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Table 2 Unadjusted Changes in IQ for Each Increase in the Blood Lead Concentration of 1 microgram per Deciliter

From: Low-level environmental lead exposure in childhood and adult intellectual function: a follow-up study

Type of Blood Lead   Full-Scale IQ Verbal IQ Performance IQ
Measurement n β ± SE p R2 β ± SE p R2 β ± SE p R2
Average late childhood 42 -1.89 ± 0.70 0.01 0.154 -1.98 ± 0.76 0.12 0.145 -1.33 ± 0.66 0.05 0.091
(mean of 4 yr and 10 yr)   (-3.30, -0.47)    (-2.68, 0.01)    (-2.68, 0.01)   
Average 43 -1.66 ± 0.75 0.03 0.106 -1.22 ± 0.83 0.15 0.050 -1.68 ± 0.68 0.02 0.129
(mean of all available)   (-3.18, -0.14)    (-3.06, -0.30)    (-3.06, -0.30)   
6 months 39 -0.90 ± 0.41 0.03 0.117 -0.80 ± 0.45 0.08 0.080 -0.81 ± 0.37 0.03 0.115
   (-1.73, -0.77)    (-1.71, 0.11)    (-1.57, -0.06)   
4 years 40 -1.26 ± 0.58 0.04 0.110 -0.96 ± 0.64 0.14 0.055 -1.25 ± 0.51 0.02 0.136
   (-2.43, -0.09)    (-2.27, 0.35)    (-2.29, 0.22)   
10 years 37 -1.95 ± 0.80 0.02 0.145 -2.84 ± 0.81 0.001 0.258 -0.52 ± 0.72 0.48 0.520
   (-3.56, -0.33)    (-4.49, 1.19)    (-1.98, 0.99)