January 2000



Regulations Should Minimize Anaerobic Criteria

European surfactant and detergent producers are seriously questioning the use of anaerobic biodegradation as a “pass/fail criterion” for determining the environmental acceptability of surfactants. The two groups have proposed that anaerobic biodegradability should have one tenth the weight, if any, of aerobic biodegradability when determining environmental risks of aerobically biodegradable surfactants, such as linear alkylbenzene sulfonate (LAS).

In a scientific review and position paper released this year, the groups note that “anaerobic biodegradation of surfactants is used as an acceptability criterion in some environmental pieces of legislation (eco-label, risk assessment, etc.), without a proper evaluation of the relevance of such a characteristic.” While the two groups agree that the absence of aerobic biodegradation can lead to adverse environmental effects, they point out that “the lack of anaerobic biodegradation does not seem to be correlated with any apparent environmental problem …”

In reaching their conclusions, the groups reviewed the environmental importance of surfactants, based on their high volume consumption and widespread use as essential ingredients in most laundry and cleaning products. The majority of surfactants entering the environment will be degraded aerobically — less than 20% will reach anaerobic environmental compartments, such as river sediments.

The groups conclude: “The relevance of anaerobic biodegradability cannot be separated from other important properties of surfactants such as sorptive behaviour, ecotoxicity profile and above all, aerobic biodegradation rate … If a surfactant is rapidly degradable under aerobic conditions, and its transitory presence in anaerobic environments does not affect the function and structure of that environment … then its anaerobic biodegradability is of only minor importance.” They suggest that “vigilance is required” since “not all aspects of structure and function can be adequately assessed today since data is lacking” on natural anaerobic environments.

The groups also note that available screening methods to assess anaerobic biodegradation do not simulate actual environmental conditions and suggest that new methods to test surfactants and their breakdown products in anaerobic situations need to be developed and validated.

The scientific review, “Anaerobic Biodegradation of Surfactants: Review of Scientific Information 1999,” as well as a summary and position paper, were prepared by Comite Europeen des Agents de Surface et leurs Intermediaires Organiques (CESIO) and Association Internationale de la Savonnerie, de la Detergence et des Produits d’Entretien (AISE). For further information, please contact CLER at the address below.

For additional copies of The CLER Review, please contact Francie Israeli at 202/737-0171 or email