Researchers say sewage data holds clues to Flint water crisis

FLINT, MI -- Researchers from Virginia Tech university say they’ve found the first direct evidence that corrosive water caused elevated blood lead levels in Flint children.

A new study published in the peer-reviewed journal Water Research relied on years of data from routine measurements of metals in Flint’s sewage sludge, showing a connection between rising levels of lead in city waste, blood lead levels in children and use of the Flint River as a water source.

Authored by professors Marc Edwards and Sid Roy, the study used sewage to determine lead levels because of the lack of reliable lead data from drinking water sampled during the water crisis -- a time when a former Flint utilities director has said he city disregarded federal rules requiring it to seek out homes with lead plumbing for testing.

That practice produced artificially low lead levels in sampling for lead and copper in Flint, officials have said.

The study also showed two other unexpected results: Lead levels dropped after initially spiking after the water switch in April 2014, rather than getting progressively worse during the 18 months the city used river water, and lead levels in Flint sewage sludge was actually higher in 2011, while the city was using pre-treated water from Lake Huron, than at any point since.

The Water Research article says the 2011 “anomaly may have somehow been linked to treatment upsets or other events during record Detroit rainfall, which was national news in that exact time period ."

“The overall lead release (from pipes and home plumbing) was not as bad as we once feared,” Edwards said. “That was shocking. The vast majority (of the lead releases) came in those first months” after the water switch.

Edwards, whose work testing Flint River water previously showed its extreme corrosiveness, said the sewage sludge data suggests a shock to the city’s water system at the time of the switch, when the state Department of Environmental Quality did not require treatment of water to make it less corrosive, and a return to more normal readings after relatively sudden and large releases of lead.

In a news release, Roy said the excess lead in Flint water from April 2014 to October 2015 was 14 percent higher than the corresponding time period before the change in water source, giving Flint water an estimated 90th percentile water lead level of 77 to 98 parts per billion, at least five times the federal threshold of 15 ppb.

Roy and Edwards said high levels of lead in Flint’s sewage sludge in 2011 shows lead in water was sometimes a significant issue in the city even before the water crisis.

In addition to lead, the Virginia Tech researchers said levels of other metals -- cadmium, copper, nickel and zinc -- all spiked markedly in summer 2014, and it “is hypothetically possible this was due to general (shedding) of pre-existing scale from all plumbing surfaces.”

Water temperatures in the shallow Flint River fluctuated much more in both summer and winter months than Lake Huron water, the journal article says, “producing a greater possible effect of temperature on metal release from plumbing.”

The Virginia Tech research was partly funded and developed with grant funding from the U.S. Environmental Protection Agency, but has not been formally reviewed by the agency, the article says.