Toxicology research. Researcher placing samples in an auto-sampler during toxicology research. This research is investigating the toxic effects on living tissue of organophosphate chemicals. The rate and amount of absorption of the chemicals through skin is being studied. Organophosphate chemicals are widespread, being used mainly as insecticides. Overexposure can cause vomiting, diarrhoea and breathing difficulties. Prolonged exposure can lead to widespread neuromuscular damage. Photographed at Newcastle University, England.