Mercury in commercial fish: optimizing individual choices to reduce risk

Most attention to the risks from fish consumption has focused on recreational anglers and on fish caught by individuals, but the majority of fish that people eat are purchased from commercial sources. We examined mercury levels in three types of fish (tuna, flounder, bluefish) commonly available in New Jersey stores, sampling different regions of the state, in communities with high and low per capita incomes, and in both supermarkets and specialty fish markets. We were interested in species-specific levels of mercury in New Jersey fish and whether these levels were similar to data generated nationally by the Food and Drug Administration (FDA; mainly from 1990 to 1992) on the same types of fish. Such information is critical for providing public health advice. We were also interested in whether mercury levels in three common species of fish differed by region of the state, economic neighborhood, or type of store. We found significant species differences, with tuna having the highest levels and flounder the lowest levels. There were no significant differences in mercury levels as a function of type of store or economic neighborhood. There was only one regional difference: flounder from fish markets along the Jersey shore had higher mercury levels than flounder bought in other markets. We also examined mercury levels in six other commonly available fish and two shellfish from central New Jersey markets. There were significant differences in availability and in mercury levels among fish and shellfish. Both shrimp and scallops had total mercury levels < 0.02 ppm (wet weight). Large shrimp had significantly lower levels of mercury than small shrimp. For tuna, sea bass, croaker, whiting, scallops, and shrimp, the levels of mercury were higher in New Jersey samples than those reported by the FDA. Consumers selecting fish for ease of availability (present in > 50% of markets) would select flounder, snapper, bluefish, and tuna (tuna had the highest mercury value), and those selecting only for price would select whiting, porgy, croaker, and bluefish (all with average mercury levels < 0.3 ppm wet weight). Flounder was the fish with the best relationship among availability, cost, and low mercury levels. We suggest that state agencies responsible for protecting the health of their citizens should obtain information on fish availability in markets and fish preferences of diverse groups of citizens and use this information to select fish for analysis of contaminant levels, providing data on the most commonly eaten fish that will help people make informed decisions about risks from fish consumption.     

Mercury content of commercially important fish of the Seychelles,and hair mercury levels of a selected part of the population

Mercury and methyl mercury concentrations were determined in the muscle of 12 of the most important commercial fish species found in Seychelles waters. The concentration of mercury in a few of the larger specimens of Kingfish (Acanthocybium solandri), Becune (Sphyraena forsteri), Carangue balo (Caranx gymnostethus), and Bonito (Euthynnus affinis) exceeded the provisional maximum permissible level of 1.0 mg/kg of total mercury established by the Food and Drug Administration (1979) in the United States. More than half of the Dogtooth tuna (Gymnosarda unicolor) examined exceeded this level with two fish having levels of 3.3 and 4.4 ppm. The hair mercury levels of fishermen and mothers and their newborn babies have been examined since the Seychelles population has one of the highest fish consumption figures in the world (80–100 kg per person per annum), much of it being predatory species.     

Risk to consumers from mercury in bluefish (Pomatomus saltatrix) from New Jersey: Size, season and geographical effects

Relatively little attention has been devoted to the risks from mercury in saltwater fish, that were caught by recreational fisherfolk. Although the US Food and Drug Administration has issued advisories based on mercury for four saltwater species or groups of fish, there are few data on how mercury levels vary by size, season, or location. This paper examines total mercury levels in muscle of bluefish (Pomatomus saltatrix) collected from coastal New Jersey, mainly by recreational fishermen. Of primary interest was whether there were differences in mercury levels as a function of location, weight and length of the fish, and season, and in what risk mercury posed to the food chain, including people. Selenium was also measured because of its reported protective effects against mercury. Mercury levels averaged 0.35±0.02 (mean and standard error) ppm, and selenium levels averaged 0.37±0.01 ppm (N=206). In this study, 41% of the fish had mercury levels above 0.3 ppm, 20% had levels above 0.5 ppm, and 4% had levels above 1 ppm. Size was highly correlated with mercury levels, but not with selenium. While selenium levels did not vary at all with season, mercury levels decreased significantly. This relationship was not due to differences in the size of fish, since the fish collected in the summer were the smallest, but had intermediate mercury levels. Mercury levels declined from early June until November, particularly for the smaller-sized fish. While there were significant locational differences in mercury levels (but not selenium), these differences could be a result of size. The levels of mercury in bluefish are not sufficiently high to cause problems for the bluefish themselves, based on known adverse health effects levels, but are high enough to cause potential adverse health effects in sensitive birds and mammals that eat them, and to provide a potential health risk to humans who consume them. Fish larger than 50 cm fork length averaged levels above 0.3 ppm, suggesting that eating them should be avoided by pregnant women, children, and others who are at risk.     

