W8 PM Ecotoxicology of Agrochemicals and Pharmaceuticals
Wednesday, 16 November 2005: 1:50 PM - 5:30 PM in 337-338

(BAR-1117-839584) The influence of soil type on the outcome of laboratory toxicity studies conducted with Collembola.

Barrett, K¹, Gray, J¹, Wainwright, M, ¹ Huntingdon Life Sciences, Huntingdon, Cambridgeshire, UK

ABSTRACT- As part of the regulatory data package of both agrochemicals and pharmaceuticals,where there is expected to be prolonged exposure of soil dwelling species, it is recommended that a laboratory toxicity study is conducted with a species of Collembolan (springtail). The recommended ISO guideline allows some degree of choice in the soil used in the study. The two soils most commonly used are LUFA 2.2 (standard sandy loam soil) or an artificial soil as used for the OECD earthworm toxcity evaluation. The artificial soil has a signiificantly higher organic carbon content. To compare the influence of soil type on the observed toxicity, a laboratory study was performed to compare survival and reproduction in the two soil types, following exposure to residues of dimethoate (a commonly used toxic reference substance). Reproduction in the control treatments was significantly higher in the artificial soil than in the LUFA 2.2 soil. Dimethoate was also found to be less toxic in artificial soil than in the LUFA 2.2 soil. The EC50 values for survival and fecundity respectively were approximately 3 and 15 times less than for LUFA 2.2. These results indicate that the choice of soil type should be taken into consideratin when interpreting the data from standard labortory evaluations.

Key words: collembola, soil, toxicity