Isomer-Specific Hexabromocyclododecane (HBCDD) Levels in Top Predator Fish from Across Canada and 36-Year Temporal Trends in Lake Ontario

Exposure of Peregrine Falcons to Halogenated Flame Retardants: A 30 Year Retrospective Biomonitoring Study across North America

Compared to aquatic ecosystem, terrestrial systems have been subjected to fewer investigations on the exposure to halogenated flame retardants (HFRs). Our study utilized peregrine falcon eggs collected from multiple habitats across North America to retrospectively explore both spatial distribution and temporal changes in legacy (e.g., polybrominated diphenyl ethers) and alternative HFRs over a 30 year period (1984-2016). The results reveal intensive HFR exposure in terrestrial ecosystems and chemical-specific spatiotemporal distribution patterns. The correlations between egg levels of the selected HFRs and human population density clearly illustrated a significant urban influence on the exposure of this wildlife species to these HFRs and subsequent maternal transfer to their eggs. Temporal analyses suggest that, unlike aquatic systems, terrestrial ecosystems may undergo continual exposure to consistently high levels of legacy HFRs for a long period of time. Our findings collectively highlight the effectiveness of using peregrine eggs to monitor terrestrial exposure to HFRs and other bioaccumulative chemicals and the need for continuous monitoring of HFRs in terrestrial ecosystems.

Varying Diet Composition Causes Striking Differences in Legacy and Emerging Contaminant Concentrations in Killer Whales across the North Atlantic

Lipophilic persistent organic pollutants (POPs) tend to biomagnify in food chains, resulting in higher concentrations in species such as killer whales (Orcinus orca) feeding on marine mammals compared to those consuming fish. Advancements in dietary studies include the use of quantitative fatty acid signature analysis (QFASA) and differentiation of feeding habits within and between populations of North Atlantic (NA) killer whales. This comprehensive study assessed the concentrations of legacy and emerging POPs in 162 killer whales from across the NA. We report significantly higher mean levels of polychlorinated biphenyls (PCBs), organochlorine pesticides, and flame retardants in Western NA killer whales compared to those of Eastern NA conspecifics. Mean ∑PCBs ranged from ∼100 mg/kg lipid weight (lw) in the Western NA (Canadian Arctic, Eastern Canada) to ∼50 mg/kg lw in the mid-NA (Greenland, Iceland) to ∼10 mg/kg lw in the Eastern NA (Norway, Faroe Islands). The observed variations in contaminant levels were strongly correlated with diet composition across locations (inferred from QFASA), emphasizing that diet and not environmental variation in contaminant concentrations among locations is crucial in assessing contaminant-associated health risks in killer whales. These findings highlight the urgency for implementing enhanced measures to safely dispose of POP-contaminated waste, prevent further environmental contamination, and mitigate the release of newer and potentially harmful contaminants.

Temporal Trends of Legacy and Current-Use Halogenated Flame Retardants in Lake Ontario in Relation to Atmospheric Loadings, Sources, and Environmental Fate

Since the phase-out of polybrominated diphenyl ethers (PBDEs), large amounts of alternative halogenated flame retardants (AHFRs) have been introduced to the market. Due to their persistence and toxicity, halogenated flame retardants (HFRs) have become a concern for the ecosystem and human health. However, there remains limited assessment of the atmospheric loadings, sources, and environmental fate of HFRs in Lake Ontario, which receives urban-related inputs and cumulative chemical inputs from the upstream Great Lakes from Canada and the United States. We combined long-term measurements with a modified multimedia model based on site-specific environmental parameters from Lake Ontario to understand the trends and fate of HFRs. All HFRs were detected in the air, precipitation, lake trout, and herring gull egg samples throughout the sampling periods. General decreasing trends were found for PBDEs, while the temporal trends for AHFRs were not clear. Physical-chemical properties and emissions significantly influence the levels, profiles, and trends. Using the probabilistic modeling, HFR concentrations in lake water and sediment were predicted to be close to the measurement, suggesting a good performance for the modified model. The loadings from tributaries and wastewater effluent were the primary input pathways. Transformations in the water and sedimentation were estimated to be the dominant output pathway for the three HFRs.