Risk to consumers from mercury in Pacific cod (Gadus macrocephalus) from the Aleutians: fish age and size effects

While there has been considerable attention devoted to the risks to high level consumers from mercury in freshwater fish, relatively little attention has been devoted to saltwater fish. Although the U.S. Food and Drug Administration has issued advisories based on mercury for four saltwater species or groups of fish, there are few data on mercury levels generally, or on the risk these levels pose to the fish themselves or to consumers of marine fish. We examined total mercury levels in liver and muscle of Pacific cod (Gadus macrocephalus) collected from the northern Pacific and Bering Sea waters around Nikolski, Amchitka, and Kiska Islands in the Aleutian Chain (Alaska). We were interested in whether there were differences in mercury levels as a function of location, weight, length, and age of the fish, and what risk mercury posed to the food chain, including people. Fish were aged by examining otoliths, and we measured selenium because of its reported protective effects against mercury. Regression models indicated that 27% of the variation in levels of mercury was due to tissue examined and age, while 67% of the variation in levels of selenium was due to tissue, length, and age. Mercury levels were significantly higher in the muscle than the liver, and the reverse was true for selenium. Mercury levels were negatively correlated with selenium levels, and positively correlated with length, weight, and age. There were no gender differences in mercury or selenium levels. The mean levels of mercury in muscle (0.17 ppm wet weight) are within the range known to cause adverse effects in sensitive birds and mammals. Only 4% of the Pacific cod samples had mercury levels above 0.5 ppm, the action level promulgated by many states and countries, and none were above the 1 ppm action level of the U.S. FDA.     

Awareness and knowledge of methylmercury in fish in the United States

In the 1970s several states in the Great Lakes region became concerned about mercury contamination in lakes and rivers and were the first to issue local fish consumption advisories. In 2001, the Food and Drug Administration (FDA) advised pregnant women, nursing mothers, young children, and women who may become pregnant not to consume shark, swordfish, king mackerel, and tilefish and recommended that these women not exceed 12 ounces of other fish per week. In 2004, FDA reissued this advice jointly with the U.S. Environmental Protection Agency (EPA) and modified it slightly to provide information about consumption of canned tuna and more details about consumption of recreationally caught fish. Though several studies have examined consumers' awareness of the joint FDA and EPA advisory as well as different state advisories, few used representative data. We examined the changes in awareness and knowledge of mercury as a problem in fish using the pooled nationally representative 2001 and 2006 Food Safety Surveys (FSS) with sample sizes of 4482 in 2001 and 2275 in 2006. Our results indicated an increase in consumers' awareness of mercury as a problem in fish (69% in 2001 to 80% in 2006, p<.001). In our regression models, we found that in both years, parents having children less than 5 years of age were more aware of mercury in fish and knowledgeable about the information contained in the national advisories about mercury in fish (p<.01) than other adults. In both 2001 and 2006, women of childbearing age (aged 18–45) were less aware and knowledgeable about this information than other women. However, women of all age groups had larger gains in awareness and knowledge than their male counterparts during this time. Participants' race, education, income, region, fish preparation experiences, having a foodborne illness in the past year, and risk perceptions about the safety of food were significant predictors of their awareness and knowledge.     

