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Anyone who knows about public health will likely list the national effort to get poisonous lead out of peoples' environments as one of the major victories of the last century — alongside the near-eradication of polio, the development of antibiotics, and the drastic reduction in smoking.
Lead poisoning is far less common now than it was in the 1980s. Between 1976 and 1980, a whopping 77.8% of American children had elevated lead levels in their bloodstreams. That number's now down to about 1.6%, which is very good news.
Even barely-detectable levels of lead in children's' bloodstreams can impair brain function and hurt their prospects for healthy and happy lives. There's no effective treatment for or known safe level of lead in the bloodstream. So fewer kids getting exposed means more people whose brains can develop to their full potential.
But the ongoing crisis in Flint, Michigan brought to light how limited and unequal the efforts to un-lead America have been. And a new study published April 27 in the journal Pediatrics suggests that the problem is much worse than official numbers suggest.
The researchers used advanced statistical modeling based on data from the National Health and Nutrition Examination Survey —which does its own lead screening on kids all over the country — to predict how many children should be found with lead poisoning across the U . Then they compared those numbers to the total number of case reports that states have provided to the Centers for Disease Control.
They found that for every one of the more than 600,000 cases of childhood lead poisoning reported to the CDC between 1999 and 2010, another poisoned child went undetected. That's 600,000 cases of lead poisoning missing from the official record, which brings the total to 1.2 million cases across the United States in that time period.
That problem seems to stem from the fact that the US got ahead of itself when it came to tackling lead contamination.
The number of lead poisoning cases declined dramatically toward the end of the 20th Century. Thanks to efforts from the Environmental Protection Agency, lead was stripped out of common products like gasoline and paint. Major local and federal governmental efforts were also initiated to identify and cleanup lead already present in peoples' homes and soil.
In 1991, the Centers for Disease Control recommended that every child in America be screened for lead in their bloodstreams.
By 1997, amid falling rates, those standards were relaxed. The CDC decided that each state could decide for itself whether to screen for and report lead poisoning — though the CDC said poorer families reliant on Medicaid (and more at risk of living in contaminated areas) should still ideally be screened. By 2009, even that recommendation was "softened," so states weren't expected to push Medicaid recipients toward screening
Because of that, the researchers write, communities across the country may have lead poisoning problems without any public health officials knowing of them.
According to the researchers' estimates, certain areas of the country miss more cases of lead poisoning than others. Arizona, Colorado, Florida, Georgia, Kentucky, Nevada, New Mexico, Oklahoma, Oregon, Tennessee, and Washington all miss at least 80% of lead poisoning cases, the researchers suggest, even though they report the lead poisoning cases they catch to the CDC.
Alabama, Alaska, Arkansas, Hawaii, Idaho, Montana, North Dakota, South Carolina, South Dakota, Wyoming, and Utah and don't report any cases at all to the CDC, and don't participate in standardized national screening processes.
Some states, mostly in the Northeast and upper Midwest, seem to catch a majority of cases, but there are just 10 states (New York, Ohio, Missouri, New Hampshire, Massachusetts, Pennsylvania, Wisconsin, Connecticut, Illinois, and Rhode Island) that seem to catch more than 90%.
Most of the undetected cases are likely concentrated in poor and minority areas in the South and West, and many likely have poisoning rates significantly higher than Flint.
Now, the researchers write, the task for public health officials is to find them.