Last week, scientists monitoring the water in Flint, Michigan announced that the levels of lead in the water have drastically decreased and are “now back to the normal levels for a city with old lead pipes.” At a press conference, the experts said the situation was no longer a crisis. Nevertheless, the impact of Flint’s water catastrophe will still resonate for years to come: According to a new working paper, the increase of lead in the water system had major effects on the fertility of Flint citizens.

The period that Flint residents were exposed to tainted water was long enough that water consumption affected the fertility and birth outcomes of Flint, explain economists Daniel Grossman, Ph.D., and David Slusky, Ph.D. in the paper.

They analyzed live birth and fetal death data taken from 2007 to 2015 from 15 Michigan cities and Flint, discovering that fertility rates decreased by 12 percent among Flint women and fetal death rates increased by 58 percent. Overall, the health of Flint children at birth was worse compared to children born in other Michigan cities.

Flint River michigan
Flint River is now considered a safe water source.

Between 198 and 276 more children would have been born if Flint if the water was not contaminated with lead, Grossman and Slusky write in the paper. They note that Flint residents weren’t having any less sex at the time, according to data from the American Time Use Survey. This allowed them to conclude that “either Flint residents were unable to conceive children, or women were having more miscarriages during this time.”

Flint resumed sourcing its water from Flint River in the spring of 2014, after Michigan’s Department of Environmental Quality declared that the water cleanup had been successful. For years, it had been the main source of water for the town until 1967, when citizens became concerned about water pollution from the state’s auto industry. Later analysis revealed the water was tainted with lead, but a lead advisory was not issued by city officials until September 2015. It wasn’t until then that the city stopped using Flint River as its main source of water.

The effects of lead on fetal health have not been studied greatly, but some studies exist. In 2013, a paper in Environmental Science and Technology on fetal death that occurred when lead water levels were at a dangerous state in Washington, D.C. between 2000 and 2004 found that water in lead is linked to an increase in fetal deaths and a reduction in birth rate. Citing similar studies, Grossman and Slusky write that “recent studies have linked maternal lead exposure to fetal death, prenatal growth abnormalities, reduced gestational period, and reduced birth weight.”

A lead service line water pipe is exposed by a City of Flint, Michigan work crew as workers prepare to replace the pipe at the site of the first Flint home with high lead levels to have its lead service line replaced under the Mayor's Fast Start program on March 4, 2016.

They mention that lead testing in infants is “not routinely performed,” despite plenty of research clearly showing how important in utero health is to the long-term health of an individual.

We know, for example, that when an adult has high lead content in their blood, nearly all organ systems are affected detrimentally and there is a high chance that person will develop cardiovascular problems, high blood pressure, and impairment to their nervous system. Children are much more vulnerable to lead toxicity than adults, and it can delay pubertal onset in boys and girls.

For their part, the citizens of Flint seem well aware that, as resident Mona Munroe-Younis told the New York Times, “we’ve got a year to go in this recovery.” Slusky and Grossman hope that their work will have a role in aiding this recovery and serve as a reminder in years to come.

“In the future we would like to have a government that is more responsive and more active in ensuring that the water that comes out of people’s taps is safe,” says Slusky.

If you liked this article, check out this video of an app that flags unsafe drinking water.