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American Journal of Epidemiology Advance Access published online on March 18, 2008
American Journal of Epidemiology, doi:10.1093/aje/kwn034
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American Journal of Epidemiology © The Author 2008. Published by the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oxfordjournals.org.

Original Contribution

Maternal Fish Intake during Pregnancy, Blood Mercury Levels, and Child Cognition at Age 3 Years in a US Cohort

Emily Oken1, Jenny S. Radesky1, Robert O. Wright2, David C. Bellinger3, Chitra J. Amarasiriwardena4, Ken P. Kleinman1, Howard Hu5 and Matthew W. Gillman1,6

1 Department of Ambulatory Care and Prevention, Harvard Medical School and Harvard Pilgrim Health Care, Boston, MA
2 Department of Medicine, Children's Hospital Boston and Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, Boston, MA
3 Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA
4 Department of Environmental Health, Harvard School of Public Health, Boston, MA
5 Department of Environmental Health, University of Michigan, Ann Arbor, MI
6 Department of Nutrition, Harvard School of Public Health, Boston, MA

Correspondence to Dr. Emily Oken, Department of Ambulatory Care and Prevention, 133 Brookline Avenue, Boston, MA 02215 (e-mail: emily_oken{at}harvardpilgrim.org).

Received for publication September 20, 2007. Accepted for publication January 29, 2008.


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 
The balance of contaminant risk and nutritional benefit from maternal prenatal fish consumption for child cognitive development is not known. Using data from a prospective cohort study of 341 mother-child pairs in Massachusetts enrolled in 1999–2002, the authors studied associations of maternal second-trimester fish intake and erythrocyte mercury levels with children's scores on the Peabody Picture Vocabulary Test (PPVT) and Wide Range Assessment of Visual Motor Abilities (WRAVMA) at age 3 years. Mean maternal total fish intake was 1.5 (standard deviation, 1.4) servings/month, and 40 (12%) mothers consumed >2 servings/week. Mean maternal mercury level was 3.8 (standard deviation, 3.8) ng/g. After adjustment using multivariable linear regression, higher fish intake was associated with better child cognitive test performance, and higher mercury levels with poorer test scores. Associations strengthened with inclusion of both fish and mercury: effect estimates for fish intake of >2 servings/week versus never were 2.2 (95% confidence interval (CI): –2.6, 7.0) for the PPVT and 6.4 (95% CI: 2.0, 10.8) for the WRAVMA; for mercury in the top decile, they were –4.5 (95% CI: –8.5, –0.4) for the PPVT and –4.6 (95% CI: –8.3, –0.9) for the WRAVMA. Fish consumption of ≤2 servings/week was not associated with a benefit. Dietary recommendations for pregnant women should incorporate the nutritional benefits as well as the risks of fish intake.

child development; fatty acids, omega-3; fishes; mercury; pregnancy

Abbreviations: CI, confidence interval; DHA, docosahexaenoic acid; EPA, eicosapentaenoic acid; PPVT, Peabody Picture Vocabulary Test; SD, standard deviation; WRAVMA, Wide Range Assessment of Visual Motor Abilities


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 
Fish and other seafood may contain beneficial nutrients such as n-3 fatty acids as well as harmful contaminants such as mercury. Methylmercury is a demonstrated neurotoxicant to which the fetal brain is particularly sensitive (1, 2). A well-designed cohort study in the Faroe Islands found that prenatal exposure to organic mercury from maternal fish and pilot whale consumption during pregnancy was associated with subtle neurodevelopmental deficits in children, such as poorer performance on some tests of language and intelligence (3, 4). In a cohort from the Seychelle Islands, however, investigators did not find evidence for a neurodevelopmental risk from prenatal methylmercury exposure resulting from ocean fish consumption (5). Those studies did not examine the overall relation of fish intake with child cognitive development. In 2001, the US Environmental Protection Agency recommended that pregnant women avoid consuming fish types high in mercury and limit their total fish intake to no more than two 6-ounce servings per week (1 ounce = 28.3 g) (6). Following the advisory, some pregnant women decreased their fish intake (7).

Fish and other seafood are the primary dietary source for elongated polyunsaturated n-3 fatty acids including docosahexaenoic acid (DHA), an integral structural component of the brain. Prenatal or early postnatal DHA supplementation may improve child development (8–11). Because most pregnant women do not consume adequate dietary DHA, limiting fish consumption might further reduce access to this essential nutrient (12, 13).

