Are Fish Consumption Advisories for the Great Lakes Adequately Protective against Chemical Mixtures?

Chemical mixtures of mercury, PCBs, PFAS, and pesticides in freshwater fish in the US and the risks they pose for fish consumption

BACKGROUND

Freshwater fish are important food sources that also pose risks to human and wildlife health because of the bioaccumulation of environmental chemicals in their tissues. Although most studies, fish consumption advisories, and regulations focus on individual contaminants, fish consumers are exposed to mixtures of chemicals, including legacy contaminants and contaminants of emerging concern, that can have combined effects. Chemicals of emerging concern represent one source of hazard, but legacy contaminants can still pose threats to fish consumers due to their persistence in the environment.

OBJECTIVES

We investigate the following questions: 1) Do different chemicals correlate with one another in fish tissue, and if so, how? 2) How do levels of different chemicals in fish tissue vary by time and location? and 3) How do observed chemical levels compare with risk-based screening levels?

METHODS

Using several national data sources established and maintained by the US Environmental Protection Agency (NRSA, NCCA-GL, GLENDA, and NLFTS), this study examines the co-occurrence of chemicals in freshwater fish in lakes, ponds, streams, and rivers in the US.

RESULTS

We determine that organic contaminants correlate with one another, but generally not with mercury; organic chemicals have declined over time, but mercury has not; and fish concentrations of legacy contaminants-even those banned for decades-continue to exceed risk-based screening levels.

DISCUSSION

Despite some successes in curtailing release of pollutants, some contaminants in fish tissue have not declined and legacy and emerging pollutants continue to pose risks to fish consumers in the US. Correlations between chemicals in fish tissue suggest that exposures to mixtures is prevalent in the US but that organic contaminants do not generally correlate with mercury-noteworthy particularly since fish consumption advisories in the US are frequently driven by the level of mercury, and do not account for exposure to multiple contaminants. While programs such as the National Aquatic Resource Surveys (NARS) Program seek to systematically monitor contaminants in fish tissue and other environmental indicators, continuous support from the US federal government is required to sustain this monitoring. Moreover, greater legislative and regulatory efforts are required at both the state and federal levels to reduce continuing sources and ongoing contamination.

One Health assessment of persistent organic chemicals and PFAS for consumption of restored anadromous fish

BACKGROUND

Restoration efforts have led to the return of anadromous fish, potential source of food for the Penobscot Indian Nation, to the previously dammed Penobscot River, Maine.

OBJECTIVE

U.S. Environmental Protection Agency (EPA), Penobscot Indian Nation's Department of Natural Resources (PINDNR), and Agency for Toxic Substances and Disease Registry (ATSDR), measured contaminants in six species of anadromous fish. Fish tissue concentrations were then used, along with exposure parameters, to evaluate potential human and aquatic-dependent wildlife risk.

METHODS

PINDNR collected, filleted, froze, and shipped fish for analysis of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), dioxins/furans, and per- and polyfluoroalkyl substances (PFAS). Contaminant levels were compared to reference doses (where possible) and wildlife values (WVs).

RESULTS

Chemical concentrations ranged from 6.37 nanogram per gram (ng/g) wet weight (ww) in American Shad roe to 100 ng/g ww in Striped Bass for total PCBs; 0.851 ng/g ww in American Shad roe to 5.92 ng/g ww in large Rainbow Smelt for total PBDEs; and 0.037 ng/g ww in American Shad roe to 0.221 ng/g ww in Striped Bass for total dioxin/furans. PFAS concentrations ranged between 0.38 ng/g ww of PFBA in Alewife to 7.86 ng/g ww of PFUnA in Sea Lamprey. Dioxin/furans and PFOS levels indicated that there are potential human health risks. The WV for mink for total PCBs (72 ng/g) was exceeded in Striped Bass and the WV for Kestrel for PBDEs (8.7 ng/g) was exceeded in large Rainbow Smelt. Mammalian wildlife consuming Blueback Herring, Striped Bass, and Sea Lamprey may be at risk based on PFOS WVs from Canada.

IMPACT

Anadromous fish returning to the Penobscot River potentially could represent the restoration of a major component of tribal traditional diet. However, information about contaminant levels in these fish is needed to guide the tribe about consumption safety. Analysis of select species of fish and risk calculations demonstrated the need for a protective approach to consumption for both humans and wildlife. This project demonstrates that wildlife can also be impacted by contamination of fish and their risks can be as great or greater than those of humans. A One Health approach addresses this discrepancy and will lead to a healthier ecosystem.