Concentrations and health risk assessment of total mercury in canned tuna marketed in Southest Brazil

The aim of this research was to determine total mercury (Hg) content in 69 canned tuna of 13 brands marketed in southwest Brazil. All values are reported in μg.g⁻¹ wet weight basis. Potential health risk was estimated on the basis of mercury concentration and average consumption (175 g/per week) of fish in Brazil comparing to PTWI of 1.6 μg.kg⁻¹ (FAO/WHO, 2010). A large variation in the concentration of mercury in different species was observed. Mean mercury concentration was 0.256 ± 0.215 μg.g⁻¹ with a highest value of 1.060 μg.g⁻¹ in a single can. In general average concentration was below the legislation of 1.0 μg.g⁻¹ for predatory species (BRASIL, 2010). Estimate weekly intake (EWI) varied 0.2–1.7 μg.kg⁻¹. For the analyzed brands and Brazilian fish consumption, no human health risk is likely to occur. However one brand was higher than PTWI of 1.6 μg.kg⁻¹ showing no safety for specific risk group. Further studies including specific data on canned tuna consumption in specific populations will be needed as well as the fish type, fish size and fishing location.     

Bioavailability to rats of selenium in various tuna and wheat products

Bioavailability of selenium (Se) in tuna and wheat at various stages of processing was studied in rats. The protein source of the rat diets was torula yeast with Se supplied by either raw, precooked or canned tuna, or whole wheat flour, whole wheat bread or bran. Sodium selenite was used as the standard. Each Se source was fed at three levels: 0.05, 0.10 and 0.15 ppm. By using increase in glutathione peroxidase (GSH-Px) activity in liver, kidney and whole blood as an indicator of bioavailability, no differences were found among the three tuna products or among the three wheat products tested. However, significantly lower GSH-Px activity was found in the combined tuna groups as compared to the combined wheat groups, suggesting that selenium in wheat was more available than that in tuna. There was a significant increase in the liver Se content of rats fed all levels of Se in canned tuna and in kidney, blood and muscle Se of rats fed 0.10 and 0.15 ppm Se in canned tuna in comparison to the tissue Se content in rats fed these same levels of Se in raw or precooked tuna. Since this did not correspond with an increase in GSH-Px activity it was concluded that it did not represent increased bioavailability of canned tuna. Thus, food processing does not appear to affect Se availability, but Se appears to be more available in wheat than tuna.     

Mid infrared spectroscopy coupled with chemometric tools for qualitative analysis of canned tuna with sunflower medium

The most common frauds of tuna cans supply chain concern the substitution or mixing of valuable tuna species with cheaper ones, which is strictly prohibited by the European regulation. The aim of this work was to investigate the ability of mid-infrared (MIR) spectroscopy as a rapid and non-destructive tool to identify canned bigeye, yellowfin and skipjack tunas and detect their presence in a binary mixture of canned tunas. The MIR spectra were acquired on 232 canned tunas produced at the pilot scale. The factorial discriminant analysis (FDA) was applied to the first 5 principal components (PCs) of the principal component analysis (PCA) of the three spectral regions: 3000–2800 cm⁻¹, 1700–1500 cm⁻¹ and 1500–900 cm⁻¹. A robust model was created with correct classification amounting to 90.38% that was tested on 30 commercial canned tuna. A total (100%) of correct classification was obtained for skipjack tuna, while misclassification was observed for cans labelled as bigeye and yellowfin suggesting an adulteration action or mislabelling during process technology.     

