Net effects explains the benefits to children from maternal fish consumption despite methylmercury in fish

Philip Spiller*, Edwin van Wijngaarden, Heather Adams, J Strain, Emeir McSorley, Maria Mulhern, Marie Conway, Allison Yates, Clark Carrington, P Michael Bolger, Kara Morgan, Caroline M Taylor, Nicholas Ralston, Michael Crawford, Joseph Hibbeln, J Thomas Brenna, Gary Myers

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

2 Citations (Scopus)
24 Downloads (Pure)


In 2001 the U.S. Food and Drug Administration (FDA) issued precautionary advice to pregnant women to limit fish consumption over concern that the methylmercury content might harm their children’s neurodevelopment. This concern was based largely on results from an epidemiological study of mothers primarily exposed to methylmercury from consuming pilot whale. Subsequently, FDA and the World Health Organization/Food and Agriculture Organization (WHO/FAO) undertook independent assessments of fish consumption that considered net effects from both fish nutrients, primarily omega-3 fatty acids, as beneficial and methylmercury as harmful. Both assessments estimated that when mothers regularly consume fish during pregnancy, their children are likely to have improved neurodevelopment compared to children of non-fish eaters despite their exposure to methylmercury. These estimated improvements included gains of two to over five full scale IQ points from levels of maternal consumption that are achievable in most of the world. Consistent with those estimates, human research on fish consumption and child neurodevelopment from more than 200,000 mother-child pairs now collectively reports 51 beneficial associations with neurodevelopmental outcomes and three adverse associations, the latter with no discernable pattern. These associations include full scale IQ gains similar to, or somewhat higher than, those estimated by FDA and FAO/WHO. Also consistent with the FDA and FAO/WHO estimates, research has reported beneficial associations with fish consumption when pregnant women are exposed to methylmercury from fish in excess of the U.S. Environmental Protection Agency’s (EPA) Reference Dose (RfD). Our analysis evaluates how the net effects approach as utilized by FDA and FAO/WHO provides a holistic explanation for these results with implications for public health policy. This concordance of net effects modeling and empirical scientific evidence supports a clarification of current public health recommendations to focus on greater fish consumption by pregnant women for their children’s neurodevelopment.
Original languageEnglish
Pages (from-to)195-205
Number of pages11
Early online date20 Oct 2023
Publication statusPublished - 1 Dec 2023

Bibliographical note

Funding Information: Taylor acknowledges that she was supported by a Medical Research Council (MRC) Career Development Award (grant number MR/T010010/1 ) and author Edwin van Wijngaarden is funded by NIH grant R24 ES029466 . Authors Philip Spiller, P. Michael Bolger, Clark Carrington, and Kara M. Morgan acknowledge that they were involved in the development of the FDA assessment of net effects. Additionally J.J. Strain chaired the Expert Consultation that developed the FAO/WHO risk and benefit assessment and P. Michael Bolger and Clark Carrington participated in that assessment.

Publisher Copyright: © 2023 Elsevier B.V. All rights reserved.


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