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Analytical Testing for 1,4-Dioxane in Soaps, Shampoos and Personal Care Products

1,4-Dioxane (dioxane) is found in household products such as detergents, shampoos, body lotions, dishwashing soap, pharmaceuticals and cosmetics. It is a manufacturing by-product of the ethoxylation process. Ethoxylation is a chemical process in which ethylene oxide (1,2 epoxyethane) is added to fatty acids in order to make them more soluble in water. This process makes degreasing agents such as sodium lauryl sulphate less abrasive and gives products enhanced foaming properties. Unless removed under precise conditions, small amounts of dioxane are produced during ethoxylation. Dioxane, however, is unlisted in the ingredients of most products, as it is generally considered an accidental by-product of the production process. In personal care products dioxane enters

the environment via waste streams, such as wastewater treatment plants and landfills. The U.S. Food and Drug Administration (FDA) has provided guidance to manufacturers about a process called “vacuum stripping” to help minimize the amount of dioxane in their final product. Manufacturers of personal care products should conduct laboratory analysis to determine the levels of dioxane in their products, and manufacturers using dioxane in their processes should analyze their waste streams for possible dioxane content.

Analytical Methodology

Complicated matrices like soap, shampoo and lotions can cause significant analytical problems, making it difficult to obtain accurate and reproducible sample concentrations, especially at lower limits of detection in the part per billion range. To address these issues, Columbia Analytical uses a heated headspace sampler with a GC/MS. A sodium chloride-treated aliquot of sample is heated to drive the dioxane into a sample vessel’s headspace. This headspace sample is directly injected into the GC/MS in SIM mode to measure the dioxane concentration. The use of this method allows for a sufficient dynamic range and also decreases the time to reach equilibrium from one hour to less than 15 minutes. To enhance the accuracy and precision of the GC/MS SIM method, the labeled compound dioxane-d8 is used as the internal standard.

Analytical Testing for 1,4-Dioxane in Soaps, Shampoos and Personal Care Products

Sample Matrix Test Method Reporting Limit(μg/L or ppb)

Shampoos, Soaps and Personal Care Products

EPA 8260B SIM, isotope dilution (headspace extraction) 5.0 *

Aqueous liquids EPA 8260B 100

Aqueous liquids EPA 8270C SIM, LVI andisotope dilution 1.0 **

Soil and Sediment EPA 8270C SIM, LVI andisotope dilution 2.0 μg/Kg

*Due to the difficulty with some matrices a 5-fold dilution may be performed, resulting in an increased Method Report Limit of 25 ppb.**Lower detection limits are available.

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800.695.7222

Health Risks of Dioxane

The EPA has classified dioxane as a “Group B2” probable human carcinogen of low carcinogenic hazard. Dioxane is presently banned throughout the European Union and has been listed since 1988 as a chemical known to cause cancer or reproductive toxicity under the State of California’s Proposition 65. The National Institute for Occupational Safety and Health (NIOSH) indicates that dioxane can cause symptoms including dizziness, vomiting, unconsciousness, abdominal pain, and eye irritation. The NIOSH international chemical safety card on dioxane also indicates that dioxane can be absorbed through the skin, which is of considerable concern, considering its ubiquity in many personal care products.

There is little scientific data available on the effects of long-term exposure to dioxane on human health. However, exposure to carcinogenic compounds is believed to have the strongest effect during growth and development stages. Therefore, the greatest concern about dioxane in personal care products is the potential exposure of children. No official information exists about specific age-related dioxane effects, such as whether children differ from adults in their susceptibility. There are also few or no studies concerning chronic low-level exposure; however, since the effects of many carcinogens are cumulative, low-level exposure beginning at a young age may result in considerable cancer risk over time.

Dioxane Information for Consumers

To identify potential dioxane containing products, consumers should search product ingredient lists for indications of ethoxylation including “myreth”, “oleth”, “laureth”, “ceteareth”, and other “eth” compounds, as well as “PEG,” “polyethylene,” “polyethylene glycol,” “polyoxyethlene,” or “oxynol” in ingredient names. If consumers have further questions about the presence of dioxane in a particular product they should contact the manufacturer by calling the phone number on the product for more details; for instance, whether the manufacturer is using “vacuum stripping” to decrease dioxane levels, and what are the dioxane levels in the product.

Unfortunately, it can be difficult to ascertain which products were made using processes that involve chlorinated solvents and may have produced dioxane. Due to the potential health risks entailed in the use of personal care products that contain dioxane as a by-product of manufacturing, and especially since children’s exposure to dioxane should be minimized until the long-term effects of exposure during development have been ascertained, manufacturers should provide consumers with information on dioxane content.

For more information on testing for 1,4 Dioxane insoaps, shampoos and personal care products contact

the Rochester Laboratory at 585.288.5380or visit http://www.caslab.com/1-4-Dioxane-Testing