Table 1 Essential characteristics and review of the articles included in the meta-analysis.
From: Sex differences in children’s cognitive functions and phthalates exposure: a meta-analysis
Authors | Country | Tools and tool name | Timing of phthalate assessment | Study period, number of subjects, and age at intelligence assessment age (year) | Phthalates | Major findings |
|---|---|---|---|---|---|---|
Cho et al. 2010 | South Korea | Tool: WIS Tool name: KEDI-WIS | Postnatal | Study period: 2008 Number of subjects: 344 boys and 323 girls Age at intelligence assessment: 9.05 y | MEHP, MEOHP, and MBP | (n = 667); There is a negative association between increasing MEHP phthalate concentrations and the sum of DEHP metabolite concentrations and the Wechsler Intelligence Scale for children’s vocabulary score; however, among girls, there is no significant association between these variables. |
Kim et al. 2011 | South Korea | Tool: Bayley (MDI) Tool name: Bayley BSID-II | Prenatal | Study period: 2006–2009 Number of subjects: 235 boys and 225 girls Age at intelligence assessment: 0.50 y | MEOHP, MEHHP, MBP, and ∑DEHP | (n = 460); The results suggest that prenatal exposure to phthalates may be inversely associated with MDI and PDI in infants, especially males, at 6 months of age. |
Whyatt et al. 2012 | The United States | Tool: Bayley (MDI) Tool name: Bayley BSID-II | Prenatal | Study period: 1999–2006 Number of subjects: 157 boys and 140 girls Age at intelligence assessment: 0.70 y | MEHP, MEOHP, MEHHP, MECPP, ∑DEHP, MBzP, MiBP, and MnBP | (n = 297); Results suggest that prenatal exposure to phthalates may adversely affect a child’s mental, motor, and behavioral development during preschool. |
Doherty et al. 2017 | The United States | Tool: Bayley (MDI) Tool name: Bayley BSID-II | Prenatal | Study period: 1998–2002 Number of subjects: 131 boys and 116 girls Age at intelligence assessment: 2.67 y | MEHP, MEOHP, MEHHP, MECPP, ∑DEHP, MBzP, MiBP, MnBP, MEP, and MCPP | (n = 247); There are no associations between phthalate metabolite concentrations and performance on the MDI or PDI in boys and girls combined. However, among girls, metabolite associations may be inversely associated with MDI and PDI. Conversely, we observed multiple weakly positive associations among boys. |
Huang et al. 2017 | Taiwan | Tool: WIS Tool name: WPPSI-R | Postnatal | Study period: 2012–2013 Number of subjects: 67 boys and 41 girls Age at intelligence assessment: 4.60 y | MEHP, MEOHP, MEHHP, ∑DEHP, MiBP, MnBP, and ∑DBP | (n = 204); The findings suggested that the current exposure to phthalates for school-aged children aged ≥6– < 12 years was significantly and negatively associated with VCI performance. Maternal IQ was slightly positively associated with neurodevelopment for participants aged ≥3– < 12 years. The data revealed that the current exposure to DEHP and DBP might affect the children’s nervous system, which might be shown in their language learning or expression ability. |
Tool: WIS Tool name: WISC-IV | Postnatal | Study period: 2012–2013 Number of subjects: 56 boys and 40 girls Age at intelligence assessment: 7.60 y | ||||
Jankowska et al. 2019 | Poland | Tool: WIS Tool name: IDS (Fluid intelligence) | Prenatal | Study period: 2007–2014 Number of subjects: 57 boys and 72 girls Age at intelligence assessment: 7 y | MEHP, ∑DEHP, MBzP, MiBP, MnBP, and MEP | (n = 123); The results suggested that the IDS analyses focused on a child’s cognitive and psychomotor development are inconclusive. There was a significantly negative association between phthalates and fluid intelligence and cognition during early childhood, while positive associations have been found during the prenatal period. |
Tsai et al. 2020 | Taiwan | Tool: WIS Tool name: WISC-IV | Postnatal | Study period: Not reported Number of subjects: 42 boys and 26 girls Age at intelligence assessment: boys = 8.70 y and girls = 9.20 y | Nor reported | (n = 68); According to the results of this article, the possibility of an adverse impact of phthalate on neurodevelopment may exist, particularly in boys. |
Rosolen et al. 2022 | Italy | Tool: WIS Tool name: WISC-IV | Postnatal | Study period: 2014–2016 Number of subjects: 150 boys and 150 girls Age at intelligence assessment: 7 y | MBzP, MiBP, MnBP, and MEP | (n = 900); In NAC-II, a direct association between FSIQ and biomarkers of DEHP was found. In contrast, in OCC, the relationship between biomarkers of DEHP and FSIQ tended to be inverse but imprecise (p ≥ 0.10). No associations were found in the PCB cohort. In conclusion, these results do not provide evidence for an association between concurrent phthalate exposure and IQ in children. |
Denmark | Tool: WIS Tool name: WISC-V | Postnatal | Study period: 2018–2019 Number of subjects: 165 boys and 135 girls Age at intelligence assessment: 7 y | |||
Slovakia | Tool: WIS Tool name: WISC-III | Postnatal | Study period: 2014–2017 Number of subjects: 133 boys and 167 girls Age at intelligence assessment: 11 y | |||
Gennings et al. 2022 | Sweden | Tool: WIS Tool name: WISC-IV | Prenatal | Study period: 2007–2017 Number of subjects: 332 boys and 346 girls Age at intelligence assessment: 7 y | MEP, MBP, MBzP, and ∑DEHP | (n = 678); The findings suggested that early prenatal exposure to phthalates is associated with lower levels of cognitive functioning at age seven. This adverse association is particularly stronger in boys. |
