The search for Antarctic organisms that can be used for pharmaceutical and other commercial purposes — called “extremophiles” for their ability to thrive in harshly cold, dry, and salty conditions — is pushing international patent law to the breaking point and threatening the fragile Antarctic environment, concludes a United Nations study released on Sunday. The Antarctic Treaty System, the international agreement currently governing activity on the world’s southernmost continent, does not regulate private development, but makes the region open to scientific research. “Bioprospecting” groups often contain a mix of government and private representatives, making it difficult to distinguish between research and commercial activities. “If bioprospecting is done properly, it can be useful and beneficial for all and can have a minimum impact on the environment, but you want it to be controlled to prevent companies from causing significant environmental damage or disrupting the scientific operations down there,” said Sam Johnston, one of the study’s authors.