Photo: AP

Lead levels that shoot above 5 micrograms per deciliter of blood in children under the age of six are considered dangerous and can inhibit the child’s growth and cause learning disabilities and behavioral problems. A report released by the Center for Disease Control and Prevention on Friday found the odds of a young child living in Flint Michigan contracting such high levels of lead in their blood system rose by 50 percent after the city switched its water supply from Detroit’s water system to the Flint River in April 2014.

The river supplied Flint residents with water contaminated with corrosion from old pipes for eighteen months.

Flint went back to using Detroit’s water system in October. However, it wasn’t until Thursday that federal officials deemed Flint’s filtered tap water safe enough for everyone to drink, including pregnant women, nursing mothers, and children under the age of six. The amount of lead in the children’s bloodstreams returned to pre-crisis levels after last fall.

The report’s results are based on blood tests conducted on 7,300 of the 9,600 children younger than six living in Flint during the water crisis.

The CDC report explicitly identifies the contaminated Flint River water, which Michigan officials likely knew was toxic before the public did, as the cause of high lead levels in Flint children:

When the source of the water supply was switched to the Flint River, without appropriate corrosion control measures, young children who drank the water had blood lead levels that were significantly higher than when the source of water was the Detroit water system.

A report from a panel appointed by Michigan Governor Rick Snyder to investigate the water crisis called it a case of “environmental injustice” and concluded that:

Flint residents, who are majority black or African American and among the most impoverished of any metropolitan area in the United Sates, did not enjoy the same degree of protection from environmental and health hazards as that provided to other communities.

Patrick Breysse, director of the CDC’s National Center for Environmental Health said in a statement that the Flint water crisis was, “entirely preventable, and a startling reminder of the critical need to eliminate all sources of lead from our children’s environment.”