The battle against lead poisoning became most visible when in 1960s Clair Cameron Patterson (1922-1995), a leading CA Institute of Technology researcher, discovered its toxic levels in the environment and in human bones and subsequently its harmful effects on human mind and physiology.
In Neil deGrasse Tyson's remake of the Cosmos: A Spacetime Odyssey, his story is prominently featured as he faced serious backlash from the "industry" of his time and suffered set backs in his own career when his research funding by many organizations was pulled and he lost his position at the National Research Council (1971). While determining the age of Earth using lead levels in meteorite samples, he noted extremely high lead levels in the environment, largely attributed to gasoline, canned goods and paint processing.
While lead poisoning affects almost all body systems, its psychological and neurological impact is devastating. As per the Agency for Toxic Substances & Disease Registry, "there may be no lower threshold for some of the adverse neurological effects of lead in children". Amounts less than 10µg/dL could be harmful. The Agency cites studies from the 1980s showing that for every 10 µg/dL increase in blood lead levels, IQ was found to be lower by four to seven points. The effects of lead poisoning might be physically undetectable initially and could begin with subtle psychological symptoms or just irritability. It could progress to gait unsteadiness, cognitive deficits, seizures, coma and even death.
The old paint in homes (1960s and before) as well as water pipes remain as sources of lead poisoning. Since Flint, MI a number of other communities are reporting highly contaminated water supplies (exact level of lead exposure is unclear). These settings happen to be either rural as in Sebring, Ohio or impoverished minority (mostly black) communities such as St. Joseph, LA. Arthur Delaney of Huffington Post rightly notes that there is no national plan to get rid of the lead pipes. The Safe Drinking Water Act fails to mandate replacing these pipes thanks to the interest groups representing a new "industry" pushing back against regulations.
For its part, the Center for Disease Control acknowledges that approximately half a million U.S. children (1-5 years) have been exposed to lead with blood levels above 5µg/dL (level at which action is urged). CDC's Childhood Lead Poisoning Prevention Program has goals of eliminating blood lead levels ≥ 10 µg/dL.
The water crisis in Flint, MI was of several months in the making. The warnings from experts including that of Dr. Mona Hanna-Attisha who had refused to back down despite the State's repeated denials to acknowledge the problem were ignored. Adding a corrosive barrier could have potentially prevented the iron in the water from dispersing lead from the pipes, although a relatively easy task, it also had no guarantees of success. This exercise in negligence had inevitably resulted in serious consequences to the physical and mental health of its residents.
Unfortunately, Flint's dilemma is not likely to be the last of it that we have seen. Today, we have at least some understanding, education and awareness of this issue but we clearly lack the policy commitments to bring about a much-needed change in the very infrastructure that is the source of this problem to begin with.