The measurementof the decayofradioactiveisotopes, especiallyuranium, strontium, rubidium, argonandcarbon, has allowedgeologists to morepreciselydetermine the ageof rock formations.
Cancer incidence in children under age ten living near New York and New Jersey nuclear plants increased 4-5 years after increases in average Strontium-90 in baby teeth, and declined 4-5 years after Sr-90 averages dropped.