The original study “Demographic Implications of Lead Poisoning for Eagles Across North America,” was published in the journal Science https://www.science.org/
The abstract
https://www.science.org/doi/10.1126/science.abj3068
Click on Authors Info & Affiliations, primarily U.S. Geological Survey, Conservation Science Global, Inc. ( https://consciglobal.org/ ) and U.S. Fish and Wildlife Service

The short version
https://www.science.org/content/article/nearly-half-bald-eagles-have-lead-poisoning