Heavy metals in commercial fish in New Jersey

Levels of contaminants in fish are of particular interest because of the potential risk to humans who consume them. While attention has focused on self-caught fish, most of the fish eaten by the American public comes from commercial sources. We sampled 11 types of fish and shellfish obtained from supermarkets and specialty fish markets in New Jersey and analyzed them for arsenic, cadmium, chromium, lead, manganese, mercury, and selenium. We test the null hypothesis that metal levels do not vary among fish types, and we consider whether the levels of any metals could harm the fish themselves or their predators or pose a health risk for human consumers. There were significant interspecific differences for all metals, and no fish types had the highest levels of more than two metals. There were few significant correlations (Kendall tau) among metals for the three most numerous fish (yellowfin tuna, bluefish, and flounder), the correlations were generally low (below 0.40), and many correlations were negative. Only manganese and lead positively were correlated for tuna, bluefish, and flounder. The levels of most metals were below those known to cause adverse effects in the fish themselves. However, the levels of arsenic, lead, mercury, and selenium in some fish were in the range known to cause some sublethal effects in sensitive predatory birds and mammals and in some fish exceeded health-based standards. The greatest risk from different metals resided in different fish; the species of fish with the highest levels of a given metal sometimes exceeded the human health guidance or standards for that metal. Thus, the risk information given to the public (mainly about mercury) does not present a complete picture. The potential of harm from other metals suggests that people not only should eat smaller quantities of fish known to accumulate mercury but also should eat a diversity of fish to avoid consuming unhealthy quantities of other heavy metals. However, consumers should bear in mind that standards have a margin of safety.     

Ranking the contributions of commercial fish and shellfish varieties to mercury exposure in the United States: Implications for risk communication

Fish and shellfish have important nutritional benefits, and US per capita seafood consumption has increased substantially since 2002. Recent research has reinforced concerns about adverse effects of methylmercury exposure, suggesting that methylmercury doses associated with typical US rates of fish consumption may pose measurable risks, with no threshold. These converging trends create a need to improve risk communication about fish consumption and mercury. The analysis performed here identifies the relative importance of different fish and shellfish as sources of mercury in the US seafood supply and proposes improved consumer advice, so that the public can benefit from fish consumption while minimizing mercury exposure. I have quantified contributions to total mercury in the US seafood supply by 51 different varieties of fish and shellfish, then ranked and sorted the 51 varieties in terms of relative impact. Except for swordfish, most fish with the highest mercury levels are relatively minor contributors to total inputs. Tuna (canned light, canned albacore and fresh/frozen varieties) accounts for 37.4 percent of total mercury inputs, while two-thirds of the seafood supply and nine of the 11 most heavily consumed fish and shellfish are low or very low in mercury. Substantial improvement in risk communication about mercury in fish and seafood is needed; in particular, several population subsets need better guidance to base their seafood choices more explicitly on mercury content. I have sorted the 51 seafood varieties into six categories based on mercury levels, as a framework for improving risk communication in this regard.     

Factors contributing to the difference of hair mercury concentrations between the sexes

Scalp hair samples were collected by mail from 97 married couples who were living in several places in Okinawa-prefecture and supposedly had no specific exposure to mercury compounds. They were selectively analysed for organic and inorganic mercury content and the difference of hair mercury concentration between the sexes was discussed in relation to the frequency of fish intake, fish species, drinking habits and permanent-wave hair treatment. Results obtained were as follows: 1) The increase in hair levels of organic and inorganic mercury concentrations was roughly proportional to the dietary intake of fish in the range from none or low to moderate frequencies for both husbands and wives. However, this increase was not proportional to the dietary intake of fish in the range from moderate to high frequencies, showing almost the same level irrespective of the frequency of fish intake. 2) Though husbands and wives had dietary consumption patterns quite similar to each other, husbands were found to have higher hair organic mercury levels than wives, the average values being 6.40 ppm with a standard deviation of 4.69 ppm for husbands and 2.86 ppm with a standard deviation of 1.97 ppm for wives, respectively. The difference was statistically significant. No significant difference between the sexes was detected for inorganic mercury concentrations. However, a highly significant positive correlation coefficient for organic mercury and also a significant positive correlation coefficient for inorganic mercury were found between husbands and wives. 3) Hair without permanent-wave treatment showed higher levels of organic mercury concentrations than hair with permanent-wave treatment for both husbands and wives. Drinkers also had higher levels of hair mercury as compared to non-drinkers. However, the lower levels of organic mercury concentrations in women's hair than in men's hair were not fully explained by these factors. 4) Both men and women who showed higher hair levels of organic mercury had a preference for highly predatory fish such as tuna and bonito, which probably contributed most to the human intake of mercury.     

