Test No. 233: Sediment-Water Chironomid Life-Cycle Toxicity Test Using Spiked Water
or Spiked Sediment
This Guideline is designed to assess the effects of prolonged exposure of chemicals
to the life-cycle of the sediment-dwelling freshwater dipteran Chironomus sp. First
instar chironomid larvae are exposed to five concentrations of the test chemical in
sediment-water systems. The test substance is spiked into the water or alternatively
the sediment, and first instar larvae are subsequently introduced into test beakers
in which the sediment and water concentrations have been stabilised. Chironomid emergence,
time to emergence, and sex ratio of the fully emerged and alive midges are assessed.
Emerged adults are transferred to breeding cages, to facilitate swarming, mating and
oviposition. The number of egg ropes produced and their fertility are assessed. From
these egg ropes, first instar larvae of the 2nd generation are obtained. These larvae
are placed into freshly prepared test beakers (spiking procedure as for the 1st generation)
to determine the viability of the 2nd generation through an assessment of their emergence,
time to emergence and the sex ratio of the fully emerged and alive midges. All data
are analysed either by a regression model to estimate the concentration that would
cause X% reduction in the relevant endpoint, or by using hypothesis testing to determine
a No Observed Effect Concentration (NOEC).
Published on July 23, 2010Also available in: French
In series:OECD Guidelines for the Testing of Chemicals, Section 2: Effects on Biotic Systemsview more titles