Benzotriazole ultraviolet stabilizers (BZT-UVs) are emerging contaminants whose presence in airborne dust, aerosol particles, and consumer products strongly suggests multiphase chemistry is important for their environmental fate. The first multiphase experiments of nm-thick films of 2-(2H-1,2,3-Benzotriazol-2-yl)-4,6-bis(2-methylbutan-2-yl)phenol (UV-328) with gas phase oxidants (OH, O3) were conducted in a flow tube, with transformation products identified using liquid chromatography-high resolution mass spectrometry. With an OH exposure of ∼0.8 ppt for 3 days, oxidation products were identified with either 1 or 2 oxygen atoms added to the parent molecule and benzotriazole (BT). Reactions with O3 at 250 ppb for 3 days produced only benzotriazole, whereas experiments at a much higher exposure led to a variety of ring-opened products with up to 4 oxygen atoms added to the parent molecule, including carboxylic acid and aldehyde groups. To act as a guide for the oxidative environmental fate of BZT-UVs, the observed products were used to propose reaction pathways for UV-328 with OH and O3. Analysis of a used traffic cone plastic sample identified UV-328 and two OH radical transformation products. This study identifies benzotriazole (C6H5N3) as a multiphase transformation product for BZT-UVs.

Passive air sampling (PAS) using polyurethane foam (PUF) disks has been used to monitor air contamination from current-use pesticides (CUPs). However, its accuracy has hardly been studied. To assess effectiveness of PUF-PAS for measuring CUPs, 18 PUF-PAS devices were deployed for 1-6 weeks at a school near banana plantations in Costa Rica. Simultaneously, every week air was sampled with high and low volume active air samplers (AAS) for 24 h and 7 days, respectively. Extracts were analyzed using microwave-assisted extraction and LC-MS/MS. Nine CUPs (ethoprophos, difenoconazole, cadusafos, chlorpyrifos, fenpropidin, fenpropimorph, pyrimethanil, spiroxamine, and terbufos) were detected by both PAS and AAS. Concentrations were highest for pyrimethanil (34.3 ng/m3) followed by fenpropidin (9.0 ng/m3) and terbufos (8.4 ng/m3). An average sampling rate of 3.4 m3/day was estimated for PUF-PAS using Lo-AAS data, like previously reported in literature. After 3 weeks of deployment, PUF-PAS detected eight out of nine pesticides, similar to the AAS methods. However, after 4 weeks of deployment, substantial losses (≥50%) were observed for all CUPs except pyrimethanil, likely due to oxidative degradation. We therefore recommend a maximum deployment time of 3 weeks under tropical conditions. These findings support PUF-PAS as a cost-effective alternative for AAS in tropical regions.

Food trade has reshaped global food systems by decoupling where food is produced from where it is consumed, raising concerns about how chemical exposure and responsibility are redistributed across borders. We review research at this intersection, drawing on studies that span multiple chemical classes, food commodities, spatial scales, and disciplinary traditions. The evidence base is rapidly expanding, and studies differ in how contaminants are represented, exposure quantified, and trade conceptualized, limiting comparability and policy relevance. The reviewed studies show that food trade can increase or reduce exposure depending on commodity origin, contamination level, consumption pattern, and substitution of domestic foods. Responsibility attribution, however, remains underdeveloped. Upstream chemical pressure can be allocated to final demand, but this allocation is rarely connected to receptor exposure. Exposure can be quantified, but it is rarely linked to the demand or production activity that generated the chemical use or release. As chemical pollution increasingly constrains the safe operating space of food systems, integrating embedded contaminant pathways with embodied accounting is needed to avoid confusing residue transfer with burden displacement or exposure reduction with responsibility shifting, and to guide governance in an interconnected global economy.

