This document provides a reliable and repeatable method for simultaneous assessment of both exposure and toxicity of manufactured nano-objects (MNOs) using Tetrahymena sp. The ingested, internalized material (MNOs) indicates aquatic exposure.This document is intended to be used by all the centers working with nano(eco)toxicity of MNOs and capable of culturing of Tetrahymena sp. The method uses Tetrahymena sp. to assess exposure and effects of MNOs. In addition, the test can be used by centers (laboratories) interested in investigating the biological interaction of MNOs with living cells.This method is applicable to nano-objects such as nanoparticles, nanofibres of certain size (in a µm size range), nanoplates, as well as their aggregates and agglomerates.