January 13, 1999

New Studies Confirm Alkylphenols and Alkylphenol Ethoxylates Are Biodegradable

The Alkylphenols Bulletin periodically notifies manufacturers and users of alkylphenols and their derivatives of national and international developments of interest. For further information, please contact the APE Research Council at the address below.

Four recent, independent laboratory tests confirm that nonylphenol and octylphenol, as well as nonylphenol ethoxylates and octyphenol ethoxolates, are biodegradable. These substances can be classified as "inherently biodegradable" under internationally recognized test methods.

In one study, biodegradation was measured using the Organization for Economic Cooperation and Development (OECD) 301B test method, also known as the modified Sturm test. The test measures the formation of carbon dioxide (CO2 ), a measure of ultimate biodegradation or mineralization. The results demonstrate that nonylphenol (NP), octylphenol (OP), nonylphenol ethoxylates (NPE-1.5, NPE-9) and octylphenol ethoxylates (OPE-1.5 and OPE-9) are extensively biodegraded within the standard 28-day test period. The extent of mineralization ranged from 45% for NPE-1.5 to 80% for OPE-1.5. Based on the results, these APs and APEs meet the OECD test criteria for "inherently biodegradable" substances.

These results confirm and expand upon two earlier tests using OECD biodegradation test methods. In one test, complete biodegradation (to CO2 and water) of NPE-9 and NP was measured using the OECD 301B test method. In another test, complete biodegradation of NP was measured using the OECD 301F test method, which measures oxygen consumption, another measure of mineralization. The results of both tests demonstrate that NPE-9 and NP are extensively mineralized and meet the OECD "inherently biodegradable" criteria.

Another test used the International Standards Organization (ISO) Headspace CO2 Evolution method to measure the complete biodegradation of NPE-9. The ISO test method is an improvement over the OECD 301B test method and currently is being evaluated in Europe as part of proposed revisions to the European Union regulations on the biodegradability of detergent ingredients. In this test, conducted in the United States, 70% of NPE-9 was completely biodegraded within 28 days.

For more information about these studies, please contact the APE Research Council at 202-637-9071 or e-mail: info@aperc.org.

 

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