Fred Mettler, a radiation expert at the University of New Mexico, puts the number of worldwide cancer deaths outside the highly contaminated zone at perhaps 5,000, for a total of 9,000 Chernobyl-associated fatal cancers, saying "the number is small (representing a few percent) relative to the normal spontaneous risk of cancer, but the numbers are large in absolute terms". The same report outlined studies based on data found in the Russian Registry from 1991 to 1998 that suggested that "of 61,000 Russian workers exposed to an average dose of 107 mSv about percent of all fatalities that occurred may have been due to radiation exposure".