The overall effect of fish consumption during pregnancy, incorporating the risks as well as the benefits, remains uncertain. A few recent studies, including a reanalysis of data from the Faroe Islands cohort, have found that, on balance, maternal fish intake is associated with improved child cognitive development (14–16). In the present study, we used prospectively collected information on maternal diet and mercury levels during pregnancy to examine the risks and benefits of maternal prenatal fish intake on child development at age 3 years.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 References
 
Population and study design
Subjects were participants in Project Viva, a prospective prebirth cohort study in Massachusetts (13, 14). Mothers provided informed consent at study recruitment (1999–2002), and the human subjects committee of Harvard Pilgrim Health Care approved all protocols. Of 2,128 women who delivered a live singleton infant, 1,579 were eligible for the age-3-year visit because they had completed a prenatal dietary questionnaire and had not disenrolled. We had information on maternal fish intake, stored maternal blood samples, and cognitive test results for children aged 3 years for 896 mother-child pairs. Available funding allowed measurement of erythrocyte mercury from 341 mothers. We selected women with an available maternal hair sample (n = 98) and who experienced preterm or small-for-gestational-age birth (n = 45) to ensure that the prevalence of these characteristics in the group of women studied in the present analysis closely mirrored the prevalence in the overall cohort. We also assayed a random sample of 198 of the remaining 753.

Compared with the 1,238 mothers not included in this study, the 341 mothers included had similar fish intakes (1.5 vs. 1.7 servings/week) and were slightly older (32.6 vs. 31.9 years), were more likely to be White (82 vs. 65 percent), were better educated (41 vs. 30 percent with a graduate degree), were less likely to smoke (8 vs. 13 percent), and had higher Peabody Picture Vocabulary Test (PPVT) scores (108.8 vs. 104.6). For included children compared with those not included, gestational length (39.4 vs. 39.5 weeks) and fetal growth (0.24 vs. 0.18 (z value)) were similar, but breastfeeding duration was longer (7.0 vs. 6.0 months).

Exposures
Maternal fish intake
At the second-trimester study visit, participants completed a semiquantitative food frequency questionnaire, which we modified for pregnancy from a well-validated instrument used in several large cohort studies (17, 18). We previously calibrated this questionnaire against erythrocyte levels of elongated n-3 fatty acids (19). The questionnaire quantified average frequency of consumption of more than 140 foods and beverages during the previous 3 months, including four questions on intake of fish: canned tuna fish (3–4 ounces); shrimp, lobster, scallops, clams (1 serving); dark-meat fish (e.g., mackerel, salmon, sardines, bluefish, swordfish (3–5 ounces)); and other fish (e.g., cod, haddock, halibut (3–5 ounces)). Six frequency response options ranged from "never/less than 1 per month" to "1 or more servings per day." We combined responses to the four questions to estimate average total fish intake.

Red blood cell mercury
At the second-trimester visit, we obtained blood specimens in Vacutainer tubes (Becton, Dickinson and Company, Franklin Lakes, New Jersey) containing ethylenediaminetetraacetic acid. We centrifuged tubes at 2,000 rpm for 10 minutes at 4°C to separate plasma from erythrocytes, which we then washed with chilled saline. We stored erythrocyte aliquots at –70°C. Because of inhomogeneity of the erythrocyte sample, we diluted the thawed sample 1:1 by weight with deionized water, froze samples overnight, then centrifuged thawed samples at 30,000 rpm for 30 minutes at 20°C (L8-M Ultracentrifuge with Ti-70; Beckman Coulter, Inc., Fullerton, California) to remove cell membranes. We performed total mercury assays by using the Direct Mercury Analyzer 80 (Milestone Inc., Monroe, Connecticut). Results were reported as mercury content in the original red cell sample. The detection limit is 0.5 ng/ml of sample, and the percentage recovery for quality control standards is about 90–110 percent. Reproducibility for duplicate analysis was approximately 20 percent.

