banning more than trace amounts of 1,4-dioxane in cosmetics, personal care products, and cleaning formulations in response to 1,4-dioxane concerns with New York’s drinking water.

New York Governor Andrew Cuomo signed into law the New York Senate Bill No. 4389B/A 6295A to regulate 1,4-dioxane on December 9, 2019. The law amends or adds sections 35-0105, 37-0115, and 71-3703 of New York’s Environmental Conservation Law, effective January 1, 2022. This means that for the first time, New York is banning the sale of household cleaning, cosmetic, and personal care products that do not meet the limitations of 1,4-dioxane. Under this law, home and personal care products (other than cosmetics) containing more than 2 ppm 1,4-dioxane after December 31, 2022 and 1 ppm by December 31, 2023 will be banned. Regarding cosmetics, the limitation of 1,4-dioxane is 10 ppm by December 31, 2022.

Additionally, California is considering 1,4-dioxane under its Safer Consumer Products regulation for personal care and cleaning products. California adopted warning or disclosure requirements for 1,4-dioxane in products, and the Office of Environmental Health Hazard Assessment (OEHHA) has listed 1,4-dioxane as a carcinogen under Proposition 65 since 1988. OEHHA assigned it a safe harbor level for exposure of 30 µg/day NSRL.

The California Safe Cosmetics Act of 2005 requires manufacturers of cosmetics sold in California to provide the Division of Environmental and Occupational Disease Control in the Department of Health Services with a list of cosmetic products that contain a chemical identified as a carcinogen under Proposition 65. The Cleaning Product Right to Know Act of 2017 mandates a website posting of a list of nonfunctional constituents of cleaning products, which applies to cleaning products sold in California on or after January 1, 2020.

In any action, California may also include other markets such as paints/coatings, oilfield, crop protection, industrial and institutional cleaners and degreasers, etc. As 1,4-dioxane also occurs in many oxygenated solvents (such as butyl glycol), California’s upcoming regulation might initiate a new wave of solvent replacement by surfactants as it happened with the tightening of VOC rules over a decade ago.

These current and possible future regulations mean reducing 1,4-dioxane in every ingredient is now critical to ensure compliance.

Oxiteno and 1,4-Dioxane

In 2019, Oxiteno USA started one of the most advanced manufacturing sites in the world for the production of ethoxylates, including a broad array of nonionic surfactants. By combining natural or synthetic hydrocarbons (most commonly fatty alcohols) with ethylene oxide, Oxiteno synthesizes ethoxylates which are widely used in household and personal care products, while also supplying key ingredients for crop protection agrochemicals, industrial and institutional cleaners, oil and gas drilling and production auxiliaries, food additives, and for use in polymer synthesis.

Oxiteno sources several of its key raw materials for plant-based surfactants from renewable resources that are prepared using sustainable and eco-friendly methods. For instance, Oxiteno can utilize lauryl alcohol from palm plants that are harvested using sustainable farming methods (RSPO). Oxiteno´s new manufacturing plant in Pasadena (Texas) was designed using state-of-the-art technology, further enhanced by the know-how amassed by Oxiteno in its plants over 40 years of experience.

With Oxiteno’s state-of-the-art technologies along with its proprietary industrial practices, Oxiteno USA can reduce the presence of the 1,4-dioxane byproduct in its line of ethoxylates. The advanced technologies used by Oxiteno limit the 1,4-dioxane formation during the ethoxylation step and improve its ability for capturing/sequestering this by-product, ensuring safe and environmentally friendly products.

Oxiteno is acting today to ensure that its products are ready for the regulations of tomorrow. Using clever chemistry and novel engineering, researchers and engineers at Oxiteno have proven the ability of the Pasadena plant to efficiently reduce the amount of 1,4-dioxane by limiting the amount formed as a monomer-adduct and the amount released as a polymer-adduct. Additionally, Oxiteno is exploring newly synthesized products that are less prone to produce 1,4-dioxane as a polymer adduct.

Oxiteno has launched during 2020 American Cleaning Institute Congress its line of high purity low dioxane surfactants, whose certificates of analysis state less than 1 ppm of 1,4-dioxane. Those are low dioxane versions of Oxiteno´s main surfactants, but new low dioxane products can also be added to the list by request of formulators. Our line includes the following natural ethoxylated alcohols, polyethylene glycols, synthetic ethoxylated alcohols, and polysorbates:

Natural Ethoxylated Alcohols

Polyethylene Glycols

Synthetic Ethoxylated Alcohols

Polysorbates

Therefore, formulators do not need to replace cost-effective and well understood nonionic surfactants by lower-performing molecules that reduce customer satisfaction and have a higher carbon footprint. Technology allows Oxiteno to offer the surfactants needed by the US industry in conformance with the recently implemented regulations.

Oxiteno recognizes the importance of safety and is committed to both providing a safe work environment for their employees as well as making safer, more environmentally friendly products for all markets served.

For further questions or inquiries for low dioxane products, please feel free to contact Oxiteno USA today!