Survival and reproduction effects of microplastics from three agricultural mulching films on Folsomia candida, Sinella curviseta, Heteromurus nitidus and Ceratophysella denticulata (Collembola)

An estimated 467 kt of plastic used in agriculture annually end up in European soils, potentially breaking down into secondary microplastics (MPs). Not much is known about the possible effects of these MPs on organisms residing in the soil. To properly assess their environmental risk, experimental data is needed on the toxicity of MPs to the survival and reproduction of model organisms. This study aimed at assessing the toxicity of three MP types derived from commonly used agricultural plastics to different Collembola species, representing an important and highly diverse class of soil arthropods. Starch- polybutadiene adipate terephthalate blend (starch-PBAT blend) MPs were produced from mulching films that were artificially aged by mechanical recycling. MPs were also made from virgin low density polyethylene (LDPE) mulching films and from linear low density polyethylene (LLDPE) films that underwent the same mechanical recycling process as the starch-PBAT blend films. Four Collembola species were tested: Folsomia candida, Sinella curviseta, Heteromurus nitidus and Ceratophysella denticulata, representing epedaphic, hemiedaphic and euedaphic, as well as sexually reproducing and parthenogenetic species. Each species was exposed in Lufa 2.2 soil spiked with nine MP concentrations: 0.0016, 0.008, 0.04, 0.2, 1, 2, 3, 4 and 5 % (w/w dry soil) and a control without additional MPs added to the soil. No dose-dependent effects were found for any of the exposed organisms, to any of the MPs tested. The results of this study suggest that the MPs used in this study, derived from commonly applied agricultural plastics, do not pose an immediate hazard to Collembola.