Table 4.
Characteristics of the 18 studies that conducted sex-stratified analyses
| Author, Year | Age (Years) | Neurodevelopment | Effect on Boys | Effect on Girls | p-value of Interaction | Manganese Concentrations |
|---|---|---|---|---|---|---|
| Neurodevelopmental outcomes from cohort studies | ||||||
| Claus Henn 2018 [37] | 6–16 | Cognition | ↓ | NS | NA | Teeth: 12ab (n = 138) |
| Dion 2018 [20] | 10.5–18 | Cognition | ↑ (W-Mn) | ↓ (W-Mn) | < 0.01 (W-Mn) | Drinking water: 14.5 μg/Lc (n = 287), hair: 1.4 μg/gc (n = 274) |
| Gunier 2015 [31] | 0.5, 1, 2 | Cognition and motor | NS | ↓ | 0.02 (Cognition), 0.03 (Motor) | Teeth: prenatal: 0.51 ± 0.19bd (n = 197), postnatal: 0.20 ± 0.23bd (n = 193) |
| Mora 2015 [38] | 7, 9, 10.5 | Cognition and motor | ↑ | NS | < 0.1 | Teeth: prenatal: 0.50 ± 0.18bd (n = 248), postnatal: 0.19 ± 0.21bd (n = 244) |
| Mora 2018 [33] | 1 | Cognition | NS | ↓ | 0.01 | Maternal hair: 3.7 ± 5.4 μg/gd (n = 661), maternal blood: 24.4 ± 6.2 μg/Ld (n = 571) |
| Rahman 2017 [69] | 10 | Cognition | NS | ↑ | < 0.081 | Drinking water: 339 μg/La (n = 1265) |
| Takser 2003 [34] | Newborns | Motor | ↓ | NS | 0.03 | Cord blood: 38.5 μg/Lc (n = 222), maternal blood: 20.4 μg/Lc (n = 222), maternal hair: 0.36 μg/gc (n = 173), newborns hair: 0.75 μg/gc (n = 173), placenta: 0.1 μg/gc (n = 200) |
| Zhou 2019 [39] | 6–8 | Cognition | ↑ | NS | NA | Cord blood: 29.29 ± 1.48 μg/L (n = 296), urine: 0.66 ± 3.81 μg/L (n = 207) |
| Neurodevelopmental outcomes from cross-sectional studies | ||||||
| Bauer 2017 [42] | 10–14 | Cognition | NS | ↓ | 0.05 | Teeth: prenatal: 0.42cb (n = 142), postnatal: 0.12cb (n = 142) |
| Bouchard 2011 [16] | 6–13 | Cognition | NS | ↓ | 0.55 (H-Mn), 0.14 (W-Mn) | Hair: 0.7 μg/ga (n = 302), drinking water: 0.8 μg/La (n = 362) |
| Bouchard 2018 [8] | 6–14 | Cognition | NS (Toe nail), ↑ (W-Mn) | ↓ (Toe nail), NS (W-Mn) | 0.028 (Toe nail), 0.015 (W-Mn) | Toe nail: 2.0 μg/gc (n = 258), hair: 0.3 μg/gc (n = 258), saliva: 1.1 μg/Lc (n = 226), drinking water: 5.2/7.3 μg/Lc (boy: 127, girl: 132) |
| Carvalho 2018 [46] | 7–12 | Cognition | ↓ | NS | 0.047 | Hair: 11.5 μg/ga (n = 70) |
| Chiu 2017 [48] | 11–14 | Motor | NS (Prenatal and postnatal), ↓ (Childhood) | ↓ (Prenatal and postnatal), NS (Childhood) | < 0.05 (Prenatal), < 0.01 (Postnatal), 0.01 (Childhood) | Teeth: prenatal: 0.43ab (n = 189), postnatal: 0.13ab (n = 185) |
| Hernandez-Bonilla 2016 [54] | 7–11 | Cognition | NS | ↓ | < 0.15 | Hair: control: 0.55 μg/gc (n = 119), exposed: 5.25 μg/gc (n = 148) |
| Menezes-Filhoet 2014 [62] | 7–12 | Behavior | NS | ↓ | NA | Hair: boys: 12.1 μg/ga (n = 34), girls: 12.4 μg/g a (n = 36) |
| Rink 2014 [41] | 1.1–3.7 | Cognition | ↑ | NS | < 0.05 | Hair: 0.98 ± 0.74 μg/gd (n = 60) |
| Riojas-Rodríguez 2010 [6] | 7–11 | Cognition | NS | ↓ | NA | Control: hair: 0.57 μg/g, blood: 8.22 μg/Lc (n = 93), exposed: hair: 12.13 μg/g, blood: 9.71 μg/Lc (n = 79) |
| Torres-Agustinet 2013 [67] | 7–11 | Cognition | NS | ↓ | NA | Control: hair: 0.6 μg/g, blood: 8.0 μg/La (n = 95), exposed: hair: 12.6 μg/g, blood:9.5 μg/La (n = 79) |
↓: Negative association; ↑: Positive association; NA Not available; NS No significant association. a: Median; b: 55Mn: 43Ca the area under the curve (AUC) × 104; c: Geometric mean; d: Mean ± standard deviation. H-Mn Manganese in hair; W-Mn Manganese in drinking water