Wet Weight Content Research Articles

Human exposure to per- and polyfluoroalkyl substances (PFAS) via the consumption of fish leads to exceedance of safety thresholds

Per- and polyfluoroalkyl substances (PFAS) receive global attention due to their adverse effects on human health and the environment. Fish consumption is a major source of human PFAS exposure. The aim of this work was to address the lack of harmonization within legislations (in the EU and the USA) and highlight the level of PFAS in fish exposed to pollution from diffuse sources in the context of current safety thresholds. A non-exhaustive literature review was carried out to obtain PFAS concentrations in wild fish from the Norwegian mainland, Svalbard, the Netherlands, the USA, as well as sea regions (North Sea, English Channel, Atlantic Ocean), and farmed fish on the Dutch market. Median sum wet weight concentrations of PFOA, PFNA, PFHxS, and PFOS ranged between 0.1 µg kg−1 (farmed fish) and 22 µg kg−1 (Netherlands eel). Most concentrations fell below the EU environmental quality standard (EQSbiota) for PFOS (9.1 µg kg−1) and would not be defined as polluted in the EU. However, using recent tolerable intake or reference dose values in the EU and the USA revealed that even limited fish consumption would lead to exceedance of these thresholds – possibly posing a challenge for risk communication.

Determining nutrients, dry matter, and pH of liquid organic manures using visual and near-infrared spectrometry

In agriculture, overfertilization with liquid organic manures (LOM) is causing environmental issues including eutrophication of non-agricultural ecosystems and nitrate pollution of groundwater. To avoid such problems, a precise and demand-oriented fertilization with LOM is needed. This can only be achieved if the nutrient composition of the LOM is known. However, traditional chemical analysis is cost- and time-intensive and furthermore dependent on a representative sample. Optical spectrometry in the visible and near-infrared range could provide an efficient alternative, if a chemometric calibration assures sufficient accuracy. To improve chemometric calibration, this study investigated several spectral preprocessing and regression algorithms, and compared predictions based either on dry or wet weight concentration. In addition, the capability of low-cost spectrometers was evaluated by simulating low-resolution spectra with smaller wavelength ranges. The reflectance spectra of 391 pig manure, 155 cattle manure, and 89 biogas digestate samples were used to predict plant macronutrients (N, P, K, Mg, Ca, S), micronutrients (Mn, Fe, Cu, Zn, B), dry matter (DM) and pH. The experiments demonstrate the general aptness of optical spectrometry to accurately predict DM, pH and all nutrients except boron in pig, cattle, and digestate LOM, even with simulated low-cost spectrometers. Best results show r2 between 0.80 and 0.97, ratios of performance to interquartile distance (RPIQ) between 2.1 and 7.8, and mean absolute errors normalized by the median (nMAE) between 5 and 36 %. The regression methods PLSR, LASSO, and least angle regression predominantly performed best. The innovative preprocessing methods named simple ratios (SR) and normalized differences (ND) proved to be very useful algorithms, especially for N and P predictions, outperforming the accuracy of classical techniques in several cases. Concentrations on dry weight basis improved predictions of K, Mn, and pH.

Tissue-specific and stereoselective accumulation of Dechlorane Plus isomers in two predator fish in a laboratory feeding study

The tissue-specific bioaccumulation of Dechlorane Plus (DP) isomers was investigated in two predator fish species (redtail catfish, RF; and oscar fish, OF) that were feeding on tiger barb (TB), which was exposed to syn-DP and anti-DP isomers. The biotransformation potential of DP isomers was examined by in vitro metabolism using fish liver microsomes. No difference in accumulation behaviors of DP isomers was observed between RF and OF, and the accumulation of both syn- and anti-DP isomers exhibiting a linear increase trend with the exposure time in all fish tissues. The assimilation efficiencies and depuration rates for syn-DP and anti-DP were determined to be the highest in the liver. Biomagnification factors (BMFs) for both syn-DP and anti-DP were higher than one in the serum and gastrointestinal tract of fish, whereas were less than one in the other tissues. The wet-weight concentrations of DP isomers in tissues were significantly correlated with the lipid contents in both fish species, indicating that the tissue distribution of DP isomers occurred through passive diffusion to the lipid compartments in vivo. Tissue-specific compositions of DP isomers were observed, with anti-DP selectively accumulating in the liver, gonad, serum, and gills, whilst syn-DP in the carcass and GI tract. However, after being normalized of all tissues, the fish showed no selective accumulation of DP isomers during the exposure period, and selective accumulation of syn-DP was observed during the depuration period. No potential DP metabolites were detected in the fish tissues and in vitro metabolism systems. The main cause of this stereoselective DP isomer accumulation could have been the selective excretion of anti-DP isomer through the fish feces.