Assessment of trace elements in canned fishes (mackerel, tuna, salmon, sardines and herrings) marketed in Georgia and Alabama (United States of America)

The concentrations of mercury and 13 other trace metals in 104 canned fish samples purchased within the states of Georgia and Alabama (United States of America) were determined using the direct mercury analyzer (DMA) and the inductively coupled plasma-optical emission spectrometer (ICP-OES). The ranges obtained for the elements analyzed in mg/kg (wet weight) are as follows: Hg (0.02–0.74), Ag (0.0–0.20), As (0.0–1.72), Cd (0.0–0.05), Cr (0.0–0.30), Fe (0.01–88.4), Pb (0.0–0.03), Mn (0.01–2.55), Ni (0.0–0.78), Co (0.0–0.10), Cu (0.01–5.33), Sn (0.04–28.7), V (0.0–0.31) and Zn (0.14–97.8). Three tuna samples had Hg level above the European dietary limit of 0.5 mg Hg/kg. The mean Hg concentrations in the tuna (285 μg/kg) and sardine (107 μg/kg) brands were higher than the averages posted by the pink salmon (36.1 μg/kg), red salmon (32.8 μg/kg) and mackerel (36.4 μg/kg) brands. Two tuna samples and a sardine sample exceeded the Australian permissible limit of 1 μg/g inorganic arsenic (wet weight). Two samples (brand 15: herring) had zinc levels exceeding the Food and Agriculture Organization (FAO) recommended limit of 40 mg/kg and two pink salmons also exceeded the Brazilian regulatory limit of 0.1 mg Cr/kg. One tuna sample had a cadmium level slightly exceeding the Codex Committee on Food Additives and Contaminants draft guideline of 0.50 mg Cd/kg. However, the concentrations of lead, cadmium and copper were below the corresponding MAFF guidelines of 2.0, 1.0 and 30 mg/kg, respectively. Also, based on the United States Environmental Protection Agency (US EPA) health criteria for carcinogens, there are no health risks with respect to Pb, Cr, Cu and Zn concentrations in canned fishes analyzed. The result of the one-way analysis of variance (ANOVA) conducted on the data suggested that significant variations (P<0.05) existed in the concentrations of Hg, As, Co, Cr, Cu, Fe, Mn, Sn, V, and Zn across the various fish species and canned fish brands analyzed. The estimated weekly intakes of Hg, As, Cd, Pb, Sn, Fe, Cu and Zn for a 60 kg adult consuming 350 g of fish/week were below the respective provisional tolerable weekly intakes (PTWI) in μg/kg body weight for: Hg: 5; As: 15; Cd: 7; Pb: 25; Sn: 14000; Fe: 5600; Cu: 3500; and Zn: 7000.     

Mercury levels in freshwater fish of the state of South Carolina

Summary Samples of fish from freshwater sources of rivers, lakes and ponds all over the state of South Carolina were collected during the Summer of 1974 and 1975. The fish collected were Bass,A Bluegill, Redbreast, Catfish, Shad, Carp, Crappie, Mudfish and Pike. Samples were analyzed using the flameless atomic absorption procedure outlined by Hatch and Ott, and Uthe et al as modified for use with Perkin-Elmer, Coleman MAS-50 mercury analyzer. Triplicate samples of fish tissue were analyzed by wet digestion method. The mean mercury levels in ppb were determined for baseline mercury levels. A significant finding of this report is that those species for which fish of widely differing weights were analyzed, larger fish had higher mercury levels. Mercury levels exceeding the U.S. Food and Drug Administration guideline of 500 ppb for fish tissues have been found in the Mudfish from Edisto River and Pike fish from Lake Murray. Higher levels of mercury occurred in the highly vascularized blood tissues of liver and kidney than in muscle. Carnivorous and bottom-feeding fishes are the most reliable indicators of mercury pollution.     

