GreenScreen EM is a development of Gentronix's core technology, providing a protocol for assessment of genotoxicity and cytotoxicity in environmental monitoring and routine screening of aqueous samples. GreenScreen EM uses specialist, portable, robust instrumentation and a cuvette based protocol. measure the cell density and fluorescence of the yeast cells. The instrument is called the GreenScreen YETI - Yeast Environmental Toxicity Indicator. The YETI is powered by rechargeable internal batteries. Cuvettes are placed in the light-tight chamber and density and fluorescence readings are displayed digitally. The readings obtained are recorded and entered into a supplied software template. Acute toxicity (EC50, LOEC) and genotoxicity (LOEC) results are then automatically calculated, and graphically displayed.