Total mercury, methylmercury, and selenium concentrations in blue marlin Makaira nigricans from a long-term dataset in the western north Atlantic

Mercury in seafood is a neurotoxicant that threatens human health. Dynamic rates of mercury emission, re-emission, and atmospheric deposition warrant studies into mercury concentrations in fish because many are consumed by humans and can serve as sentinels of mercury levels in the environment. We modeled trends in total mercury content in an apex marine fish predator, Atlantic blue marlin Makaira nigricans, whose muscle tissues were opportunistically sampled from North Carolina (USA) sportfishing tournaments over a discontinuous time period: between 1975 and 77 and 1998–2021 (n = 148). The model-estimated influence of marlin weight on total mercury concentration was constant across years (shared slope) allowing for comparisons of weight-corrected mercury concentrations among years. Weight-corrected total mercury concentrations revealed an inter-decadal decline of approximately 45 % between the 1970s and late 1990s and then variable but relatively stable concentrations through 2021. The mean (SD) wet weight concentration of total mercury was 9.47 (4.11) from 1975 to 77 and 4.17 (2.61) from 2020 to 2021. Methylmercury and selenium were measured on a subset of fish to address questions related to human health and consumption. Methylmercury levels (mean = 0.72 μg/g) were much lower than total mercury (mean = 4.69 μg/g) indicating that total mercury is not a good proxy for methylmercury in Atlantic blue marlin. Selenium, examined as a Se:Hg molar ratio and as a selenium health benefit value (HBVSe), showed high protective value against mercury toxicity. Long-term trends in the concentration of mercury in blue marlin should continue to be monitored to determine whether policies to mitigate anthropogenic contributions to global mercury are achieving their intended goals and to provide information to inform safe human consumption.

Evaluation of Normalization Approaches for Quantitative Analysis of Bile Acids in Human Feces.

Quantitative analysis of bile acids in human feces can potentially help to better understand the influence of the gut microbiome and diet on human health. Feces is a highly heterogeneous sample matrix, mainly consisting of water and indigestible solid material (as plant fibers) that show high inter-individual variability. To compare bile acid concentrations among different individuals, a reliable normalization approach is needed. Here, we compared the impact of three normalization approaches, namely sample wet weight, dry weight, and protein concentration, on the absolute concentrations of fecal bile acids. Bile acid concentrations were determined in 70 feces samples from healthy humans. Our data show that bile acid concentrations normalized by the three different approaches are substantially different for each individual sample. Fecal bile acid concentrations normalized by wet weight show the narrowest distribution. Therefore, our analysis will provide the basis for the selection of a suitable normalization approach for the quantitative analysis of bile acids in feces.

Prevalence of anticoagulant rodenticide exposure in red-tailed hawks (Buteo jamaicensis) and utility of clotting time assays to detect coagulopathy.

