Persistent Organohalogens in Paired Fish Fillet and Eggs: Implications for Fish Consumption Advisories

Fish consumption is associated with both health benefits from high-quality proteins, minerals, vitamins, and fatty acids and risks from contaminants in fish. Fish consumption advisories are issued by many government agencies to keep exposure to contaminants at a safe level. Such advisories are typically based on fillets and neglect consumption of other fish parts such as eggs by certain subpopulations. To evaluate potential for dietary exposure to toxic organic chemicals via fish eggs, we analyzed polybrominated diphenyl ethers (PBDEs), polychlorinated naphthalenes (PCNs), dioxin-like polychlorinated biphenyls (dlPCBs), and polychlorinated dibenzodioxins/furans (PCDD/Fs) in paired fillet and eggs of fish from a tributary to Lake Ontario, one of the North American Great Lakes. All wet weight based concentrations in fish eggs were statistically higher than in the paired fillet samples. In fish eggs, concentrations of Σ₁₄PBDEs, Σ₁₄PCNs, and Σ₁₂dlPCBs were 41–118, 0.3–1.7, and 30–128 ng/g wet weight (ww), respectively; Σ₃PCDD/Fs and total (dlPCB+ PCDD/Fs) toxic equivalents (TEQs) were 4–22 and 9–54 pg/g ww, respectively. In fillet samples, Σ₁₄PBDEs, Σ₁₄PCNs, and Σ₁₂dlPCBs were 4–116, 0.05–0.66, and 6–85 ng/g, respectively; Σ₃PCDD/Fs and TEQs were 2–10 and 3.4–31 pg/g ww, respectively. In contrast, the fillets had higher lipid normalized concentrations than the paired egg samples, suggesting that these chemicals did not reach equilibrium between the fillets and eggs. Accordingly, measured concentrations in eggs or empirical relationship with fillet rather than prediction from equilibrium partitioning model should be used to evaluate contaminant exposure via consumption of fish eggs. For fatty fish from the lower Great Lakes area, we suggest one fillet meal be reduced from the advised fish consumption frequency for consumptions of 207 ± 37, 39 ± 2, 105 ± 51, and 119 ± 9 g fish eggs of brown trout, Chinook salmon, Coho salmon, and rainbow trout, respectively

Projecting Fish Mercury Levels in the Province of Ontario, Canada and the Implications for Fish and Human Health

Fish mercury levels appear to be increasing in Ontario, Canada, which covers a wide geographical area and contains about 250 000 lakes including a share of the North American Great Lakes. Here we project 2050 mercury levels in Ontario fish, using the recently measured levels and rates of changes observed during the last 15 years, and present potential implications for fish and human health. Percentage of northern Ontario waterbodies where sublethal effects of mercury on fish can occur may increase by 2050 from 60% to >98% for Walleye (WE), 44% to 59–70% for Northern Pike (NP), and 70% to 76–92% for Lake Trout (LT). Ontario waterbodies with <i>unrestricted</i> fish consumption advisories for the <i>general population</i> may deteriorate from 24–76% to <1–33% for WE, 40–95% to 1–93% for NP, and 39–89% to 18–86% for LT. Similarly, Ontario waterbodies with <i>do not eat</i> advisories for the <i>sensitive population</i> may increase from 32–84% to 73–100% for WE, 9–72% to 12–100% for NP, and 19–71% to 24–89% for LT. Risk to health of Ontario fish and humans consuming these fish may increase substantially over the next few decades if the increasing mercury trend continues and updated advisories based on continued monitoring are not issued/followed

Fish Mercury Levels Appear to Be Increasing Lately: A Report from 40 Years of Monitoring in the Province of Ontario, Canada

Recent mercury levels and trends reported for North America suggest a mixed (positive/negative) outlook for the environmental mercury problem. Using one of the largest consistent monitoring data sets in the world, here we present long-term and recent mercury trends in Walleye, Northern Pike, and Lake Trout from the Province of Ontario, Canada, which contains about one-third of the world’s fresh water and covers a wide geographical area (1.5 and 3 times larger than France and Germany, respectively). Overall, the results indicate that the fish mercury levels either declined (0.01–0.07 μg/g decade) or remained stable between the 1970s and 2012. The rates of mercury <i>decline</i> were substantially greater (mostly 0.05–0.31 μg/g decade) during the 1970s/80s possibly in response to reductions in mercury emissions. However, Walleye and Pike levels have generally <i>increased</i> (0.01–0.27 μg/g decade) in recent years (1995–2012), especially for northern Ontario (effect sizes for differences between the two periods ranged from 0.39 to 1.04). Proportions of Walleye and Pike locations showing a flat or increasing trend increased from 26–44% to 59–73% between the 1970s/80s and 1995–2012. Mercury emissions in North America have declined over the last few decades, and as such it is logical to expect recovery in fish mercury levels; however, other factors such as global emissions, climate change, invasive species, and local geochemistry are likely affecting the response time and magnitude

Evaluation and Interconversion of Various Indicator PCB Schemes for ∑PCB and Dioxin-Like PCB Toxic Equivalent Levels in Fish

Polychlorinated biphenyls (PCBs) remain chemicals of concern more than three decades after the ban on their production. Technical mixture-based total PCB measurements are unreliable due to weathering and degradation, while detailed full congener specific measurements can be time-consuming and costly for large studies. Measurements using a subset of indicator PCBs (iPCBs) have been considered appropriate; however, inclusion of different PCB congeners in various iPCB schemes makes it challenging to readily compare data. Here, using an extensive data set, we examine the performance of existing iPCB3 (PCB 138, 153, and 180), iPCB6 (iPCB3 plus 28, 52, and 101) and iPCB7 (iPCB6 plus 118) schemes, and new iPCB schemes in estimating total of PCB congeners (∑PCB) and dioxin-like PCB toxic equivalent (dlPCB-TEQ) concentrations in sport fish fillets and the whole body of juvenile fish. The coefficients of determination (<i>R</i>²) for regressions conducted using logarithmically transformed data suggest that inclusion of an increased number of PCBs in an iPCB improves relationship with ∑PCB but not dlPCB-TEQs. Overall, novel iPCB3 (PCB 95, 118, and 153), iPCB4 (iPCB3 plus 138) and iPCB5 (iPCB4 plus 110) presented in this study and existing iPCB6 and iPCB7 are the most optimal indicators, while the current iPCB3 should be avoided. Measurement of ∑PCB based on a more detailed analysis (50+ congeners) is also overall a good approach for assessing PCB contamination and to track PCB origin in fish. Relationships among the existing and new iPCB schemes have been presented to facilitate their interconversion. The iPCB6 equiv levels for the 6.5 and 10 pg/g benchmarks of dlPCB-TEQ₀₅ are about 50 and 120 ng/g ww, respectively, which are lower than the corresponding iPCB6 limits of 125 and 300 ng/g ww set by the European Union