AbstractAirborne pesticide contamination at schools near intensive agriculture remains poorly characterized, particularly with respect to spatial and long-term temporal variability, despite its importance for assessing children’s pesticide exposure. We characterized airborne pesticide contamination at 37 rural schools in Matina, Costa Rica, an area of intensive banana production.Passive polyurethane foam air samplers were deployed for four weeks in 2019 and 2022. At a subset of 11 schools, measurements from 2010–2011, 2019, and 2022 enabled assessment of changes spanning more than a decade. We used mixed-effects linear models and geospatial analyses to evaluate temporal changes, associations with proximity to banana plantations, and spatial contamination patterns.Seventeen pesticides were detected, including nine fungicides, six insecticides, one herbicide, and one insecticide synergist. Nearly all samples (≥95%) contained at least five pesticides, with a median of nine pesticides per sample, indicating widespread co-occurrence of airborne pesticides in school environments. Categorical measures of proximity to banana plantations provided better model fit for fungicide concentrations than continuous measures. Compared with schools located within 100 m of banana plantations, fungicide concentrations were 58–88% lower at schools >400 m away, whereas concentrations at schools 100–400 m away were similar. Among the 11 repeatedly sampled schools, chlorpyrifos concentrations declined over time, pyrimethanil concentrations increased, and ethoprophos concentrations decreased initially and subsequently increased. Spatial contamination patterns differed among pesticides and between sampling periods.Airborne contamination by multiple pesticides was widespread at rural schools near banana plantations, with concentrations varying by plantation proximity, pesticide, and sampling period. Our findings suggest categorical distance measures may better characterize spatial variation in contamination than continuous measures. Changes observed at repeatedly sampled schools further demonstrate that contamination patterns are not temporally stable, underscoring the value of repeated environmental monitoring for characterizing pesticide contamination in communities near intensive agriculture.

Humans are exposed to complex mixtures of environmental chemicals, raising two questions: how many chemicals may elicit toxicity at realistic exposure levels, and whether toxicity is driven by the mixture effects of numerous chemicals. Here, we propose a probabilistic model addressing both questions using large-scale chemical–protein interaction data from affinity selection mass spectrometry. Across 3.51 million interactions from 407,271 compounds and 110 human proteins, we observe a log-log relationship between binding probability and binding affinity. This model predicts that human toxicity is dominated by a small number (~100) of potent chemicals and their analogues under a Pareto law, rather than by the cumulative contributions of numerous weak compounds. These findings challenge the long-standing emphasis on mixture effects and instead support a ‘key driver’ hypothesis.

In a globally connected world, chemical production and the manufacturing, use, and end-of-life disposal of products may occur in different countries. Whereas this can lower emissions of toxic organic chemical and therefore human and wildlife exposures in countries with consumer economies, manufacturing countries and those involved in the handling of waste are "virtually importing" emissions and exposures. Here, we illustrate the feasibility of characterizing toxic chemical emissions, exposures, and health risks embodied in international trade using the example of the fungicide chlorothalonil applied in the cultivation of bananas in Costa Rica, which are exported to Europe and North America. The international virtual flow of chlorothalonil embodied in the banana trade is in the 100s of tonnes per year and exceeds by many orders of magnitude the flows via long-range atmospheric transport and as residue in the traded commodity. Quantifying the flows of toxic chemicals embodied in international trade in chemicals, products, food, feed, and waste, and the resulting exposure and health effects, is key to revealing the responsibility of consumers for the risk associated with toxic chemical use.

The atmospheric gas phase is underrepresented in non-target screening of environmental organic chemicals, partly due to limited evidence on sorbent suitability. Here, we developed and optimized a workflow for non-target analysis (NTA) of styrene-divinylbenzene copolymeric (XAD) resin-based air samples that involves both gas (GC) and liquid chromatography (LC) high-resolution mass spectrometry (HRMS). More than 60 000 features were detected in passive air samplers (PAS) deployed over 4 to 48 weeks. Of ~34 000 features retained after blank filtration, ~14 000 (41%) showed an increasing signal with deployment time, suggesting that they represent substances with volatility and degradability sufficiently low for accumulation on XAD without substantial re-evaporation or degradation during the prolonged sampling period. Such linear uptake is a prerequisite for comparing PAS-derived signals across deployments and chemical classes. Chemical identification by reference standards (level 1) and spectral library matching (level 2) initially identified/annotated 116 compounds, many of which were bioactive and/or brown carbon species. Combining advanced downstream computational workflows of feature-based molecular networking (FBMN) and in silico prediction (NAP/MetFrag) allowed for the structural annotation (level 3) of >8300 LC-HRMS features, including several compounds of natural and anthropogenic origin which were not previously reported in the atmospheric gas phase. Several long-chain fatty acids showed rapid early increases implausible with atmospheric origins and are likely to originate from microbial growth on the resin. Overall, our results demonstrated that XAD is a sorbent compatible with comprehensive NTA and suitable for time-integrated passive sampling of a diverse range of gas-phase organic chemicals from the atmosphere.