Anticoagulant rodenticides (ARs) continue to be used across the United States as a method for controlling pest rodent species. As a consequence, wild birds of prey are exposed to these toxicants by eating poisoned prey items. ARs prevent the hepatic recycling of vitamin K and thereby impede the post-translational processing of coagulation factors II, VII, IX, and X that are required for procoagulant complex assembly. Through this mechanism of action, ARs cause hemorrhage and death in their target species. Various studies have documented the persistence of these contaminants in birds of prey but few have attempted to use affordable and accessible diagnostic tests to diagnose coagulopathy in free-ranging birds of prey. In our study free-ranging red-tailed hawks were found to be exposed to difethialone and brodifacoum. Eleven of sixteen (68%) livers tested for AR exposure had detectable residues. Difethialone was found in 1/16 (6%), and brodifacoum was detected in 10/16 (62%) liver samples that were tested for rodenticide residues. Difethialone was found at a concentration of 0.18 ug/g wet weight and brodifacoum concentrations ranged from 0.003-0.234 ug/g wet weight. Two out of 34 (6%) RTHA assessed for blood rodenticide had brodifacoum in serum with measured concentrations of 0.003 and 0.006 ug/g. The range of clotting times in the prothrombin time (PT) and Russell's viper venom time assays for control RTHA were 16.7 to 39.7 s and 11.5 to 91.8 s, respectively. One study bird was diagnosed with clinical AR intoxication with a brodifacoum levels in blood of 0.006 and 0.234 ug/g wet weight in blood and liver respectively, a packed cell volume (PCV) of 19%, and PT and RVVT times of >180 s. No correlation was found between PT and RVVT in the control or free-range RTHA, and there was no relationship found between the presence of liver anticoagulant residues and clotting times in the PT and RVVT.

Tissue-specific accumulation, transformation, and depuration of fipronil in adult crucian carp (Carassius auratus)

Accumulation and biotransformation of pesticides in fish tissues are essential to assess their toxicity and associated human exposure risk. The mechanisms on time-dependent and tissue-specific accumulation and transformation of fipronil in adult fish are limited. An experiment consisting of 25-d uptake of fipronil at two levels (10 and 50 μg/L) and 25-d depuration in adult crucian carp (Carassius auratus) was conducted. Fipronil concentration at 25-d exposure was tissue-specific with the order of liver > kidney > blood > muscle. The uptake rate constant of fipronil in the liver (low exposure group: 2.38 ± 0.27 L/kg/d; high exposure group: 1.10 ± 0.11 L/kg/d) was significantly higher than that in other tissues (p < 0.05), and the lowest in muscle (low exposure group: 0.10 ± 0.01 L/kg/d; high exposure group: 0.16 ± 0.11 L/kg/d). The bioconcentration factors of fipronil in different tissues were 1.04–12.7 L/kg wet weight and 177–4268 L/kg lipid. The tissue–blood distribution coefficients of the liver and kidney were lower than 1 based on lipid normalized concentration but higher than 1 based on wet weight concentration, suggesting fipronil was dispersed into other tissues mainly via blood in the lipid-combination pattern. Fipronil sulfone had 1.2–32 times higher concentration and longer depuration time than fipronil, implying fipronil sulfone was more retender in fish bodies. The estimated daily intake of fipronil via fish muscle consumption at 25-d exposure was 8.5–101 and 27–320 ng/kg bw/d for adults and children, respectively. Overall, the human health risk of fipronil and its metabolites with consumption of the polluted fish cannot be negligible.

Distribution and ten-year temporal trends (2009–2018) of perfluoroalkyl substances in gull eggs from Spanish breeding colonies