Levels, distribution and risk assessment of hexabromocyclododecane (HBCD) in fish in Xiamen, China

In this study, hexabromocyclododecane (HBCD) was detected in 114 fish samples collected from 6 administrative regions of Xiamen city, China. HBCD amounts ranged between ND (not detected) and 2.216 ng g^-1 ww (mean, 0.127 ± 0.318 ng g^-1 ww). Besides, α-HBCD was the main diastereoisomer in these fish specimens, followed by β-HBCD. Meanwhile, γ-HBCD was not detected in any of the samples. Significant differences were recorded among fish species. The results indicated that the levels and detection rates of HBCD were higher in Trachinotus ovatus compared with other aquatic organisms. Therefore, Trachinotus ovatus could be used as a marine biological indicator of HBCD. Within the regions investigated, Siming was significantly different from Jimei, Haicang, and Xiang'an. The spatial distribution of HBCD concentrations indicated higher mean levels in samples collected from Haicang, Jimei, and Xiang'an, respectively, with the highest detection rates in Jimei and Xiang'an, which might be related to geographical location and intense industrial and urban activities. Estimation of daily HBCD intake was performed according to fish consumption in Xiamen residents. The medium bound HBCD amounts in fish were approximately 0.073 and 0.088 ng kg bw^-1d^-1 for male and female residents of Xiamen, respectively. Exposure doses of HBCD indicated no health concern for Xiamen residents.

Update of the risk assessment of hexabromocyclododecanes (HBCDDs) in food

The European Commission asked EFSA to update its 2011 risk assessment on hexabromocyclododecanes (HBCDDs) in food. HBCDDs, predominantly mixtures of the stereoisomers α-, β- and γ-HBCDD, were widely used additive flame retardants. Concern has been raised because of the occurrence of HBCDDs in the environment, food and in humans. Main targets for toxicity are neurodevelopment, the liver, thyroid hormone homeostasis and the reproductive and immune systems. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour in mice can be considered the critical effects. Based on effects on spontaneous behaviour in mice, the Panel identified a lowest observed adverse effect level (LOAEL) of 0.9 mg/kg body weight (bw) as the Reference Point, corresponding to a body burden of 0.75 mg/kg bw. The chronic intake that would lead to the same body burden in humans was calculated to be 2.35 μg/kg bw per day. The derivation of a health-based guidance value (HBGV) was not considered appropriate. Instead, the margin of exposure (MOE) approach was applied to assess possible health concerns. Over 6,000 analytical results for HBCDDs in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary LB exposure to HBCDDs were fish meat, eggs, livestock meat and poultry. The CONTAM Panel concluded that the resulting MOE values support the conclusion that current dietary exposure to HBCDDs across European countries does not raise a health concern. An exception is breastfed infants with high milk consumption, for which the lowest MOE values may raise a health concern.

Spatiotemporal characteristics and pollution level of brominated flame retardants in bivalves from Fujian southern coastal areas

The concentration and spatiotemporal distribution of brominated flame retardants (BFRs), including hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA), were analyzed in bivalves from Fujian southern coastal areas. The concentrations of HBCD and TBBPA ranged from ND (not detected) to 5.540 ng·g-1 (ww) (median of 0.111 ng·g-1) and ND to 0.962 ng·g-1 (ww) (median of ND), respectively. In addition, α-HBCD was found as the predominant diastereoisomer in all the studied samples, followed by β-HBCD and γ-HBCD. The spatial distribution of BFRs showed a peak distribution, with the content being higher in the marine environment of Xiamen and Quanzhou, in South Fujian, and lower toward the marine environment of Zhangzhou, and Putian. BFRs contamination level was correlated to the bay geographical location and proximity to local industries. Furthermore, the results of the study showed a seasonal variation pattern: summer > autumn > spring > winter. This study provides base information on the contamination status of these BFRs in the marine environment of southern Fujian.

Concentrations and Long-Term Temporal Trends of Hexabromocyclododecanes (HBCDD) in Lake Trout and Walleye from the Great Lakes

Hexabromocyclododecane (HBCDD) is a hazardous, persistent, bioaccumlative brominated flame retardant. To investigate how its use has affected the Great Lakes, total HBCDD (∑HBCDD) concentrations and temporal trends in homogenized whole fish samples from the Great Lakes region (1978 to 2016) were determined. ∑HBCDD concentrations (ng/g ww) for each lake are Erie (0.49-2.60), Ontario (3.12-8.90), Michigan (3.91-9.01), Superior (5.69-13.1), and Huron (5.57-13.7). Early years (1978 to 1992) showed no significant trend. However, recent trends (2004 to 2016) suggest concentrations are increasing in Lakes Erie and Ontario, decreasing in Lakes Superior and Michigan, and not changing in Lake Huron. Decreasing trends for Lakes Superior and Michigan are likely the result of decreased usage of the compound globally, regionally, and locally. For the other lakes, increasing or zero trends are consistent with food web changes due to invasive species and climate change, which has caused more intense storms and less ice cover leading to increased sediment resuspension.

