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Associations of gestational and childhood exposure to lead, cadmium, and fluoride with cognitive abilities, behavior, and social communication at 4 years of age: NICE birth cohort study.Abstract
Highlights
- Early-life low-level cadmium exposure appeared associated with decreased cognitive abilities.
- More expected, low-level prenatal lead exposure was linked to reduced cognitive development.
- Fluoride exposure was not associated with child full-scale or verbal cognition.
- Cadmium associations with behavioral and social communication problems were inconclusive.
- Fluoride and lead were not associated with social communication but were indicative of behavioral problems.
Background
… NICE (Nutritional Impact on the Immunological Maturation during Childhood in relation to the Environment) is a prospective birth-cohort in the Norrbotten county, northern Sweden, established by recruitment of pregnant women between 2015 and 2018 (NCT05809479) (Barman et al., 2018). The main objectives are to assess the impact of early-life environment on immune maturation, allergy development, growth, cognitive and behavioral development, and oral health. During the first visit to the local maternity units, expecting parents were given information about the NICE study.
… The distribution characteristics of maternal and child lead, cadmium, and fluoride concentrations, as well as of the lead and cadmium cord blood concentrations for all children are presented in Table 2. All cord blood and child concentrations are also
presented for boys and girls separately (Table 2). There were no differences in child metal and fluoride concentrations by child sex.
…Urinary fluoride concentrations were slightly higher in women with a university degree compared to those who had not completed university (median: 0.74 mg/L vs 0.68 mg/L, P=0.003).
Table 2. Lead, cadmium, and fluoride concentrations in mothers during pregnancy (=gestational week 29) and children at 4 years of age; for all children, and for girls and boys separately.
Empty Cell | All participants | 5th-95th perc. | Range | Girls | Boys | P-value a | |||
---|---|---|---|---|---|---|---|---|---|
N | Median | N | Median | N | Median | ||||
Gestational erythrocyte lead (ug/kg) | 456 | 11.2 | 5.9–25.3 | 3.8–147.8 | – | – | – | – | – |
Cord blood erythrocyte lead (ug/kg) | 314 | 7.8 | 4.0–18.8 | 2.5–37.0 | 172 | 7.8 | 142 | 8.0 | 0.653 |
Child erythrocyte lead (ug/kg) | 250 | 16.0 | 7.8–41.4 | 5.4–85.7 | 139 | 15.6 | 111 | 16.4 | 0.882 |
Gestational urinary cadmium (ug/L)b | 454 | 0.10 | 0.04–0.27 | 0.02–0.97 | – | – | – | – | – |
Gestational erythrocyte cadmium (ug/kg) | 456 | 0.29 | 0.14–0.68 | 0.05–5.69 | – | – | – | – | – |
Cord blood erythrocyte cadmium (ug/kg) | 314 | 0.04 | 0.002–0.131 | 0.002–1.094 | 172 | 0.04 | 142 | 0.04 | 0.636 |
Child urinary cadmium (ug/L)b | 398 | 0.04 | 0.02–0.10 | 0.003–0.36 | 203 | 0.04 | 195 | 0.04 | 0.128 |
Child erythrocyte cadmium (ug/kg) | 250 | 0.15 | 0.06–0.26 | 0.01–0.34 | 139 | 0.15 | 111 | 0.16 | 0.509 |
Gestational urinary fluoride (mg/L)b | 441 | 0.72 | 0.3–1.88 | 0.07–6.4 | – | – | – | – | – |
Child urinary fluoride (mg/L)b | 397 | 0.86 | 0.31–2.26 | 0.04–5.7 | 203 | 0.81 | 194 | 0.90 | 0.525 |
- a P-values for differences between girls and boys were obtained using the Mann-Whitney test.
- b Urinary cadmium and fluoride concentrations are adjusted to the median specific gravity (1.017 for the mothers and 1.016 for the children).
… Gestational and child urinary fluoride concentrations were not associated with cognitive outcomes (Table 3, Supplemental Table 6).
… Urinary fluoride concentrations were not associated with CBCL scores (Table 4 & Supplemental Table 10), except for a potential association of gestational urinary fluoride concentrations with increasing externalizing problems B [CI 95% CI]: 0.9 [-0.3, 2.0]), per doubling (Table 4). Additional analyses using the ADHD scale of the CBCL showed an association of gestational urinary fluoride concentrations with slightly higher ADHD raw scores (B [CI 95% CI]: 0.3 [0.0, 0.6], per doubling, Table 5; B [CI 95% CI]: 0.1 [-0.0, 0.3], per 0.5 mg/L increase, Supplemental Table 11). The SRS-2 total score appeared unrelated to cadmium, lead, and fluoride exposure (Table 6 & Supplemental Table 12). Child sex did not modify the association between lead, cadmium, and fluoride and SRS-2 outcomes in any meaningful or consistent way (Table 6).
… Appendix A. Supplementary data
The following is the Supplementary data to this article:
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