OECD 218/219: Sediment-Water Chironomid Toxicity Test Using Spiked Sediment/Spiked Water

Long-term studies with Chironimus species are required for the risk assessment of e.g. insect growth regulators and for active substances which absorb to and persist in sediments and additionally have a potential toxicity to invertebrates based on the results of previous acute studies.

The chronic Chironomus studies are performed following two different exposure scenarios:

  • spiking of the water column to simulate a pesticide spray drift (OECD 219)
  • spiking of the sediment to address risks from exposure to contaminated sediment, particularly if there is an accumulation of the compound in the sediment over time (OECD 218)

Study Design

Test organisms

Chironomus species occur in aquatic habitats in high abundance and diversity. Larvae of these midges are typical sediment dwellers and an important prey for fish, the adults also for birds. Chironomus riparius is bred in a laboratory culture. Freshly laid egg masses are taken from the breeding culture 4 to 5 days before test start.

Larvae of Chironomus riparius dwelling in the sediment

Course of the test

First instar larvae of Chironomus riparius are exposed to the test item for 28 days to assess the impact on full maturation of the larvae to adult midges. 20 first instar chironomid larvae per test beaker with at least 4 replicates (6 for the control) per test item concentration are exposed in a sediment-water system.

For the spiked water test design larvae are placed into the test beakers 24 hours before application of the test substance.

In case of the spiked sediment design, the sediment is spiked first and after a stabilisation period of 48 hours the larvae are introduced.

The concentrations of the test substance in the pore water, the overlying water, and the sediment are analysed at test start and test end. Additional analytical measurements during the test are possible if required. To confirm the sensitivity of the test system a toxic reference is tested once per year.


LOEC, NOEC, EC50 (EC20, EC10) for  the total number of adults emerged (emergence rate) and the time to emergence (development rate). During the emergence period daily counts are performed and the sex of the adults is determined. The maximum exposure duration is 28 days.

Guidelines and literature

  • OECD Guideline for the Testing of Chemicals 218: "Sediment-Water Chironomid Toxicity Test Using Spiked Sediment"
  • OECD Guideline for the Testing of Chemicals 219: "Sediment-Water Chironomid Toxicity Test Using Spiked Water"