Gull eggs are excellent bioindicators of environmental pollution as reflect the contamination levels of coastal areas, especially of persistent and bioacumulative compounds such as perfluoroalkyl substances (PFAS). This study aims to evaluate the geographical distribution and 10-year temporal trends (2009–2018) of 17 PFAS in eggs of two gull species (Larus michahellis and Larus audouinii) from 5 main Spanish colonies. ∑PFAS ranged from 13.7 ± 5.9 to 164 ± 17 ng g−1 wet weight and higher concentrations were observed in L. audouinii than in L. michahellis. Perfluorooctane sulfonate (PFOS) was the predominant compound in all samples, followed by perfluoroundecanoic acid (PFUnA) and perfluorotridecanoic acid (PFTriDA). Perfluorododecanoic acid (PFDoA), perfluorodecanoic acid (PFDA) and perfluorooctanoic acid (PFNA) were also found in all studied areas but at lower concentrations, while perfluorooctanoic acid (PFOA) was only detected in the Medes Islands. Principal Component Analysis revealed the co-occurrence of the 6 detected PFAS, and differentiated samples from Ebro Delta and Medes Islands, both located in the North-Eastern Mediterranean Sea, with high contribution of all PFAS, from Chafarinas and Atlantic Islands with lower concentration levels and variability. Also, different patterns were observed among colonies, suggesting the fish-based diet plays an important role in PFAS bioaccumulation. In all colonies, except for the Medes Islands, ∑PFAS decreased through the 10-year study period, with PFOS, PFUnA, and PFTriDA showing a significant concentration reduction in a colony-specific manner. This study demonstrates the usefulness and importance of continuous systematic long-term monitoring to determine the geographical distribution and temporal variations of PFAS in marine protected areas using gull eggs as bioindicators of environmental pollution.

Regional variation in mercury bioaccumulation among NW Atlantic Golden (Lopholatilus chamaeleonticeps) and Blueline (Caulolatilus microps) Tilefish

Mercury (Hg) concentrations in fishes from the NW Atlantic Ocean pose concern due to the importance of this region to U.S. fisheries harvest. In this study, total Hg (THg) concentrations and nitrogen stable isotope (δ15N) values were quantified in muscle tissues sampled from Golden (Lopholatilus chamaeleonticeps) and Blueline (Caulolatilus microps) Tilefish collected during a fishery-independent survey conducted in the NW Atlantic to compare bioaccumulation patterns between these species. Total Hg concentrations averaged (±SD) 0.4 ± 0.4 μg/g dry weight (d.w.) for L. chamaeleonticeps and 1.1 ± 0.7 μg/g d.w. for C. microps with <2% of all sampled fish, those >70 cm fork length, exceeding the most restrictive USEPA regulatory guidelines for human consumption (THg > 0.46 μg/g w.w.), when converted to wet weight concentrations. The THg concentrations reported here for individuals from the NW Atlantic stock are comparable to those reported for similarly sized individuals collected from the SW Atlantic stock but notably lower than those reported for Gulf of Mexico L. chamaeleonticeps, indicating different Hg exposure and assimilation kinetics for fish from the NW Atlantic, and highlights the broad geographic variability of Hg bioaccumulation among Tilefish stocks. Caulolatilus microps had higher δ15N values relative to L. chamaeleonticeps and a pattern of decreasing THg concentrations was also present from south to north across the study range. It is concluded that this trophic difference and spatial pattern in Tilefish THg concentrations emphasizes the habitat and resource partitioning mechanisms described for these sympatric species that permits their coexistence in the continental shelf environment. Importantly, regional variability in THg concentrations accentuate the possible roles of fine-scale biotic and abiotic processes that can act to regulate Hg bioaccumulation among individuals and species.

Common Eider and Herring Gull as Contaminant Indicators of Different Ecological Niches of an Urban Fjord System.