Health benefits and health risks of contaminated fish consumption: Current research outputs, research approaches, and perspectives

Background

Fish contains high-quality omega-3 fatty acids, protein, vitamins, and minerals and due to this it is termed as an essential component of a balanced diet. But there have been concerns raised about the risks of consuming fish that is contaminated with toxins such as methylmercury, polychlorinated biphenyls (PCBs), dioxins, pesticides, and plastic waste. Consumption of contaminated fish containing these pollutants is raising global mortality and morbidity rates.

Scope and approaches

The review examines the current research outputs on the health benefits and potential health risks of fish consumption. The review also discusses various approaches to mitigating the health problems caused by fish consumption, highlights the roles of balancing the risks and benefits when consuming fish.

Key findings and conclusion

Different findings indicated that contaminants cause cancer, kidney failure, adverse neurological effect, cardiovascular diseases, and so on to vulnerable groups such as pregnant, child breast-feeding and children. In conclusion, there is a need to get more tangible evidence about the advantages and disadvantages of fish consumption to safeguard the wellbeing of the society.

Increasing mercury bioaccumulation and biomagnification rates of Nile perch (Lates niloticus L.) in Winam Gulf, Lake Victoria, Kenya

The Nile perch (Lates niloticus L.) commercial fishery for Lake Victoria in East Africa is an important source of revenue and employment. We focused on shifts in food web structure and total mercury (THg) bioaccumulation and biomagnification in Nile perch, and lower food web items collected from Winam Gulf (Kenya) sampled 24 years apart (1998 and 2022). Stable isotope carbon (δ13C) values were higher in all species from 2022 compared to 1998. Stable nitrogen isotope (δ15N) values in baseline organisms were lower in 2022 compared to 1998. In Nile perch, δ15N values were correlated with total length, but the δ15N-length regressions were steeper in 1998 compared to 2022 except for one large (158 cm) Nile perch from 1998 with an uncharacteristically low δ15N value. Total Hg concentrations were lower in lower trophic species from 2022 compared to 1998. However, the THg bioaccumulation rate (as a function of fish length) in Nile perch was greater in 2022 compared to 1998 resulting in 24.2 % to 42.4 % higher wet weight dorsal THg concentrations in 2022 Nile perch for market slot size (50 to 85 cm) fish. The contrasting observations of increased THg bioaccumulation with size in 2022 against decreases in the rate of trophic increase with size and lower THg concentrations of lower food web items imply reduced fish growth and potential bioenergetic stressors on Winam Gulf Nile perch. All samples except 1 large Nile perch (139 cm total length collected in 2022) had THg concentrations below the European Union trade limit (500 ng/g wet weight). However, for more vulnerable individuals (women, children and frequent fish eaters), we recommend a decrease in maximum monthly meal consumption for 55-75 cm Nile perch from 16 meals per month calculated for 1998 to a limit of 8 meals per month calculated for 2022.

Biodilution of Organic Species of Arsenic in Freshwater Food Webs

Arsenic can accumulate in freshwater biota, sometimes reaching potentially harmful levels. However, the toxicity of arsenic strongly depends on which arsenic species are present. Although organic species are considered less harmful than inorganic ones, they have not been extensively studied in freshwater environments, and drivers of variation in arsenic speciation among sites and taxa remain unclear. We assessed concentrations of two organic arsenic species, arsenobetaine (AsB) and dimethylarsinic acid (DMA), in fish and invertebrates from three lakes near Sudbury, Ontario, Canada-a region with widespread mining impacts. Both AsB and DMA were detected in most samples (n = 212), varying across a wide range of concentrations (<0.001-30.144 and <0.006-5.262 mg/kg dry wt, respectively). The lake with the most severe mining impacts typically had the highest concentrations (designated by square brackets []) of AsB and DMA. In contrast, the percentage of total arsenic made up by AsB (%AsB) and DMA (%DMA) did not vary significantly between lakes. Arsenic speciation in fish muscle varied with fish size, selenium concentrations, and trophic elevation (inferred from nitrogen stable isotope ratios δ15 N), but relationships with dietary carbon source (inferred from carbon stable isotope ratios δ13 C) were more varied. Within all three lake food webs, [AsB] and [DMA] typically underwent biodilution, decreasing with trophic elevation (i.e., δ15 N). Although the aforementioned factors explained some variation in arsenic speciation, there remains considerable unexplained variation. Further studies on arsenic speciation in freshwater biota should target a wider diversity of taxa to better understand drivers of variation in arsenic speciation. In addition, research emphasizing the percentage of inorganic arsenic and other organic arsenic species is needed to improve environmental and human health risk assessments. Environ Toxicol Chem 2024;00:1-14. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

What can we learn from 28 years of monitoring of fish tissue polychlorinated biphenyls in Michigan's rivers?

