MODEL RELEASED. Toxicology research. Toxicologist using a microscope to study a muscle tissue sample during research. The tissue sample is seen pinned to a colourless plate (lower left). The electro- chemical effects of organophosphate chemicals on the tissue are being investigated. A probe is measuring the electrical changes as the chemical is applied. Organophosphates are frequently used in insecticides. Over-exposure can cause vomiting, diarrhoea and breathing difficulties. Prolonged exposure can lead to widespread neuromuscular damage. Photographed at Newcastle University, England.