Just a week after Michigan mayor Karen Weaver declared a state of emergency over elevated levels of lead in children’s blood, a new study published in the American Journal of Public Health reveals the strongest evidence of a link between elevated blood-lead levels and the city of Flint’s poor water system.

Researchers cited in April 2014, the post-industrial city of Flint — the largest city in Michigan's Genesee Country — changed its water supply from the Detroit-supplied Lake Huron water to the Flint River. The change was meant to save the city money and was only temporary; they were awaiting a new pipeline to Lake Huron in 2016. But shortly after the switch, residents voiced concern about the new water’s color, taste, odor, and their health. Some were experiencing skin rashes, and water tests detected Escherichia coli in the distribution system. Also around this time an unusual number of children had elevated levels of lead in their blood.

Lead is a potent neurotoxin, and in children, elevated blood levels (BLLs) can have developmental and biological effects, researchers said; "most notably intelligence, behavior, and overall life achievement." The Centers for Disease Control and Prevention cited BLLs increased the likelihood of learning disabilities; poorer performance on tests; and being non-proficient in math, science, and reading.

The Huffington Post cited Michigan State officials dismissed more than one report from the Michigan Department of Health and Human Services warning against "higher than usual" lead poisoning rates among children under the age of 16 living in Flint. But is the water change solely to blame?

That's what the present study set out to find. Researchers received BLLs for children younger than 5 years before and after the water source change in Flint in an effort to assess the percentage of elevated BLLs in both time periods. They used medical records to calculate the age they were tested and geocoded the data with a dual-range address locator, though they "derived overall neighborhood-level socioeconomic disadvantage from census block group variables intended to measure material and social deprivation."

The results revealed a "statistically significant increase" in the number of children living in Flint with BLLs from before the water change to the Flint children in the post-period. Before the change, 2.4 percent of children had higher BLLs compared to 4.9 percent of children after the water change.

What’s more is in urban areas with high levels of socioeconomic disadvantage and minority populations, there seemed to be a problem with higher BLLs. "A review of alternative sources of lead exposure reveals no other potential environmental confounders during the same time period," researchers said.

Since no alternative source could point to another cofounder, the present findings offer the strongest evidence for the link between Flint’s water source change and children’s higher BLLs. Dr. Mona Hanna-Attisha, the report's lead writer and an assistant professor at Michigan State University, told AP everybody who drank or cooked with Flint’s new water was exposed to lead.

"Lead in drinking water is different from lead from other sources, as it disproportionately affects developmentally vulnerable children and pregnant mothers," Hanna-Attisha and her team explained in their report. "Children can absorb 40 percent to 50 percent of an oral dose of water-soluble lead compared with 3 percent to 10 percent for adults. In a dose–response relationship for children aged 1 to 5 years, for every 1-ppb increase in water lead, blood lead increases 35 percent. The greatest risk of lead in water may be to infants on reconstituted formula."

While AP reported "lead exposure is irreversible and no level is safe," it doesn’t affect all children the same. Hanna-Attisha pointed to "good nutrition" as a method of prevention given this better helps "the body excrete toxins instead of absorbing them."

Perhaps better than adhering to a healthy diet is the development of public health programs that educate both children and parents on the signs and side effects of lead poisoning, including but not limited to anemia, low academic achievement, and any unusual behavior changes. In fact, early childhood education was considered a primary method of prevention in the CDC’s April 2015 report on children affected by lead.

"Primary prevention strategies that control or eliminate lead sources before children are exposed remain the pre-eminent public health approach to the problem of lead poisoning and are the only effective way to prevent the neurodevelopmental and behavioral abnormalities associated with lead exposure," Dr. Patrick N. Breysse, director of the CDC’s National Center for Environmental Health and Agency for Toxic Substance and Disease Registry, prefaced the report’s findings.

Since hundreds of thousands of children already have experienced blood lead levels known to impair academic performance and affect life success, in and outside of Flint, Breysse said we need "strategies that restore individuals to an optimal level of functioning after damage is done."

The report concluded everyone from the government, to pediatric health care providers and children’s parents need more opportunities to learn the "importance of age appropriate blood lead testing and of primary prevention efforts. They may also need to be informed about the need for vigilance in the period after a test result and at critical transition points in educational expectations such as first, fourth, and sixth grades, and about early intervention programs and the merits of accepting a referral to them."

Source: Attisha MH, et al. Elevated Blood Lead Levels in Children Associated With the Flint Drinking Water Crisis: A Spatial Analysis of Risk and Public Health Response. American Journal of Public Health. 2015.