Fatty acids
We summed contributions to intake of the elongated marine fatty acids DHA and eicosapentaenoic acid (EPA) from all foods and supplements. We also estimated intake of DHA + EPA from fish alone. To obtain estimates of fatty acid content, we used the Harvard nutrient database, which is based on US Department of Agriculture publications as well as other published sources and personal communications, and it has been used in other studies of n-3 fatty acid intake (13, 20, 21).

We also analyzed the fatty acid content of packed maternal erythrocytes with gas-liquid chromatography following a single thaw, to determine levels of DHA and EPA. Methods have been described in detail elsewhere (22, 23). Coefficients of variation were 6.5 percent for DHA and 4 percent for EPA.

Cognitive outcomes in children aged 3 years
Trained research assistants administered two cognitive tests to enrolled children in either the child's home or a research office. The PPVT evaluates receptive vocabulary among children aged 2 years or older based on a nationally stratified reference sample (24). PPVT scores are strongly correlated (r ≥ 0.90) with verbal and full-scale intelligence quotient on the Wechsler Intelligence Scale for Children-III (24). Mothers also completed the PPVT. The Wide Range Assessment of Visual Motor Abilities (WRAVMA) (25) evaluates three domains of visual motor development: visual-spatial (matching test), visual-motor (drawing test), and fine-motor skills (pegboard test), which are used to generate a total standard score. This test has norms for children aged 3 years or older, is moderately correlated with intelligence quotient (r ~ 0.60), and is sensitive to other neurotoxicants such as lead (25, 26). We calculated child age at testing in months and days.

Covariates
Using interviews and questionnaires, we collected self-reported maternal race/ethnicity, age, education, parity, smoking, alcohol consumption, marital status, household income, prepregnancy weight and height, and paternal education. We determined a Western diet score according to intake of red and processed meats, refined grains, desserts, and snack foods and a prudent diet score according to intake of fruits, vegetables, legumes, fish, and poultry (27). We obtained child sex, birth weight, and delivery date from the medical record. We determined birth-weight-for-gestational-age z value ("fetal growth") based on US national reference data (28). We collected hair samples at delivery from 211 mothers (14), of whom 98 were included in the present analysis. On postpartum questionnaires, mothers reported duration of breastfeeding and the child's primary language. We obtained clinical screening lead levels for 139 children.

Statistical analysis
We studied bivariate associations of participant characteristics with maternal fish intake by using t tests and chi-square analysis. We examined associations among the primary exposures by using Spearman's correlation and simple linear regression.

We used multivariate linear regression to examine associations of participant characteristics and exposures of interest with child cognitive test scores. Because current guidelines (29) recommend that pregnant women consume up to two servings a week of fish and shellfish, we categorized fish intake as never, ≤2, and >2 servings per week. We categorized mercury at the top decile or below because our measure of total mercury in packed erythrocytes does not easily translate to categorization according to the benchmark dose for whole-blood mercury (2). We analyzed associations of fish intake and mercury levels individually with each outcome, and then we included both measures in prediction models.

We began collecting maternal hair samples in February 2002 and continued through the end of the study. During this period, 409 participants delivered, of whom 302 were approached for collection of a hair sample and 34 were ineligible (hair too short or in braids); 211 of the remaining 270 (78 percent) consented to provide a hair sample. In the subset of mothers whose hair was collected at delivery, 10 percent had hair mercury levels of >1.2 ppm (14). Thus, we anticipate that erythrocyte mercury in the top decile of our population likely corresponds to a hair mercury level of >1.2 ppm, the level used to determine the US Environmental Protection Agency reference dose (2). Ninety-eight women with hair mercury results also had blood available for mercury assay.

In secondary analyses, we studied fish intake and mercury levels simultaneously, using the following five categories: low mercury/fish intake >2 weekly servings; low mercury/fish intake ≤2 weekly servings; mercury top decile/fish intake >2 weekly servings; mercury top decile/fish intake ≤2 weekly servings; and never fish intake. Exclusion of the one woman who reported never consuming fish but was in the top decile of mercury levels did not alter results. We also studied intake of canned tuna fish, fish types excluding canned tuna, and fish types excluding shellfish. We also modeled dietary and erythrocyte levels of DHA + EPA and maternal blood mercury as continuous predictors.