Lead,cadmium and mercury in canned and unprocessed tuna: six-years monitoring survey,comparison with previous studies and recommended tolerable limits

Fishery products, in particular those belonging to tuna species, widely present in the human diet, may represent a toxicological issue because of the level of contamination by heavy metals (e.g., lead, cadmium and mercury) and the average per capita consumption. Control of food safety is one of the pillars to the public health safeguard, therefore the official laboratories are in charge of checking the compliance of food products with quality standards for these toxic elements.. From 2014 to 2019, 108 tuna samples, canned or unprocessed, were checked at the laboratory of the Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata (Italy). One canned tuna was non-compliant for cadmium (0.22 mg kg^-1), and twelve fresh tuna samples (11% of total) showed mercury content above the permitted level. Mean mercury concentrations in fresh and canned tuna (0.517 and 0.207 mg kg^-1, respectively) confirm that this element represents a serious toxicological issue. Exposition to mercury, and markedly in its organic form, due to tuna consumption, was found to be significant and may pose a risk for the most sensitive consumer groups (i.e., children).     

Relation between trophic position and mercury accumulation among fishes from the Tongue River Reservoir,Montana

Concentrations of total mercury were determined in muscle tissue from northern pike (Esox lucius), sauger (Stizostedion canadense), walleye (S. vitreum), black crappie (Pomoxis nigromaculatus), and white crappie (P. annularis) collected from the Tongue River Reservoir, Montana, prior to extensive surface coal-mine development in the region. Mercury concentrations in fish flesh increased with fish size and age; larger individuals of all five species exceeded the U.S. Food and Drug Administration's mercury concentration guideline of 0.5 μg/g. The rate of mercury accumulation was faster in the piscivorous species (northern pike, saugers, and walleyes) than in the planktivores (black crappies and white crappies). Differences in mercury uptake rates among the various species appeared to be directly related to the quantity of mercury eaten: results are discussed in relation to published models of mercury accumulation by fishes.     

Hair methylmercury levels of mummies of the Aleutian Islands, Alaska

Ancient human hair specimens can shed light on the extent of pre-historic exposures to methylmercury and provide valuable comparison data with current-day exposures, particularly for Indigenous Peoples who continue to rely upon local traditional food resources.Human hair from ancient Aleutian Island Native remains were tested for total and methylmercury (Hg, MeHg) and were radiocarbon dated. The remains were approximately 500 years old (1450 A.D.). For four adults, the mean and median total hair mercury concentration was 5.8 ppm (SD=0.9). In contrast, MeHg concentrations were lower with a mean of 1.2 ppm (SD=1.8) and a median of 0.54 ppm (0.12-3.86). For the five infants, the mean and median MeHg level was 1.2 ppm (SD=1.8) and 0.20 ppm (0.007-4.61), respectively. Segmental analyses showed variations in MeHg concentrations in 1-cm segments, consistent with fluctuations in naturally occurring exposure to mercury through dietary sources. The levels are comparable to or lower than those found in fish and marine mammal-eating populations today who rely far less on subsistence food than pre-historic humans. The findings are, therefore, compatible with increased anthropogenic release of trace metals during the past several centuries.     