Tetrabromobisphenol A and hexabromocyclododecane isomers in breast milk from the general population in Beijing, China: Contamination levels, temporal trends, nursing infant's daily intake, and risk assessment

Two currently used brominated flame retardants (BFRs), α, β, γ-hexabromocyclododecane (HBCDD) and tetrabromobisphenol A (TBBPA), were measured in 111 breast milk samples from 37 Beijing mothers. Each mother provided one milk sample per month for 3 months. HBCDD was detected in almost all samples, and the median level reached 5.67 ng g^-1 lipid weight (lw). α- HBCDD was the most abundant isomer (median: 4.23 ng g^-1 lw), followed by γ- and β-HBCDD. For TBBPA, a relatively lower detecting frequency (64%) and contamination level (median: 1.57 ng g^-1 lw) were obtained. A comparison to our previous study revealed that the occurrence of TBBPA and HBCDD in Beijing human milk significantly rose from 2011 to 2014, whereas another commonly used class of BFRs, polybrominated diphenyl ethers (PBDEs), showed significantly decreased during this period. However, a comparison among currently used BFRs showed that levels of some BFRs, such as HBCDD, surpassed those of PBDEs, which indicated that PBDEs were no longer the primarily used BFR in China. However, no significant temporal trends for BFR levels were observed over the 3 months of lactation. Daily intakes of TBBPA and HBCDD were calculated for nursing infants and the median TBBPA and HBCDD intakes via breastfeeding were 6.62 and 26.4 ng kg^-1 bw day^-1, respectively. These values were several times higher than those for adults via food consumption. However, risk assessment using the margin of exposure approach indicated that intakes of TBBPA and HBCDD via breastfeeding can scarcely cause significant health risks to infants.

Bioaccumulation and biomagnification of hexabromocyclododecane (HBCDD) in insect-dominated food webs from a former e-waste recycling site in South China

Hexabromocyclododecane (HBCDD) has frequently been detected in wildlife. However, there is limited research on its bioaccumulation and biomagnification in insect-dominated aquatic and terrestrial food webs. This study investigated the occurrence of HBCDD in insects and their predators collected from a former e-waste contaminated pond and its surrounding region. The concentrations of ƩHBCDD (sum concentrations of α-, β-, and γ-HBCDDs) ranged from nd to 179 ng g^-1 lipid weight. α-HBCDD was the predominant diastereoisomer in all biotic samples, and the contribution of α-HBCDD was higher in predators than in prey insects. A significantly positive linear relationship was found between ƩHBCDD concentrations (lipid weight) and trophic levels based on δ¹⁵N in aquatic organisms (p < 0.05), while trophic dilution was observed in the terrestrial food web. This result indicates an opposite trophic transfer tendency of HBCDD in terrestrial and aquatic ecosystems. The biomagnification factor (BMF) for α-HBCDD was higher in terrestrial birds (2.03) than in frogs (0.29), toads (0.85), and lizards (0.63). This may be due to differences between poikilotherms and homeotherms in terrestrial ecosystems.

Elucidating the Variability in the Hexabromocyclododecane Diastereomer Profile in the Global Environment

Hexabromocyclododecane (HBCDD) is a hazardous flame retardant subject to international regulation. Whereas γ-HBCDD is a dominant component in the technical HBCDD mixture, the diastereomer profile in environmental samples shows substantial temporal and spatial variations, ranging from γ- to α-HBCDD-dominant. To explain such variability, we simulate the global emissions and fate of HBCDD diastereomers, using a dynamic substance flow analysis model (CiP-CAFE) coupled to a multimedia environmental fate model (BETR-Global). Our modeling results indicate that, as of 2015, 340-1000 tonnes of HBCDD have been emitted globally, with slightly more γ-HBCDD (50%-65%) than α-HBCDD (30%-50%). Emissions of γ-HBCDD primarily originate from production and other industrial processes, whereas those of α-HBCDD are mainly associated with the use and end-of-life disposal of HBCDD-containing products. Presently, α-HBCDD dominates the contamination in the air of populated areas, while γ-HBCDD is more abundant in remote background areas and in regions with HCBDD production and processing facilities. Globally, the relative abundance of α-HBCDD is anticipated to increase after production of HBCDD is banned. Due to isomerization, α-HBCDD accumulates to a larger extent than γ-HBCDD in Arctic surface media. Since α-HBCDD is more persistent and bioaccumulative than other diastereomers, isomerization has bearing on the potential environmental and health impacts on a global scale.