We included covariates that were of a priori interest as independent predictors of child cognition, namely, maternal age, prepregnancy body mass index, prenatal smoking and alcohol consumption, race/ethnicity, marital status, and education; paternal education; and child sex, fetal growth, gestation length, duration of breastfeeding, primary language, and age at testing. We modeled all covariates as presented in tables 1 and 2; we also included missing categories for maternal education (2 percent), smoking (1 percent), and paternal education (5 percent). Additional adjustment for household income, maternal Western or prudent dietary pattern, depression at 6 months postpartum, child body mass index, or test administrator did not substantially change estimates for fish or mercury, so we did not include these factors in our final models. We performed all analyses by using SAS version 9.1 software (SAS Institute, Inc., Cary, North Carolina).


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  		TABLE 1. Parental and child characteristics* according to maternal second-trimester fish intake among 341 mother-child pairs in Project Viva, Massachusetts, 1999–2002

 

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  		TABLE 2. Associations of parental and child characteristics with child test scores at age 3 years, Project Viva, Massachusetts, 1999–2002

 

   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 References
 
Mean maternal fish intake was 1.5 (standard deviation (SD), 1.4; range, 0–7.5) weekly servings, and 40 (12 percent) mothers consumed more than two weekly fish servings, whereas 47 (14 percent) never consumed fish (table 1). Mean erythrocyte total mercury was 3.8 (SD, 3.8; range, 0.03–21.9) ng/g, with 35 mothers above the 90th percentile of 9.1 ng/g. Mean child age at testing was 38.4 (SD, 2.2) months, and child test scores were 105.7 (SD, 13.8) for the PPVT, 99.9 (SD, 10.3) for drawing, 99.8 (SD, 10.3) for pegboard, 107.8 (SD, 14.1) for matching, and 103.2 (SD, 10.5) for the WRAVMA total score.

Maternal fish intake was directly correlated with erythrocyte total mercury (Spearman's r = 0.42, p < 0.0001), with an unadjusted increase of 0.94 (95 percent confidence interval (CI): 0.66, 1.21) ng/g of mercury for each weekly fish serving. The likelihood of being in the top decile of erythrocyte mercury was 2 percent for those who never consumed fish but 23 percent for those who consumed fish more than twice weekly (table 1). Otherwise, maternal or child characteristics did not differ significantly according to maternal fish intake (p > 0.05 for all characteristics in table 1). Among 98 mothers for whom data were available, mean hair mercury level was 0.53 (SD, 0.47; range, 0–2.3) mcg/g. Hair mercury was correlated with erythrocyte total mercury (Spearman's r = 0.46, p < 0.0001) and with fish intake (Spearman's r = 0.49, p < 0.0001). An increase of 1 ppm of hair mercury was associated with an increase of 4.5 (95 percent CI: 3.3, 5.8) ng/g in erythrocyte mercury.

Participant characteristics were generally associated with child test scores in the anticipated directions (table 2). For example, scores were higher among children who were born with higher fetal growth (birth weight adjusted for gestational age), were girls, were firstborn, and were older at testing (table 2).

After adjustment for parent and child characteristics, maternal fish intake of >2 weekly servings, compared with never, was directly associated with higher child WRAVMA drawing and total scores (table 3). Associations strengthened with adjustment for mercury levels, with the largest effects seen for the WRAVMA drawing (6.4, 95 percent CI: 2.1, 10.7) and total (6.4, 95 percent CI: 2.0, 10.8) scores, and generally positive associations were also found on the other tests (table 3 and figure 1). We saw no evidence for an advantage of fish consumption at or below two weekly servings compared with never (table 3). Exclusion of the four participants who reported taking prenatal fish oil supplements did not materially change results. The interaction between fish intake and breastfeeding duration was not significant (p = 0.08 for the PPVT model and p = 0.38 for the WRAVMA model).


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  		TABLE 3. Associations of maternal fish intake during pregnancy* with child cognitive test results at age 3 years among 341 mother-child pairs in Project Viva, Massachusetts, 1999–2002

 

Figure 1
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  		FIGURE 1. Associations of maternal second-trimester fish intake (>2 weekly servings vs. never) and erythrocyte mercury levels (top decile vs. below) with child cognitive test results at age 3 years, Project Viva, Massachusetts, 1999–2002. Effect estimates were adjusted for each other as well as for parent and child characteristics. CI, confidence interval; PPVT, Peabody Picture Vocabulary Test; WRAVMA, Wide Range Assessment of Visual Motor Abilities.

