Scientists at the University of Michigan say they have confirmed the source of the lead that filled drinking water after the city of Flint, Mich. began sourcing from the Flint River in 2014.
The cause wasn't broken water mains as one Department of Environmental Quality official suggested, but the omission of an additive that is normally used in water city treatment. The mineral, orthophosphate, blocks lead corrosion in service line pipes, which have in the past, been made of lead. Without the inhibitor, the pipes will slough off lead particles, which are then washed into the water source.
"[In] April 2014, the City began drawing and treating water from a new source, the Flint River, without adequate corrosion control (orthophosphate)," said the researchers. It treated the water from the Flint River with chlorine, presumably figuring that would be sufficient.
In order to confirm that it was poor water treatment procedures and not the city's Polar Vortex winters of 2014 and 2015 that caused the disaster, the researchers tracked down a list of U.S. water utilities that did use orthophosphate in their water systems and compared them with water utilities that experienced rampant problems with lead poisoning. They then compared metal scrapings from pipes in 26 utilities that used a lead inhibitor and samples from 10 service lines in the Flint water district. Lastly, they examined pipe scrapings from London, Ont. Canada, where lead poisoning had also been detected.
The scientists discovered that in city pipes where orthophosphate had been introduced, lead corrosion was minimized. The Flint and London, Ont. pipes, however, showed significant damage from lead corrosion. Cross-section cuts of corroded pipes also revealed a ragged surface that had been "eaten away" by the polluted water, confirming that the "missing lead" had been deposited into the residents' drinking water.
"If we average that release over the entire period the city received Flint River water, it would suggest that on average, the lead concentration would be at least twice the EPA action level of 15 parts per billion," explained Terese Olson, an associate professor of civil and environmental engineering at University of Michigan's Environmental Science and Technology Letters. Olson is the lead researcher for the study.
Olson said some of the lead would have been consumed by residents and some may still be stored in residents' plumbing system, since lead isn't automatically washed down the drain.
"In other words, there is a chance that some of that lead is a potential health risk even after the lead service line is removed," said Olson.
Further, other types of pipes, like steel, can actually absorb the lead that passes through it. That continues the risk of future contamination, said Brian Ellis, a co-author and associate professor of civil and environmental engineering. Lead exposure can present a long-term challenge.
With all of the concerns about the dangers of lead poisoning in children, one would think city utilities would be required to use lead inhibitor treatments. But the Environmental Protection Agency only regulates a portion of the utilities in the country. It also doesn't enforce restrictions on lead in drinking water, though it does provide guidance as to maximum levels. Some experts feel that that recommended limit of 15 µg/L is too high and should be lowered.
One positive outcome of this research is that cities now have a greater understanding of the snowball effect of water pollution. Years of industrial dumping into the Flint River contributed to a "water quality change" that in the end, helped set the stage for lead poisoning of some estimated 8,000 children. Cleaning up water sources and regulating what utilities can and can't do with public water systems should be a key issue in today's communities.
But the factors that led Flint to make the decision to use a decades-long polluted water source begs questions as well about the priorities that cities and states make when it comes to accessing and supplying a public water supply.
Flint's water woes didn't start with an arbitrary decision to change water sources. It started with politics, dysfunction and failed negotiations that ultimately forced officials to choose a wrong course.
The question now, is whether the city and state can set the groundwork to ensure that there is good leadership and informed decision-making when it comes to protecting the public's most vital resource and the safety of the city's future generations.