Partial lead-pipe replacements bring down levels of toxins

By Ronnie Cohen

Reuters Health - New research clarifies the benefits of having utilities replace municipal lead water-service lines, even when the pipe that enters a home continues to be made of the metal that can impair children’s brain development.
Previous studies based on laboratory setups showed that partial replacements of old service lines made of lead could increase corrosion and elevate lead levels at the tap, said Michele Prevost, professor of environmental engineering at Polytechnique Montreal in Quebec, Canada. The studies prompted some municipalities to leave aging lead pipes in place at otherwise opportune times to change them.
But the new study found that compared to homes with no water line replacement, homes with partial replacements had lower levels of lead in the water. Although lead continued to leach into the water, lead levels were significantly lower after partial replacements.
The message, according to senior author Prevost: “Don’t stop the utilities from replacing what they can.”
Because utilities are responsible for just part of water lines, and homeowners are responsible for the rest, utilities frequently must decide whether to replace just their portion of lead pipes.
The best way to handle lead pipes is to change them out entirely by replacing both the homeowners’ and the utility’s pipes, Prevost said in a phone interview. When not possible, however, she said the new study in Environmental Science and Technology shows that partial replacements can lower lead levels.
Dr. Jennifer A. Lowry, chair of the American Academy of Pediatrics’ council on environmental health, said the finding of decreased lead concentrations after partial replacements made sense.
“But, anytime you disrupt the line, flakes of lead and other things will break off and contaminate the line. So, you need to flush the line before it is used,” she said by email. Lowry, chief of toxicology and environmental health at Children’s Mercy Kansas City, was not involved with the new study.
The remaining problem, Prevost said, is that no one has yet figured out how to sufficiently flush.
“We know we need to flush it well, but we don’t know how long,” she said. “It’s a bit of a Russian roulette.”
“Immediately after replacement, if you don’t flush the water, the lead concentrations are so high that one single glass of water could represent an acute dose, enough to give a child lead poisoning,” she said.
Lowry stressed the importance of alerting the public when water lines are being replaced so they know to wait until the water is safe before they drink it. She also stressed the importance of recognizing that multiple lead sources - paint, jewelry and foods, for example, in addition to drinking water - can contaminate children simultaneously.
The new study examined levels of drinking water in 33 Canadian households with partly replaced pipe. Immediately after partial replacements, lead levels spiked as high as 30,485 micrograms per liter. But they dropped to as low as 7 micrograms per liter after 30 minutes of flushing.
During the course of 20 months, water lead levels decreased, but in 61 percent of the study samples they still exceeded 10 micrograms per liter, the World Health Organization’s cautionary level.
The lowest lead levels were seen in homes with lines that were partially replaced more than two years before the study began or that received a full upgrade.
The U.S. Environmental Protection Agency and the U.S. Centers for Disease Control and Prevention caution that there is no safe level of exposure to lead. A neurotoxin, it is particularly harmful to young children and to the unborn children of pregnant women.
Lead can impair children’s neurodevelopment and has been tied to lower intelligence, learning disabilities, antisocial behavior and even criminality. In adults, lead can cause hypertension and cardiovascular disease.
In 1986, Congress banned the use of lead in pipes conveying drinking water. But lead pipes still carry drinking water to millions of Canadians and Americans, including in Flint, Michigan.
Flint's water contamination problem emerged after the city switched its water source from Lake Huron to the Flint River in 2014. The more corrosive river water caused lead to leach from pipes. Flint switched back to the previous water system in 2015.

SOURCE: Environmental Science and Technology, online August 9, 2017.