Monitoring, fate and transport, and risk assessment of organic pollutants in the environment: CREST publications during 2019–2023

Abstract

Organic pollutants are potential hazards for human health and are pivotal contributors to ecological imbalances. The spectrum of chemicals in research on organic pollutants has continually evolved, which is influenced by industrial advancements, scientific breakthroughs, and regulatory frameworks. A comprehensive analysis of 30 review articles on organic pollutants published during 2019-2023 in Critical Reviews in Environmental Science and Technology (CREST) provides good perspectives on the trajectory of organic pollutants in the environment. This synthesis delineates the recent advancements in two domains: (1) innovative monitoring technologies (sensor, extraction method, bio-indicator, and radioactive tracer); and (2) fate and transport, and risk assessment of organic pollutants. However, research on organic pollutants needs better monitoring techniques, matrix-related transformation methodologies, and realistic risk assessment tools. The development of novel strategies to monitor and manage organic pollutants, coupled with evaluations of ecosystem impacts under field conditions, is paramount.

Graphic abstract

Keywords:

• Biomarker and radioactive tracer
• transformation and toxicity
• sensor and extraction method
• emerging organic pollutants
• human health
• matrix-related transformation

1. Background

Organic pollutants pose significant threats to both human health and ecological stability, thereby receiving considerable attention (Gwenzi et al., 2018). Past research highlights the environmental persistence and bioaccumulation nature of these pollutants, illuminating their consequent detrimental effects on human and ecological health (Alharbi et al., 2018). In humans, they can induce a range of health complications, from hormonal disruption and developmental anomalies to liver toxicity and immune system impairment (Vos et al., 2000). Equally, in ecosystems, they cause biodiversity degradation, inflict harm upon non-target species, precipitate population declines in top predators, and stimulate deleterious algal blooms in aquatic habitats (Bezerra et al., 2019; Reid et al., 2019). Thus, the impacts of organic pollutants are pervasive and multifaceted, affecting both human health and ecological integrity.

Chemicals of concern in organic pollution research have been shaped by industrial progress, scientific discovery, and environmental regulation (Sousa et al., 2018). The research has expanded from a focus on persistent organic pollutants in the 2000s to emerging contaminants such as pharmaceuticals and personal care products (PPCP) and per- and poly-fluoroalkyl substances (PFAS) (Christensen et al., 2022). Some organic pollutants are endocrine disruptors, interfering with hormonal systems and leading to reproductive and developmental issues while some may induce antimicrobial resistance, a rising public health concern (Schug et al., 2011). Further, PFAS resist degradation and contaminate water sources, with their exposure being associated with developmental issues, liver toxicity, and immune system dysfunction in humans (Bell et al., 2021). From persistent organic pollutants to emerging organic pollutants, research in organic pollutants continues to evolve, reflecting our increasing awareness and capabilities in identifying and mitigating the impacts of organic pollutants on the environment.

Recent research advances have enriched our understanding on the behaviors and potential risks posed by organic pollutants. Enhanced analytical techniques and innovative research methodologies of organic pollutants have demystified their transport and transformation mechanisms of diverse pollutants, thereby facilitating a more integrated comprehension. Simultaneously, significant advancements in risk assessment models allow for a more precise quantification of their impacts on human health and ecosystems. Between 2019–2023, CREST published 30 review papers on organic pollutants, covering topics from low-cost, high-sensitivity monitoring technologies to fate and transport, and risk assessment of key organic pollutants. This collection aims to offer an up-to-date review of the recent knowledge advancements regarding organic pollutants in the environment. It also seeks to identify current research gaps and propose future research directions.

2. Monitoring technologies

The advent of sophisticated analytical techniques, such as gas/liquid chromatography (GC/LC) coupled with mass spectrometry (MS), revolutionized the detection and quantification of organic pollutants. Their scientific investigation in complex matrices also has been significantly advanced by innovations in extraction methods. For extraction methods, traditional techniques like liquid-liquid extraction and solid-phase extraction (SPE) have been complemented by newer technologies such as solid-phase microextraction and stir bar sportive extraction. With improved sensitivity and selectivity, they are advantageous to extract trace-level pollutants, including emerging pollutants like PPCPs and PFAS. Biomarkers elucidate the biological effects of organic pollutants, while radioactive tracers allow for precise monitoring of their movement and distribution, thereby enhancing the precision of organic pollutant monitoring. CREST in 2019-2023 published 11 reviews covering recent advancements of major types of monitoring technologies, which not only improve our ability to analyze organic pollutants, but also allow for more efficient research and risk assessment of organic pollutants.

2.1. Sensors and biomarkers

Sensors, as low-cost, rapid, and target-oriented technologies, have seen considerable developments. These improvements have led to the creation of miniaturized, portable, and highly sensitive devices for in situ and real-time monitoring of organic pollutants. These sensors, including optical sensors and electrochemical sensors, offer advantages in terms of rapid response, ease of use, and the potential for continuous monitoring. There are three publications on this topic, including Kudłak and Wieczerzak (2020), Kumar et al. (2019) and Sarfo et al. (2019).

