Model Ecosystem

The goal of all the environmental fate and effects testing at P&G is to make sure our products will not affect the environment. So, the best place to test the toxicity of our ingredients would be in the real environment. Because of the value of the environment and the possibility of effects, this would not be an appropriate approach. Instead of using the real environment, we use small parts of the environment that have been isolated. These are called "model ecosystems" or "mesocosms ."

Set-Up A model ecosystem is the highest tier of ecotoxicity testing available. Definitions of model ecosystems vary, but they are usually fairly large (>10 meters long for streams, >10,000 litres for ponds), can be indoors or outdoors, contain a diverse array of species and are sustainable for long periods of time. Basically, these are slices of the environment that have been moved into the laboratory for experimental work.

The advantages for using model ecosystems are many and include:

• They allow study of environmental fate and effects at the same time.
• The test system is very realistic and help us understand how to use in vitro, acute and chronic information to better protect the environment
• Testing is carefully controlled (light levels, chemical concentration, river flow). This level of control could not be found in the environment.
• Complex aquatic communities containing hundreds of species can be evaluated at the same time. Most of these species cannot be cultured or tested under laboratory conditions.
• Interactions among species are included so that effects on one species can cause effects on other organisms.

Belanger, S.E., 1997. Literature Review and Analysis of Biological Complexity in Model Stream Ecosystems: Influence of Size and Experimental Design. Ecotoxicology and Environmental Safety, 36, pp. 1-16.

• Belanger, S.E., Bowling, J.W., Lee, D.M., Leblanc, E.M., Kerr, K.M., Mcavoy, D.C., Christman, S.C., and Davidson, D.H., 2002. Integration of Aquatic Fate and Ecological Responses to Linear Alkyl Benzene Sulfonate (LAS) in Model Stream Ecosystems. Ecotoxicology and Environmental Safety, 52, pp. 150-171.
• Dyer, S.D., and Belanger, S.E., 1999. Determination of the Sensitivity of Stream Mesocosms. Environmental Toxicology and Chemistry, 18, pp. 2903-2907.
• Dyer, S.D., White-Hull, C.E., and Shepherd, B.K., 2000. Assessments of Chemical Mixtures via Toxicity Reference Values Overpredict Hazard to Ohio Fish Communities. Environmental Science and Technology, 34, pp. 2518-2524.
• Morrall, D.D., Belanger, S.E., and Dunphy, J.C., 2003. Acute and Chronic Aquatic Toxicity Structure-Activity-Relationships for Alcohol Ethoxylate Surfactants. Ecotoxicology and Environmental Safety. In Press.
• Verhaar, H.J.M., Dewolf, W., Dyer, S., Legierse, K.C.H.M., Seinen, W., and Hermens, J.L.M., 1999. An LC50 vs. Time Model for the Aquatic Toxicity of Reactive and Receptor-Mediated Compounds. Consequences for Bioconcentration Kinetics and Risk Assessment. Environmental Science and Technology, 33, pp. 758-763.
• Versteeg, D.J., Belanger, S.E., and Carr, G.J., 1999. Understanding Single Species and Model Ecosystem Sensitivity: A Data Based Comparison. Environmental Toxicology and Chemistry, 18, pp. 1329-1346.
• Versteeg, D.J., and Rawlings, J.M., 2003. Bioconcentration and Toxicity of Dodecylbenzene Sulfonate (C12LAS) to Aquatic Organisms Exposed in Experimental Streams. Archives of Environmental Contamination and Toxicology, 44, pp. 237-246.
• Versteeg, D.J., Stanton, D.T., Pence, M.A., and Cowan, C.E., 1997. Effects of Surfactants on the Rotifer, Brachionus Calyciflorus, in a Chronic Toxicity Test and the Development of Qsars. Environmental Toxicology and Chemistry, 16, pp. 1051-1058.