Derek C. G. Muir

Measuring dissolved concentrations of polybrominated diphenyl ethers (PBDEs) and non-BDE flame retardants on a global scale provides critical insights into the effectiveness of the Stockholm Convention. In the present study, we deployed passive sampling devices at 43 seawater and freshwater sites covering 21 countries from 2016 to 2020. The detection frequencies were 20-94% for BDE congeners and 33-42% for dechlorane plus, higher than those (0-20%) for other target compounds. The median concentrations of dissolved Σ₉PBDE (sum of BDE-28, -47, -66, -85, -99, -100, -153, -154, and -183) were 0.28 and 0.64 pg L^-1 in seawater and freshwater, respectively. The concentrations of dissolved Σ₉PBDE, along with published data, slightly increased before 2016 and remained steady from 2016 to 2018, indicating delayed effects of the global phaseout of technical Penta- and Octa-BDEs. The log-transformed concentrations of individual BDE congeners were better correlated with regional gross domestic product than with population density. The potential ecological risk of BDE-47 was low, and there was a lack of key risk indicators for other compounds. The present study documented the delayed response of the aquatic environment to the regulatory actions on reducing PBDE emissions.

Molecular docking for high throughput screening binding of chemicals to functional protein related to health impact.

The monitoring of contaminants in Arctic wildlife is mainly designed for long-range transported chemicals and supports international initiatives to mitigate global threats from chemical pollution. As human activities increase in the Arctic, the question of potential impacts of local pollution on wildlife exposure has emerged. In this study, we examined the current monitoring practices and the state of knowledge of pollutants in Arctic ringed seals (Pusa hispida) from Canada, Greenland, Norway, Russia, and Alaska. We complemented this synthesis with a case study of ringed seal exposure from different locations in Canada (2008–2022) to test the potential influence of local pollution sources. Multivariate constrained ordination was applied to examine the effects of ringed seals biological metrics (age, sex, length, and stable isotopes as dietary proxies), settlement size, and potential local contaminant sources (infrastructures, industries) on contaminant concentrations [polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), per- and polyfluoroalkyl substances (PFAS), polybrominated diphenyl ethers (PBDEs), trace elements] in seals. Results indicated that biological data, location, local source variables and sampling year explained 8.4% (PBDEs), 31.8% (OCPs), 41.0% (trace elements), 45.1% (PFAS), and 65.8% (PCBs) of the contaminant variation in seals through time. Variation partitioning showed that, out of these percentages, local source variables uniquely explained less than 4% of variation for PBDEs, OCPs, trace elements and PFAS compared to 17.5% for PCBs. Results suggest an effect of local contaminant sources that is tightly linked to study site characteristics as well as seal biology. Local sources should be identified and assessed at sampling sites close to communities to ensure efficient contaminant monitoring and effectiveness of mitigation measures.

Local sources of persistent organic pollutants (POPs) and Chemicals of Emerging Arctic Concern (CEACs) from use in communities, shipping, and industrial activity contribute to contamination as does long-range environmental transport. Increased human activity in the Arctic as the climate warms may enhance the significance of local sources. Furthermore, climate change may lead to secondary sources of POPs and CEACs from existing reservoirs in the Arctic. This review examines the emerging evidence for releases from these secondary sources of formerly deposited POPs and CEACs as the Arctic climate warms and the potential for future releases with increased infrastructure development and economic activity. Arctic permafrost degradation represents an important source of natural and anthropogenic polycyclic aromatic hydrocarbons (PAHs), and indications exist of releases of POPs related to permafrost thaw, from previous deposition as well as waste sites. Deposition of POPs and some CEACs to Arctic glaciers is relatively well studied while fewer studies explore the impacts of remobilization. Expansion of economic development has the potential for increasing emissions or creating new sources of CEACs in the Arctic. The predicted northward expansion of agriculture, aquaculture, and ship traffic could bring increased emissions of CEACs to northern waters, including pesticides not previously used in the Arctic. Increased industrial chemical use, e.g. fire-fighting foams, flame retardants, lubricant and plastic additives, is likely to occur following the expansion of infrastructure such as airports, seaports, mining, and oil and gas development. While PAHs are relatively well-studied, there is an urgent need for environmental measurements and modelling of emissions of CEACs associated with the expansion of economic activity in the Arctic as well as to predict the future release of legacy POPs from secondary sources, particularly from permafrost.