Polychlorinated biphenyls (PCBs) are an important part of chemical legacies in the Laurentian Great Lakes basin. Used in industrial products worldwide, PCBs are now extensively monitored because of their potential toxicity to humans. Fish consumption is a major pathway for exposure. Edible portion (i.e., fish fillet) data from Michigan's fish tissue PCB monitoring program were evaluated using regression statistics, principal component analysis, and t-tests to answer three questions: (1) How do fish tissue total PCB concentrations vary across Michigan's rivers? (2) Are the PCB congener patterns uniformly distributed among tested sites and species? (3) Do monitoring methods limit our ability to discern trends in fish tissue PCB concentrations? Our results indicate that although contaminated sites have been successfully identified, based on higher PCB concentrations in samples from Areas of Concern (AOCs) compared to non-AOC sites, 77% of fish samples from 2010 to 2015 exceeded the safe fish tissue PCB concentration for unrestricted consumption (97 g/day) by sensitive populations. The PCB congener profiles vary among species and locations. Results demonstrate that these data are not useful for supplementing ongoing spatial and temporal trend analysis. Only 15 of the 83 species + waterbody pairs had adequate data for evaluating temporal trends with more than three data points. In general, the trends at each location varied based on the analytical method. Conclusions from this work can inform revisions to existing monitoring programs and improve our ability to protect human health. Integr Environ Assess Manag 2023;19:152-162. © 2022 SETAC.

The speciation of arsenic in the muscle tissue of inland and coastal freshwater fish from a remote boreal region

Elevated concentrations of total arsenic (As) have been reported in boreal freshwater fish in both human-impacted and relatively pristine areas. We assessed the arsenic speciation profiles in muscle tissue of six fish species (n = 300) sampled from nine locations across a remote freshwater watershed in northern Ontario, Canada, extending from inland headwater lakes to the coastal marine confluence. Of the five arsenic species measured, only arsenobetaine (AsB) and dimethylarsinic acid (DMA) were detected in these fish. Riverine fish had up to 10-fold higher total [As] when compared to lacustrine fish. On average, these riverine fish also had higher percentages of AsB (%AsB, 60 ± 26%) and lower percentages of unmeasured arsenic (%UNM, 20 ± 21%), compared to lacustrine fish (28 ± 18% and 52 ± 21% %AsB and %UNM, respectively). DMA percentages (%DMA) were relatively consistent across the watershed, averaging 20 ± 21% across all fish. We examined ecological drivers of As speciation and found that %AsB increased slightly with fish weight in large-body predatory fish, but not in forage fish or insectivores. Furthermore, %AsB was positively related to trophic elevation (inferred from δ¹⁵N) in lacustrine fish across 3 out of 4 communities and within some populations. Lastly, riverine fish with a more marine-based diet had markedly higher %AsB when compared to fish with more freshwater-based diets, indicating an effect of anadromy on arsenic speciation. Overall, knowledge on arsenic speciation in freshwater fish has been limited and these results indicate potential drivers that can be considered in future studies. Furthermore, the absence of toxic inorganic As species in these boreal fish is an important consideration for future environmental monitoring practices and risk assessments, some of which assume 10-20% of total [As] in fish is present as toxic inorganic As. Additional studies on As bioaccumulation and biotransformation are needed in freshwater systems, particularly at the base of aquatic food webs.

Envisioning healthy futures: Youth perceptions of justice-oriented environments and communities in Northern British Columbia Canada

Through an anti-colonial and critical race theoretical framework as well as arts-based methods (photovoice) that engage Indigenous and non-Indigenous youth, we explore the question: what do youth perceive as healthy and just environments and communities? Youth identified two overarching, strength-based messages: Firstly, youth demonstrate the need for a structural-level analysis of the conditions that influence individual-level outcomes of environmental health. Secondly, youth perspectives on healthy and justice-oriented environments and communities challenge environmental health scholars to consider youth as powerful actors. Youth perspectives of healthy and justice-oriented communities present a necessarily structural perspective to consider not only the impacts of environmental decision-making on health, but the conditions that have allowed for harmful impacts. In doing so, youth demonstrate the need for intersectional and complex understandings of health and wellbeing when discussing the environment. And, as we argue here, challenge us as scholars of environmental health to do the same.

Persistent and toxic chemical pollutants in fish consumed by Asians in Chicago, United States

