LAS BIODEGRADATION AND SAFETY IN RIVERS AND STREAMS
 

Field studies, which monitor the real-world behavior of a substance, indicate that linear alkylbenzene sulfonate (LAS) biodegrades rapidly and completely and does not accumulate in the environment. Extensive aquatic toxicity and risk as sessment data from more than 30 years of use as a detergent surfactant confirm that LAS is safe for aquatic populations, based on levels confirmed through field studies.

  • Effective biological treatment removes 99 percent of the LAS present in wastewater, leaving only trace amounts that continue to biodegrade in rivers and streams receiving treated wastewater.(1)

  • "Half-life" refers to the amount of time it takes for microbes to completely break down half the amount of a chemical in water. A study in Rapid Creek, South Dakota, found LAS half-lives ranging fro m 0.15 to 0.5 days, demonstrating rapid biodegradation following treatment. Using higher test concentrations, a similar study of surface waters near Austin, Texas, confirmed that LAS quickly disappears in the aquatic environment.(2-4)

  • A comparison between recent study results and data from a 1973-1986 U.S. monitoring study confirm that LAS is not accumulating in the environment. Even though greater use has increased concentration s of LAS entering sewage treatment plants, LAS concentrations in outgoing water (effluent) have actually diminished. Thus, the low levels of LAS in streams and rivers are not increasing over time, despite greater LAS usage.(1,5)

  • The U.S. Geological Survey's Mississippi River monitoring studies indicate that under normal conditions (effective treatment and normal river flow) LAS concentrations rarely exceed 0.005 milligrams per liter (mg/L), due to effective wastewater treatment and continued biodegradation in surface waters.(6) Immediately downstream of sewage treatment plants that discharge into low dilution streams, LAS concentrations averaged 0.043 mg/L.( 1) These amounts do not harm aquatic organisms

     

  • LAS is one of the most extensively tested chemicals for acute and chronic toxicity to algae, invertebrates and fish. Laboratory tests have found "effect" levels for various aquatic species ranging from 0. 1 to 1,000 mg/L.(7) However, under real-world conditions, an LAS concentration of 0.36 mg/L has no observed effects on the biological population.(8)
    • KEY REFERENCES 1. McAvoy, D.C., W.S. Eckhoff and R.A. Rapaport. "Fate of Linear Alkylbenzene Sulfonate in the Environment." Environ. Toxicol. Chem. 12, 977-987 (1993).

    2. Larson, R.J. and A.G. Payne. "Fate of the Benzene Ring of Linear Alkylbenzene Sulfonate in Natural Waters." Appl. Environ. Microbiol. 41, 621-627 (1981).

    3. Larson, R.J. and R.L. Perry. "Use of the Electrolytic Respirometer to Measure Biodegradation in Natural Waters." Wat. Res. 15, 697-702 (1981).

    4. Nielsen, A.M., L.N. Britton, G.L. Russell, T.P. McCormick and P.A. Filler. "Microbial Mineralization of Dialkyltetralin Sulfonate (DATS) in Soil and Aquatic Systems." Presented at the 13th Annual Meeting, Society of Environmental Toxicology and Chemistry (Cincinnati, OH, November 8-12, 1992).

    5. Rapaport, R.A. and W.S. Eckhoff. "Monitoring Linear Alkylbenzene Sulfonate in the Environment: 1973-1986." Environ. Toxicol. Chem. 9, 1245-1257 (1990).

    6. Tabor, C.F., Jr., L.B. Barber II and D.D. Runnells. "Anionic Surfactants in the Mississippi River: A Detailed Examination of the Occurrence and Fate of Linear Alkylbenzene Sulfonate." Preprint extended abstracts, 205th Annual Meet ing, American Chemical Society, pp. 52-55 (Denver, CO, March 28-April 2, 1993).

    7. Kimerle, R.A. "Aquatic and Terrestrial Ecotoxicology of Linear Alkylbenzene Sulfonate." Tenside Surf. Det. 26, 169-176 (1989).

    8. Fairchild, J.F. and T. LaPoint. "Evaluation of a Laboratory-Generated NOEC for Linear Alkylbenzene Sulfonate in Outdoor Experimental Streams." Environ. Toxicol. Chem. 12, 1763-1775 (1993).

    ADDITIONAL REFERENCES
    • Cavalli, L.A., A. Gallera and A. Landone. "LAS Removal and Biodegradation in a Wastewater Treatment Plant." Environ. Toxicol. Chem. 12, 1777-1788 (1993).

    • Hong, S.U. "Assessment of Environmental Impact and Safety of Synthetic Detergents in Korea." First International Symposium on the Synthetic Detergent (Seoul, October 21, 1992).< /P>

    • Larson, R.J., T.M. Rothgeb, R.J. Shimp, T.E. Ward and R.M. Ventullo. "Kinetics and Practical Significance of Biodegradation of Linear Alkylbenzene Sulfonate in the Environment." J. Amer. Oil. Chem. Soc. 70, 645-657 (1993).

    • Matthijs, E. and H. de Henau. "Determination of LAS." Tenside Surf. Det. 24, 193 (1987).

    • Matthijs, E. and M. Stalmans. "Monitoring of LAS in the North Sea." Tenside Surf. Det. 30, 29-33 (1993).

    • Mieure, J.P., M.L. Trehy and R.A. Kimerle. "Factors Which Influence Surfactant (LAS) Toxicity in Aquatic Ecosystems." Proceedings of the 3rd World Conference on Detergents: Glob al Perspectives, pp. 245-247 (AOCS Press, Champaign, IL, 1994).

    • Unpublished data submitted to CLER by CONDEA Vista (February 1996).
    • Painter, H.A. "Anionic Surfactants." The Handbook of Environmental Chemistry, Vol. 3, Part F, pp. 1-88 (Springer-Verlag, New York, NY, 1992).

    • Rapaport, R.A., R.J. Larson, D.C. McAvoy, A.M. Nielsen and M. Trehy. "The Fate of Commercial LAS in the Environment." 3rd CESIO International Surfactants Congress & Exhibition -- A World Market, Section E, pp. 78-88 (London, June 1-5, 1992).

    • Snchez Leal, J., M.T. Garca, R. Toms, J. Ferrer and C. Bengoechea. "Linear Alkylbenzene Sulfonate Removal." Tenside Surf. Det. 31, 253-256 (1994).

    • Swisher, R. D. in Surfactant Biodegradation, pp. 431-445 (Marcel Dekker, New York, NY, 1987).

    • Takada, H., R. Ishiwatari and N. Ogura. "Distribution of Linear Alkylbenzenes (LABs) and Linear Alkylbenzene Sulfonates (LAS) in Tokyo Bay Sediments." Estuarine, Coastal, She lf Sci. 35, 141-156 (1992).

       

    • Takada, H., K. Mutoh, N. Tomita, T. Miyadzu and N. Ogura. "Rapid Removal of Linear Alkylbenzene Sulfonates (LAS) by Attached Biofilm in an Urban Shallow Stream." Wat. Res. 28, 1953-1960 (1994).

      • Last updated on May 1996

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