Researchers at the National Institute for Occupational Safety Health (NIOSH) studied 50 children and concluded "children of lead-exposed construction workers were six times more likely (relative risk = 6.1; 95 percent confidence interval 0.9, 147.2) to have a blood lead level of 10 micrograms/deciliter, or greater than the children [of workers in non-lead industries]." And as a result, the researchers concluded children of occupationally-exposed workers are a "high-risk" population.
Let's see if you would come to the same conclusion.
First, the reported results are not statistically significant (i.e., the lower end of the 95 percent confidence interval is less than the no-difference-in-risk cut-off point of 1.0). Results that are not statistically significant are usually deemed to flaky to be relied upon.
Second, the reported confidence interval—0.9 to 147.2—is H-U-G-E. Such a wide confidence interval indicates a lot of variability—too much—among the data. This is not unusual in such a SMALL study (only 31 "exposed" children).
Third, no health effects—e.g., brain damage—were noted in any of the children. This is not surprising given the target blood lead level of 10 micrograms/deciliter is an arbitrary, CDC-defined level that has no basis in science. Even the highest blood lead level measured in the study—17.9 micrograms/deciliter—is not associated with any discernible health effects.
So where's the brain damage? In the children or the researchers?
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