Consumption of seafood brings health benefits but may increase the ingestion of contaminants. Compared with other ethnic groups in the U.S., Asians consume seafood more frequently. However, there is little information about how culturally specific fish consumption contributes to exposure to toxicants. In this work, we surveyed fish consumption among Chinese, Korean and Vietnamese communities and purchased 103 seafood samples from local markets in Chicago. Each sample was analyzed for mercury (Hg) and 92 organic chemicals including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), and Dechlorane Plus and related compounds (DPs). The rank order of pollutant concentration in all samples was Hg ≫ Σ₆₆PCBs > Σ₁₇OCPs > Σ₈PBDEs > Σ₈DPs. Positive correlations were noted among most contaminant groups. Bluefish, pike and tuna steak had the highest mean Hg (>1 mg/kg). The mean Σ₆₆PCBs was highest in pike and bluefish (>100 ng/g) followed by pollock and mackerel (>40 ng/g). Overall, octopus, shrimp and tilapia were the least contaminated; while pike, bluefish, and pollock were the most contaminated. Omega-3 fatty acids were more strongly affiliated with the organic contaminants than mercury. A risk assessment identified seven types of fish that should have consumption limitations and six that should not be consumed. For these seafoods, consumption advice based on Hg levels would adequately protect health. In the survey participants, 17% of seafood mass consumed is from types of fish that should be limited to 1 or 2 meals/week, while 7% of the seafood mass consumed comes from types that should not be consumed at all. This work adds additional contaminants to the profile of health risks resulting from fish consumption among Asian Americans, which can be used in interventions aimed at conserving consumption of healthy fish while avoiding contaminants.

Characterization of Halogenated Organic Compounds in Pelagic Sharks and Sea Turtles Using a Nontargeted Approach

Halogenated organic compounds (HOCs) in marine species collected from the Atlantic Ocean [3 shortfin mako (Isurus oxyrinchus) and 1 porbeagle (Lamna nasus)], and 12 sea turtles collected from the Pacific Ocean [3 loggerhead (Caretta caretta), 3 green (Chelonia mydas), 3 olive ridley (Lepidochelys olivacea), and 3 hawksbill (Eretmochelys imbricata)] were analyzed with a nontargeted analytical method using two-dimensional gas chromatography coupled to high-resolution time-of-flight mass spectrometry. Sharks and sea turtles had distinct HOC profiles. Halogenated methoxyphenols (halo-MeOPs) were the most abundant compound class identified in sea turtle livers, while polychlorinated biphenyls (PCBs) were the most abundant in shark livers. In addition to legacy contaminants and halo-MeOPs, a total of 110 nontargeted/novel HOCs (NHOCs) were observed in the shark livers. Shortfin mako collected from the northern Gulf of Mexico contained the largest number (89) and most diverse structural classes of NHOCs. Among all NHOCs, a group of compounds with the elemental composition C₁₄H_12-nCl_n (n = 5-8) exhibited the highest concentrations, followed by chlorocarbazoles and tris(chlorophenyl) methanes (TCPMs). Using nontargeted workflows, a variety of known and unknown HOCs were observed, which demonstrate the need to develop more complete chemical profiles in the marine environment.

Proteomic analysis of the lake trout (Salvelinus namaycush) heart and blood: The beginning of a comprehensive lake trout protein database

Lake trout (Salvelinus namaycush) are a top-predator species in the Laurentian Great Lakes that are often used as bioindicators of chemical stressors in the ecosystem. Although many studies are done using these fish to determine concentrations of stressors like legacy persistent, bioaccumulative and toxic chemicals, there are currently no proteomic studies on the biological effects these stressors have on the ecosystem. This lack of proteomic studies on Great Lakes lake trout is because there is currently no complete, comprehensive protein database for this species. Here, we employed proteomics approaches to develop a lake trout protein database that could aid in future research on this fish, in particular exposomics and adductomics. The current study utilized heart tissue and blood from two lake trout. Our previous work using lake trout liver revealed 4194 potential protein hits in the NCBI databases and 3811 potential protein hits in the UniProtKB databases. In the current study, using the NCBI databases we identified 838 proteins for the heart and 580 proteins for the blood tissues in the biological replicate 1 (BR1) and 1180 potential protein hits for the heart and 561 potential protein hits for the blood in BR2. Similar results were obtained using the UniProtKB databases. This study builds on our previous work by continuing to build the first comprehensive lake trout protein database and provides insight into protein homology through evolutionary relationships. This data is available via the PRIDE partner repository with the dataset identifier PXD023970.

Impacts of water level fluctuations on mercury concentrations in hydropower reservoirs: A microcosm experiment

Hydropower generation, a renewable source of electricity, has been linked to elevated methylmercury (MeHg) concentrations in impoundments and aquatic biota. This study investigates the impact of water level fluctuations (WLF) on MeHg concentrations in water, sediment, and fish. Using a set of controlled microcosm experiments emulating the drawdown/refill dynamics and subsequent sediment exposure to air experienced in reservoirs, we demonstrate that less frequent WLFs, and/or increased exposure of sediment to air, can lead to elevated MeHg concentrations in sediment, and total mercury (THg) and MeHg concentrations in water. In examining the effects of WLF frequency (two-day, weekly, and monthly), the monthly treatment displayed the highest THg and MeHg water levels, while the weekly treatment was characterized by the highest MeHg levels in the sediment. Our work supports emerging evidence that longer duration between WLF creates a larger surface area of sediment exposed to air leading to conditions conducive to higher MeHg concentrations in sediments and water. In contrast, THg, MeHg, and fatty acid trends in fish were largely inconclusive characterized by similar among-treatment effects and minimal temporal variability over the course of our experiment. This result could partly be attributed to overall low mercury levels and simple "worm-forage fish" food web in our experiment. To elucidate the broader impacts of water fluctuations on aquatic chemistry and biota, other factors (e.g., longer WLF cycles, dissolved organic matter, temperature, more complex food webs) which modulate both methylation rates and food web dynamics must be considered.

