Current Insights

• spiking of the water column to simulate a pesticide spray drift
  
• spiking of the sediment to simulate a persistence of chemicals in sediment

• OECD Guidelines for Testing of Chemicals, No. 218: "Sediment-Water Chironomid Toxicity Test Using Spiked Sediment", adopted April 13, 2004.
  
• OECD Guidelines for Testing of Chemicals, No. 219: "Sediment-Water Chironomid Toxicity Test Using Spiked Water", adopted April 13, 2004.

Besides the chronic studies we offer an acute study lasting for 48 hours to examine whether a chemical shows acute effects. This study is tailor-made and based on different guidelines, also taking into account the guidelines for chronic testing.

Test Organisms
Chironomus riparius is bred in our own laboratory culture. Freshly laid egg masses are taken from the breeding culture 4 to 5 days before test start. The larve begin to hatch 2 to 3 days later and remain in the first instar phase for 2 to 3 days. For the chronic study designs 20 first instar chironomid larvae are exposed per test replicate.

Study Design
First instar larvae of Chrionomus riparius are exposed to the test item for 28 days to assess the impact on full maturation of the larvae to adult midges. The larvae are exposed in a sediment-water system. For the spiked water test design the first instar 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 first instar larvae are introduced. The concentrations of the test substance are analysed at test start and test end to verify dosage of the test item. 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.

Endpoints
The measured endpoints are the total number of adults emerged (emergence rate) and the time to emergence (development rate). In the controls 70% of the larvae should emerge between day 12 and 23 after insertion to the test vessels. During the emergence period daily counts are performed. The maximum exposure duration is 28 days. The test may be terminated 5 days after emergence of the last adult in the control. The data are analysed by a regression model to calculate Effect Concentrations. Furthermore the No Observed Effect Concentration and the Lowest Observed Effect Concentration are determined.

Dr. Heiner Albus (Managing Director)
Phone: +49 6154 697 347
Email: heiner.albus@ibacon.com