Environmental degradation increasingly threatens the existence of the world’s 300 million indigenous people, as do disease and poverty, according to a report released Friday by the World Health Organization. For example, populations in the Arctic have been exposed to very high levels of industrial contaminants. Native peoples in Alaska often lack safe drinking water and adequate sewage disposal. And indigenous cultures in the Pacific are threatened by nuclear testing, waste dumping, mining, logging, and the spread of tourism development, the report found. The WHO pledged to do more to combat these problems, as well as others that lead to health problems and starvation among indigenous peoples.