 
The 28 mothers (8 percent) who reported eating canned tuna at least twice weekly had children with higher scores on the PPVT (3.7, 95 percent CI: –0.9, 8.3) and WRAVMA total (5.6, 95 percent CI: 1.4, 9.8) compared with the 130 mothers (38 percent) who reported never eating tuna fish. The 11 mothers (3 percent) who reported consuming more than two weekly servings of fish other than canned tuna had children with higher scores on the WRAVMA total (6.1, 95 percent CI: –0.7, 12.8) but not on the PPVT (–1.4, 95 percent CI: –8.9, 6.1) compared with the 97 (28 percent) who reported eating no fish excluding tuna. Effect estimates for intake of more than 2 weekly servings of the three fish types excluding shellfish were 4.3 (95 percent CI: –0.5, 9.0) for the PPVT and 5.9 (95 percent CI: 1.6, 10.3) for the WRAVMA total score.

Among children for whom we obtained clinical lead results, lead levels were not correlated with either maternal fish consumption (Spearman's r = –0.01, p = 0.88) or mercury levels (Spearman's r = 0.03, p = 0.76). Additional adjustment for lead level in multivariable models did not alter effect estimates for fish or mercury on child cognitive test scores (results not shown).

Mean intake of DHA + EPA from fish was 128 (SD, 128; range, 0–843) mg/day, and mean intake from all sources was 149 (SD, 154; range, 0–1,605) mg/day. For each 100 mg of maternal daily DHA + EPA intake from fish, children had PPVT scores that were 0.5 (95 percent CI: –0.5, 1.5) points higher and WRAVMA total scores that were 1.1 (95 percent CI: 0.1, 2.0) points higher. Neither intake of DHA + EPA from all dietary sources nor the DHA + EPA content of maternal erythrocytes was associated with child cognition (data not shown).

Higher maternal erythrocyte mercury levels were associated with worse child test performance, with stronger associations after adjustment for fish intake (table 4). We observed the strongest adverse associations of mercury levels with the PPVT (–4.5, 95 percent CI: –8.5, –0.4), WRAVMA matching (–6.0, 95 percent CI: –10.9, –1.1), and WRAVMA total (–4.6, 95 percent CI: –8.3, –0.9) tests, with associations that were somewhat less strong but still suggestive of an inverse relation for the WRAVMA drawing and pegboard tests (table 4 and figure 1).


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  		TABLE 4. Associations of maternal second-trimester erythrocyte mercury levels with child cognitive test results at age 3 years among 341 mother-child pairs in Project Viva, Massachusetts, 1999–2002

 
We next examined maternal fish intake and mercury levels simultaneously. Compared with children whose mothers reported never consuming fish, children of women with mercury levels below the top decile but fish intake above two weekly servings had higher WRAVMA total scores (5.9 points, 95 percent CI: 1.0, 10.9). Children whose mothers consumed more than two weekly fish servings and whose mercury levels were in the top decile also had somewhat higher WRAVMA scores, whereas children of mothers who consumed up to two weekly servings of fish and had mercury levels in the top decile had somewhat lower WRAVMA scores (table 5).


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  		TABLE 5. WRAVMA* total score for children aged 3 years according to maternal prenatal fish intake and mercury levels, Project Viva, Massachusetts, 1999–2002

 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
References
 
In this US cohort with moderate levels of fish consumption, pregnant women who ate more fish had higher erythrocyte mercury levels. Among their children, higher prenatal mercury exposure was associated with lower developmental test scores at age 3 years. Nevertheless, we observed no overall adverse effect upon child development with higher maternal fish intake. Rather, maternal fish intake more than twice a week was associated with improved performance on tests of language and visual motor skills.

These results support our earlier findings among a smaller subset of our study population that we assessed at age 6 months with a single outcome (14). The present results derive from a larger sample of children whom we assessed at age 3 years with well-validated developmental tests that are correlated with intelligence quotient. Our findings show broadly consistent results for tests of language as well as visual-spatial, visual-motor, and fine-motor skills, suggesting that the benefit of fish consumption spans these developmental domains.

