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. Author manuscript; available in PMC: 2014 Jun 5.
Published in final edited form as: N Engl J Med. 2003 Apr 17;348(16):1517–1526. doi: 10.1056/NEJMoa022848

Figure 2. IQ as a Function of Lifetime Average Blood Lead Concentration.

Figure 2

IQ was assessed with use of the Stanford–Binet Intelligence Scale, fourth edition. The line represents the relation between IQ and lifetime average blood lead concentration estimated by the covariate-adjusted penalized-spline mixed model. Individual points are the unadjusted lifetime average blood lead and IQ values. To convert values for lead to micromoles per liter, multiply by 0.0483.