It takes an average of seven to nine years and an investment of about $55 million to develop, test, and market a new genetically engineered product. Because of this great cost, companies have sought to patent the results of their discoveries. In 1980 the Patent and Trademark Office of the . Department of Commerce issued its first patent on an organism that had been produced with recombinant DNA. The patent was for an oil-eating bacterium that could be used to clean up oil spills from ships and storage tanks. Since then, hundreds of patents have been granted for genetically altered bacteria, viruses, and plants. In 1988 the first patent was issued on a transgenic animal, a strain of laboratory mice whose cells were engineered to contain a cancer-predisposing gene. The mice are used to test low doses of suspected carcinogens, or cancer-causing substances, and to test the effectiveness of anticancer therapies.