Comparison of Recreational Fish Consumption Advisories Across the USA

PURPOSE OF REVIEW

Our comparative analysis sought to understand the factors which drive differences in fish consumption advisories across the USA - including exposure scenarios (acute and chronic health risk, non-cancer and cancer health endpoints), toxicity values (reference dose, cancer slope factor, acute tolerance level), and meal size and bodyweight assumptions.

RECENT FINDINGS

Fish consumption provides essential nutrients but also results in exposure to contaminants such as PCBs and methylmercury. To protect consumers from the risks of fish contaminants, fish consumption advisories are established, most often by state jurisdictions, to estimate the amount of a certain fish species a person could consume throughout their lifetime without harm. However, inconsistencies in advisories across the USA confuse consumers and undermine the public health goals of fish advisory programs. To date, no rigorous comparison of state and national fish consumption advisories has been reported. Our work identifies discrepancies in key assumptions used to derive risk-based advisories between US states, reflecting differences in the interpretation of toxicity science. We also address the implications for these differences by reviewing advisories issued by contiguous states bordering two waterbodies: Lake Michigan and the Lower Mississippi River. Our findings highlight the importance of regional collaboration when issuing advisories, so that consumers of self-caught fish are equipped with clear knowledge to make decisions to protect their health.

Mercury in the fish of New York's Great Lakes: A quarter century of near stability

We collected 849 fish of 16 species from New York portions of Lake Erie, Lake Ontario and the intervening Niagara River and its tributary Cayuga Creek, and analyzed fillets from individual fish for total mercury. Concentrations ranged from 0.029 to 1.090 ppm wet weight, with 92% below the EPA tissue residue criterion of 0.3 ppm, and thus not posing an undue risk from human consumption. We compared these 2010-2017 results to historical data spanning 40 years to assess temporal changes. The temporal pattern was generally consistent among water bodies and species: Mercury concentrations differed little between the most recent collections and fish taken from 1999-2008 and 1988-1996, while concentrations in all three of these periods were generally lower than in 1970. Smallmouth Bass from Lake Ontario were an exception with a continued decline, likely due to diet change following the introduction of exotic prey. Overall, though, fish tissue mercury concentrations from these large water bodies, which integrate regional influences, appear to have changed little in the last quarter century. We also report a consistent spatial pattern for multiple species having lower mercury concentrations in Lake Erie than in Lake Ontario over the period of record.

Assessing Human Health Risks from Per- and Polyfluoroalkyl Substance (PFAS)-Impacted Vegetable Consumption: A Tiered Modeling Approach

Irrigation water or soil contaminated with per- and polyfluoroalkyl substances (PFASs) raises concerns among regulators tasked with protecting human health from potential PFAS-contaminated food crops, with several studies identifying crop uptake as an important exposure pathway. We estimated daily dietary exposure intake of individual PFASs in vegetables for children and adults using Monte Carlo simulation in a tiered stochastic modeling approach: exposures were the highest for young children (1-2 years > adults > 3-5 years > 6-11 years > 12-19 years). Using the lowest available human health toxicity reference values (RfDs) and no additional exposure, estimated fifth percentile risk-based threshold concentrations in irrigation water were 38 ng/L (median 180 ng/L) for perfluorooctanoate (PFOA) and 140 ng/L (median 850 ng/L) for perfluorooctane sulfonate (PFOS). Thus, consumption of vegetables irrigated with PFAS-impacted water that meets the current 70 ng/L of PFOA and PFOS U.S. Environmental Protection Agency's lifetime health advisory for drinking water may or may not be protective of vegetable exposures to these contaminants. Hazard analyses using real-world PFAS-contaminated groundwater data for a hypothetical farm showed estimated exposures to most PFASs exceeding available or derived RfDs, indicating water-to-crop transfer is an important exposure pathway for communities with PFAS-impacted irrigation water.

