Drug safety is a major focus of pharmaceutical microbiology. Pathogenic bacteria, fungi such as yeasts and moulds and toxins produced by microorganisms are all possible contaminants of medicines; although stringent, regulated processes are in place to ensure the risk is minimal. Pharmaceutical microbiology is an applied branch of Microbiology. It involves the study of microorganisms associated with the manufacture of pharmaceuticals e.g. minimizing the number of microorganisms in a process environment, excluding microorganisms and microbial biproducts like exotoxin and endotoxin from water and other starting materials, and ensuring the finished pharmaceutical product is sterile. Other aspects of pharmaceutical microbiology include the research and development of anti-infective agents, the use of microorganisms to detect mutagenic and carcinogenic activity in prospective drugs, and the use of microorganisms in the manufacture of pharmaceutical products like insulin and human growth hormone.