The first major product of agricultural biotechnology was recombinant bovine growth hormone (rbGH, also know as rbST), a drug produced by Monsanto to increase milk production in cows. Following worldwide debate about its safety, it was approved in the United States in 1993 but rejected in Canada and Europe in 1999. In Science and Social Context Lisa Mills looks at how regulatory scientists arrive at conclusions about product safety, given the constraints of the environment in which they work.