As water officials at Flint, Michigan, continue to deal with the unfolding health crisis associated with elevated lead levels in the town's drinking water, scientists who initially discovered lead in the tap water of a Flint household have analyzed galvanized iron water pipes that were removed from the "ground zero" home — where the first child with high levels of lead in their blood was identified — for testing.
There tests confirm that the lead particles that had built up on the internal surface of the galvanized iron pipes was in all probability the source of lead contaminants in the water.
Lead levels in Flint's tap water spiked following a switch in the town's water supply in April 2014, when the city opted for the Flint River as its drinking water source. After the switch, water officials failed to treat the water line with a corrosion-control remedy to keep the lead-containing layers of rust stable within the water pipelines.
Soon thereafter, residents began complaining that their water looked and smelt odd. Then, when LeeAnne Walters' family fell ill she contacted Marc Edwards, a Virginia Tech engineer, requesting that he come an test their water.
Thirty-two water samples were collected from the Walters' residence, all of which contained lead at levels that exceeded the 14 microgram per liter actionable standard set by the EPA. Four of the samples had lead concentrations that exceeded 5,000 micrograms per liter — the threshold at which lead is declared hazardous waste, and one sample had lead concentrations of 13,200 micrograms per liter.
Edwards and his research team have since analyzed the galvanized iron water pipes that connected the lead pipes from the service line to the Walters' home. Their findings, which were recently published in the American Chemical Society journal, Environmental Science & Technology, show that high concentrations of lead in the household's tap water correlated with levels of zinc, tin and cadmium — components used in the internal lining of the pipes.
According to the authors, the results suggest that because no corrosion inhibitors were added to the water extracted from the Flint River, the water caused the layers of rust (including the lead attached to it) to be released from the internal wall of the iron pipes.
The scientists conclude that the combination of lead service pipes followed by galvanized iron water pipes supplying the home, is very likely to pose a health risk to residents living in other towns and cities that have this type of configuration.
They recommend replacing the lead service pipes as a good first step, but suggest that lead accumulation on aging galvanized iron water pipes potentially poses both a short- and long-term health concern.
Kelsey J. Pieper, Min Tang, and Marc A. Edwards. Flint Water Crisis Caused By Interrupted Corrosion Control: Investigating "Ground Zero" Home Environ. Sci. Technol. (Feb 1, 2017), DOI: 10.1021/acs.est.6b04034