U.S. Democratic Sens. Hillary Clinton (N.Y.) and Harry Reid (Nev.) yesterday proposed creating a national tracking system to monitor both chronic diseases and environmental pollution so that any correlations between the two could be more easily identified and studied. Last year, the two senators held hearings in Fallon, Nev., which is home to a cluster of childhood leukemia cases, and Long Island, N.Y., which is home to an above-average rate of breast cancer. Clinton said, “Whether these clusters are actual or perceived, the rates of chronic diseases in our country is, unfortunately, rising. And we don’t know why.” The findings of the proposed tracking system would be made public through a national environmental health report.