Seabirds like gulls are common indicators in contaminant monitoring. The herring gull (Larus argentatus) is a generalist with a broad range of dietary sources, possibly introducing a weakness in its representativeness of aquatic contamination. To investigate the herring gull as an indicator of contamination in an urban-influenced fjord, the Norwegian Oslofjord, we compared concentrations of a range of lipophilic and protein-associated organohalogen contaminants (OHCs), Hg, and dietary markers in blood (n = 15), and eggs (n = 15) between the herring gull and the strict marine-feeding common eider (Somateria mollissima) in the breeding period of May 2017. Dietary markers showed that the herring gull was less representative of the marine food web than the common eider. We found higher concentrations of lipophilic OHCs (wet weight and lipid weight) and Hg (dry weight) in the blood of common eider (mean ± SE ∑PCB = 210 ± 126 ng/g ww, 60 600 ± 28 300 ng/g lw; mean Hg = 4.94 ± 0.438 ng/g dw) than of the herring gull (mean ± SE ∑PCB = 19.0 ± 15.6 ng/g ww, 1210 ± 1510 ng/g lw; mean Hg = 4.26 ± 0.438 ng/g dw). Eggs gave opposite results; higher wet weight and lipid weight OHC concentrations in the herring gull (mean ± SE ∑PCB = 257 ± 203 ng/g ww, 3240 ± 2610 ng/g lw) than the common eider (mean ± SE ∑PCB = 18.2 ± 20.8 ng/g ww, 101 ± 121 ng/g lw), resulting in higher OHC maternal transfer ratios in gulls than eiders. We suggest that the matrix differences are due to fasting during incubation in the common eider. We suggest that in urban areas, herring gull might not be representative as an indicator of marine contamination but rather urban contaminant exposure. The common eider is a better indicator of marine pollution in the Oslofjord. The results are influenced by the matrix choice, as breeding strategy affects lipid dynamics regarding the transfer of lipids and contaminants to eggs and remobilization of contaminants from lipids to blood during incubation, when blood is drawn from the mother. Our results illustrate the benefit of a multispecies approach for a thorough picture of contaminant status in urban marine ecosystems. Integr Environ Assess Manag 2021;17:422-433. © 2020 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Methylmercury bioaccumulation among different food chain levels in the EEZ of Qatar (Arabian Gulf)

Methylmercury (MeHg) concentrations in three different species from different trophic levels with different amounts of Hg exposures were determined for the first time in the EEZ of Qatar. Sampling was conducted during autumn 2017 in two nearshore (Palm Tree and Al-Besheriya Islands) and two offshore locations (Sherawoo and Ishat Islands). Fish muscle and liver tissues were analyzed according to the US Environmental Protection Agency Method 1630. The lowest mean MeHg concentration was found to be 42.3 ppb wet weight in the lower trophic level fish Gerres oyena due to small fish size and trophic level; whereas, the highest MeHg concentration was found in higher trophic level sharks Rhizoprionodon oligolinx and Chiloscyllium arabicum with mean wet weight concentrations of 712 ppb and 166 ppb, respectively. Linear relationships were found between fish body size (weight, length, age) and MeHg concentrations. MeHg bioaccumulation was found to be higher in liver than in muscle tissue; however, there was no significant difference in tissue MeHg accumulation as well as, the concentrations between the four locations. The present study concludes that MeHg in most of the fish tissues is within the allowable limits and pose no threat to public health. Only the higher trophic level shark Rhizoprionodon oligolinx was found to have a MeHg concentration higher than the US EPA advisory level of 0.3 ppm. However, consumers should still be encouraged to eat smaller sized younger fish from lower trophic levels, which would be safer than larger older species from higher trophic levels.

Differential Bioaccumulation of Mercury and Selenium in Stomach Contents and Tissues of Three Colorado, USA, Cutthroat Trout Populations.

Total mercury (THg) and selenium (TSe) levels were measured in stomach contents (SC) and twelve tissues of cutthroat trout (Oncorhynchus clarkii) occurring in three high-elevation lakes of Colorado, USA, inhabiting watersheds absent past and current mining activities. For 32 of 36 tissues, including muscle, mean THg wet weight (ww) concentrations were greater than in the diet (SC) for all sites, indicating biomagnification. Ranges of THg (µg/kg ww) for SC and stomach tissue (ST) were 1.23-73.54 and 14.55-61.35, respectively. Selenium concentrations in fish muscle were not greater than in the SC indicating a trophic transfer factor < 1.0. However, in several other tissues, mean Se dry weight (dw) levels were greater than in SC for all three lakes. Ranges of TSe for SC and ST were 166-7544 and 797-7523 (µg/kg dw), respectively. The muscle to egg/ovary ratio for Se averaged 2.30, 4.60, and 2.68 for the three populations. The variability of SC (planktonic vs. benthic) and differential distributions of THg and TSe in SC and organ-tissues generated questions focusing on the seasonal, physiological, and genetic drivers of these organometal(loid)s in subalpine trout.

