A new bioassay for the ecotoxicological testing of VOCs on groundwater invertebrates and the effects of toluene on Niphargus inopinatus

► A new bioassay for testing the toxicity of VOCs on groundwater fauna is presented. ► Results on the toxicity of toluene to Niphargus inopinatus are now available. ► Henry equilibrium needs to be considered when bioassays with VOCs are designed. ► Methodological aspects related to “difficult-to-test substances” are discussed.