Validation of interlaboratory studies on toxicity in water samples

10 pages, 2 figures, 4 tables.-- Available online Dec 21, 2006.-- Issue title: Emerging tools as a new approach for water monitoring.Toxicity tests are important for assessing the impact of chemicals on aquatic ecosystems because they indicate toxic effects of complex chemical mixtures. Several methods have been developed for rapid assessment of the dangerous biological effects of samples. These methods can be important improvements for comprehensive environmental monitoring and complementary tools for implementing the new environmental directives and regulations in Europe. However, toxicity tests using different species have shown different sensitivities and endpoints, and only a limited number of tests have been standardized and validated. In order to verify the quality of biological measurements, to estimate the analytical precision of different participating laboratories using the same test, and to determine if statistically significant differences exist between results of participating laboratories, different interlaboratory exercises have been carried out. In this overview article, we present and discuss the most advanced aspects of current aquatic toxicity methodologies, as well results of different roundrobin exercises.This work was supported by the EU through the SWIFT-WFD project (SSPI-CT-2003-502492), and by the Ministerio de Ciencia y Tecnología through project CTM2005-24255-E. Marinella Farré expresses thanks for the support from the Ministerio de Educación y Ciencia through the Juan de la Cierva program.Peer reviewe