Hydroelectric reservoir inundation (Rio Madeira Basin, Amazon) and changes in traditional lifestyle: impact on growth and neurodevelopment of pre-school children.

OBJECTIVE: To assess the dependence on fish consumption of families and its impact on nutritional status and neurodevelopment of pre-school children.
DESIGN: Cross-sectional study that measured children's hair mercury (HHg) as an indicator of family fish consumption, growth (anthropometric Z-scores, WHO standards) and neurological (Gesell developmental scores (GDS)) development.
SETTING: Traditional living conditions among families residing in the area adjacent to the Samuel Dam (Western Amazon) hydroelectric reservoir.
SUBJECTS: Two hundred and forty-nine pre-school children (1-59 months of age) from families transitioning from the traditional Amazonian lifestyle.
RESULTS: Family fish consumption was significantly correlated with children's HHg concentration (Spearman's r=0.246, P<0.0001); however, HHg had no significant association with growth (Z-scores). Overall, the prevalence of severe malnutrition, i.e. stunting (height-for-age Z-score (HAZ)≤-3), underweight (weight-for-age Z-score (WAZ)≤-3) and wasting (weight-for-height Z-score (WHZ)≤-3) was 5.2% (n 13), 0% and 0.8% (n 2), respectively. The prevalence of moderate stunting (HAZ≥-3 to ≤-2), underweight (WAZ≥-3 to ≤-2) and wasting (WHZ≥-3 to ≤-2) was 8.8% (n 22), 2.4% (n 6) and 4.8% (n 12), respectively. Although 76% of the children showed adequate GDS (>85), multiple regression analysis showed that fish consumption (as HHg) had no impact on GDS, but that some variables did interact significantly with specific domains (motor and language development).
CONCLUSIONS: The study showed that the families' shift in fish consumption had no negative impact on the growth of young children and that ensuing methylmercury exposure has not been a noticeable neurodevelopmental hindrance.