Concentrations, toxic equivalence, and age-corrected trends of legacy organic contaminants in Lake Champlain lake trout: 2012-2018

Our study is the first comprehensive, multi-year assessment of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), organochlorine pesticides (OCPs), polychlorinated naphthalenes (PCNs), polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans (PCDD/Fs) lake trout concentrations and trends in Lake Champlain (LC). Lake trout whole-fish, fillets, and eggs were collected over the 2012-2018 study period. Total PCB concentrations (395.7 ng/g wet weight (ww)) were the highest average concentration of any contaminant grouping reported in this study. Whole-fish lake trout modeling revealed highly significant (p < 0.05) log-linear correlations for all dioxin-like contaminants measured. Overall contaminant decreases for the 2012-2018 period ranged from 20.9% (total PCNs) to 39.3% (2378-TCDD). Contaminant decreases for total PCBs and total-5-PBDEs were 30.9% and 48.3%, respectively. Of particular significance were the measured total PBDE concentrations (74.3 ng/g ww) found in LC whole-fish lake trout. Log-linear forecasting indicates that whole-fish lake trout TEQs will be below the guidelines protective of wildlife thresholds during the periods 2035-2047 (TRG_bird) and 2062-2088 (TRG_mammal). Based on current USEPA guidelines, all lake trout fillets from Lake Champlain analyzed for this study exceed the human health cancer screening value of 0.15 pg-TEQ/g ww by a substantial margin (average = 8.61 pg-TEQ/g ww). Dioxin-like trend data collected for Lake Champlain indicates that the mechanisms of contaminant uptake, trends, and yearly percent decline reflect those found in the Great Lakes.

Arsenic, chromium, and other elements of concern in fish from remote boreal lakes and rivers: Drivers of variation and implications for subsistence consumption

Eating fish provides numerous health benefits, but it is also a dominant pathway for human exposure to contaminants. Many studies have examined mercury (Hg) accumulation in fish, but fewer have considered other elements, such as arsenic (As) and chromium (Cr). Recently, freshwater fish from several pristine boreal systems across northern Ontario, Canada, have been reported with elevated concentrations of As and Cr for reasons that are not well understood. Our goal was to investigate the ecological and environmental influences over concentrations of As, Cr, and other elements in these fish to better understand what affects metal uptake and the risk to consumers. We measured 10 elements (including As, Cr, Hg) as well as carbon (δ¹³C), nitrogen (δ¹⁵N), and sulfur (δ³⁴S) stable isotopes in 388 fish from 25 lake and river sites across this remote region. These data were used to determine the effect of: 1) trophic ecology; and 2) watershed geology on piscine elemental content. Overall, most element concentrations were low, often below provincial advisory benchmarks (ABs). However, traces of Hg, As, Cr, and selenium (Se) were detected in most fish. Based on their exceedance of their respective ABs, the most restrictive elements on fish consumption in these boreal systems were Hg > As > Cr. Arsenic and Se, but not Cr concentrations were related to fish size and trophic ecology (inferred from δ¹³C and δ¹⁵N), suggesting bioaccumulation of the former elements. Fish with enriched δ³⁴S values, suggestive of anadromous behaviour, had marginally lower Hg but higher Se concentrations. Modeling results suggested a strong effect of site-specific factors, though we found weak trends between piscine elemental content and geological features (e.g., mafic intrusions), potentially due to the broad spatial scale of this study. Results from this study address gaps in our understanding of As and Cr bioaccumulation and will help to inform fish consumption guidelines.

Use of a Food Web Bioaccumulation Model to Uncover Spatially Integrated Polychlorinated Biphenyl Exposures in Detroit River Sport Fish

We applied and tested a bioenergetic-based, steady-state food web bioaccumulation model to predict polychlorinated biphenyl (PCB) exposures in sport fish of the Detroit River (USA-Canada), which is a Great Lakes area of concern. The PCB concentrations in the sediment and water of the river were found to exhibit high spatial variation. The previously contained areas of high contamination may have spread to adjacent food webs as a result of fish movements. This process may cause biased predictions in single-compartment bioaccumulation models. We performed multiple simulations and contrasted model predictions against a database of 1152 fish sample records comprising 19 sport fish species. The simulations evaluated 4 spatial scales (river-wide, 2-nation, 4-zone, and 6-zone models) to reveal how the spatial heterogeneity of contamination and species-specific movements contribute to variation in fish PCB exposures. The model testing demonstrated that the 2-nation model provided the most accurate global prediction of fish contamination. However, these improvements were not equally observed across all species. The model was subsequently calibrated for poorly performing species, by allowing cross-zone exposures, demonstrating the importance of accounting for specific ecological factors, such as fish movement, to improve PCB bioaccumulation prediction, especially in highly heterogeneous water systems. Environ Toxicol Chem 2019;38:2771-2784. © 2019 SETAC.

