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Updated: Mar 21, 2026

Long-term Behavioral and Reproductive Consequences of Embryonic Exposure to Low-dose Toxicants
Published on: March 6, 2018
Traditional living in the Amazon: Extended breastfeeding, fish consumption, mercury exposure and neurodevelopment
Rejane C Marques1, Luciana Abreu2, José V E Bernardi3
1a Universidade Federal do Rio de Janeiro , Rio de Janeiro , RJ , Brasil ;
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.
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