The second largest American Indian tribe will join a federally funded study examining environmental factors affecting children’s health, a step toward restoring trust following battles over researchers’ use of tribal blood samples.

The data-sharing agreement brokered by the National Institutes of Health between the Navajo Nation and researchers at Johns Hopkins University Baltimore and RTI International could be a gateway for more tribes to join similar partnerships, David R. Wilson, director of the NIH Tribal Health Research Office, told Bloomberg...