Toxicity of methyl tert butyl ether to soil invertebrates (springtails: Folsomia candida, Proisotoma minuta, and Onychiurus folsomi) and lettuce (Lactuca sativa)

Abstract

Experiments were conducted to assess the toxicity of methyl tert butyl ether (MTBE) to three species of Collembola (Proisotoma minuta, Folsomia candida, and Onychiurus folsomi) and lettuce (Lactuca sativa L.) using an artificial Organization for Economic Cooperation and Development (OECD) soil and field-collected sandy loam and silt loam soil samples. Soil invertebrate tests were carried out in airtight vials to prevent volatilization of MTBE out of the test units and to allow for direct head-space sampling and gas chromatography-mass spectrometry (GC-MS) analysis for residual MTBE. The use of the airtight vial protocol proved to be very successful, in that the measured MTBE concentrations at the beginning of the experiments were within 95% of nominal concentrations. The test methods used in this study could be used to test the toxicity of other volatile organic compounds to Collembola. The soil invertebrates tested had inhibitory concentration (ICx) and lethal concentration (LCx) values that ranged from 242 to 844 mg MTBE/kg dry soil. When the three test species of Collembola were tested under identical conditions in the artificial OECD soil, O. folsomi was the most sensitive collembolan, with a median inhibitory concentration (IC50; reproduction) of 296 mg MTBE/kg dry soil. The most sensitive endpoint for lettuce was an IC50 for root length of 81 mg MTBE/kg dry soil after 5 d of germination in OECD soil. Data on the loss of MTBE from the three test soils over time indicated that MTBE was retained in the silt loam soil longer than in either the sandy loam or the artificial OECD soil.

Evaluation of a new battery of toxicity tests for boreal forest soils: Assessment of the impact of hydrocarbons and salts

“…Overall, test performance was comparable, in that the boreal collembolan and earthworm species were able to meet the same test validity criteria specified for the standard test methods [9,11]; no criteria have been established for oribatid mites. Proisotoma minuta also has wide distribution within Canada [29] and has been used more frequently than F. nivalis in soil toxicity testing [29][30][31], although little information is provided on the variation in performance in control soils, nor is the sex of the test species specified. Folsomia nivalis is known to have a widespread nearctic distribution [26] and has been recommended for use in forest-related toxicological studies because of its prevalence [27] and high reproduction potential [28].…”

“…In comparison, the reproductive output in this study was 92 AE 49 and 217 AE 46 juveniles in the hydrocarbon and salt reference soils, respectively. Proisotoma minuta also has wide distribution within Canada [29] and has been used more frequently than F. nivalis in soil toxicity testing [29][30][31], although little information is provided on the variation in performance in control soils, nor is the sex of the test species specified. Proisotoma minuta is a sexually reproducing species [32] (also confirmed in this study); as such, variation in the ratio of males to females is likely to yield variation in the reproductive output within a study.…”