Background: Scientific and regulatory efforts have been taken in the past 60 years to tackle chemical pollution. Evaluating the benefits and efficacy of chemical regulations is essential for convincing society of the necessity of such efforts. This study quantifies chemical pollution and exposure in a hypothetical world without chemical regulation, and assesses whether it would have led to a transgression of the safe operating space for humanity. Methods: Using polychlorinated biphenyls (PCBs) as indicator chemicals, we reconstruct their production and use in the absence of control measures. Based on estimations with a mechanistic modelling framework comprising the models CiP-CAFE, BETR-Global, and PROTEX, we contrast “historically observed” global emissions, environmental burdens, human exposures, and health hazards with those in a “world avoided” scenario. Findings: Without control measures, we estimate 6-fold higher cumulative global PCB emissions from 1930 to 2025, and a 7-fold higher global environmental PCB burden by 2025. The relative difference is particularly large in oceanic, less industrialized, and polar regions. A 34-fold higher human exposure suggests that at least 40% of the human population would have experienced average exposure exceeding a health-based threshold by 2025. Interpretation: The counterfactual analysis indicates that national and global regulatory measures targeting chemical pollution have prevented the transgression of a planetary boundary for novel entities. Simulations of the global risks posed by toxic chemicals under different regulatory scenarios can inform the delineation of the safe operating space.

Interest in per- and polyfluoroalkyl substances (PFASs) in the remote atmosphere now extends to perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs) with short (nC < 4), medium (3 < nC < 13), and long (nC > 12) alkyl chains. A liquid chromatography-mass spectrometry method for the combined analysis of PFASs of variable chain length was applied to 204 high volume active air samples collected at Alert, Nunavut (82° 30' N 62° 20' W) between March 2014 and October 2023. Short-chain PFASs (scPFASs) were detected frequently (>75%) and at the highest median concentrations (trifluoroacetic acid (TFA): 20 pg/m3, perfluoropropionic acid (PFPrA): 1.1 pg/m3, perfluorobutanoic acid (PFBA): 3.7 pg/m3), while nC > 10 PFAS were sparsely detected (detection frequency [DF] < 20%). Using a suspect-screening approach, hexafluoro-2,2-propanediol (HF2OH) and hexafluoroisopropanol (HFIPA) were confirmed in Arctic air at DF exceeding 75%. We find that concentrations of TFA and HF2OH were significantly correlated with temperature and increased during snowmelt periods, suggesting local emission or precursor release followed by degradation processes. The modified OECD LRTP and Pov assessment tool supported the potential of HFIPA and HF2OH to undergo long-range atmospheric transport. Time trend analysis reveals that after a short period of stable or declining levels in the mid-2010s, concentrations of PFBA, PFOA, and PFOS in Arctic air are increasing again since 2019, which may be a useful consideration when evaluating the effectiveness of the Stockholm Convention's listing of PFOA and PFOS.

