Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.07.192278v1?rss=1 Authors: Shin Woong Kim, Walter R. Waldman, Matthias C. Rillig Abstract: With an increasing interest in the effects of microplastic in the soil environment, there is a need to thoroughly evaluate potential adverse effects of these particles as a function of their characteristics (size, shape, and composition). In addition, extractable chemical additives from microplastic have been identified as an important toxicity pathway in the aquatic environment. However, we currently know little about effects of such additives in the soil environment. In this study on nematodes (Caenorhabditis elegans), we adopted an ecotoxicological approach to assess the potential effects of thirteen different microplastics with different characteristics and extractable additives. We found that toxic effects appear to increase in the order of low-density polyethylene (LDPE) film < polypropylene (PP) fragments < high-density polyethylene (HDPE) fragments {approx} polystyrene (PS) fragments < polyethylene terephthalate (PET) fragments {approx} polyacrylicnitrile (PAN) fibers. Acute toxicity was mainly attributed to the extractable additives: when the additives were extracted, the toxic effects of each microplastic disappeared in the acute soil toxicity test. The harmful effects of LDPE film and PAN fibers increased when the microplastics were maintained in soil for a long-term period with frequent wet-dry cycles. We here provide clear evidence that microplastic toxicity in the soil is highly related to particle characteristics and extractable additives. Our results suggest that future experiments consider extractable additives as a key explanatory variable. Abstract art/Table of contents O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=90 SRC="FIGDIR/small/192278v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@83ac34org.highwire.dtl.DTLVardef@9ea9fcorg.highwire.dtl.DTLVardef@a9fb67org.highwire.dtl.DTLVardef@1b85de6_HPS_FORMAT_FIGEXP M_FIG C_FIG Copy rights belong to original authors. Visit the link for more info