This article presents a summary of a collaborative research program involvi
ng five European research groups, that was partly funded by the European Co
mmission under its Environmental Research Program. The objective of the pro
gram was to develop aquatic toxicity tests that could be used to obtain dat
a for inclusion at Level 2 of the Risk Evaluation Scheme for the Notificati
on of Substances as required by the 7th Amendment to EC Directive 79/831/EE
C. Currently only a very limited number of test methods have been described
that can be used for this purpose and these are based on an even smaller n
umber of test species. Tests based upon algae (Chlamydomonas reinhardi, Sce
nedesmus subspicatus, and Euglena gracilis), protozoa (Tetrahymena pyriform
is), rotifera (pyriformis calyciflorus), crustacea (Gammarus pulex), and di
ptera (Chironomus riparius) were developed. The tests encompassed a range o
f end points and were evaluated against four reference chemicals: lindane,
3,4-dichloroaniline (DCA), atrazine, and copper. The capacity of the tests
to identify concentrations that are chronically toxic in the field was addr
essed by comparing the effects threshold concentrations determined in the l
aboratory tests with those determined for similar and/or related species an
d end points in stream and pond mesocosm studies. The lowest no-observed-ef
fect concentrations (NOEC), ECx, or LCx values obtained for lindane, atrazi
ne, and copper were comparable with the lowest values obtained in the mesoc
osms. The lowest chronic NOEC determined for DCA using the laboratory tests
was approximately 200 times higher than the lowest NOEC in the mesocosms.
(C) 2000 Academic Press.