Monsanto was one of four groups to introduce genes into plants, and was among the first to conduct field trials of genetically modified crops. Monsanto was one of the first companies to apply the biotechnology industry business model to agriculture, using techniques developed by biotech drug companies. Monsanto’s roles in agricultural changes, biotechnology products and lobbying of government agencies and roots as a chemical company have surrounded the company in controversies. The company once manufactured controversial products such as the insecticide DDT, PCBs, Agent Orange and recombinant bovine growth hormone. Its seed patenting model was criticized as biopiracy and a threat to biodiversity. In September 2016 Monsanto agreed to accept Bayer’s offer to purchase the company for $66 billion, pending regulatory approval.