Validation of a Four-Day Ceriodaphnia Toxicity Test and Statistical Considerations in Data Analysis

Abstract

This study evaluated the technical feasibility of a shorter alternative to the U.S. Environmental Protection Agency (EPA)‐recommended 7‐d chronic toxicity test with Ceriodaphnia dubia. The results of 4‐d and 7‐d Ceriodaphnia dubia toxicity tests, conducted concurrently, were compared using treated municipal effluent, metals, PCP, ethylene glycol, phenol and surfactants. The experimental technique was similar for both studies with the exception of the duration and age of the test species at test initiation. The 4‐d static‐renewal test was initiated with 3‐day‐old Ceriodaphnia dubia, and 1‐day‐old organisms were used in the 7‐d tests. The chronic values of the replicated studies, based on survival and young production, were within a factor of two in approximately 70% of the total tests conducted and in all tests conducted with municipal effluent. Based on the available results, the 4‐d toxicity study appears to be a technically valid alternative to the EPA‐recommended 7‐day test, particularly for treated municipal effluent. An important factor in toxicity testing is the use of valid statistical procedures. The validity of the various methods for Ceriodaphnia dubia depends upon their appropriate use; however, it is difficult to justify the widespread use of multiple comparison methods, particularly Dunnett's procedure.

Ambient toxicity testing in the Chesapeake Bay watershed using freshwater and estuarine water column tests

“…Masters et al [15] have suggested a similar explanation for a freshwater zooplankton species (C. dubia) experiencing lower reproduction in control water than ambient water. The controls contained only phytoplankton and nutrients introduced during feeding.…”

Toxicity Evaluation of Waters from a Tributary of the River Po Using the 7-DayCeriodaphnia dubiaTest

“…Their mean dissolved concentrations (±SD) in the River Lambro were 25.5 (±17.6) and 14.7 g/liter (±7.5), respectively, with maximum values of 28.2 g/liter of nickel and 70.5 g/liter of zinc (Pettine et al, 1996). The chronic values reported for C. dubia (7-day test) ranged between 40 and 140 g/liter of zinc (Masters et al, 1991) and the NOEC of nickel resulted at 7.5 g/liter (Kszos et al, 1992). Schubauer-Berigan et al (1993) determined the 48 hr LC 50 of zinc and nickel to C. dubia and found 95 and 13 g/liter, respectively.…”

Report of the OECD Workshop on Statistical Analysis of Aquatic Toxicity Data

“…Masters et al (1991) noted the experimental dependence of the NOEC and suggest that multiple comparisons procedures have been both over-used and mis-used. They favour the use of biologically-based concentration-response models.…”