Lead has been used in pipes and plumbing dating back to ancient times, but its role as a public health hazard only emerged in recent decades. Ancient Romans used lead pipes to carry water from the aqueducts into their homes and were even aware high exposure to lead was dangerous. Only in the 1970s did scientists discover the dangerous consequences even low doses of lead pose to health, particularly for children. Pediatrician and child psychiatrist Herbert Needleman ran a series of studies measuring lead in children’s teeth in the 1970s. He published the first scientific study saying even relatively low lead exposure can reduce I.Q.s, shorten attention spans, delay language proficiency and cause behavioral problems. As lead was banned in consumer products, the number of children being exposed dropped by about 90 percent. However, there are tremendous reservoirs of lead remaining in the environment as legacy of past heavy uses, according to Harvard University’s David Bellinger. “In most places in the U.S., we use the children to tell us where the lead is,” Bellinger said. “We wait for a child to be overexposed before there’s investigation into that child’s environment.” An example of this made news headlines this past year when it was revealed the water supply in Flint, Michigan was contaminated with lead. Although communities can protect themselves from exposure to lead pipes by adding, the local government in Flint did not take the necessary steps to prevent leeching when they changed water sources. Some 10 million homes in the U.S. are still connected to lead pipes. They are easy to recognize, and anyone who suspects their presence should have their water tested immediately.