About the initiative
The Evidence Center was recently commissioned by the National Academies of Sciences, Engineering, and Medicine (NASEM) to conduct a series of systematic reviews to support the work of the committee on The Role of Seafood in Child Growth and Development. The committee was tasked with reviewing and balancing the nutritional benefits of seafood consumption while also considering the balance with exposure to environmental toxicants and other contaminants.
Role of the Evidence Center
To support the work of the committee, the Evidence Center conducted a comprehensive literature search, identified existing evidence and provided a summary of the evidence. Subsequently, the Evidence Center completed a series of rigorous systematic reviews that focus on the relationship between seafood consumption and consequent nutritional and toxicant exposures during pregnancy or lactation or during childhood or adolescence on child health outcomes. This work has resulted in several reports and publications, including:
- Seafood Toxicant Exposure During Pregnancy, Lactation, and Childhood and Child Outcomes: A Scoping Review
- Associations Between Maternal Polychlorinated Biphenyls (PCBs) Exposure from Seafood Consumption during Pregnancy and Lactation and Child Growth: A Systematic Review and Meta-Analysis
- Association Between Maternal Lead Exposure from Seafood Consumption and Neurodevelopment: A Systematic Review
- Seafood and neurocognitive development in children: A systematic review
- Seafood during pregnancy and lactation and child neurocognitive development: A systematic review
- Mercury exposure and childhood outcomes: an overview of systematic reviews
Publications
Seafood Toxicant Exposure During Pregnancy, Lactation, and Childhood and Child Outcomes: A Scoping Review
Key Points
This study aimed to describe the scope of the evidence associated with seafood-related toxicant exposure and child outcomes and to identify toxicant-outcome pairs that may have sufficient evidence to conduct a systematic review.
Findings
81 studies were included: 69 studies on exposure during pregnancy and lactation and 14 on exposure during childhood. The number of studies varied by toxicant and exposure population (maternal; child): mercury (n = 49; 7), methylmercury (n = 13; 3), polychlorinated biphenyls (PCBs; n = 11; 1), selenium (n = 11; 1), lead (n = 9; 3), perfluoroalkyl and polyfluoroalkyl substances (n = 8; 2), dichlorodiphenyltrichloroethane (n = 5; 1), arsenic (n = 4; 4), cadmium (n = 4; 4), zinc (n = 3; 2), polybrominated diphenyl ethers (n = 3; 1), dioxin-like compounds (n = 3; 0), iron (n = 2; 1), and magnesium (n = 1; 1). No studies examined polybrominated biphenyls, polycyclic aromatic hydrocarbons, iodine, aldrin, dieldrin, chlordane, chlorpyrifos, or microplastic exposures. Outcomes also varied by exposure population (maternal;child): neurodevelopment (n = 35; 9), child exposure biomarkers (n = 22; 4), growth (n = 17; 1), other adverse events (n = 4; 0), cardiometabolic (n = 3; 2), chronic disease indicators (n = 2; 0), and immune-related (n = 1; 2). Twelve maternal toxicant-outcome pairs had ≥3 studies, including mercury, methylmercury, lead, PCBs, perfluoroalkyl and polyfluoroalkyl substances, and arsenic as exposures and neurodevelopment, child exposure biomarkers, growth, and cardiometabolic as outcomes. For child exposure, only mercury and neurodevelopment had ≥3 studies. In conclusion, this scoping review shows relevant evidence for 14 of the 22 toxicants. Only 12 maternal and 1 child toxicant-outcome pairs, the majority of which examined maternal (methyl)mercury exposure, had ≥3 studies, our cutoff for consideration for systematic review.
Meaning
This scoping review indicates a paucity of research examining seafood toxicants beyond mercury and exposure during childhood. Systematic reviews are required to evaluate the associations for each toxicant-outcome pairs.
Associations Between Maternal Polychlorinated Biphenyls (PCBs) Exposure from Seafood Consumption during Pregnancy and Lactation and Child Growth: A Systematic Review and Meta-Analysis
Key Points
Beyond its nutritional benefits, seafood is a source of toxicant exposure including polychlorinated biphenyls (PCB). The association of PCB exposure from seafood intake during pregnancy and/or lactation (PL) and child growth outcomes is uncertain. This systematic review investigated the evidence and quantified the association between PCB exposure during PL from seafood intake and child growth outcomes.
Findings
PCB exposure during PL was weakly but significantly associated with lower birthweight [rp = -0.07; 95% confidence interval (CI): -0.12, -0.02; n = 5], but showed no association with birth length (rp = -0.04; 95% CI: -0.09, 0.02; n = 4) and head circumference (rp = -0.03, 95% CI: -0.09, 0.03; n = 3).
Meaning
The evidence suggests minimal to no link between PCB exposure from seafood during PL on child growth outcomes but with low to very low certainty.
Association Between Maternal Lead Exposure from Seafood Consumption and Neurodevelopment: A Systematic Review
Key Points
Despite the essential nutrients, maternal seafood consumption during pregnancy or lactation (PL) is also a potential source of toxins, including lead (Pb). The association between exposure to Pb from seafood during PL on children’s neurodevelopment is uncertain. This systematic review assessed the association of exposure to Pb from seafood during PL on children’s neurodevelopment.
Findings
Four included articles from three prospective cohort studies in Asia examined cognition, motor development, and behavior in children 12-60 months. Only one study reported an analysis between seafood intake and lead concentrations during PL which showed a weak, insignificant association. Pb concentrations were not associated with child cognitive development or behavioral problems, but a weak, negative association with child motor development was reported. The certainty of evidence was very low due to few included studies with some or high risk of bias. Higher seafood intake in this evidence favored positive developmental outcomes from one prospective cohort study, though significance varied.
Meaning
Overall, evidence was not available to address a direct association between Pb exposure from seafood intake during PL and child neurodevelopment. Several other limitations resulted in a very low certainty of overall evidence.