The authors examined the lead rust inside 10 service lines around Flint. They took samples from each line, and noted the texture of the rust, along with its chemical composition. Using these variables, the authors calculated that the average service line around Flint released around 18 grams of lead during 17 months when the lines were not properly controlled for corrosion.
Lead author of the study, Terese Olson, says on Science Daily, “this is the amount of lead that would have entered a single home. 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.”
Olsen and her team noted that the heavy metal seeped through the water system and caused the lines to become faulty. Moreover, due to the lines not being treated for corrosion, the lead could have been easily consumed by us unknowingly. The team further noted that while it is possible for some of the lead to have been washed down the drain, a larger percentage of the metal would have remained in home plumbing. This means that Flint residents could still be in danger of ingesting the metal in their drinking water, even after a lead service line is removed.
This is because galvanized steel pipe -- the most common kind of pipe used in people’s homes -- can act as sponges for lead, holding the metal for weeks or months, and then later releasing contaminated particles into the water.
Data from the Flint service lines perturbed the researchers. Aside from examining the pipes under a scanning electron microscope, they also inspected the chemical makeup of these lines. Flint pipes had a greater aluminum and magnesium ratio compared to similar figures from 26 other water utilities.
“We estimate how much lead was ‘missing’ in order to bring the Flint lead scale into line with the amount of aluminum and magnesium that was reported in other communities. That missing lead represents what was leached from the pipes during the Flint corrosion episode,” Olsen said.
The team explained that aging lead pipes become particularly problematic if not treated correctly. They disclaim, however, that even current water treatment technologies are not enough to prevent the oxidation process that occurs in all lead pipes. What these treatments are useful for, they said, is mitigating the formation of rust along the lines.
In Flint’s case, local government authorities decided to switch water utilities to save money; stemming the addition of a crucial compound called orthophosphates which prevents lead from rusting. In doing so, the Flint government changed the chemistry within their own pipelines. This caused the absurd rate in which lead leaked off and caused the water system to become defective. (Related: Flint, Michigan, isn't the only U.S. city plagued by lead problems.)