Benzotriazoles (BZTs) and benzothiazoles (BTs) are high-production-volume chemicals utilized in many different commercial products and industrial processes, such as metal corrosion inhibitors, vulcanization accelerators, plastic-associated UV stabilizers, and pharmaceutical precursors. This study assessed age, gender, and temporal trends of BZTs and BTs in deidentified surplus pathology urine samples, pooled and stratified by age, gender, and sample collection year from a general Australian population (168 pools representing 16,800 individuals). Tolyltriazole (TTri), 5,6-dimethyl-1H-benzotriazole (DMBZT), 1,3-benzothiazole (BTH), 2-hydroxybenzothiazole (2-OH-BTH), and 2-aminobenzothiazole (2-amino-BTH) were detected in >50% of the pools. TTri was frequently detected in pooled samples representing <= 45-year-olds (both genders). Concentrations of DMBZT, BTH (females), 2-OH-BTH, and 2-amino-BTH (females) increased with age significantly, with adults (>15 years old) showing higher levels than children (<= 15 years old). Gender differences in DMBZT concentrations (females > males) were observed across all sampling years and only in some for TTri (males > females: >45 years old), BTH (females > males), and 2-amino-BTH (males > females). A temporal increase in BTH, 2-OH-BTH, and 2-amino-BTH levels within the studied period (2012-2023) has been observed. Our findings suggest ongoing exposure of the Australian general population to BZTs and BTs, highlighting age, gender, and temporal trends of these compounds as measured via their urinary concentrations.

Polycyclic aromatic hydrocarbons (PAHs), released from petrogenic, pyrogenic or diagenetic sources (degradation of wood materials), are of global concern due to their adverse effects, and potential for long-range transport. While dissolved PAHs have been frequently reported in the literature, there has been no consistent approach of sampling across water bodies. Passive samplers from the AQUA/GAPS-MONET initiative were deployed at 46 sites (28 marine and 18 freshwater), and analyzed for 28 PAHs and six polycyclic musks (PCMs) centrally. Freely dissolved PAH concentrations were dominated by phenanthrene (mean concentration 1500 pg L^-1; median 530 pg L^-1) and other low molecular weight compounds. Greatest concentrations of phenanthrene, fluoranthene, and pyrene were typically from the same sites, mostly in Europe and North America. Of the PCMs, only galaxolide (72% of samples) and tonalide (61%) were regularly detected, and were significantly cross-correlated. Benchmarking of PAHs relative to penta- and hexachlorobenzene confirmed that the most remote sites (Arctic, Antarctic, and mountain lakes) displayed below average PAH concentrations. Concentrations of 11 of 28 PAHs, galaxolide and tonalide were positively correlated (P < 0.05) with population density within a radius of 5 km of the sampling site. Characteristic PAH ratios gave conflicting results, likely reflecting multiple PAH sources and postemission changes.

An ice core dated 1967–2016 represents the longest Arctic deposition record for perfluoroalkylcarboxylic acids (PFCAs) and the longest global record of perfluoroalkylsulfonic acids (PFSAs), providing unique insights into their long-range transport.

Bottlenose dolphins (Tursiops truncatus) are keystone and sentinel species in the world's oceans. We studied correlations between per- and polyfluoroalkyl substances (PFAS) and their stress axis. We investigated associations between plasma biomarkers of 12 different PFAS variants and three cortisol pools (total, bound, and free) in wild T. truncatus from estuarine waters of Charleston, South Carolina (n = 115) and Indian River Lagoon, Florida (n = 178) from 2003 to 2006, 2010-2013, and 2015. All PFAS and total cortisol levels for these dolphins were previously reported; bound cortisol levels and free cortisol calculations have not been previously reported. We tested null hypotheses that levels of each PFAS were not correlated with those of each cortisol pool. Free cortisol levels were lower when PFOS, PFOA, and PFHxS biomarker levels were higher, but free cortisol levels were higher when PFTriA was higher. Bound cortisol levels were higher when there were higher PFDA, PFDoDA, PFDS, PFTeA, and PFUnDA biomarkers. Total cortisol was higher when PFOA was lower, but total cortisol was higher when PFDA, PFDoDA, PFTeA, and PFTriA were higher. Additional analyses indicated sex and age trends, as well as heterogeneity of effects from the covariates carbon chain length and PFAS class. Although this is a cross-sectional observational study and, therefore, could reflect cortisol impacts on PFAS toxicokinetics, these correlations are suggestive that PFAS impacts the stress axis in T. truncatus. However, if PFAS do impact the stress axis of dolphins, it is specific to the chemical structure, and could affect the individual pools of cortisol differently. It is critical to conduct long-term studies on these dolphins and to compare them to populations that have no or little expose to PFAS.