Table 1 Characteristics and summary findings of studies that investigated pre- and perinatal cadmium exposures on cognitive development
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, tester, sex, birth order, birth weight, home environment (HOME score), maternal BMI (early pregnancy), maternal IQ, socio-economic status, arsenic, and lead | Maternal urinary Cd | Median (5th and 95th percentile): 0.63 (0.18-2.0) μg/L (specific gravity-adjusted) | WPPSI FSIQ | A doubling of maternal U-Cd inversely associated with FSIQ at 5 years of age. | M/H |
[16] | 6 months | 718 | South Korea | Cohort | Gender, birth weight, maternal age and delivery, height, education, family income, breast feeding | Maternal blood Cd | Geometric mean: 1.4 ± 1.7 μg/L in early pregnancy, 1.5 ± 1.4 μg/L in late pregnancy | BSID-II mental development index | Effect modification between Pb and Cd during late pregnancy | M/H |
[10] | 4 years | 385 | Spain | Cohort | child's age, quality of neuropsychological test, child's sex, maternal perceptive-performance IQ at child's aged 14 months, maternal verbal IQ at child's aged 4 years, maternal social class, country of birth, mental health, age, child's mood changes and neuropsychological disorder | Maternal urinary Cd twice during pregnancy (1st and 3rd trimester) | Median: 0.55 ng/mL (1st trimester) and 0.53 ng/mL (3rd trimester) | MSCA (McCarthy Scales of Children's Abilities) | No statistically significant association between Cd and MSCA score | H |
5 years | 119 | South Korea | Cohort | Sex of child, maternal age, educational level of both parents, family income, maternal BMI. | Maternal blood | Mean: 1.49 ± 0.39 μg/L | K-WPPSI (Korean version of the Wechsler preschool and primary Scale of Intelligence, revised edition (WPPSI-R), FSIQ | Association with declining performance IQ, but not cognitive IQ. | L | |
[23] | 5 years | 97 | China | cohort | Maternal age, BMI, maternal education, family income, passive smoking, Pb | Cd in cord blood | Mean: 0.44 ± 0.43 μg/L | WPPSI | Association between cord blood and VIQ | L |
[17] | 4 years | 575 | Greece | Cohort | Examiner, child sex, age at testing (years), and maternal age, parity, marital status, and tobacco smoking (never/ever), urinary lead | Maternal urinary Cd | Mean 0.54± 0.39 μg/L (specific gravity-adjusted) | McCarty Scale of Children's Abilities | Maternal urinary cadmium levels ≥ 0.8 ug/L) inversely associated with children's general cognitive score | M/H |
[40] | 1 year | 149 | China | Cross-sectional | Maternal age, IQ, pre-pregnancy BMI, smoking, meat-consumption. Parental education, household income, infant gender, birth weight, gestational age, Pb, Hg, etc. | Maternal blood Cd | Median 4.24 μg/L, range 0.13- 4.55 μg/L | Gesell Development Domains | Lower development quotient in social domain of Gesell Dev. Schedule | H |
[11] | 4-5 years | 302 | Spain | Cohort | child gender, psychologist, child age at neuropsychological assessment, social class, maternal smoking during pregnancy, pre-pregnancy BMI | Cd in placenta homogenates | Median 4.1 ng/g | McCarty Scale of Children's Abilities WASI | No association | M/H |
[41] | at ages 5 and 8 years | 276 | USA | Cohort | maternal depression, maternal IQ, sociodemographic factor, exposure to tobacco, lead and ∑PCB | Maternal urinary Cd | Geometric mean 0.17 ± 2.29 μg/g creatinine | Bayley Scale of Infant Development II, the Wechsler Preschool and Primary Scales of Intelligence III and IV | No significant association | M/H |
[42] | school age 6-7 years | 296 | China | Cohort | sex, maternal age at delivery, maternal education level, family annual income, family inhabitation area and passive smoking | cord blood and children's urine | Geometric mean urinary Cd 0.18 ± 2.37 μg/L (specific gravity-adjusted); geometric mean cord blood Cd 0.36 ± 2.01 μg/L | Wechsler Intelligence Scale for Children-Chinese Revised (WISC-CR) | Cord blood Cd and urinary Cd was negatively associated with FSIQ but only in boys; in girls, only urinary Cd was negatively associated with IQ | M/H |
[26] | 2 years | 3542 | Japan | cohort | Pre-pregnancy BMI, diabetes, occupation, household income, education smoking, age at delivery, marital status, parity, Pb, Hg | Maternal and cord blood Cd | Maternal blood mean: 0.79 ± 0.39 μg/L; cord blood mean: 0.05 ± 0.02 μg/L | Kyoto Scale of Psychological Development | Maternal blood Cd associated with lower DQ in boys among smoking mothers and those with diabetes | M/H |