One of the challenges arising during non-targeted analysis (NTA) is that the number of detected chemical features is generally too large for detailed processing and interpretation. Here, we illustrate how the analysis of spatial trends in peak intensities can be an effective tool to prioritize chemical features in NTA. Specifically, features detected by gas chromatography and high-resolution mass spectrometry in soil and air samples, collected along an altitudinal transect on an urban mountain in Canada, were successfully grouped into different categories based on spatial trends with site altitude. The motivation was to identify features whose abundance increases in soil with increasing elevation, as the ability for amplification at higher elevations could characterize contaminants of concern to mountain ecosystems. Potential matching candidates were first selected by comparing empirically detected accurate masses and isotope distributions of chemical features with those in chemical databases. These potential candidates were then ranked by comparing MSMS spectra with fragments predicted in silico. Several highly ranked matches, as well as structurally related compounds, which were largely halogenated methoxylated benzenes and organochlorine pesticides, were then subjected to targeted analysis with analytical standards. Several of these compounds, including pentachloroanisole, tricamba, and 3,4,5-trichloroveratrole, were identified as having spatial patterns consistent with mountain cold-trapping, as evidenced by organic carbon-normalized soil concentrations that show a significant increase with elevation. Our study clearly demonstrated that spatial trend analysis holds considerable promise as a tool to guide chemical identification and prioritization during NTA.

The pervasive presence of microplastic in food raises the question of how this presence influences the uptake of organic contaminants from the gastrointestinal tract. Depending on the relative contamination of diet and microplastics, the latter can act either as a vector of contaminants facilitating biological uptake or as a contaminant sink whose sorptive capacity does not diminish during digestion. A comprehensive understanding of these effects ultimately requires the quantification of the effect of microplastics on the thermodynamic driving force responsible for diffusion from the gut lumen to the tissues of an organism. Using silicone-based equilibrium sampling, we quantified the effect of polyvinyl chloride (PVC) microplastics on the fugacity of polychlorinated biphenyls (PCBs) and two polymer additives in dietary and fecal samples of a zoo-housed polar bear. Although PVC microplastics at concentrations well above current observations reduced the fugacities of spiked isotopically labeled PCBs in the polar bear diet and feces slightly, but significantly, leaching from these microplastics greatly elevated fugacities of the additives UV-328 and octabenzone in these samples. The impact of microplastics in the diet on the biological uptake of environmental hydrophobic organic contaminants is likely to be negligible. Microplastics have the potential to be effective vectors for the dietary uptake of polymer additives.

Personal care products (PCPs) contain contaminants of emerging concern. Despite increasing reports of their presence in polar regions, the behavior of PCP ingredients under cold environmental conditions remains poorly understood. Snow collected around Villum Research Station at Station Nord, Greenland, between December 2018 and June 2019 was extracted in a stainless steel clean-room and analyzed for seven fragrance materials, four organic UV-filters and an antioxidant using gas chromatography-tandem mass spectrometry. All twelve target PCPs were detected, with elevated concentrations during two sampling events potentially tied to air mass transport from northern Europe and the northern coasts of Russia. To contextualize the presence of these PCP chemicals in high Arctic snow, we estimated their (i) partitioning properties as a function of temperature, (ii) equilibrium phase distribution and dominant deposition processes in the atmosphere at temperatures above and below freezing, and (iii) potential for long-range environmental transport (LRET). Even though most PCPs are deemed to be gas phase chemicals predominantly deposited as vapors, rapid atmospheric degradation is expected to limit their LRET. On the other hand, the less volatile octocrylene is expected to be sorbed to atmospheric particles, removed via wet and dry particle deposition, and possibly exhibit a higher potential for LRET by being protected from attack by photooxidants. The contrast between consistent detection of PCP chemicals in high Arctic snow and relatively low estimated LRET potential emphasizes the need for further research on their real-world atmospheric behavior under cold conditions.