Mercury exposure from domestic and imported estuarine and marine fish in the U.S. seafood market

BACKGROUND: Methylmercury exposure causes a variety of adverse effects on human health. Per capita estimates of mercury exposure are critical for risk assessments and for developing effective risk management strategies. OBJECTIVE: This study investigated the impact of natural stochasticity in mercury concentrations among fish and shellfish harvested from the Atlantic Ocean, Pacific Ocean, and foreign shores on estimated mercury exposures. METHODS: Mercury concentrations and seafood consumption are grouped by supply region (Atlantic Ocean, Pacific Ocean, and foreign shores). Distributions of intakes from this study are compared with values obtained using national FDA (Food and Drug Administration) mercury survey data to assess the significance of geographic variability in mercury concentrations on exposure estimates. RESULTS: Per capita mercury intake rates calculated using FDA mercury data differ significantly from those based on mercury concentration data for each supply area and intakes calculated for the 90th percentile of mercury concentrations. CONCLUSIONS: Differences in reported mercury concentrations can significantly affect per capita mercury intake estimates, pointing to the importance of spatially refined mercury concentration data. This analysis shows that national exposure estimates are most influenced by reported concentrations in imported tuna, swordfish, and shrimp; Pacific pollock; and Atlantic crabs. Collecting additional mercury concentration data for these seafood categories would improve the accuracy of national exposure estimates.     

Maternal fish consumption, mercury levels, and risk of preterm delivery

BACKGROUND: Pregnant women receive mixed messages about fish consumption in pregnancy because unsaturated fatty acids and protein in fish are thought to be beneficial, but contaminants such as methylmercury may pose a hazard. METHODS: In the Pregnancy Outcomes and Community Health (POUCH) study, women were enrolled in the 15th to 27th week of pregnancy from 52 prenatal clinics in five Michigan communities. At enrollment, information was gathered on amount and category of fish consumed during the current pregnancy, and a hair sample was obtained. A segment of hair closest to the scalp, approximating exposure during pregnancy, was assessed for total mercury levels (70-90% methylmercury) in 1,024 POUCH cohort women. RESULTS: Mercury levels ranged from 0.01 to 2.50 pg/g (mean = 0.29 microg/g; median = 0.23 microg/g). Total fish consumption and consumption of canned fish, bought fish, and sport-caught fish were positively associated with mercury levels in hair. The greatest fish source for mercury exposure appeared to be canned fish. Compared with women delivering at term, women who delivered before 35 weeks' gestation were more likely to have hair mercury levels at or above the 90th percentile (> or = 0.55 microg/g), even after adjusting for maternal characteristics and fish consumption (adjusted odds ratio = 3.0; 95% confidence interval, 1.3-6.7). CONCLUSION: This is the first large, community-based study to examine risk of very preterm birth in relation to mercury levels among women with low to moderate exposure. Additional studies are needed to see whether these findings will be replicated in other settings.     

Maternal fish consumption, hair mercury, and infant cognition in a U.S. Cohort

Fish and other seafood may contain organic mercury but also beneficial nutrients such as n-3 polyunsaturated fatty acids. We endeavored to study whether maternal fish consumption during pregnancy harms or benefits fetal brain development. We examined associations of maternal fish intake during pregnancy and maternal hair mercury at delivery with infant cognition among 135 mother-infant pairs in Project Viva, a prospective U.S. pregnancy and child cohort study. We assessed infant cognition by the percent novelty preference on visual recognition memory (VRM) testing at 6 months of age. Mothers consumed an average of 1.2 fish servings per week during the second trimester. Mean maternal hair mercury was 0.55 ppm, with 10% of samples > 1.2 ppm. Mean VRM score was 59.8 (range, 10.9-92.5). After adjusting for participant characteristics using linear regression, higher fish intake was associated with higher infant cognition. This association strengthened after adjustment for hair mercury level: For each additional weekly fish serving, offspring VRM score was 4.0 points higher [95% confidence interval (CI), 1.3 to 6.7]. However, an increase of 1 ppm in mercury was associated with a decrement in VRM score of 7.5 (95% CI, -13.7 to -1.2) points. VRM scores were highest among infants of women who consumed > 2 weekly fish servings but had mercury levels 相似文献