Dioxins in Great Lakes fish: Past, present and implications for future monitoring

Dioxins/furans are considered among the most toxic anthropogenic chemicals, and are ubiquitous in the environment including in the North American Great Lakes, which contain one fifth of the world's surface freshwater. Our exposure to dioxins/furans is mainly through contaminated diet. Elevated levels of dioxins/furans in Great Lakes fish have resulted in issuance of fish consumption advisories. Here we examine spatial/temporal trends of dioxins/furans in the edible portion (fillet) of fish from the Canadian waters of the Great Lakes using the data collected by the Province of Ontario, Canada. Our analyses show that the Toxic Equivalent (TEQ) dioxin/furan concentrations declined between 1989 and 2013 in Lake Trout from Lakes Ontario, Huron and Superior by 91%, 78% and 73%, respectively, but increased in Lake Whitefish from Lake Erie by 138%. An expanded dataset created by combining our data with historical Lake Ontario Lake Trout measurements from the literature showed a greater decline of >96% (from 64 to 2.3 pg/g) between 1977 and 2013. Measurements collected for 30 types of fish show overall low levels but local/regional concerns at some locations in Lakes Huron, Erie and Ontario. Dioxins/furans are globally present in foodstuff and "zero concentration" target is considered impractical. Based on the observations for the Great Lakes in the context of risk to human health from eating fish, it is concluded that comprehensive monitoring of dioxins/furans can be replaced with targeted locations and/or indicator species, and the saved resources can be more efficiently utilized for monitoring of other priority or emerging contaminants.

Perfluoroalkyl substances (PFASs) in edible fish species from Charleston Harbor and tributaries, South Carolina, United States: Exposure and risk assessment

Concentrations of 11 PFASs were determined in muscle and whole fish for six species collected from Charleston, South Carolina (SC) for the assessment of potential health risks to humans and wildlife. Across all species and capture locations, total PFAS levels in whole fish were significantly higher than fillets by a factor of two- to three-fold. Mean ∑PFAS concentrations varied from 12.7 to 33.0 ng/g wet weight (ww) in whole fish and 6.2-12.7 ng/g ww in fillets. For individual whole fish, ∑PFASs ranged from 12.7 ng/g ww in striped mullet to 85.4 ng/g ww in spotted seatrout, and in fillets individual values ranged from 6.2 ng/g ww in striped mullet to 27.9 ng/g ww in spot. The most abundant compound in each species was perfluorooctane sulfonate (PFOS), comprising 25.5-69.6% of the ∑PFASs. Striped mullet had significantly lower relative amounts of PFOS compared to all other species and higher relative amounts of PFUnDA compared to Atlantic croaker, spotted seatrout, and spot. Unlike whole fish, PFAS levels in fillets varied significantly by location with higher ∑PFOS from the Ashley River than the Cooper River and Charleston Harbor, which reflects the levels of PFASs contamination in these systems. In whole fish, differences in relative concentrations of PFOS, PFNA, and PFDA occurred by capture location, suggestive of different sources. PFOS concentrations for southern flounder and spotted seatrout fillets were within the advisory range to limit fish consumption to 4 meals a month. PFOS levels exceeded screening values to protect mammals in 83% of whole fish examined and represent a potential risk to wildlife predators such as dolphins.

Evaluation of an Educational Campaign to Improve the Conscious Consumption of Recreationally Caught Fish

Consumption guidelines are a common way of improving conscious consumption behaviors in areas where game fish are known to contain contaminants. However, guideline information can be difficult to distribute, and effectiveness difficult to measure. To increase the distribution and effectiveness of guideline information for the Detroit River, an educational campaign was launched in 2010, which included distribution of pamphlets with consumption information, posting of permanent signs at popular fishing locations, and hiring River Walkers to personally communicate with anglers. In 2013 and 2015, we conducted in-person surveys of active shoreline anglers to determine the effectiveness of education and outreach efforts. Results from the survey indicated that 55% of anglers were aware of the guidelines in 2013, and by 2015 36% had communicated the information to family or friends. However, anglers were often unwilling to reduce consumption of popular game species, despite high contaminant levels. Encouragingly, black anglers were most likely to supplement their diet with species lower in contaminants. Our results suggest that utilizing multiple educational strategies including reaching out directly to individual anglers may improve conscious consumption behavior among the targeted population, providing a template for educational campaigns to successfully target vulnerable populations.