Despite benzotriazole UV stabilizers (BT-UVs) being widely used since the 1960s, few empirical data on their atmospheric presence exist. UV-328 was added to the Stockholm Convention on Persistent Organic Pollutants, based in part on model calculations indicating atmospheric long-range transport potential. We investigated the atmospheric occurrence of BT-UVs at multiple sites that differ greatly in their proximity to potential sources. UV-P, UV-328, UV-234, UV-326, UV-329, and UV-327 were quantified in active air samples collected in suburban Toronto, on Saturna Island in the Salish Sea, at Point Petre on Lake Ontario, and in Alert, Nunavut, as well as in XAD-resin based passive air samplers deployed at sites in British Columbia and Quebec. As the most volatile BT-UV, UV-P was present in the gas phase across all sampling locations, with higher concentrations in urban areas. The five less volatile BT-UVs were present only in active air samples from suburban Toronto and were not found above detection limits (0.03-1.7 pgm-3) anywhere else. Empirical evidence thus does not support model predictions of long-range atmospheric transport of particle-bound BT-UVs. Predictions based on simple model calculations should be supported by empirical data if they are to be used as the basis for regulatory decisions.

Biomagnification is the process that leads to the chemical potential of organic contaminants in an organism exceeding that in its diet. Despite its obvious importance, studies on biomagnification in humans are rare, in particular those that seek to quantify and characterize interindividual differences in biomagnification potential. Applying a method based on equilibrium sampling and chemical analysis of paired dietary and fecal samples we determined the thermodynamic limit to biomagnification (BMFlim) as well as a feces-based biomagnification factor (BMFF) for a selection of polychlorinated biphenyls in five human volunteers sharing the same diet over a period of five days. Four younger participants displayed similar BMFlim and BMFF, while an older participant's BMFlim and BMFF were higher by factors of up to 5 and 7, respectively. These differences were due to divergent dietary digestion efficiencies, with lipid assimilation efficiency ranging from 93 to 99%. Small sample size prevented us from confirming whether lipid assimilation efficiency is influenced by the participants' gut microbiomes. Fugacities in blood and feces, were highly correlated for each participant, but the relationships were different between participants. Only the younger participants had contaminant fugacities in blood that greatly exceeded those in feces, consistent with a fat flush effect, whereas contaminants were close to chemical equilibrium between blood and feces in the older participant. Differences in biomagnification are likely to contribute to the variability in contaminant levels within a population that is typically observed in biomonitoring.

Artisanal and small-scale gold mining (ASGM) is one of the largest primary sources of mercury (Hg) pollution in the atmosphere globally; however, there is a paucity of atmospheric Hg data in ASGM areas. We measured atmospheric gaseous elemental mercury (GEM) concentrations and stable Hg isotopes at fine spatial resolution in the Madre de Dios region of Peru, where ASGM is a major source of Hg. This study employed new passive air samplers that overcome logistical challenges in measuring atmospheric Hg in remote locations. Regional GEM concentrations were elevated (∼1.3 to 11 ng m-3) compared to the background (<1 ng m-3), with very high GEM levels (∼10 to >5000 ng m-3) associated with mining areas and gold shops. Because ASGM-derived GEM is isotopically distinct, its contribution to regional and local atmospheric Hg was estimated using an isotope mixing model and found to be generally over 70%. We also show that vegetation is taking up ASGM-derived GEM, affecting both the concentrations and isotope compositions of GEM as well as in foliage and litter samples. This supports vegetation uptake as a key removal process of GEM from the atmosphere and therefore a major source of Hg to terrestrial ecosystems and soils, which is heightened in ASGM regions.

Benzotriazole UV stabilizers (BZT-UVs) are industrial additives of emerging environmental concern, with UV-328 recently listed under the Stockholm Convention on Persistent Organic Pollutants and several congeners listed as Substances of Very High Concern in Europe. However, their distribution and fate in coastal environments remain poorly understood. This study investigated the spatial and seasonal variations of dissolved and suspended particulate matter (SPM)-bound BZT-UVs in surface water from the St. Lawrence River, Estuary and Gulf (SLREG) and the coast of Vancouver and Victoria, spanning Canada's east and west coasts. BZT-UV contamination was higher in the SLREG, with peak UV-328 levels in July, likely due to increased summer use. Most congeners were more abundant in the SPM from July to October in the St. Lawrence Estuary, while elevated UV-329 levels in April suggest a distinct source, possibly related to snowmelt. These seasonal variations may influence the exposure of local species to BZT-UVs. While the concentrations of the dissolved BZT-UVs in most samples are expected to pose minimal ecological risks, the concentrations of some BZT-UVs in a few samples from the upper estuary of the SLREG may pose moderate to high risk in summer, highlighting the need for further assessment.

