Scientists at the University of Utah recently analyzed human hair samples dating back roughly 100 years. Their findings show that lead levels in people were about 100 times higher before environmental laws were put in place. The study, published in the journal PNAS, reveals a steady drop in lead exposure thanks to rules like the ban on leaded gasoline. The researchers point out that while historical evidence proves these regulations have worked well to protect health, some of these rules are currently being scaled back by the Trump administration. Researchers stress that the data shows just how much these laws have helped the public over the last century.