Erratum: "Prenatal Exposure to DDT and Pyrethroids for Malaria Control and Child Neurodevelopment: The VHEMBE Cohort, South Africa".

Erratum: "Prenatal Exposure to DDT and Pyrethroids for Malaria Control and Child Neurodevelopment: The VHEMBE Cohort, South Africa".

A field study in support of the monitoring of priority substances in German freshwater fish: derivation of fillet-to-whole fish conversion factors

BackgroundBioaccumulating contaminants in surface waters are preferably monitored in fish for assessing the related risks to and via the aquatic environment. Consequently, the European Water Framework Directive (WFD) requires a monitoring of certain priority substances such as mercury, polybrominated diphenyl ethers (PBDE), perfluorooctane sulfonic acid and its derivatives (PFOS), hexachlorobenzene (HCB), hexabromocyclododecanes (HBCDD) and polychlorinated dioxins/dioxin-like compounds (dioxins) in freshwater and coastal fish. Tissue levels have to comply with biota environmental quality standards (EQSs) given in Directive 2013/39/EU. EQSs are justified either by risks for human health (assessed on the basis of fillet) or secondary poisoning of wildlife (based on whole fish). To support the practical implementation of the WFD biota monitoring in Germany, comparative investigations of target fish species caught at six sites were performed.ResultsAt each site, at least three fish species listed in a national guidance document were sampled (e.g., chub, roach, bream, perch). Beside biometric data, concentrations of seven priority substances were determined in pooled fillet and carcass samples and whole fish data were calculated. The EQSs for PBDE and mercury were exceeded in nearly all fillet and whole fish samples. PFOS was above the EQS at several sites especially in perch, while HCB exceeded the EQS only at one site (Elbe River). All fillet and whole fish samples complied with the EQSs for dioxins and HBCDD. Based on wet weight concentrations of a homogeneous set of 20 composite sample pairs of 3–5 year-old fish, the following fillet-to-whole fish conversion factors were derived: mercury 0.81, PBDE 5.4, HCB 3.6, PFOS 2.7, dioxins 5.3, and HBCDD 1.8.ConclusionsRecommendations on selection of target fish species, age or tissue given by EU and national guidance documents are practical and feasible. However, further adjustments of the samplings such as the determination of site-specific length–age relationships are required from both ecological and risk assessment perspectives. The derived conversion factors allow the translation of fillet-to-whole fish concentrations (and vice versa), and thus the EQS compliance assessment for the appropriate tissue (fillet for human health, whole fish for wildlife risks) if only one tissue is investigated.

Polychlorinated biphenyl exposure and DNA methylation in the Anniston Community Health Survey

ABSTRACTAnniston, Alabama was home to a major polychlorinated biphenyl (PCB) production facility from 1929 until 1971. The Anniston Community Health Survey I and II (ACHS-I 2005–2007, ACHS-II 2013–2014) were conducted to explore the effects of PCB exposures. In this report we examined associations between PCB exposure and DNA methylation in whole blood using EPIC arrays (ACHS-I, n = 518; ACHS-II, n = 299). For both cohorts, 35 PCBs were measured in serum. We modelled methylation versus PCB wet-weight concentrations for: the sum of 35 PCBs, mono-ortho substituted PCBs, di-ortho substituted PCBs, tri/tetra-ortho substituted PCBs, oestrogenic PCBs, and antiestrogenic PCBs. Using robust multivariable linear regression, we adjusted for age, race, sex, smoking, total lipids, and six blood cell-type percentages. We carried out a two-stage analysis; discovery in ACHS-I followed by replication in ACHS-II. In ACHS-I, we identified 28 associations (17 unique CpGs) at p ≤ 6.70E-08 and 369 associations (286 unique CpGs) at FDR p ≤ 5.00E-02. A large proportion of the genes have been observed to interact with PCBs or dioxins in model studies. Among the 28 genome-wide significant CpG/PCB associations, 14 displayed replicated directional effects in ACHS-II; however, only one in ACHS-II was statistically significant at p ≤ 1.70E-04. While we identified many novel CpGs significantly associated with PCB exposures in ACHS-I, the differential methylation was modest and the effect was attenuated seven years later in ACHS-II, suggesting a lack of persistence of the associations between PCB exposures and altered DNA methylation in blood cells.