In response to increasing production and application volumes, organophosphate esters (OPEs) have emerged as pervasively detected contaminants in various environmental media, with concentrations often exceeding those of traditional organic contaminants. Despite the recognition of the atmosphere's important role in dispersing OPEs and a substantial number of studies quantifying OPEs in air, investigations into atmospheric phase distribution processes are rare. Using measurements of OPEs in the atmospheric gas and particle phase, in precipitation, and in surface water collected in southern Canada, we explored the seasonal concentration variability, gas–particle partitioning behaviour, precipitation scavenging, and air–water equilibrium status of OPEs. Whereas consistent seasonal trends were not observed for OPE concentrations in precipitation or atmospheric particles, gas phase concentrations of several OPEs were elevated during the summer in suburban Toronto and at two remote sites on Canada's eastern and western coast. Apparent enthalpies of air–surface exchange fell mainly within or slightly above the range of air–water and air–octanol enthalpies of exchange, indicating the influence of local air–surface exchange processes and/or seasonally variable source strength. While many OPEs were present with a notable fraction in both the gas and particle phase, no clear relationship with compound volatility was apparent, although there was a tendency for higher particle-bound fractions at a lower temperature. High precipitation scavenging ratios for OPEs measured at the two coastal sites are consistent with low air–water partitioning ratios and the association with particles. Although beset by large uncertainties, air–water equilibrium calculations suggest net deposition of gaseous OPEs from the atmosphere to the Salish Sea and the St. Lawrence River and St. Lawrence Estuary. The measured seasonal concentration variability is likely less a reflection of temperature-driven air–surface exchange and instead indicates that more OPEs enter or are formed in the atmosphere in summer. More research is needed to better understand the atmospheric gas–particle partitioning behaviour of the OPEs and how it may be influenced by transformation reactions.

Releases of chlorinated paraffins (CPs) have led to long-term human exposure globally. Differences in CP use patterns (indoors vs outdoors) and temporal release trends in different regions may be reflected in differences in the extent and pathways of long-term exposure to CPs between human populations. We used the dynamic mechanistic model PROTEX to simulate releases and environmental fates of CPs in China, Canada, and Europe from 1930 to 2020 and contrast the resultant exposures for different birth cohorts. Predicted environmental and human body concentrations agree with measurements from the three regions. Far-field exposure pathways dominate for all cohorts even in China where CP indoor use is high. Longitudinal exposure trends differ between generations and regions due to the divergent release trends. Perinatal exposure causes high body concentrations in infants and children born in years with peak releases. Due to human elimination half-lives that are short relative to the period of release, cross-sectional concentration-age trends have similar shapes regardless of release trend and sampling time. These results imply that whereas use patterns and release trends add to the influence of physicochemical properties on relative exposure pathway importance and cross-sectional concentration-age trends, the release trends are the main factors shaping longitudinal exposure trends.

Organophosphate esters (OPEs) have emerged as pervasive environmental contaminants, with concentrations often exceeding those of traditional flame retardants and plasticizers by orders of magnitude. Here, we present concentrations of OPEs in the atmospheric gas phase collected using passive air samplers deployed in the coastal regions of Quebec and British Columbia in southern Canada. Four OPEs, i.e., tri-n-butyl phosphate (TBP), tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), and tris (phenyl) phosphate (TPhP) were reliably and ubiquitously detected, with TCPP showing the highest level, followed by TBP. Concentration levels of TCPP and TCEP are correlated with each other and with population, possibly indicating emission from consumer products. Spatial patterns of TBP and TPhP are more indicative of industrial usage, with airports possibly being a major source for TBP. The positive relationships between atmospheric OPEs and population are influenced by ambient temperature, whereby the size of the populated area around a sampling site influencing the air concentration appears to be decreasing at higher temperatures.