In July, when New York officials announced the results of testing for lead in the water at more than 1,500 New York City school buildings, they said less than 1 percent of samples showed lead concentrations that exceeded Environmental Protection Agency (EPA) guidelines. The officials assured parents, the water was safe to drink.
But a review of how the testing was conducted suggests that the amount of lead in the water that students consume could be greater than the results indicate, the New York Times reports.
The night before samples were taken, water outlets in the schools were turned on fully for two hours. This “pre-stagnation flushing” cleans most soluble lead and lead particles from pipes and thus reduces lead levels temporarily, according to the Times. In February, however, the Environmental Protection Agency (EPA) recommended against pre-stagnation flushing saying that flushing “may potentially lower the lead levels as compared to when it is not practiced.” The EPA does not regulate the testing of water in schools, but its guidelines for school water testing recommend mimicking normal water consumption patterns when taking samples, according to the Times.
Prof. Mark Edwards, a professor of civil engineering at Virginia Tech says, “The results should be thrown into the garbage, and the city should start over.” Prof. Edwards helped uncover the dangerously high lead levels in the water in Flint, Michigan. The Flint water crisis touched off scrutiny into lead contamination of drinking water nationwide.
Dr. Yanna Lambrinidou, who has worked with Dr. Edwards on water testing in Washington, D.C., and elsewhere, said, “Flushing is inappropriate any time you want to assess lead concentrations coming out of individual taps.” Lambrinidou said water in schools is often stagnant for long periods because water is not used after school hours, or on weekends, holidays, and other breaks. Sample should be taken under conditions similar to conditions when children drink the water, Lambrinidou said.
Dan Kass, a deputy commissioner in the city’s Department of Health and Mental Hygiene, said flushing is intended to create a consistent baseline for the tests, regardless of whether the samples were taken on a Monday morning after a building had been closed for the weekend or collected on another day of the week, according to the Times.
After contractors finished flushing in school buildings, they left for about eight hours and returned around 5 a.m. to take samples. At each tap or outlet, they took a sample of the first water out of the tap, known as the first draw. Then the water was run for 30 seconds before the second draw was taken. When a second-draw sample shows an elevated lead concentration, this indicates a problem with a more sustained source of lead in the plumbing, the Times explains.
Michigan officials have been criticized for advising flushing before residents took water samples in their homes. Experts say flushing hid the severity of the lead problem in many homes. Two state environmental officials have been charged with violating the Michigan Safe Drinking Water Act with the flushing instructions.
Five hundred ten of the New York City’s 1,520 occupied school buildings had at least one outlet where the first-draw water sample had a lead concentration over 15 parts per billion, the EPA’s “action level” for lead in municipal water systems. And 153 buildings had at least one outlet where the second-draw sample exceeded the threshold. Eight buildings had at least one outlet with a lead concentration over 500 parts per billion.
Lead exposure is particularly dangerous for young children. The Centers for Disease Control and Prevention (CDC) says here is no known identified safe blood lead level. “Exposure to lead can seriously harm a child’s health.” High levels of lead in the blood can affect mental development and damage organs. Even low levels of lead can affect intellectual development, the ability to pay attention, and academic performance.