Contribution of mesocosm testing to a single-step and exposure-driven environmental risk assessment of engineered nanomaterials

Environmental risk assessment of nanomaterials generally relies on a decision-tree based strategy which provides guidance and protocols for the determination of a collection of hazard end-points. Mesocosm testing is based on a different approach. This method consists in monitoring the evolution of a re-created miniature ecosystem subsequent to a nanomaterial contamination. The only decision in this risk assessment strategy is the definition of an environmentally relevant exposure scenario (incl. dose), which, given current analytical capabilities, may unfavorably affect the nature and precision of parameters and endpoints to be determined. Despite these limitations, mesocosm testing bears clear advantages for the determination of both exposure and hazard in a single experiment, and for producing dependable and intercomparable data.