These results also extend findings from other populations that have suggested benefits from maternal prenatal n-3 fatty acid or fish intake. Children of women randomized to receive prenatal fish oil supplementation had higher mental processing scores and better eye-hand coordination (8, 9). In a recent publication of data from the United Kingdom, Hibbeln et al. (15) found that children of mothers who ate three or more fish servings per week were less likely to have suboptimal scores on tests of intelligence quotient and behavior at 7–8 years of age, but the authors did not observe any benefit of seafood intake below compared with above three servings per week. In that study, there was no measure of mercury, although, in an earlier publication from a subset of the same population, levels of mercury in umbilical cord tissue were not associated with development in infancy (30). Additionally, in a reanalysis of data from the Faroe Islands cohort, whose seafood intake and mercury exposure are much higher, Budtz-Jorgensen et al. (16) reported that maternal fish intake during pregnancy was associated with somewhat higher performance on all seven outcomes studied at ages 7 and 14 years. Similar to our findings, in that study the effects of fish and mercury were each strengthened with mutual adjustment.

We observed associations of mercury levels with child cognition at exposure levels substantially lower than in populations previously studied. Our findings suggest that no lower threshold exists for the adverse effects of prenatal mercury exposure.

In previous cohort studies, biomarkers of mercury exposure included mercury in maternal hair collected at or after delivery (4, 5, 14, 31) and in umbilical cord blood (4). In Project Viva, we did not retain cord blood erythrocytes, and we collected hair from a small number of mothers. We measured total mercury in maternal erythrocytes based on evidence that more than 90 percent of the total blood mercury resides in the erythrocytes (2) and that about 95 percent of the mercury in red blood cells is methylmercury, with some of the inorganic mercury derived from demethylated methylmercury (32). Maternal first- or second-trimester blood mercury is highly correlated with blood mercury collected at delivery and with cord blood levels (33–37). Thus, good evidence exists that the sample we used is a suitable proxy for fetal methylmercury exposure.

Advantages of the present study include assessment of maternal diet during pregnancy with a validated dietary questionnaire, well-established outcome measures, and measurement of a number of parent and child characteristics, including maternal PPVT scores. Although women in our population were generally well educated and were employed, their fish and dietary DHA intake was similar to that reported in other general populations in North America (12, 38, 39). Nevertheless, this study has several limitations. It is possible that unmeasured confounding may account for at least part of the observed findings. In particular, we did not assess home environment. We did not measure other contaminants that may be found in fish, such as polychlorinated biphenyls. Accounting for the harms of polychlorinated biphenyls would be expected to suggest an even stronger benefit of the nutrients in fish but might weaken estimates for mercury. It is possible that women in other populations who consume fish types with different amounts of nutrients and contaminants may experience less of a benefit or even perhaps overall harm from higher prenatal fish intake. In addition, we did not measure other neurodevelopmental domains, such as overall intelligence, that might be differently associated with the nutrients or toxicants in fish.

We previously reported that mothers in Project Viva consumed less fish after dissemination of a federal mercury advisory in January 2001 and reduced their intake of even those fish types not included in the advisory (7). Subsequent advisories and expert reviews have emphasized the nutritional benefits of fish (29, 40), but they have continued to recommend that pregnant women consume no more than two weekly fish servings (29). Our finding that the benefit of fish intake is strengthened with adjustment for mercury levels suggests that if mercury contamination were not present, the cognitive benefits of fish intake would be greater. Maternal consumption of fish lower in mercury and reduced environmental mercury contamination would allow for stronger benefits of fish intake. Recommendations for fish consumption during pregnancy should take into account the nutritional benefits of fish as well as the potential harms from mercury exposure.


   ACKNOWLEDGMENTS
 
This project was supported by grants from the National Institutes of Health (Bethesda, Maryland; HD34568, HL68041, HD44807, ES00002, P01ES012874) and by Harvard Medical School and the Harvard Pilgrim Health Care Foundation.

The authors appreciate the invaluable assistance with the mercury assays they received from Rebecca Doigan, Dr. Innocent Jayawardena, Kelly Konopacki, Nicola Lupoli, and Dr. Chinweike Ukomadu.

Dr. Gillman has received grant support from Mead Johnson Nutritionals (Evansville, Indiana). Dr. Bellinger served as a member of an expert panel for a study conducted by the Harvard Center for Risk Analysis evaluating the benefits and risks of seafood consumption, with funding from the National Food Producers Association.


   References
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 

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