Traditional living in the Amazon: Extended breastfeeding, fish consumption, mercury exposure and neurodevelopment

Ann Hum Biol. 2016 Jul;43(4):360-70. doi: 10.1080/03014460.2016.1189962. Epub 2016 Jun 21.


Background: Features of traditional living in the Amazon Basin (high fish consumption and long breastfeeding) are likely to expose children to Mercury (Hg).

Aim: To study neurodevelopment in 690 children in relation to prolonged breastfeeding and mercury exposure.

Subjects and methods: Three groups of breastfeeding children were formed: Group 1 (breastfed for 6 months), Group 2 (7-12 months) and Group 3 (extending up to 24 months). Neurodevelopment was assessed as age of walking, age of talking and the Bayley Scales of Infant Development-BSID. Mercury exposure was assessed from Thimerosal-containing vaccines and fish consumption from hair Hg (HHg).

Results and conclusions: HHg increased in children and decreased in mothers at 24 months. Frequency of fish consumption was significantly correlated with maternal HHg at birth (Spearman's r = 0.8583; p = 0.0001); likewise, there was a significant correlation between duration of breastfeeding and children's HHg (Spearman's r = 0.15; p = 0.0018). Extended breastfeeding did not influence the Mental Development Index-MDI or Psychomotor Development Index-PDI, but maternal education and HHg (marker of fish consumption) interacted positively and significantly with both. Frequency of maternal fish consumption and education had a positive association with BSID scores; it is speculated that maternal education and nutrients in fish have an opposing effect on Hg exposure.

Keywords: Methylmercury; ethylmercury; hair; lactation; milestones.

MeSH terms

  • Animals
  • Brazil
  • Breast Feeding*
  • Child Development*
  • Feeding Behavior / physiology*
  • Female
  • Fishes*
  • Geography
  • Humans
  • Infant
  • Maternal Exposure*
  • Mercury / analysis*
  • Nervous System / growth & development*
  • Principal Component Analysis
  • Young Adult


  • Mercury