DETROIT – Virginia Tech researchers who exposed the lead problem in Flint, Michigan, gave an upbeat opinion of the city’s water quality Thursday after finding no detectable levels of the toxin in nearly half of 162 homes tested in July.

Marc Edwards still urged residents to drink only filtered tap water or bottled water while the system heals itself. But at the same time, he said “the wind is kind of at our back” as long as the water continues to be treated with phosphates to reduce corrosion, a critical step that was missing when Flint used the Flint River for 18 months.

“This is nearing the end of the beginning of the end of the public health disaster response,” said Edwards, an expert in environmental engineering. “Flint water now looks like it’s entering a range that’s considered normal for other U.S. cities.”

Edwards and other researchers spoke at a news conference in Blacksburg, Virginia. He is credited with blowing the whistle a year ago on high levels of lead in Flint’s drinking water, although it took several more weeks for Michigan Gov. Rick Snyder and federal regulators to finally acknowledge that the city of roughly 100,000 residents had a disaster.

While waiting for a pipeline to be built to Lake Huron, Flint drew water from the Flint River but didn’t treat it for corrosion. As a result, a protective coating inside pipes broke down, releasing lead from old pipes and fixtures. Flint now gets water from a Detroit regional system.

Edwards and his team have taken water samples from 162 randomly selected homes since August 2015. The researchers said 45 per cent of homes had no detectable lead levels in July, compared to 37 per cent in March and 9 per cent a year ago.

“Things are dramatically better now,” Edwards said.

It’s not clear when state and federal regulators will declare that unfiltered tap water is safe to drink. On July 29, Snyder reported more encouraging results from separate water tests conducted by the state at more than 160 Flint homes. More than 93 per cent were at or below the federal threshold, although no level of lead exposure is considered safe.

Even low levels of lead in blood can affect IQ, the ability to pay attention and performance in school, according to the government.

The governor welcomed the new findings by the Virginia Tech team.

“Statements from independent experts will reassure residents who may have lost some trust in government,” Snyder said.

Flint Mayor Karen Weaver also welcomed the results, although she wants all lead water lines at homes replaced. A few dozen have been completed, and contracts were approved Wednesday for the next phase of work. The state is providing $27 million.

“We hope to have crews out on the job within the next couple of weeks,” Weaver said.

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