Comparisons of tissue distributions and health risks of perfluoroalkyl acids (PFAAs) in two fish species with different trophic levels from Lake Chaohu, China

Perfluoroalkyl acids (PFAAs) are a type of persistent organic pollutants that are widely distributed in multiple environmental media and organisms and have a teratogenic effect on and toxicity to animals and humans. The residual levels of seventeen PFAAs in the tissues of two regular consumption fish species, Culter erythropterus and Aristichthys nobilis in Lake Chaohu were measured by a high-performance liquid chromatograph – mass spectrometer (HPLC-MS). The distributions of PFAAs and the effect of the lipid contents were analyzed, and the health risks of typical PFAAs were evaluated. The results showed that perfluorohexanoic acid (PFHxA) was the predominant contaminant (80.50 ± 58.31 ng/g and 19.17 ± 12.57 ng/g wet weight, ww), followed by perfluorooctanesulfonic acid (PFOS) (55.02 ± 34.82 and 14.79 ± 6.24 ng/g, ww) in both fish. The level of total PFAAs was the highest in the liver tissues of Culter erythropterus (359.87 ng/g, ww) and the lowest in the kidney tissues in A. nobilis (10.06 ng/g, ww). Due to the higher trophic level of C. erythropteru, the total PFAA concentrations were significantly higher in all tissues than those in A. nobilis. Liver muscle ratio of C. erythropteru was the highest, indicating the most accumulation in the liver. The concentrations of PFAAs in fish tissues were influenced by the lipid content, resulting in a difference between the lipid-normalized concentrations and the wet weight concentrations of the PFAAs. The non-carcinogenic risks of PFOS were higher than those of PFOA through the ingestion of C. erythropterus and A. nobilis. Both the carcinogenic and non-carcinogenic risks of C. erythropterus were greater than those of A. nobilis, and fish tissue intake could cause an increasing of risks up to 60%, indicating that long-term and large amount ingestion of carnivorous fish and related tissues with higher trophic level, such as C. erythropterus should be avoided.

Mercury and selenium concentrations in Scyphozoan jellyfishes and pyrosomes from Monterey Bay National Marine Sanctuary

Gelatinous zooplankton including jellyfishes, pyrosomes, and salps serve as important prey items for a number of marine species; however, relatively few studies have examined contaminant concentrations in these animals. Scyphozoans (Aurelia sp., Chrysaora colorata, C. fuscescens, and Phacellophora camtschatica) and Thaliaceans (Pyrosoma sp.) were collected from 2009 to 2011 from Monterey Bay National Marine Sanctuary and analyzed for total mercury and selenium concentrations. In general, mercury (0.0001–0.0016 μg/g wet weight) and selenium (0.009–0.304 μg/g wet weight) concentrations of the sampled organisms were low; however, the two Pyrosoma sp. had total mercury and selenium concentrations that were one order of magnitude higher than the Scyphozoans. There was a significant positive relationship between mercury and selenium concentrations in jellyfishes and pyrosomes, suggesting a potential detoxification mechanism in these lower trophic level organisms. This study provides evidence that trophic transfer of mercury and selenium likely occurs through ingestion of gelatinous prey.

Residues, bioaccumulations and biomagnification of perfluoroalkyl acids (PFAAs) in aquatic animals from Lake Chaohu, China