Levels, patterns, trends and significance of polychlorinated naphthalenes (PCNs) in Great Lakes fish

Polychlorinated naphthalenes (PCNs) were introduced to market about a century ago and their production is thought to have ceased by the early 1980s. However, relatively limited knowledge exists on their abundance in the edible portion of a variety of Great Lakes fish to aid in understanding their potential risk to human consumers. We studied levels, patterns, trends and significance of PCNs in a total 470 fillet samples of 18 fish species collected from the Canadian waters of the Great Lakes between 2006 and 2013. A limited comparison of fillet and wholebody concentrations in Carp and Bullhead was also conducted. The ∑PCN ranged from 0.006-6.7ng/g wet weight (ww) and 0.15-190ng/g lipid weight (lw) with the dominant congeners being PCN-52/60 (34%), -42 (21%) and -66/67 (15%). The concentrations spatially varied in the order of the Detroit River>Lakes Erie>Ontario>Huron>Superior. PCN-66/67 was the dominating congener contributing on average 76-80% of toxic equivalent concentration (TEQ_PCN). Contribution of TEQ_PCN to TEQ_Total (TEQ_{Dioxins+Furans+dioxin-likePCBs+PCNs}) was mostly <15%, especially at higher TEQ_Total, and PCB-126 remains the major congener contributing to TEQ_Total. The congener pattern suggests that impurities in PCB formulations and thereby historical PCB contamination, instead of unintentional releases from industrial thermal processes, could be an important source of PCNs in Great Lakes fish. A limited temporal change analysis indicated declines in the levels of PCN-66/67 between 2006 and 2012, complemented by previously reported decrease in PCNs in Lake Ontario Lake Trout between 1979 and 2004. The whole body concentrations were 1.4-3.2 fold higher than the corresponding fillets of Carp and Bullhead. Overall, the study results suggest that only targeted monitoring of PCNs in Great Lakes fish, especially at the Detroit River, Lake Erie and Lake Ontario, is necessary to assess continued future improvements of this group of contaminants of concern.

Mercury Temporal Trends in Top Predator Fish of the Laurentian Great Lakes from 2004 to 2015: Are Concentrations Still Decreasing?

Mercury (Hg) concentration trends in top predator fish (lake trout and walleye) of the Great Lakes (GL) from 2004 to 2015 were determined by Kendall-Theil robust regression with a cluster-based age normalization method to control for the effect of changes in lake trophic status. When data from the GLs (except Lake Erie) are combined, a significant decreasing trend in the lake trout Hg concentrations was found between 2004 and 2015 with an annual decrease of 4.1% per year, consistent with the decline in regional atmospheric Hg emissions and water Hg concentrations. However, a breakpoint was detected with a significant decreasing slope (-8.1% per year) before the breakpoint (2010), and no trend after the breakpoint. When the lakes are examined individually, Lakes Superior and Huron, which are dominated by atmospheric Hg inputs and are more likely than the lower lakes to respond to declining emissions from areas surrounding the GL, have significant decreasing trends with rates between 5.2 and 7.8% per year from 2004 to 2015. These declining trends appear to be driven by decreasing regional atmospheric Hg emissions although they may be partly counterbalanced by other factors, including increasing local emissions, food web changes, eutrophication, and responses to global climate change. Lakes Michigan, Erie and Ontario may have been more impacted by these other factors and their trends changed from decreasing to non-decreasing or increasing in recent years.

Polybrominated diphenyl ethers (PBDEs) in Great Lakes fish: Levels, patterns, trends and implications for human exposure

Levels of polybrominated diphenyl ethers (PBDEs) were measured in edible portions of Great Lakes fish, with the goal of examining patterns/trends and evaluating implications for human exposure. A total of 470 fillets of 18 fish species collected from various parts of the Canadian waters of the Great Lakes between 2006 and 2013 were analyzed for 17 (expanded to 33 in 2009) PBDEs. For a limited number of species, fillet to whole body and fillet to eggs PBDEs were compared to examine pattern and concentration among tissue types. Levels and patterns of PBDEs varied dramatically within and among the 18 fish species. Bottom dwelling Common Carp (and White Sucker) exhibited the highest ∑PBDE levels (27-71ng/g). Lake Trout and Lake Whitefish from Lake Superior had higher levels than those from the other Great Lakes; otherwise the spatial trend was Lake Ontario≫Erie~Huron~Superior. The measured levels would result in restriction on consumption of only Common Carp from the Toronto waterfront area, which is in proximity to the most urbanised region on the Canadian side of the basin. Deca-BDE was the major congener in panfish, while BDE-47 was the major congener in top predators and its contribution to ∑PBDE increased with the contamination. Although ∑PBDE was related to fish length and lipid content when all measurements were pooled, the relationships were variable for individual sampling events (species/location/year). Whole body ∑PBDE for bottom dweller Brown Bullhead and Common Carp were 2.6-4.9 times greater and egg ∑PBDE for four fatty Salmon/Trout species were same to 6.5 times greater than the corresponding fillet concentrations. Levels of major lower brominated PBDEs appear to have declined in fish fillets by 46-74% between 2006/07 and 2012. Although PBDE in existing consumer items will remain in-use for a while, it will likely not result in appreciable accumulation of PBDEs in fish. Based on an overall assessment, regular monitoring of PBDEs in Great Lake fish can be replaced with targeted surveillance and focus can be shifted to other in-use flame retardants.