Bioassay to Assess Toxicity of Water-Dispersed Engineered Nanomaterials in Plants, Scientific Operating Procedure Series: Toxicology (T)

摘要

Determining the toxicity of engineered nanomaterials (ENMs) to plants is important from an environmental perspective. Due to the absence of standardized phytotoxicity test methods for ENMs, a number of methods have been used and have produced inconsistentand, consequently, unusableresults. This document describes a scientific operating procedure (SOP) to test the effects of plant chronic exposure to low doses of ENMs. The SOP is not specific to any particular ENM, but is designed to be applicable to any ENM that can be dispersed in water. Relying on Col-0, the highly homozygous wild-type laboratory strain of Arabidopsis, the method mitigates biological variance inherent in bioassay-based tests. In vitro growth conditions allow for the use of uniform synthetic growth medium and the exclusion of microbes. The detection of toxicity threshold is based on measuring the number of rosette leaves and the total exposed leaf area. If a physiological impact on the plant is detected, it is confirmed by the detection of ENM-induced changes in gene expression at the toxicity threshold to ensure that gene expression analysis is performed on plants grown at sublethal ENM concentrations. ENM-induced gene expression changes are then validated with the independent method of real-time quantitative PCR (qPCR).