Residual levels of perfluoroalkyl acids (PFAAs) in seven species of aquatic animals were analyzed by liquid chromatography-mass spectrometry. The distribution, composition, bioaccumulation, and biomagnification of PFAAs and their effect factors were studied. The results showed that: 1) Wet weight concentrations of 17 PFAAs in the aquatic animals ranged from 1.77 to 38.65 ng/g, with a mean value of 12.71 ± 9.21 ng/g. PFOS was the predominant contaminant (4.57 ± 4.57 ng/g, 6.76%–46.25%), followed by PFDA (1.95 ± 1.37 ng/g, 11.68%–21.25%) and PFUdA (1.84 ± 1.21 ng/g, 9.73%–35.34%. 2) PFAA residual levels in Culter erythropterus (30.98 ± 6.65 ng/g) were the highest, followed by Hemibarbus maculatus (16.79 ± 1.88 ng/g), while the PFAA levels in Carassius auratus were the lowest (2.22 ± 0.60 ng/g). 3) Biota-water bioaccumulation factors (BAFs), biota-suspended solid accumulation factors (BSSAFs) and biota-sediment accumulation factors (BSAFs) ranged from 0.35 to 12,370.51, 7.77 to 8452.92 and 9.10 to 6984.61, respectively. Bioaccumulation by shrimp and snails was significantly affected by Kow. 4) Food web magnification factors were greater than 1, indicating that biomagnification of PFAAs occurs across trophic levels. The bioaccumulation and biomagnification of PFAAs were significantly correlated with carbon chain length.

Biomagnification and enantiomeric profiles of organochlorine pesticides in food web components from Zhoushan Fishing Ground, China

Trophodynamics and chiral signatures of organochlorine pesticides (OCPs), including dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs), and chlordanes in a food web from Zhoushan Fishing Ground, China, were studied. Residues of OCPs in all teleost fishes were within food safety levels. Strong positive correlations were found between trophic levels (TLs) and wet weight concentrations of target chemicals, with trophic magnification factors (TMFs) from 4.17 to 9.77. Lipid contents and TLs significantly correlated, which indirectly affect the bioaccumulation processes of OCPs. The consistently racemic EF values of α-HCH, as well as invariability of the relative proportions of HCH isomers in different marine species implied that HCHs in animals originate directly from the surrounding environment. However, in vivo biotransformation and/or elimination of o,p′-DDT cannot be precluded. TMFs of the individual enantiomers further suggest that the influence of achiral biotransformation is too minor to induce enantioselective biomagnification of chiral OCPs through the studied food web.

Mercury and selenium in fishes from the Tapajós River in the Brazilian Amazon: An evaluation of human exposure

This work aimed to evaluate associated risks of fish consumption to human health, concerning mercury (Hg) and selenium (Se) concentrations in fish species largely consumed in the Tapajós River basin in the Brazilian Amazon. Total mercury (THg), methylmercury (MeHg) and Se concentrations were measured in 129 fish specimens from four sites of the Tapajós River basin. Estimated daily intake (EDI) of Hg and Se were reported regarding fish consumption. EDI were compared with the reference value of provisional tolerable daily intake proposed by the World Health Organization (WHO). Se:Hg ratios and selenium health benefit values (Se HBVs) seem to offer a more comprehensive fish safety model. THg concentrations in fishes ranged from 0.03 to 1.51 μg g−1 of wet weight (w.w.) and MeHg concentrations ranged from 0.02 to 1.44 μg g−1 (w.w.). 80% of the samples were below the value of Hg recommended by the WHO for human consumption (0.5 μg g−1 w.w.). However, Hg EDI exceeded the dose suggested by the United States Environmental Protection Agency (0.1 μg kg−1 day−1), due to the large level of fish consumption in that area. Se concentrations in fishes ranged from 0.02 to 0.44 μg g−1 w.w. An inverse pattern was observed between Hg and Se concentrations in the trophic chain (highest levels of Se in the lowest trophic levels). The molar ratio Se:Hg and Se HBVs were higher in iliophagous and herbivorous fishes, which is noteworthy to reduce toxic effects of Hg contamination. For planktivores, the content of Se and Hg was almost equimolar. Carnivorous fishes – with the exception of Hemisorubim platyrhynchos and Pseudoplatystoma fasciatum –, showed Se:Hg ratios <1. Thus, they do not act as a favorable source of Se in the diet. Therefore, reduced intake of carnivorous fishes with preferential consumption of iliophages, herbivores and, to some extent, even planktivores should be promoted as part of a healthier diet.