Analytical Testing for 1,4-Dioxane

1,4-Dioxane (dioxane) is a chemical of concern for its potential health effects as a carcinogen and irritant. It is commonly found in personal care products such as detergents, shampoos, body lotions, and cosmetics, and is widely used as an industrial solvent and stabilizer in manufacturing processes (e.g., electronics, metal finishing, fabric cleaning, pharmaceuticals, herbicides, pesticides, antifreeze, paper, etc.). Currently, there are no established limits on the amount of dioxane in personal care products nor is it specifically regulated in manufacturing wastewater streams that may impact the surrounding environment. 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 Options of Dioxane Testing

Dioxane testing can be performed by various analytical methods, depending on the specific data requirements. Some methods can achieve lower detection limits more accurately and reliably than others.

Columbia Analytical uses a number of procedures to detect dioxane, depending on the sample matrix and the data quality objectives of the project, including those that detect amounts below any current state advisory levels.

Dioxane can be detected using EPA 8260; however, its high water solubility causes relatively high reporting limits. Routine organic extraction procedures like those traditionally used for EPA 8270 analyses produce low recoveries (approximately 50% or less).

To increase sensitivity, Columbia Analytical uses an extraction procedure that allows an increase in the extraction efficiency of dioxane into the non-aqueous phase to 80-90%. To further increase sensitivity, the process uses gas chromatography with mass spectroscopy (GC/MS) in conjunction with isotope dilution, large volume injection, and selective ion monitoring (SIM).

Complicated matrices like soap, shampoo and lotions can cause additional 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 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.

 
Health Risks of Dioxane

The EPA has classified 1,4-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.

 
Sources of Dioxane in the Environment

1,4-Dioxane is a man-made compound primarily used as an industrial solvent or solvent stabilizer for chlorinated solvents or volatile organic compounds (VOCs). It has a high potential for entering the environment, due to its volatility and solubility in water. Industrial solvents are used in a wide variety of manufacturing processes (e.g., electronics, metal finishing, fabric cleaning, pharmaceuticals, herbicides, pesticides, antifreeze, paper, etc.). As a stabilizer, 1,4-Dioxane prevents the breakdown of chlorinated solvents during the manufacturing process. Releases of chlorinated solvents, or spent solvents disposed of improperly, can be a primary source of dioxane in the environment.

1,4-Dioxane is also found in household products such as detergents, shampoos, body lotions, dishwashing soap, pharmaceuticals and cosmetics. Dioxane 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. Dioxane in personal care products 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.

Dioxane has been detected in surface and ground waters throughout the United States. An additional concern is that traditional remediation technologies used for sites contaminated with chlorinated solvents are ineffective at removing dioxane.

 
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 1,4-Dioxane testing, contact Columbia Analytical at 1-800-695-7222 or via their website: www.caslab.com.

 
References:

1. The Campaign for Safe Cosmetics, http://safecosmetics.org/article.php?id=414. Retrieved 10/28/2009.
2. State of California OEHHA Safe Drinking Water and Toxic Enforcement Act of 1986, updated September 11, 2009 (Proposition 65). Chemicals known to the State to cause cancer or reproductive Toxicity. Retrieved 12/15/2009.
3. FDA 1,4-Dioxane (1,4-Diethyleneoxide), http://www.fda.gov/Cosmetics/ProductandIngredientSafety/PotentialContaminants/ucm101566.htm. Retrieved 01/15/2010.
4. EPA Integrated Risk Information System, 1,4-Dioxane (CASRN 123-91-1), www.epa.gov/ncea/iris/subst/0326.htm. Retrieved 10/28/2009.
5. Agency for Toxic Substances and Disease Registry (ASTDR); Toxicological Profile for 1,4 Dioxane (Draft for Public Comment) Atlanta, GA: US Department of Public Health and Human Services, Public Health Service. Retrieved 10/28/2009.
6. “International Chemical Safety Card”. National Institute for Occupational Safety and Health. http://www.cdc.gov/niosh/ipcsneng/neng0041.html. Retrieved 01/23/2010.
7. “OPPT Chemical Fact Sheets 1,4-Dioxane (CAS No. 123-91-1)”. United States Environmental Protection Agency. http://www.epa.gov/opptintr/chemfact/dioxa-fs.txt. Retrieved 01/23/2010.