Since the 1960s, the federal Centers for Disease Control has repeatedly lowered the blood lead level at which public health actions are triggered, according to the Union of Concerned Scientists, a nonprofit founded by scientists and students at the Massachusetts Institute of Technology seeking to use science to address global issues.
In 1960, a blood lead level of at least 60 micrograms per deciliter would have prompted public health actions. In 1975, the CDC had reduced the threshold to 30 micrograms per deciliter.
In 1985 — seven years after lead-based paint was banned — CDC officials reset the level to 25 micrograms per deciliter. In 1991, the CDC deemed children who tested higher than 10 micrograms per deciliter to have a blood lead “level of concern.”
In 2012, the reference level at which the CDC recommends public health action was set to 5 micrograms per deciliter.
The CDC bases its current threshold off of the 2.5 percent of children who tested the highest for lead in the two previous editions of its National Health and Nutrition Examination Survey, a program of studies to determine the overall health of adults and children in the United States.
In other words, approximately 2.5 percent of children had blood lead levels above 5 micrograms per deciliter at the time CDC officials cut the threshold to five.
“Even low levels of lead in blood have been shown to affect I.Q., ability to pay attention and academic achievement,” according to the CDC’s website. “And effects of lead exposure cannot be corrected.”
