June 26, 2001

Alkylphenols Bulletin: New Assessment Affirms Safety Of NPEs In Biosolids Used For Fertilizer

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.

A "Preliminary Assessment of Ecological Risks from Nonylphenol in Municipal Sewage Sludge Following Wastewater Treatment" demonstrates that the low levels of nonylphenol (NP) and nonylphenol ethoxylates (NPEs) present in biosolids (sludge) from sewage treatment pose little or no risk to soil or terrestrial organisms when biosolids are used as fertilizer. The assessment by Charles Staples (Assessment Technologies, Inc.) et al. was presented at two recent scientific conferences; the Aquatic Toxicity Workshop in Winnipeg, Manitoba, Canada in October 2001 and the Society of Environmental Toxicology and Chemistry annual meeting in Baltimore, Maryland, USA in November 2001.

The assessment notes that the maximum amount of NP and other NPE biodegradation intermediates in soil from biosolids application is more than 10 times lower than NP concentrations that have no effect on earthworms or other soil organisms, or on plant crops such as soy, sorghum or sunflower. Data from several recent studies (Bennie (1999); Bennie and Webber (2000); and LaGuardia et al. (2001)) on the levels of these compounds found in sludge samples were included in the assessment.

Other data presented in the assessment demonstrate that NP and NPEs biodegrade (90% or more in 90 days) adequately in biosolids added to soil under normal conditions of use and that NP has little potential to migrate into groundwater (even groundwater only 3 feet (90 cm) below the soil-biosolids layer).

NPEs are widely used as cleaning agents (surfactants) and in various industrial processes. Spent NPEs in wastewater in North America are sent to sewage treatment plants. Well-functioning treatment plants are greater than 95% effective at removing NPEs from sewage and only residual levels of NP and other NPE biodegradation intermediates are found in the biosolids produced in sewage treatment.

Sewage biosolids are sometimes used as fertilizers since they provide beneficial nutrients for soil and are a natural form of waste recycling. The use of biosolids from municipal wastewater treatment plants as fertilizer on pasture or food crops is restricted in the US and Canada. For more information regarding this assessment, or other information on alkylphenols and their derivatives, visit www.aperc.org or contact the Alkylphenols & Ethoxylates Research Council.

 

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