mercury and fish consumption on neurodevelopment in

Overview

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Key numbers

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(95% CI, −2.2 to −0.4) on the Boston Naming Test. Standard analyses showed no outcome associations with hair mercury level or fish
ical exposure assessment. At approximately age 8 years, 607 NBC tests were administered by trained study examiners (n = 2)
subset (n = 361) with fish-eating mothers, maternal hair mercury Edition (WISC-III),33 the Boston Naming Test (BNT),34 and the
measurements, and relevant covariate data were the focus of this Wide Range Assessment of Memory and Learning (WRAML).35
to a mean value of 100 (SD, 15). We analyzed 6 outcomes: WISC-III
(Table 1). Average mercury content in each of the 8 fish categories intake during pregnancy with offspring cognitive development
Table 1. Estimated total mercury levels of fish species consumed by the New Bedford Cohort mothers during pregnancy. Total mercury
b Fraction was based on self-reported (FFQ) species-specific intake during adolescence where available (eg, for adolescents who consumed category 2 fish, 66%
was bluefish and 34% was mackerel). Where species-specific data were not available, fisheries and/or domestic landings databases were used.
e On the basis of adolescent data, proportions were 34% mackerel and 66% bluefish. The consumption fraction of mackerel species was obtained from percent
f On the basis of adolescent data, proportions were 80% canned tuna and 20% fresh tuna. On the basis of National Fisheries Institute data, 75% of canned tuna
consumed was light and 25% was albacore.23
high (0.9 ppm), moderate (0.4 ppm), or low (0.1 ppm) levels of hair a particular line under the assumed theoretical relationship.
Mean (SD) hair mercury level, μg/g 361 0.63 (0.57) 61 0.51 (0.57) .14
Mean (SD) fish consumption, meals/wk 361 3.78 (3.69) 156 3.52 (4.14) .51
Mean (SD) umbilical cord serum ΣPCB4 level, ng/g 361 0.26 (0.32) 229 0.25 (0.29) .73
Breastfed <1 mo, no. (%) 361 213 (59%) 244 168 (68.9%) .02
Female sex at birth, no. (%) 361 182 (50.4%) 246 117 (47.6%) .54
Non-Hispanic White race/ethnicity, no. (%) 361 267 (74%) 246 154 (62.6%) <.01
Mean (SD) age at cognitive testing, y 361 8.11 (0.53) 245 8.25 (0.73) .01
b For mean values, P values were calculated using a 2-sample t test.
Table 3. Covariate-adjusteda slopes (and 95% CIs) for the regression of six 8-year neurocognitive outcomes on pregnancy fish intake,
by tertile of average mercury level in the fish consumed, among New Bedford Cohort participants (n = 361 for all models except
n = 360 for the Boston Naming Test and General Memory)b
Table 2 summarizes the distribution of exposures, outcomes, in maternal IQ was associated with a 0.37-point increase (95%
were included had better test scores and were more likely to be associated, except for the PS subscale (Table 3, Figures 4-6). Con-
Among the 361 participants with fish-eating mothers (360 with associated with a 0.31-point increase (95% CI, −0.20 to 0.82) in
BNT and WRAML General Memory scores), the median pregnancy IQ in the lowest AvgFishHg (hair) tertile, a decrease of 0.55 points
fish intake was 2.3 servings per week, and the mean maternal hair (95% CI, −1.59 to 0.49) in the middle tertile, and a decrease of
mercury level was 0.63 (range, 0.03-5.14) μg/g. AvgFishHg (hair) 1.22 points (95% CI, −3.11 to 0.67) in the highest tertile. How-
and AvgFishHg (diet) mercury levels were uncorrelated (Pearson’s ever, all 95% CIs for fish intake associations included the null,
fish mercury level estimates; 151 (42%) were in the middle tertile among participants consuming fish with the highest average
(26%) were in the high tertile for one estimate and the low tertile Associations using average fish mercury level estimated from
Neurocognitive development (Table 3; Figures 4-6). Again, all 95% CIs included the null except
than that of the test standardization population (mean = 100 with a 0.69-point increase (95% CI, 0.02 to 1.36) for those in the
(SD, 15)), with mean values of 98 (SD, 13), 90 (SD, 14), and lowest AvgFishHg (diet) tertile.
C and D) among New Bedford Cohort (NBC) participants assessed at age 8 years whose mothers ate fish during pregnancy (n = 361). NBC participants
ment for fish or hair mercury level (Table 4; Table S1). of fish intake with an outcome are not independent of fish type.
and omega-3 PUFA content (derived from surveillance data) neurodevelopmental measures (Table 3). Similarly, the BNT was
Table 4. Covariate-adjusteda slopes (and 95% CIs) from the regression of six 8-year neurocognitive
New Bedford Cohort participants (n = 361 for all models except n = 360 for the Boston Naming Test and
1. Sheslow D, Adams W. WRAML: Wide Range Assessment of Memory years. Neurotoxicol Teratol. 2017;59:35-42. https://doi.org/10.1016/

Methods (brief)

The study population was a subsample of persons from the
Biospecimens were collected at birth (umbilical cord blood) and exposure in previous studies, including IQ (particularly verbal
Maternal hair samples were collected approximately 10 days post-
incurred during the last trimester of pregnancy.6,17 Samples were
analyzed by atomic absorption spectroscopy at the Harvard T.H.
were below the limit of detection (0.05 μg/g hair). Covariate data were collected from questionnaires, medical
and we used species-specific intake data collected from study also adjusted for the child’s sex, race/ethnicity (non-Hispanic
were obtained from the published literature,25,26 where sample Statistical analyses and rationale for modeling
Mean mercury Sample Mean mercury Sample in categoryb
b For mean values, P values were calculated using a 2-sample t test.
missing covariate data, for a sample size of 361. associations with outcomes; for example, each point increase
tion, hair mercury, and infant cognition in a US cohort. Environ school sample: the “Seven Days for My Health” project. Int J
1. Kipnis V, Midthune D, Freedman L, et al. Bias in dietary-report Elem Res. 2007;119(3):242-254. https://doi.org/10.1007/s12011-

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Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised