Modelling seasonal and geographical n-3 polyunsaturated fatty acid contents in marine fish from the Northeast Atlantic Ocean

Demand for n-3 polyunsaturated fatty acids (n-3 PUFAs) exceeds supply. Large-scale studies on effects of season and geography of n-3 PUFAs in marine fish from the Northeast Atlantic Ocean (NEAO) may be used to optimize utilization and improve nutrition security. Using a sinusoid model, seasonal cycles of n-3 PUFAs were determined and found to be species-specific and clearly pronounced for the pelagic zooplankton feeding species. The Greenland halibut showed very little seasonal variation. The n-3 PUFA content in North Sea autumn-spawning (NSAS) herring peaked in summer, while Norwegian spring-spawning (NSS) herring and mackerel had their peak in autumn. A time shift of peaks in n-3 PUFAs between the two herring stocks was detected, likely due to different spawning strategies in addition to a delay of n-3 PUFAs flux in the northern regions of the NEAO. This study demonstrates that consideration of nutrient contents, such as n-3 PUFAs, when organizing and structuring fishery approaches may improve overall nutritional yield. Based on total annual Norwegian fish landings and seasonal variation in n-3 PUFA contents, n-3 PUFAs yield could theoretically be increased from 13.79 kilo ton per year from the current fishing tactics, to 15.54 if the pelagic species were only caught during the time of their seasonal n-3 PUFA peaks. Pelagic fish is a good source for dietary n-3 PUFAs, but harvest timing will also influence n-3 PUFAs intake by human consumers. One portion of fatty fish harvested during winter/spring may not meet the weekly intake reference nutritional guidelines for n-3 PUFAs. Marine n-3 PUFAs yields also varied geographically and decreased southwards, with the lowest values in Skagerrak. This study can serve as a model to understand patterns of reproductive cycles and geographical distribution of n-3 PUFAs in fatty fish from the NEAO and the novel approach may be useful to support sustainable, seasonal fishing programmes for optimization of n-3 PUFAs yields.

Levels of mercury, arsenic, cadmium and lead in Northeast Atlantic mackerel (Scomber scombrus) from northern European waters

Fillets from a total of 1245 Northeast Atlantic mackerel (Scomber scombrus) sampled in different fishing areas of the Northeast Atlantic during 2007-2016 were analysed for mercury, cadmium, arsenic and lead using ICPMS. Mercury levels varied from <0.01 to 0.36 mg/kg wet weight (ww) with a total mean of 0.046 mg/kg ww and were significantly higher in Skagerrak than in the North Sea, the Norwegian Sea and west of Scotland. Cadmium concentrations varied from <0.002 to 0.16 mg/kg ww with a mean value of 0.015 mg/kg ww. Only 0.24 % and 0.16 % of the sampled fish exceeded the EU's maximum levels for cadmium and mercury, respectively. Arsenic levels varied between 0.43 and 6.9 mg/kg ww with a mean value of 2.2 mg/kg ww and showed seasonal variation following variations in fat content. Lead concentrations were low and below the analytical limit of quantification (LOQ) in 97 % of the samples.

Climate change dynamics and mercury temporal trends in Northeast Arctic cod (Gadus morhua) from the Barents Sea ecosystem

The Northeast Arctic cod (Gadus morhua) is the world's northernmost stock of Atlantic cod and is of considerable ecological and economic importance. Northeast Arctic cod are widely distributed in the Barents Sea, an environment that supports a high degree of ecosystem resiliency and food web complexity. Here using 121 years of ocean temperature data (1900-2020), 41 years of sea ice extent information (1979-2020) and 27 years of total mercury (Hg) fillet concentration data (1994-2021, n = 1999, ≥71% Methyl Hg, n = 20) from the Barents Sea ecosystem, we evaluate the effects of climate change dynamics on Hg temporal trends in Northeast Arctic cod. We observed low and consistently stable, Hg concentrations (yearly, least-square means range = 0.022-0.037 mg/kg wet wt.) in length-normalized fish, with a slight decline in the most recent sampling periods despite a significant increase in Barents Sea temperature, and a sharp decline in regional sea ice extent. Overall, our data suggest that recent Arctic amplification of ocean temperature, "Atlantification," and other perturbations of the Barents Sea ecosystem, along with rapidly declining sea ice extent over the last ∼30 years did not translate into major increases or decreases in Hg bioaccumulation in Northeast Arctic cod. Our findings are consistent with similar long-term, temporal assessments of Atlantic cod inhabiting Oslofjord, Norway, and with recent investigations and empirical data for other marine apex predators. This demonstrates that Hg bioaccumulation is highly context specific, and some species may not be as sensitive to current climate change-contaminant interactions as currently thought. Fish Hg bioaccumulation-climate change relationships are highly complex and not uniform, and our data suggest that Hg temporal trends in marine apex predators can vary considerably within and among species, and geographically. Hg bioaccumulation regimes in biota are highly nuanced and likely driven by a suite of other factors such as local diets, sources of Hg, bioenergetics, toxicokinetic processing, and growth and metabolic rates of individuals and taxa, and inputs from anthropogenic activities at varying spatiotemporal scales. Collectively, these findings have important policy implications for global food security, the Minamata Convention on Mercury, and several relevant UN Sustainable Development Goals.

Co-occurrence of contaminants in marine fish from the North East Atlantic Ocean: Implications for human risk assessment

Marine fish from the North East Atlantic Ocean (NEAO) are nutrient rich and considered a valuable economic resource. However, marine fish are also a major dietary source of several contaminants, including persistent organic pollutants (POPs) and heavy metals. Using one of the world's largest seafood datasets (n > 25,000 individuals), comprising 12 commercially important fish species collected during 2006-2019 in the NEAO, we assessed the co-occurrence of elements and POPs, and evaluated potential risks to human consumers. Several positive correlations between concentrations of mercury (Hg), dioxins, polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were observed. Concentrations of Hg, dioxins, PCBs and PBDEs increased from North to South and associations between marine sediment contamination, sea temperature, and fish Hg and POPs concentrations were identified using multi-linear regression (MLR) models. In general, Hg concentrations in fillet and liver of fish were positively associated with increases in both sediment contamination and sea temperature. POPs concentrations in both fillet and liver were positively associated with increases in sediment contamination, and only POPs concentrations in the liver of benthopelagic and demersal species were found to be positively correlated with sea temperature. Using a probabilistic approach to estimate human contaminant exposure from seafood, we showed that intake of pelagic species posed the highest risk of dioxins and dioxin-like PCBs (DL-PCBs) exposure, while intake of benthopelagic and demersal species posed the highest risk of Hg exposure. This study can serve as a model to further understand the distribution, co-occurrence, and trends of contaminants in seafood harvested from the NEAO and their potential risks to human consumers.

Rapid temporal decline of mercury in Greenland halibut (Reinhardtius hippoglossoides)

Mercury (Hg) pollution in the ocean is an issue of global concern, however bioaccumulation regimes of this ubiquitous pollutant in marine apex predators have important knowledge gaps. Our fish length and stable isotope (δ¹⁵N and δ¹³C) normalized data of Greenland halibut (GH) (Reinhardtius hippoglossoides) showed that Hg bioaccumulation in fillet tissue decreased by ~35-50 %, over a ten-year period from 2006 to 2015 (n = 7 individual sampling years). Hg was predominantly in the methylmercury form (>77 %). Results from a Bayesian information theoretic model showed that GH Hg concentrations decreased with time and its associated declines in Hg air emissions, estimated trophic position, and a potentially lower degree of demersal prey use as indicated by temporal trend shifts in nitrogen (δ¹⁵N) and carbon (δ¹³C) stable isotope values. GH trophic shifts accounted for about one third of the observed temporal reduction in Hg. Our study demonstrates the importance of simultaneously considering Hg emissions, food web dynamics and trophic shifts as important drivers of Hg bioaccumulation in a marine, deep water fish species and highlights the effectiveness of Hg regulations on ocean apex predator Hg concentrations and overall seafood safety.

Mercury bioaccumulation pathways in tusk (Brosme brosme) from Sognefjord, Norway: Insights from C and N isotopes

Seafood is the main source of methylmercury (MeHg) exposure for humans and elevated total mercury (Hg) concentrations have been reported in marine fish from Norwegian fjords compared with offshore areas. Hg in tusk fillets (n = 201) and liver samples (n = 177) were measured in individuals from different habitats including offshore, coastal area, outer and inner Sognefjord. Specifically, the effects of habitat, energy sources and trophic complexity on Hg bioaccumulation pathways in tusk (Brosme brosme) were investigated using stable isotopes of carbon (δ¹³C) and nitrogen (δ¹⁵N). The concentrations of Hg in tusk increased from offshore towards inner Sognefjord. While Hg concentrations in sediment were at background levels, tusk fillet samples from 7 of 8 sites in Sognefjord had higher Hg levels than the maximum level set by European Union. Based on these findings, human consumption advice for tusk from Sognefjord was issued by the Norwegian Food Safety Authority. δ¹³C values in tusk successfully discriminated individuals from different habitats and were positively correlated to Hg concentrations in tusk across individuals, sites and habitats, outlining the potential importance of terrestrial carbon and most likely the atmospheric deposition of Hg from the catchment to the overall Hg bioaccumulation and exposure regime in tusk. Additionally, we postulate that the effects of terrestrial carbon sources increased towards inner Sognefjord and likely influenced Hg bioavailability throughout the food web. In contrast, δ¹⁵N values were patchy throughout the fjord system and although trophic position explained some of the Hg variation between individual fish, it was not correlated with Hg variation across sites and habitats. Our results suggest that tusk can accumulate high levels of Hg in fjord ecosystems and that catchment runoff is likely an important driver of Hg bioaccumulation in this species.

Cadmium in brown crab Cancer pagurus. Effects of location, season, cooking and multiple physiological factors and consequences for food safety

Brown crab Cancer pagurus is appreciated as seafood in several European countries. However, cadmium levels in crabs can be elevated and their consumption may pose a hazard for human health. To assess if cadmium poses a threat to food safety in Norway, crabs were sampled at two different locations along the Norwegian coast: one in the South of Norway and one in the North of Norway. Cadmium levels were determined in different tissues (claw meat, hepatopancreas and inner meat). To highlight specific risk factors for cadmium, the concentration of cadmium was related to different exogenous (location, cooking and season) and physiological (size, sex, moulting stage, gonad maturation stage, condition) factors. The results confirmed previous findings of much higher cadmium levels in brown crab sampled in the North of Norway compared to the South. Cooking of crabs further led to higher concentrations in claw meat. The effect of season on cadmium levels was different in the North and South and no clear patterns could be identified, probably due to a high inter-individual variation in cadmium levels. Size showed a correlation with the total amount of cadmium for crabs in the North indicating an accumulation of cadmium over time; together with a slower growth, this may lead to the higher cadmium levels, observed in the crabs from Northern Norway. The risk connected to cadmium exposure when consuming brown crab mainly depends on the consumption pattern, the parts of the crab consumed and the origin of the crab. Regardless of origin, the consumption of claw meat does not display a consumer health risk. However, the consumption of meals consisting of inner meat only and inner meat of brown crab from Northern Norway may pose a health risk.

Determination of Magnesium and Calcium in Foods by Atomic Absorption Spectrometry after Microwave Digestion: NMKL Collaborative Study

On the basis of results of the performed collaborative study, the 49th Annual General Meeting of the Nordic Committee on Food Analysis (NMKL) in The Faroe Islands, August 1995, approved this method to be printed and included in NMKL's collection of methods of analysis of foods. Eleven laboratories participated in an interlaboratory methods-performance (collaborative) study of a method for determining magnesium and calcium in foodstuffs by atomic absorption spectrometry (AAS) after wet microwave digestion. The study was preceded by a practice round of familiarization samples. The method was tested on 7 materials: 5 foods (apple, milk powder, minced fish, wheat bran, and chocolate cake) and 2 composite diets ranging in Mg content from 240 to 3900 mg/kg and in Ca content from 290 to 9300 mg/kg. The materials were presented to study participants as blind duplicates, and participants were asked to perform single determinations on each sample. Repeatability relative standard deviations (RSDr) ranged from 1.9 to 4.9% for Mg and from 2.2 to 8.1 % for Ca. Reproducibility relative standard deviations (RSDR) ranged from 4.0 to 13% for Mg and from 5.9 to 23% for Ca. For Ca, lowest RSDR values were found for samples with high concentrations of Ca (&gt;3800 mg/kg sample) and with nitrate ion residues of &lt;1.3% (w/v).

Determination of Arsenic, Cadmium, Mercury, and Lead by Inductively Coupled Plasma/Mass Spectrometry in Foods after Pressure Digestion: NMKL Interlaboratory Study

Thirteen laboratories participated in an interlaboratory method performance (collaborative) study on a method for the determination of arsenic, cadmium, mercury, and lead by inductively coupled plasma/mass spectrometry (ICP/MS) after pressure digestion including the microwave heating technique. Prior to the study, the laboratories were able to practice on samples with defined element levels (pretrial test). The method was tested on a total of 7 foodstuffs: carrot puree, fish muscle, mushroom, graham flour, simulated diet, scampi, and mussel powder. The elemental concentrations in mg/kg dry matter (dm) ranged from 0.0621.4 for As, 0.0328.3 for Cd, 0.040.6 for Hg, and 0.012.4 for Pb. The materials used in the study were presented to the participants as blind duplicates, and the participants were asked to perform single determinations on each sample. The repeatability relative standard deviations (RSDr) for As ranged from 3.8 to 24%, for Cd from 2.6 to 6.9%, for Hg from 4.8 to 8.3%, and for Pb from 2.9 to 27%. The reproducibility relative standard deviations (RSDR) for As ranged from 9.0 to 28%, for Cd from 2.8 to 18%, for Hg from 9.9 to 24%, and for Pb from 8.0 to 50%. The HorRat values were less than 1.5 for all test samples, except for the determination of Pb in wheat flour at a level close to the limit of quantitation (0.01 mg/kg dm). The study showed that the ICP/MS method is satisfactory as a standard method for elemental determinations in foodstuffs.

Spatial distribution of mercury in seawater, sediment, and seafood from the Hardangerfjord ecosystem, Norway

Hardangerfjord is one of the longest fjords in the world and has historical mercury (Hg) contamination from a zinc plant in its inner sector. In order to investigate the extent of Hg transferred to abiotic and biotic ecosystem compartments, Hg and monomethylmercury (MeHg) concentrations were measured in seawater, sediment, and seafood commonly consumed by humans. Although total mercury in seawater has been described previously, this investigation reports novel MeHg data for seawater from Norwegian fjords. Total Hg and MeHg concentrations in seawater, sediment, and biota increased towards the point source of pollution (PSP) and multiple lines of evidence show a clear PSP effect in seawater and sediment concentrations. In fish, however, similar high concentrations were found in the inner part of another branch adjacent to the PSP. We postulate that, in addition to PSP, atmospheric Hg, terrestrial run-off and hydroelectric power stations are also important sources of Hg in this fjord ecosystem. Hg contamination gradually increased towards the inner part of the fjord for most fish species and crustaceans. Since the PSP and the atmospheric Hg pools were greater towards the inner part of the fjord, it is not entirely possible to discriminate the full extent of the PSP and the atmospheric Hg contribution to the fjord food web. The European Union (EU) Hg maximum level for consumption was exceeded in demersal fish species including tusk (Brosme brosme), blue ling (Molva dypterygia) and common ling (Molva molva) from the inner fjord (1.08 to 1.89 mg kg^-1 ww) and from the outer fjord (0.49 to 1.07 mg kg^-1 ww). Crustaceans were less contaminated and only European lobster (Homarus gammarus) from inner fjord exceeded the EU limit (0.62 mg kg^-1 ww). Selenium (Se) concentrations were also measured in seafood species and Se-Hg co-exposure dynamics are also discussed.

Effects of geography and species variation on selenium and mercury molar ratios in Northeast Atlantic marine fish communities

Methylmercury (MeHg) is a potent neurotoxin that bioaccumulates in seafood. Co-occurrence of selenium (Se) may affect the bioavailability and toxicity of MeHg in organisms. Here we report the concentrations of total mercury (Hg) and Se in 17 teleost fish species (n = 8459) sampled during 2006-2015 from the North East Atlantic Ocean (NEAO) and evaluate species variation and effects of geography. Mean Hg concentration ranged from 0.04 mg kg^-1 ww in Atlantic mackerel (Scomber scombrus) and blue whiting (Micromesistius poutassou) to 0.72 mg kg^-1 ww in blue ling (Molva dypterygia). Se concentrations were less variable and ranged from 0.27 mg kg^-1 ww in Atlantic cod (Gadus morhua) to 0.56 mg kg^-1 ww in redfish (Sebastes spp.). The mean Se:Hg molar ratio ranged from 1.9 in blue ling to 43.3 in mackerel. Pelagic species had the lowest Hg concentrations and the highest Se:Hg ratios, whereas demersal species had the highest Hg concentrations and the lowest Se:Hg ratios. Se and Hg concentrations were positively correlated in 13 of the 17 species. Hg concentrations increased from the North to South in contrast to the Se:Hg molar ratio which exhibited the opposite trend. Fish from fjord and coastal areas had higher concentrations of Hg and lower Se:Hg molar ratios compared to fish sampled offshore. All species had average Se:Hg molar ratios >1 and Hg concentrations were largely below the EU maximum level of 0.5 mg kg^-1 ww with few exceptions including the deep water species tusk (Brosme brosme) and blue ling sampled from fjord and coastal habitats. Our results show that two fillet servings of tusk, blue ling or Atlantic halibut (Hippoglossus hippoglossus) exceeded the tolerable weekly intake of MeHg although the surplus Se may possibly ameliorate the toxic effects of MeHg. However, some individuals with selenium deficiencies may exhibit greater sensitivity to MeHg.

Tracing Mercury Pollution along the Norwegian Coast via Elemental, Speciation, and Isotopic Analysis of Liver and Muscle Tissue of Deep-Water Marine Fish ( Brosme brosme)

Liver and muscle tissue of tusks ( Brosme brosme) have been analyzed for their THg and MeHg concentrations and Hg isotopic signatures for tracing Hg pollution along the Norwegian coast. Clear differences between tissue types and locations were established. At five of the eight locations, the Hg concentration in muscle exceeded the maximum allowable level of 0.5 mg kg^-1 wet weight. δ²⁰²Hg values in both tissue types indicated that Hg speciation affects the bulk Hg isotopic signature. Tusk liver seems to be more sensitive to immediate changes and to anthropogenic inorganic Hg, while the muscle rather reflects the Hg accumulated over a longer period of exposure. The δ²⁰²Hg values of liver and muscle also enabled different sources of Hg and exposure pathways to be distinguished. δ²⁰²Hg_muscle-δ²⁰²Hg_liver showed a clear correlation with the % MeHg in tusk liver for the coastal waters, but not for the fjords. The absence of significant differences in Δ¹⁹⁹Hg values between both tissues of tusk from the same location suggests that in vivo metabolic processes are the underlying reason for the differences in Hg speciation and in δ²⁰²Hg values. This work highlights the importance of selecting different tissues of marine fish in future Hg monitoring programs.

Factors influencing risk assessments of brominated flame-retardants; evidence based on seafood from the North East Atlantic Ocean

Brominated flame-retardants (BFRs) such as polybrominated diphenyl ethers (PBDE) and hexabromocyclododecane (HBCD) are considered hazardous to human health. Due to their persistence, they are still present in the environment and in biota and seafood is major contributor of BFRs to human exposure. Here, we used data from >9700 samples of wild and farmed fish, fish feed and fish feed ingredients collected from the North Atlantic between 2006 and 2016 aiming to investigate factors influencing the risk assessments of BFRs. Due to most representative number of analyses, PBDEs were the main focus of investigation. Mean ∑PBDE in fillet samples ranged from below quantification in Atlantic cod fillet to 2.0 μg kg^-1 in Atlantic halibut. The main congener contributing to the ∑PBDE in all species was BDE 47. Factors affecting the level of BFR in seafood were multifaceted, and the levels were within species mainly determined by fish age, geographical origin and time of sampling. BDE 47, 99, 153 and HBCD were selected for margin of exposure (MOE) evaluation. When other sources of BFR than seafood were excluded, our risk assessment showed low risk at the current dietary intake of seafood. However, the dietary intake of BDE 99 may be of concern for toddlers when all sources are considered. The choice of fish species, dietary studies, choice of statistics, as well as exposure from other sources than seafood, were all factors that influenced the final MOE of BFRs. We propose the use of regression on order statistics as a tool for risk assessment, to illustrate means and spreads in large surveillance datasets to avoid the issue of measurements below the limit of quantification. A harmonized, updated evaluation of the risk associated with exposure to BFRs from diet, air and dust is warranted, where the fish species most commonly consumed also is taken into consideration.

Tracing simultaneous cadmium accumulation from different uptake routes in brown crab Cancer pagurus by the use of stable isotopes

High concentrations of cadmium in brown crab are an issue of food safety, and large variations between different areas have been found. To investigate the relative importance of dietary and aqueous uptake regarding the overall accumulation in brown crab, we used stable isotopes to trace the uptake from both routes simultaneously in the same animals. We demonstrated that the analytical challenges regarding background concentrations of natural isotope distribution and polyatomic interferences in the different matrices can be overcome with an appropriate analytical setup and modern mathematical corrections using a computer software. Cadmium was accumulated via both routes and was found in all measured organs at the end of the exposure phase. The obtained data were used to establish accumulation curves for both uptake routes and estimate accumulation parameters for hepatopancreas, as the most important organ in crab regarding total cadmium body burden. Using the estimated parameters in combination with naturally relevant cadmium concentrations in seawater and diet in a model, allowed us to predict the relative importance of the aqueous and dietary uptake route to the total hepatopancreas burden. According to the prediction, the dietary route is the main route of uptake in brown crab with a minimum of 98% of the accumulated cadmium in hepatopancreas originating from diet. Future studies addressing the source and accumulation of cadmium in crab should therefore focus on the uptake from feed and factors connected to foraging.

Iodine content of six fish species, Norwegian dairy products and hen's egg

Iodine is a trace element required for the production of thyroid hormones, essential for metabolism, growth and brain development, particularly in the first trimester of pregnancy. Milk and lean fish are the main dietary sources of iodine in the Norwegian diet. Thus, the aim of the present study was to provide updated analysed values of iodine concentration in six fish species, 27 selected Norwegian iodine-rich dairy foods and Norwegian hen's eggs. The iodine concentrations in the wild fish species varied between 18 μg/100 g (Atlantic halibut) and 1,210 μg/100 g (pollack). The iodine concentration of cow milk varied between 12 and 19 μg/100 g and the iodine concentration of the eggs varied between 23 and 43 μg/100 g. The results in this study deviate somewhat from the current iodine concentrations in the Norwegian Food Composition Table. This deviation may have a large impact on the assessment of the iodine intake. Hence, updated knowledge about the variation in iodine level of fish, milk, dairy products and hen's egg are of great importance when estimating the iodine intake in the population. These data will contribute substantially to future estimations of dietary iodine intake and will be made available for the public Norwegian Food Composition Table.

Cadmium in the shore crab Carcinus maenas along the Norwegian coast: geographical and seasonal variation and correlation to physiological parameters

Previously, high concentrations of cadmium have been found in the hepatopancreas of the edible or brown crab (Cancer pagurus) sampled from positions north of about 67° N, compared to regions further south along the Norwegian coast, with no clear understanding why. In order to study a similar organism in the same ecosystem, the present study analyzed 210 shore crabs (Carcinus maenas) from four different locations along the Norwegian coast, two in the North and two in the South. The physiological variables size, sex, molting stage, hepatosomatic index, carapace color, and gonad maturation were registered, in attempt to explain the high inter-individual variation in cadmium levels in hepatopancreas. In contrast to the brown crabs, the shore crabs showed no clear geographical differences in cadmium concentrations. This indicates physiological differences between the two crab species. No clear and consistent correlations were found between cadmium levels and physiological parameters, except for sex, where cadmium concentration in hepatopancreas was twice as high in males compared to females. The cadmium levels also varied with season, with approximately 40 and 60% lower cadmium concentration in April than August for male and female shore crabs, respectively. None of the analyzed cadmium concentrations in muscle meat from claws exceeded EUs food safety limit, and low cadmium levels in soup prepared from shore crabs clearly indicated that this dish is not problematic regarding food safety.

Estimating human exposure to perfluoroalkyl acids via solid food and drinks: Implementation and comparison of different dietary assessment methods

BACKGROUND

Diet is a major source of human exposure to hazardous environmental chemicals, including many perfluoroalkyl acids (PFAAs). Several assessment methods of dietary exposure to PFAAs have been used previously, but there is a lack of comparisons between methods.

AIM

To assess human exposure to PFAAs through diet by different methods and compare the results.

METHODS

We studied the dietary exposure to PFAAs in 61 Norwegian adults (74% women, average age: 42 years) using three methods: i) by measuring daily PFAA intakes through a 1-day duplicate diet study (separately in solid and liquid foods), ii) by estimating intake after combining food contamination with food consumption data, as assessed by 2-day weighted food diaries and iii) by a Food Frequency Questionnaire (FFQ). We used existing food contamination data mainly from samples purchased in Norway and if not available, data from food purchased in other European countries were used. Duplicate diet samples (n=122) were analysed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) to quantify 15 PFAAs (11 perfluoroalkyl carboxylates and 4 perfluoroalkyl sulfonates). Differences and correlations between measured and estimated intakes were assessed.

RESULTS

The most abundant PFAAs in the duplicate diet samples were PFOA, PFOS and PFHxS and the median total intakes were 5.6ng/day, 11ng/day and 0.78ng/day, respectively. PFOS and PFOA concentrations were higher in solid than liquid samples. PFOS was the main contributor to the contamination in the solid samples (median concentration 14pg/g food), while it was PFOA in the liquid samples (median concentrations: 0.72pg/g food). High intakes of fats, oils, and eggs were statistically significantly related to high intakes of PFOS and PFOA from solid foods. High intake of milk and consumption of alcoholic beverages, as well as food in paper container were related to high PFOA intakes from liquid foods. PFOA intakes derived from food diary and FFQ were significantly higher than those derived from duplicate diet, but intakes of PFOS derived from food diary and FFQ were significantly lower than those derived from duplicate diet. We found a positive and statistically significant correlation between the PFOS intakes derived from duplicate diet with those using the food diary (rho=0.26, p-value=0.041), but not with the FFQ. Additionally, PFOA intakes derived by duplicate diet were significantly correlated with estimated intakes from liquid food derived from the food diary (rho=0.34, p=0.008) and estimated intakes from the FFQ (rho=0.25, p-value=0.055).

CONCLUSIONS

We provide evidence that a food diary or a FFQ-based method can provide comparable intake estimates to PFOS and PFOA intakes derived from a duplicate diet study. These less burdensome methods are valuable and reliable tools to assess dietary exposure to PFASs in human studies.

Total Mercury, Methylmercury, Inorganic Arsenic and Other Elements in Meat from Minke Whale (Balaenoptera acutorostrata) from the North East Atlantic Ocean

Meat samples of 84 minke whales (Balaenoptera acutorostrata) mainly from the Barents Sea, collected between 1 May and 16 August 2011, were analyzed for total mercury, methylmercury, cadmium, lead, total arsenic, inorganic arsenic and selenium. The average total mercury concentration found was 0.15 ± 0.09 mg/kg, with a range from 0.05 to 0.49 mg/kg. The molar ratio of selenium to mercury varied between 1.0 and 10.3. Cadmium content ranged from 0.002 to 0.036 mg/kg, while the content of lead in whale meat ranged from <0.01 to 0.09 mg/kg. None of the whale samples exceeded established EU maximum levels for metals in fish muscle, but 4.8% and 6.8% of the samples exceeded Japanese maximum levels for total mercury and methylmercury, respectively, in whale meat. There was only minor variations in element concentrations between whales from different geographical areas, and cadmium was the only element were the concentration increased with increasing length.

Geographical trends of PFAS in cod livers along the Norwegian coast

The level of perfluorinated alkyl substances (PFAS) was determined in North East Arctic cod (Gadus morhua) liver samples from 15 Norwegian fjords and harbors. Five harbors in the eastern part of Norway, six harbors in the western part and four harbours in the northern part. A total of 200 samples were analyzed for 16 PFAS. Determination of PFAS were carried out by LC-MS/MS following sample clean up by solid phase extraction and ultracentrifugation. The predominating PFAS was PFOS, which was found to be higher than the level of quantification (1.5 μg kg-1 wet weight) in 72% of the samples. The highest level of PFOS found was 21.8 μg kg-1 wet weight in a sample from Kragerø in the eastern part of Norway. A significantly higher level of PFOS was found in the eastern fjords and harbors compared to fjords and harbors in the western and northern part of Norway. Within the northern fjords and harbors elevated PFOS levels were found in Narvik, which may indicate a local source there. Variations in PFOS of the cod livers thus reflect differences in levels of pollution between the areas.

An Outbreak of Norovirus Infection from Shellfish Soup Due to Unforeseen Insufficient Heating During Preparation

Norovirus causes large outbreaks involving all age groups and are considered the most common cause of infectious foodborne diseases worldwide. The aim of this study was to describe a norovirus outbreak connected to insufficient heat treatment during preparation of a shellfish soup in serving portions, during a company Christmas celebration in Norway, December 2013. A questionnaire sent to the employees, showed that 67 % (n = 43) of the celebration participants, reported gastrointestinal symptoms including stomach pain, vomiting, diarrhoea and light fever in the period between 24 and 48 h post celebration. Several dishes were served, including shellfish soup made with carpet shell clams (Tapes rhomboides) in porcelain cups. Consuming this soup, was the only significant risk factor for infection. Norovirus GI and GII were detected in the remaining raw shellfish. To mimic the time and temperature obtained during bivalve soup preparation, raw chopped shellfish tissue and raw cepa onion were added in porcelain cups tempered to 20 °C. To each of these cups, boiling soup base was added. The temperature in the shellfish tissue was continuously recorded, and showed a maximum of 49 °C in the period between 3 and 7 min after adding the boiling soup base. After 1 h the temperature was 30 °C. This time and temperature combination was obviously not sufficient for inactivation of norovirus present in the shellfish tissue. In conclusion, the heat-absorbing capacity of cold ingredients, utensils and table wear porcelain should not be underestimated during food production. Consumers who want to avoid eating raw shellfish, should not assume that the shellfish tissue in preparation as described in our study is adequately heat treated.

Assessment of Hg Pollution Released from a WWII Submarine Wreck (U-864) by Hg Isotopic Analysis of Sediments and Cancer pagurus Tissues

Hg pollution released from the U-864 submarine sunk during WWII and potential introduction of that Hg into the marine food chain have been studied by a combination of quantitative Hg and MeHg determination and Hg isotopic analysis via cold vapor generation multicollector inductively coupled plasma-mass spectrometry (CVG-MC-ICP-MS) in sediment and Cancer pagurus samples. The sediment pollution could be unequivocally linked with the metallic Hg present in the wreck. Crabs were collected at the wreck location and 4 nmi north and south, and their brown and claw meat were analyzed separately. For brown meat, the δ²⁰²Hg values of the individuals from the wreck location were shifted toward the isotopic signature of the sediment and, thus, the submarine Hg. Such differences were not found for claw meat. The isotope ratio results suggest direct ingestion of metallic Hg by C. pagurus but do not offer any proof for any other introduction of the submarine Hg into the marine food chain.

A baseline study of metals in herring (Clupea harengus) from the Norwegian Sea, with focus on mercury, cadmium, arsenic and lead

The Norwegian spring spawning (NSS) herring is an ecologically and economically important fish population in the Norwegian Sea. It was the first of several Norwegian fish stocks subject to a baseline study designed to give a comprehensive account of the levels of contaminants in a fish species from most of its area of distribution and during different seasons. During 2006 and 2007, 800 individual herring were sampled in their feeding areas in the Norwegian Sea in spring and autumn and at their spawning grounds off the coast of Norway during late winter. Metals including Hg, Cd, As and Pb were determined in muscle samples of individual herring, and mean concentrations±sd (mg kg(-1) ww) were: Hg: 0.04±0.03, Cd: 0.010±0.006, As: 2.2±0.6 and Pb: <0.01-0.10. Apart from one sample, no individual herring exceeded the EU's maximum level for any of these elements, as has been seen also in previous monitoring. Hg and Cd concentration increased with increasing fish age and As concentration varied seasonally, possibly due to uptake during feeding (summer), elimination during starvation (winter) and up-concentration during spawning (spring).

Contaminant levels in Norwegian farmed Atlantic salmon (Salmo salar) in the 13-year period from 1999 to 2011

BACKGROUND

Environmental pollutants such as dioxins and PCBs, heavy metals, and organochlorine pesticides are a global threat to food safety. In particular, the aquatic biota can bioaccumulate many of these contaminants potentially making seafood of concern for chronic exposure to humans.

OBJECTIVES

The main objective was to evaluate trends of contaminant levels in Norwegian farmed Atlantic salmon in light of the derived tolerable intakes.

METHODS

Through an EU-instigated surveillance programme, the Norwegian Food Safety Authority (NFSA) has between 1999 and 2011 collected more than 2300 samples of Norwegian farmed Atlantic salmon (Salmo salar) for contaminant analyses. The fillets of these fish were homogenised and analysed for dioxins, PCBs, heavy metals and organochlorine pesticides.

RESULTS

The levels of the contaminants mercury, arsenic, dioxins, dioxin-like PCBs and DDT in Norwegian farmed salmon fillet have decreased during our period of analyses. The levels of cadmium, lead and several organochlorine pesticides were too close to the limit of quantification to calculate time trends. For PCB6 and quantifiable amounts of pesticides, except DDT, stable levels were observed.

CONCLUSION

The contaminant levels in Norwegian farmed salmon have generally decreased between 1999 and 2011. Excluding other dietary sources, the levels of dioxins and dioxin-like PCBs in 2011 allowed consumption of up to 1.3kg salmon per week to reach the tolerable weekly intake. The group of contaminants which was the limiting factor for safe consumption of Norwegian farmed salmon, based on currently established TWI values, is the sum of dioxins and dioxin-like PCBs.

Mercury contamination in deep-water fish: transcriptional responses in tusk (Brosme brosme) from a fjord gradient

Recent findings have shown that deep-water fish from coastal areas may contain elevated levels of mercury (Hg). Tusk (Brosme brosme) was collected from six locations in Hardangerfjord, a fjord system where the inner parts are contaminated by metals due to historic industrial activity. ICPMS was used to determine the accumulated levels of metals (Hg, MeHg, Cd, Pb, As, and Se) in the fish, whereas oxidative status of the liver was assessed by measuring TBARS, vitamin C, vitamin E and catalase activity. To find out whether accumulated Hg triggers toxicologically relevant transcriptional responses and in order to gain genomic knowledge from a non-model species, the liver transcriptome of the gadoid fish was sequenced and assembled, and RNA-seq and RT-qPCR were used to screen for effects of Hg. The results showed high levels of accumulated Hg in tusk liver, probably reflecting an adaptation to deep-water life history, and only a weak declining outward fjord gradient of Hg concentration in tusk liver. MeHg only accounted for about 17% of total Hg in liver, suggesting hepatotoxicity of both inorganic and organic Hg. Pathway analysis suggested an effect of Hg exposure on lipid metabolism and beta-oxidation in liver. Oxidative stress markers glutathione peroxidase 1 and ferritin mRNA, as well as vitamin C and vitamin E (alpha and gamma tocopherol) showed a significant correlation with accumulated levels of Hg. Many transcripts of genes encoding established markers for Hg exposure were co-regulated in the fish. In conclusion, tusk from Hardangerfjord contains high levels of Hg, with possible hepatic effects on lipid metabolism and oxidative stress.

A baseline study on levels of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, non-ortho and mono-ortho PCBs, non-dioxin-like PCBs and polybrominated diphenyl ethers in Northeast Arctic cod (Gadus morhua) from different parts of the Barents Sea

This study is one of several baseline studies on commercially important Norwegian wild fish species that will provide information concerning metals and persistent organic pollutants (POPs) and food safety. The cod liver is a traditional food product in Norway and a potential source for POPs in the diet. The concentrations of dioxins and furans (PCDD/Fs), dioxin-like PCBs (DL-PCBs), non-dioxin-like PCBs (NDL-PCBs, PCB6) and polybrominated flame retardants (PBDEs) were determined in the liver of 784 individual Northeast Arctic cod caught at 32 positions in the Barents Sea in the period from 2009-2010. In addition, muscle samples from 30 individual cod were analysed for the same substances. The mean concentration of the sum of PCDD/Fs and DL-PCBs for all samples was 14.2 ng TEQ who-2005/kg ww with a variation between 1.0 and 151 ng TEQ/kg ww. The concentrations of POPs in the fillet samples were very low.

A baseline study of metals in cod (Gadus morhua) from the North Sea and coastal Norwegian waters, with focus on mercury, arsenic, cadmium and lead

This study is one of several baseline studies that will provide basic and reliable information about the content of undesirable substances in important species of fish caught in Norwegian waters. Concentrations of metals in the muscle and livers of 516 cod caught at 22 positions in the North Sea were analysed. An additional 687 cod were caught from 13 fjords and coastal areas along the coast of Norway. Three out of 1203 samples of muscle exceeded the maximum limit of 0.5 mg Hg kg(-1) wet weight set by the EU for foodstuffs. The mercury concentration in cod muscle was higher and the cadmium concentration in the liver was lower in the North Sea and coastal areas in the southern part of Norway than in the Barents Sea and coastal areas in the northern part of Norway. These differences are perhaps caused by differences in the cod diet.

A baseline study of levels of mercury, arsenic, cadmium and lead in Northeast Arctic cod (Gadus morhua) from different parts of the Barents Sea

This study is one of several baseline studies that will provide basic and reliable information about the content of undesirable substances in important species of fish caught in Norwegian waters. Concentrations of metals in the muscle and liver of more than 800 Northeast Arctic cod caught at 32 sites in the Barents Sea are reported. The highest concentration of both mercury in the muscle and cadmium in the liver was found in cod caught in the western part of the Barents Sea, while the highest concentration of total arsenic was found in cod from the eastern part. The arsenic concentrations varied greatly among individual fish, ranging from 0.3 to 170 mg kg(-1) wet weight in the muscle. Such high levels of total arsenic have never previously been reported in any fish, and the primary factor for these high concentrations is likely to be the shrimp in the cod diet.

Iron and zinc content of selected foods in the diet of schoolchildren in Kumi district, east of Uganda: a cross-sectional study

BACKGROUND

Iron and zinc are essential micronutrients for humans and deficiency of the two elements is widespread in the world with the highest prevalence in less developed countries. There are few data on dietary intake of iron and zinc in Uganda, and no food composition table is available. There is hardly any widely published literature that clearly documents the quality of Ugandan children's diet. Thus information of both food intake and the concentration of these trace elements in local food ingredients are needed in order to assess daily intake.

METHODS

The present study focused on the iron and zinc content in selected foods and intake of the micronutrients iron and zinc among schoolchildren in Kumi District, Uganda. Over a period of 4 weeks single 24-hour dietary recall interviews were carried out on a convenience sample of 178 schoolchildren (9-15 years old). Data from the dietary recalls was used when selecting foods for chemical analysis.

RESULTS

Results from this study showed that the iron concentrations varied, and were high in some cereals and vegetables. The zinc concentrations in foods generally corresponded with results from other African countries (Mali and Kenya). Data from the 24-hour dietary recall showed that the daily Recommended Nutrient Intake (RNI) was met for iron but not for zinc.

CONCLUSIONS

The schoolchildren of Kumi district had a predominantly vegetable based diet. Foods of animal origin were consumed occasionally. The iron content in the selected foods was high and variable, and higher than in similar ingredients from Kenya and Mali, while the zinc concentrations were generally in accordance with reported values. The total daily zinc (mg) intake does not meet the daily RNI. The iron intake is adequate according to RNI, but due to iron contamination and reduced bioavailability, RNI may not be met in a vegetable based diet. More studies are needed to investigate possible sources of contamination.

Carry-over of dietary organochlorine pesticides, PCDD/Fs, PCBs, and brominated flame retardants to Atlantic salmon (Salmo salar L.) fillets

Information on carry-over of contaminants from feed to animal food products is essential for appropriate human risk assessment of feed contaminants. The carry-over of potentially hazardous persistent organic pollutants (POPs) from feed to fillet was assessed in consumption sized Atlantic salmon (Salmo salar). Relative carry-over (defined as the fraction of a certain dietary POP retained in the fillet) was assessed in a controlled feeding trial, which provided fillet retention of dietary organochlorine pesticides (OCPs), dioxins (PCDD/Fs), polychlorinated biphenyls (PCBs), and brominated flame retardants (BFRs). Highest retention was found for OCPs, BFRs and PCBs (31-58%), and the lowest retentions were observed for PCDD/Fs congeners (10-34%). National monitoring data on commercial fish feed and farmed Atlantic salmon on the Norwegian market were used to provide commercially relevant feed-to-fillet transfer factors (calculated as fillet POP level divided by feed POP level), which ranged from 0.4 to 0.5, which is a factor 5-10 times higher than reported for terrestrial meat products. For the OCP with one of the highest relative carry-over, toxaphene, uptake and elimination kinetics were established. Model simulations that are based on the uptake and elimination kinetics gave predicted levels that were in agreement with the measured values. Application of the model to the current EU upper limit for toxaphene in feed (50 μg kg(-1)) gave maximum fillet levels of 22 μg kg(-1), which exceeds the estimated permissible level (21 μg kg(-1)) for toxaphene in fish food samples in Norway.

Post World War II orcharding creates present day DDT-problems in The Sørfjord (Western Norway)--a case study

The Sørfjord has a long history of agriculture and industry, and environmental monitoring has been conducted for decades, comprising analyses of contaminants in mussel, fish and sediments. DDT was used as an insecticide in orchards surrounding the fjord between World War II and 1970. Since the early 1990 s, elevated concentrations of DDT were found in mussels and fish. Unexpectedly, DDT-concentrations increased towards present day, despite the discontinuation of use. The highest concentrations in mussels (in 2006) corresponded to about two orders of magnitude higher than background. Analyses of sediment core sections also indicated increased input towards present day. Shifts in climatic parameters, as well as increased amounts of soil dissolved organic carbon following a decline in atmospheric sulphate deposition may have contributed to this phenomenon. We warrant the need for increased knowledge of the effects of alterations in variables acting regionally and globally on the disposition of contaminants in ecosystems.

Iodine status of adolescent girls in a population changing from high to lower fish consumption

OBJECTIVES

During the last decades, fish and milk consumption has decreased considerably in Iceland, especially among adolescents. As these food items are important dietary iodine (I) sources, the aim of the study was to assess the iodine status and dietary pattern of adolescent girls in a population changing from a high to lower consumption of milk and fish.

SUBJECTS/METHODS

Subjects were randomly selected adolescent girls (16-20 years old, n=112). A validated Food Frequency Questionnaire (FFQ) was used to evaluate food consumption and compare it with food-based dietary guidelines for milk and dairy products (2-3 portions/day) and fish (> or =2 times/week). Urine samples were collected for measuring urinary iodine (U-I) and creatinine (Cr) and blood samples for measuring serum thyroid-stimulating hormone (TSH).

RESULTS

Milk and dairy products provided 43% and fish provided 24% of the total dietary I. More than 65% of the girls consumed fish less than twice a week, and 40% consumed less than two portions of milk and dairy products per day. The median U-I concentration was 200 microg/l and the U-I/Cr ratio 138 microg I/g Cr. High intake of milk was associated with higher urinary iodine concentration, but fish intake was not found to be directly associated with urinary iodine concentration.

CONCLUSIONS

Iodine status of Icelandic adolescent girls is within the optimal range defined by the World Health Organization. It is important to monitor both iodine status and the iodine concentration of important sources of iodine, as both dietary habits and composition of food might change with time.

Stable isotope (N, C, Hg) study of methylmercury sources and trophic transfer in the northern gulf of Mexico

We combined N, C, and Hg stable isotope measurements to identify the most important factors that influence MeHg accumulation in fish from the northern Gulf of Mexico (nGOM), and to determine if coastal species residing in the Mississippi River (MR) plume and migratory oceanic species derive their MeHg from the same, or different, sources. In six coastal species and two oceanic species (blackfin and yellowfin tuna), trophic position as measured by delta(15)N explained most of the variance in log[MeHg] (r(2) approximately 0.8), but coastal species and tuna fell along distinct, nearly parallel lines with significantly different intercepts. The tuna also had significantly higher delta(202)Hg (0.2-0.5 per thousand) and Delta(201)Hg ( approximately 1.5 per thousand) than the coastal fish (delta(202)Hg = 0 to -1.0 per thousand; Delta(201)Hg approximately 0.4 per thousand). The observations can be best explained by largely disconnected food webs rooted in different baseline delta(15)N signatures (MR-plume vs oceanic) and isotopically distinct MeHg sources, with oceanic MeHg having undergone substantial photodegradation ( approximately 50%) before entering the base of the food web. Given the MR's large, productive footprint in the nGOM and the potential for exporting prey and MeHg to the adjacent oligotrophic GOM, the disconnected food webs and different MeHg sources are consistent with recent evidence in other systems of important oceanic MeHg sources.

Are Atlantic cod in Store Lungegårdsvann, a seawater recipient in Bergen, affected by environmental contaminants? A qRT-PCR survey

The aim of this study was to examine the transcriptional levels of selected genes in liver and head kidney of Atlantic cod Gadus morhua sampled in Store Lungegårdsvann, a seawater recipient situated in the middle of the city of Bergen, Norway, for effects of contaminants released from municipal sewage effluents and former dump sites. Five males and six females were caught with fish traps in Store Lungegårdsvann in 2006. Cod from a location near Jondal in the Hardanger Fjord were used as controls (five males and four females). The following 12 genes were picked as potential markers of contaminant exposure: cytochrome P-450 1A (CYP1A), cytochrome P-450 2C33-like (CYP2C33-like), cytochrome P-450 3C (CYP3C), glutathione S-transcriptase pi (GST) (detoxification and biotransformation), Mn superoxide dismutase (Mn SOD), glutathione reductase (GR), heat-shock protein 70 (HSP70) (oxidative stress), vitellogenin A (VtgA), vitellogenin B (VtgB), zona pellucida 2 (ZP2) (effects of estrogen disruptors), B-cell lymphoma 2 (Bcl-2), and cyclin-dependent kinase inhibitor 1A (CDKN1A) (radiation). The results showed that two males caught in Store Lungegårdsvann possessed high transcriptional levels of VtgA, VtgB, and ZP2 mRNA in the liver. In addition, CYP1A was 4.9-fold higher expressed in males from Store Lungegårdsvann compared to males from the reference population. CYP2C33-like mRNA expression was significantly higher (1.8-fold) in females from Store Lungegårdsvann than in females from the reference population. CYP1A was significantly lower (4.7-fold) expressed in head kidney of females from Store Lungegårdsvann than in females from Hardanger Fjord. In a follow-up examination with sexually mature cod sampled in Store Lungegårdsvann in 2007, the livers were shown to contain high levels of polychlorinated biphenyls (PCB) and dioxin-like PCB. In conclusion, fish inhabiting Store Lungegårdsvann are exposed not only to endocrine disruptors but also to other contaminants that affect the transcription of phase I biotransformation genes.

Heavy metals in the farming environment and in some selected aquaculture species in the Van Phong Bay and Nha Trang Bay of the Khanh Hoa Province in Vietnam

Aquaculture is currently one of the most rapidly growing production sectors in Vietnam. This publication describes the concentrations of heavy metals in the farming environment and some aquaculture species in the Khanh Hoa Province in Vietnam. The concentration of total As in the sediments ranged from 0.07 to 0.64 mg/kg, whereas the concentration of Hg varied from <0.0005 to 0.56 mg/kg. The corresponding concentration span for Cd and Pb, were 0.001-0.069 and 0.016-0.078 mg/kg, respectively. The concentrations of As in the aquaculture organisms spanned from 0.14 to 1.03 mg/kg. For Hg the concentrations varied from 0.1 to 0.45 mg/kg, for Cd from 0.02 to 0.10 mg/kg and for Pb from 0.07 to 0.37 mg/kg.

Organ distribution and food safety aspects of cadmium and lead in great scallops, Pecten maximus L., and Horse Mussels, Modiolus modiolus L., from Norwegian waters

The purpose of the study was to determine the levels and organ distribution of the potentially harmful inorganic elements cadmium and lead in great scallops and horse mussels from unpolluted Norwegian waters. The scallops far exceeded the EU-limit for cadmium in bivalves when all soft tissues were analysed. When only muscle and gonad were included, however, the level of cadmium was acceptable, because cadmium accumulated in the digestive gland with a mean of 52 mg/kg ww (wet weight). In horse mussel, lead was the most problematic element and the concentration varied from 1.4 to 6.6 mg/kg ww with a mean of 3.7 mg/kg ww, exceeding the EU limit of 1.5 mg Pb/kg. The highest concentration of lead was found in the kidney with an average of 120 mg/kg ww and with a maximum value of 240 mg/kg ww. The kidney tissue accounted for approximately 94% of the lead burden in the horse mussel. In order to consume these bivalves, only muscle and gonad of great scallops should be used for consumption and the kidney of horse mussel should be removed prior to consumption.

Mercury bioaccumulation and trophic transfer in sympatric snapper species from the Gulf of Mexico

Consumption of marine fish is a major route of toxic methyl mercury (MeHg) exposure to ocean apex predators and human populations. Here we explore the influence of trophic structure on total mercury (Hg) accumulation in red snapper (RS, Lutjanus campechanus) and gray snapper (GS, Lutjanus griseus) from the coastal Louisiana region of the Gulf of Mexico, west of the Mississippi River. The objectives of this investigation were to: (1) determine the effectiveness of the use of offshore recreational fishing charter boats and marinas as sources of fish samples and (2) compare species differences in Hg bioaccumulation, trophic position, and carbon sources. Our data show that length-normalized Hg concentrations (> or = 97% as MeHg in tissue of both species) were 230% greater in GS in comparison to RS collected from the same general area. Stable C and N isotope signatures (delta15N and delta13C) indicate that GS occupy a slightly higher trophic position (approximately 30% of one trophic position higher) on the Gulf food web in comparison to RS and that GS appear to incorporate higher trophic positioned prey, continually and at smaller sizes. Mercury was strongly correlated with combined delta15N and delta13C in pooled species data, arguing that most of the substantial difference in Hg bioaccumulation between RS and GS can be explained by modest differences in their trophic position and, to a lesser degree, carbon sources, which had low variation and high overlap among species. These observations demonstrate that even minor to moderate differences in trophic position and food habits in sympatric species can create relatively large differences in bioaccumulation regimes and underscores the importance of quantitative characterization of trophic structure in marine MeHg bioaccumulation studies.

Determination of arsenic, cadmium, mercury, and lead by inductively coupled plasma/mass spectrometry in foods after pressure digestion: NMKL interlaboratory study

Thirteen laboratories participated in an interlaboratory method performance (collaborative) study on a method for the determination of arsenic, cadmium, mercury, and lead by inductively coupled plasma/mass spectrometry (ICP/MS) after pressure digestion including the microwave heating technique. Prior to the study, the laboratories were able to practice on samples with defined element levels (pretrial test). The method was tested on a total of 7 foodstuffs: carrot puree, fish muscle, mushroom, graham flour, simulated diet, scampi, and mussel powder. The elemental concentrations in mg/kg dry matter (dm) ranged from 0.06-21.4 for As, 0.03-28.3 for Cd, 0.04-0.6 for Hg, and 0.01-2.4 for Pb. The materials used in the study were presented to the participants as blind duplicates, and the participants were asked to perform single determinations on each sample. The repeatability relative standard deviations (RSDr) for As ranged from 3.8 to 24%, for Cd from 2.6 to 6.9%, for Hg from 4.8 to 8.3%, and for Pb from 2.9 to 27%. The reproducibility relative standard deviations (RSDR) for As ranged from 9.0 to 28%, for Cd from 2.8 to 18%, for Hg from 9.9 to 24%, and for Pb from 8.0 to 50%. The HorRat values were less than 1.5 for all test samples, except for the determination of Pb in wheat flour at a level close to the limit of quantitation (0.01 mg/kg dm). The study showed that the ICP/MS method is satisfactory as a standard method for elemental determinations in foodstuffs.

Mercury concentration in fillets of Greenland halibut (Reinhardtius hippoglossoides) caught in the Barents Sea in January 2006

In January 2006 it was reported that Greenland halibut (Reinhardtius hippoglossoides) caught in the Barents Sea contained mercury levels that exceeded the EU's upper limit of 0.5 mg/kg wet weight for this species. To further investigate this finding, the National Institute of Nutrition and Seafood Research (NIFES) in Norway recently undertook a study to quantify the levels of mercury in Greenland halibut caught in the same area of the Barents Sea. A total of 120 Greenland halibut were caught in this area between the 28th and the 30th of January 2006. The fish were immediately frozen and shipped to the laboratory; individual fish were coded, weighed, defrosted, filleted and skinned before their mercury content was determined. Analyses were carried out on 65 individuals of Greenland halibut weighing from 0.81 kg to 7.1 kg, and 40 fish weighing more than 3 kg. The lowest mercury concentration found in muscle tissue (skinless and boneless fillet) was 0.019 mg/kg wet weight, in a fish that weighed 0.81 kg. The highest mercury concentration measured in muscle tissue was 1.1 mg/kg wet weight, from a fish that weighed 4.2 kg. Of the 65 fish analysed, 15 individuals with weight exceeding 3 kg had mercury concentrations in their muscle tissue exceeded the EU's upper limit.

PCB-containing paint and plaster caused extreme PCB-concentrations in biota from the Sørfjord (Western Norway)--a case study

The Sørfjord (Western Norway) has a long history of industry and pollution, and has been monitored for several decades. The environmental monitoring has comprised analyses of different contaminants in sea water, mussel, fish, seaweed and sediments. Measurements of polychlorinated biphenyls (PCBs) in blue mussels (Mytilus edulis) some 17 years ago indicated a local source. In 2001 severe concentrations were measured in blue mussels and further investigations disclosed the primary source of PCBs in the Sørfjord. In 2002, extreme PCB-concentrations were found in cod (Gadus morhua) from the same area. However, no induction of EROD activity was detected, indicating the limitations of this assay as marker for PCB contamination. A future scientific challenge will be to understand the specific mechanisms and effects of such PCB accumulation in fish.

