Table 2 Characteristics and summary findings of studies that investigated contemporaneous cadmium exposures on cognitive development in young children
References | Child age | Sample size | Location | Study design | Confounders accounted for | Exposure measure | Cadmium concentration | Outcome Assessment/IQ test | Observed Effect | Study Evaluation |
|---|---|---|---|---|---|---|---|---|---|---|
[18] | 5 years | 1305 | Bangladesh | Cohort | Age at testing, tester, sex, birth order, birth weight, HOME, maternal BMI early pregnancy), maternal IQ, socio-economic status, arsenic and lead | Childrens’ urinary Cd | Median (5th and 95th percentile): 0.22 (0.78-0.63) μg/L (specific gravity-adjusted) | WPPSI FSIQ | Concurrent U-Cd in children associated with decreased FSIQ, but weaker than maternal urinary levels | H/M |
[33] | 6-9 years | 261 | Spain | Cross sectional | sex, child's age, body mass index (BMI), mother's age, IQ and education, monthly family income, family status, gestational age, vegetables and cereals intake and levels of Mn, As, Pb, Hg in urine | Urinary cadmium | Geometric mean girls: 0.725, boys: 0.769 μg/g creatinine | WISC-IV | Contemporaneous urinary Cd associated with significantly lower scores in FSIQ, stronger among boys | H |
10 years | 1498 | Bangladesh | Cohort | Age, sex, birth order, birth weight, HAZ (5 year), HOME, maternal BMI (early pregnancy), maternal IQ, socio economic status, urinary arsenic and lead | Childrens’ urinary Cd | Medians of tertiles: 0.13, 0.24, 0.43 μg/L (specific gravity-adjusted) | WISC-IV | Concurrent urinary cadmium at 10 years of age negatively associated with full scale IQ. | H | |
[25] | 6-12 years | 299 | Italy | Cross sectional | sex, age, maternal nonverbal intelligence, and cognitive stimulation, home environment, socio economic status | Childrens’ urinary Cd | Median (range) 0.4 ng/mL (0-1.8) | WISC-IV | Contemporaneous urinary Cd was negatively associated with the IQ total score but did not reach statistical significance. | H |
[29] | 9-11 yr | 530 | China | Cross sectional | children's age, sex, passive smoking at home, annual family income, parent's education, and occupation | Cord blood and childrens’ urinary Cd | Mean blood Cd: 1.93 μg/L; mean urinary Cd: 1.43 μg/L | CRT-C2 (Combined Raven’s Test in China) | No association with contemporaneous urinary Cd levels, but association may have been obscured by high lead exposure | M |