Adaptation of the enchytraeid toxicity test for use with natural soil types

Assessments of chemical toxicity to soil invertebrates have been traditionally performed in formulated Standard Artificial Soil, or in standard LUFA 2.2 natural soil. Physical and chemical properties of these standard soils often do not represent the diversity of properties of natural soils and can be inadequate surrogates of exposure conditions of soil biota in the field. We investigated performance of three species of the genus Enchytraeus (E. albidus, E. crypticus, E. luxuriosus) using soil types covering a wide range of European and North American soil properties. Results showed that adult survival and juvenile production by E. albidus and E. luxuriosus were inhibited in acidic soils with pH ≤ 5, while less acidic soils having properties within following ranges: 2.5–8.0% OM, 6–26% clay, and 4–80% sand, could sustain survival and reproduction at or near validity criteria levels of enchytraeid toxicity test ISO/16387. Performance of E. crypticus in North American soils having properties within following ranges: 1.2–42% OM, 1–29% clay, and 4.4–8.2 pH, met or exceeded all validity criteria. Data established in our studies can be used for amending the validity criteria of current ISO/16387 when used with E. crypticus and OECD soil.