Field contamination of the starfish Asterias rubens by metals. Part 1: Short- and long-term accumulation along a pollution gradient

The accumulation of Cd, Pb, Zn, and Cu in the starfish Asterias rubens was studied in a Norwegian fjord characterized by a gradient of metal pollution in the sediments, ranging from very high metal concentrations at its head to much lower levels at its opening. The concentrations of metals in starfish from natural populations along the gradient (long-term accumulation) and in starfish that were transferred up the gradient (short-term accumulation) were compared. At long-term, Cd and Pb accumulations by starfish living at normal salinity (30/1000) were related to the level of contamination of the environment while Cu and, to a lesser extent, Zn accumulations appeared strictly controlled. At short-term, Pb was accumulated steadily, Cd and Zn were accumulated transiently in the pyloric caeca (fast compartment), and Cu was not accumulated at all. Depuration experiments (transfer down the gradient) showed that Cd and Pb were efficiently eliminated from the pyloric caeca but not from the body wall (slow compartment). It is concluded that Pb is chronically accumulated, without apparent control, Cd is subjected to a regulating mechanism in the pyloric caeca which is overwhelmed over the long-term; Zn is tightly controlled in the pyloric caeca and Cu in both pyloric caeca and body wall. A distinct color variety of starfish is restricted to the low salinity (22-26/1000) superficial water layer. This variety showed a different pattern of metal accumulation over the long-term. This pattern is attributed to the particular hydrological conditions prevailing in this upper layer.

The immune response to pneumococcal polysaccharide vaccine in zinc-depleted mice

Zinc depletion affects several facets of the immune system and the resistance to infections. We assessed the effect of zinc deprivation on the immune response to the pneumococcal polysaccharide antigens in the commercially available Pneumovax pneumococcal vaccine. Young female BALB/c mice were fed diets with 2.7, 5.8 or 25 micro g of elemental zinc per mg diet. After six weeks of pair feeding, there were significant differences in the mean body weights between the feeding groups and we demonstrated a dose response of the zinc level in the diet on growth. The induced zinc deficiency had no discernible effect on the antipneumococcal polysaccharide immunoglobulin M (IgM) response following immunization with the pneumococcal vaccine. Although zinc depletion has a detrimental effect on the immune system, the murine T-cell-independent response to antigens such as those in the pneumococcal polysaccharide capsule does not seem to be affected.

Fish arsenic may influence human blood arsenic, selenium, and T4:T3 ratio

The effects of an arsenic-rich fish diet and selenium (Se) supplementation on blood arsenic (As), Se, and thyroid hormones were studied in 32 women divided into four equal groups. Groups 1 and 4 received 400 microg Se-methionine daily, group 2 received 400 microg selenite daily, and group 3 received placebo tablets for 15 wk. In addition, groups 1-3 increased their fish intake, eating at least three fish dinners weekly. Mean blood Se concentrations (initially 1.68 +/- 0.24 micromol/L) increased twofold in the Se-methionine groups (p < 0.0001) and by 32% in the selenite group (p < 0.01). Group means of blood As concentrations increased by 63% (p < 0.01), 50% (p < 0.01), 106% (p < 0.01), and 29% (p < 0.05) in the four groups, respectively. Analyzed As intake from duplicate portions of consumed fish correlated with final blood As concentrations (r = 0.85, p < 0.001, n = 32). In the group not receiving Se, there was a positive correlation between final blood As concentrations and plasma T4:T3 ratio (r = 0.80, p < 0.02, n = 8). Initially, blood As concentrations correlated negatively with both T3 and T4 in plasma, but this correlation disappeared upon Se supplementation. The results demonstrate that increased intake of fish may influence blood As concentrations and that circulating thyroid hormones may be influenced by Se-As interactions.

Cadmium, lead, copper and zinc in blue mussels (Mytilus edulis) sampled in the Hardangerfjord, Norway

Cadmium, lead, copper and zinc were determined in the soft tissues of blue mussels (Mytilus edulis) sampled from four locations along the Hardangerfjord in western Norway. A source of pollution is located at the head of the fjord and the sampling was performed at various distances from this source. The results obtained in this study (1998) were compared with results from similar studies carried out in 1983 and 1992. The mean cadmium concentrations in blue mussels sampled at Måge (13 km from the source of pollution) were approximately 18 mg kg-1 fresh weight in 1983, 2.4 mg kg-1 fresh weight in 1992 and 1.1 mg kg-1 fresh weight in 1998. The mean cadmium concentrations in blue mussels sampled at Varaldsøy (105 km from the source of pollution) were approximately 5 mg kg-1 fresh weight in 1983, 0.5 mg kg-1 fresh weight in 1992 and 0.4 mg kg-1 fresh weight in 1998. The mean lead concentration in blue mussels sampled at Måge was 140 mg kg-1 fresh weight in 1983. The mean lead concentrations in 1992 and 1998 had decreased to 6 and 3 mg kg-1 fresh weight, respectively. The mean lead concentrations in blue mussels from Gravdal were 15 mg kg-1 fresh weight in 1982, 1 mg kg-1 in 1992 and less than 1 mg kg-1 fresh weight in 1998. The mean copper concentrations in blue mussels were relatively constant over this period at all locations, with a variation between 0.6 and 1.2 mg kg-1 fresh weight. The mean zinc concentration in blue mussels sampled at Måge decreased from 120 to 30 mg kg-1 fresh weight in the period between 1983 and 1998.

Pneumococcal pulmonary infection, septicaemia and survival in young zinc-depleted mice

The aim of the present study was to explore whether mice fed a diet low in Zn (2.0 mg Zn/kg diet) for a relatively short period of time were more prone to severe Streptococcus pneumoniae infection than mice fed a normal diet (25 mg elemental Zn/kg). The Zn-deficient mice were compared with mice in two Zn-adequate control groups; one pair-fed and another with free access to the diet. After 2 weeks feeding, the mice were infected intranasally under anaesthesia with a suspension containing about 10(7) pneumococci. Clinical status was observed every day and blood samples were examined for S. pneumoniae every second day for a week. All infected mice examined carried the infecting strain intranasally. The survival time and time before positive blood culture were significantly shorter in the Zn-depleted group than in the pair-fed Zn-adequate group (hazard ratios 15.6 and 3.2, and respectively). At the end of the observation period, ten of the twelve mice in the Zn-deficient group were dead while one of twelve and two of twelve were dead in the two Zn-adequate control groups. This study shows that even acutely-induced Zn deficiency dramatically increases the risk of serious pneumococcal infection in mice.

Supplementary selenium influences the response to fatty acid-induced oxidative stress in humans

The mutual influences of wheat selenium (Se) and n-3 polyunsaturated fatty acids (n-3 PUFA) on plasma Se and indicators of increased oxidative stress were investigated in a randomized, double-blind study with 31 women (23.5 +/- 3.4 yr). Groups 1 and 2 ingested 5.4 g n-3 PUFA daily (as ethyl esters), whereas groups 3 and 4 received placebo capsules. Groups 2 and 3 received 3 slices of high-Se bread daily, providing 115 micrograms Se, in addition to the 77 +/- 26 micrograms Se in the diet. Groups 1 and 4 received placebo slices. Blood samples were drawn at baseline and at 3 and 6 wk. Serum Se concentrations increased in both groups given Se-enriched bread, but significantly less in subjects given n-3 PUFA (group 2). There were no changes in the plasma ratio alpha-tocopherol:mg cholesterol or plasma ascorbic acid levels. In group 1, plasma-conjugated dienes and thiobarbituric acid-reactive substances (TBARS) rose by 130% (p < 0.005) and 126% (p < 0.005), respectively. Two-way ANOVA showed significant interaction effects of Se and n-3 PUFA on changes in conjugated dienes (p = 0.03) and TBARS (p = 0.015), Se treatment apparently modifying the peroxidative effects of n-3 PUFA. In subjects receiving n-3 PUFA, changes in conjugated dienes and TBARS were negatively correlated with changes in serum Se. In summary, n-3 PUFA modified the effect of Se supplementation, whereas Se seemed to modify the peroxidative effects of n-3 PUFA.