Author | Year | Country | Number of case group | Number of control group | Mean of IQ score in case group | Standard deviation of case group | Mean of IQ score in control group | Standard deviation of control group | Duration of the lead exposure (year) | Cognitive function measurement | Quality assessment (NOS) |
---|---|---|---|---|---|---|---|---|---|---|---|
Ibiwari C. Dike | 2020 | Nigeria | 160 | 40 | 89.46 | 13.6 | 138.24 | 14.21 | 1.5 | Raven’s standard progressive matrices | Good |
Nnenna Linda Nwobi | 2019 | Nigeria | 169 | 140 | 86.9 | 11.6 | 91.5 | 14 | 4 | Raven’s standard progressive matrices | Fair |
Todd A. Jusko | 2008 | USA | 78 | 96 | 91.47 | 12.6 | 93.9 | 14.4 | 9 | Wechsler Preschool and Primary Scale | Good |
Pamela J. Surkan | 2007 | USA | 32 | 357 | 88.75 | 12.7 | 91.92 | 10.4 | 4 | Wechsler Intelligence Scale for Children -Third Edition (WISC-III) | Good |
Katarzyna Kordas | 2006 | Mexico City | 296 | 293 | 101.95 | 15.75 | 106.4 | 14.5 | 3 | The testing battery | Fair |
Katarzyna Kordas | 2004 | Mexico City | 291 | 298 | 103.13 | 15.06 | 106.3 | 14.6 | 3 | Graphic Test of Reasoning (GTR) | Good |
Iman Al-Saleh 1 | 2001 | Saudi Arabia | 165 | 368 | 95.26 | 14.1 | 101.39 | 14.18 | 6 | Beery VMI Saudi-based standard scores | Good |
Iman Al-Saleh 2 | 2001 | Saudi Arabia | 165 | 368 | 93.51 | 14.61 | 101.37 | 15.09 | 6 | TONI Saudi-based scores and rank percentile | Good |