Contaminated water : residents of Flint still in danger

Carlos Osorio/AP/SIPA

Published the 31.07.2017 to 12.50

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In early 2016, a wave of poisonings in adults, but mostly children of the city of Flint had shocked the United States. In this town of 125,000 inhabitants of Michigan, located in the North-East of the country, a change of water supply had been pointed out by the inhabitants and researchers.

A study done at the university of Michigan has confirmed the original contemplation of the problem. By analyzing the lead piping, the scientists observed their state of degradation : the layer of lead that covered it now looks like “swiss cheese,” according to their own words. And it is the water of the local river which caused these damages.

A corrosive water

The ageing of lead piping was of course accompanied by oxidation, which is not necessarily dangerous but must be controlled, notably thanks to the treatment of the water. The change of supply has changed in Flint.

The composition of the water abstracted from the river, polluted, makes it much more corrosive. The officials of the local plant of General Motors had decided to no longer supply itself with the water that was damaging his car parts.

After the change of supply, these are whole pieces of lead that have been torn out of the pipes, instead of the few atoms that are oxidized carried in normal times. “It’s like what happens when you place the pennies in a glass of Coke,” explains Terese Olson, a researcher in civil engineering and environmental at the university of Michigan, who conducted the investigations. The acid from the Coca quickly dissolves the oxide of copper. “

Piping lead at Flint (Credits : Terese Olson)

An ever-present risk

“If we average release on the entirety of the period during which Flint received the water of the river, we estimated the concentration more than two times the limit the EPA (the us government Agency for the protection of the environment, editor’s note) “, she adds.

And, unfortunately for the people of Flint, some homes could still be contaminated. If the majority of lead particles has already been consumed or rejected in the sewers, “a party could still be stored in homes,” according to the researcher.

The houses whose pipes are made of galvanized steel are particularly at risk. This material acts as a sponge lead. Once soaked, the pipes continue to release regularly the toxic material, and for a long time. “There is a risk that part of this lead may be hazardous, even after the change of the pipes in the distribution service to the city “, is concerned Terese Olson.