Kudłak and Wieczerzak (2020) provided a critical review of the synthesis methods and application of aptamers, which are short-chain oligonucleotides, elaborating on their intrinsic properties such as specificity and selectivity in interacting with target molecules for pollutant analyses. They outlined various sensors that leverage aptamers as a vital element, ranging from electrochemical apt-sensors to optical and piezo-electric (mass-dependent) ones, highlighting aptamer-based assays as promising alternatives to animal-dependent antibody-based lateral flow assays. With the advantages and challenges of recent aptameric developments in a range of laboratory applications, the authors underlined the necessity for an interdisciplinary approach to the utilitarian development of aptamer-based tools for future applications.

The increasing demand for efficient sensing of volatile organic compounds (VOCs) emphasizes the value of metal-organic frameworks (MOFs). Given their advanced surface properties and biocompatibility, MOFs are deemed potent materials for VOC detection. However, organic ligands in MOFs with an insulating character often limit their electrical conductivity and charge mobility. Kumar et al. (2019) explored the design strategies and applications of diverse types of electrochemical sensors using MOFs for VOC detection, including conductometric, potentiometric, and amperometry sensors, highlighting strategic designs involving the doping, tagging/functionalization, and post-synthesis modification approaches for enhancing electrical conductivity. The gained knowledge facilitates the establishment of proper guidelines to maximize the performance of MOFs-based electrochemical sensing devices.

Given its exceptional analytical sensitivity and suitability for field applications, surface-enhanced Raman spectroscopy (SERS) is a prominent analytical apparatus to detect environmental toxicants in diverse matrices. Sarfo et al. (2019) highlighted the advantages of conductive solid platforms in SERS substrate development, emphasizing their role in generating diverse morphologies, high-density nanostructures, and abundant hotspots. They delved into recent innovations in materials including indium tin oxide and carbon nanotubes to fabricate SERS substrates and explore their impact on fabrication methods and SERS substrates properties. They also proposed future research on enhancing SERS sensitivity, including exploring conductive nanostructured materials and their applications in dual sensors and plasmon coupling.

Besides sensors, biomarker has also been used in research on organic pollutants. Polycyclic Aromatic Compounds (PACs) present a significant toxic threat to aquatic systems, especially fish health. Dearnley et al. (2022) highlighted the role of biliary PAC metabolites as a biomarker of short-term exposure, they also discussed various techniques to analyze fish bile infused with these metabolites. They contrasted recent environmental monitoring studies that have yielded key findings and innovative applications of this technique, including using biomarkers to gauge the extent of PAC pollution resulting from oil spills, tracking the recovery of the affected region, establishing baseline PAC exposure in unspoiled areas, and assessing pollution in urban waterways. They further emphasized the necessity for continuous research to expand the scope of biomarker-based environmental monitoring, including developing toxicity thresholds for a broader range of fish species and exploring non-lethal sampling methods.

2.2. Radioactive tracer

Compound-specific isotope analysis (CSIA) enhances organic pollutant studies by differentiating pollutant sources, tracing degradation pathways, and assessing remediation strategies, thereby providing nuanced insights into organic pollutant origins and behaviors. There are three publications on this topic, including Xiong et al. (2022b), Ya et al. (2022) and McDonald et al. (2022).

Xiong et al. (2022b) discussed the instrumental role of CSIA in identifying the sources and fates of brominated organic compounds and highlighted the recent advancements in GC combustion isotope ratio MS and GC multiple collectors coupled with inductively coupled plasma MS (ICP-MS). Furthermore, the authors delve into the assessment of kinetic isotope effects, providing critical insights into biochemical reaction mechanisms. Ya et al. (2022) highlighted the distinctive advantages of CSIA, which serves as a powerful tool to accurately quantify the sources of aromatic pollutants, decipher their sedimentary radiocarbon records, and elucidate regional energy structure and fuel consumption patterns. Future research should explore advanced isotope management, diversify CSIA applications in biogeochemical fingerprinting and pollution derivatives, and extend its use to other micropollutants.

Gamma radioisotope tracing in live animals allows real-time tracking of pollutant absorption, offering insights into their response to aquatic stressors. Despite producing in-depth longitudinal data, its complex design risks data misinterpretation due to intricate statistical models. McDonald et al. (2022) evaluated the experimental design and statistical approaches employed in contemporary aquatic live animal radiotracking studies during 2000-2020. They found some studies lacked details in experimental design or statistical analysis, with a minority misaligning their statistical approach with their chosen design. They further offered insights on data interpretation approaches from various experimental designs, detailing their respective merits and drawbacks. Future research should underscore the ethical, logistical, and fiscal challenges in employing live animal radiotracking techniques.

2.3. Advanced extraction methods

Extraction methods, serving as cornerstone technologies in pollutant analysis, have undergone significant improvement. Compared to traditional extraction methods, advanced extraction methods not only boast attributes of enhanced selectivity, stability, and reusability but also promise reduced sample preparation time, minimized solvent usage, and enhanced accuracy of trace-level detections. There are three publications on this topic, including Wu et al. (2021), Guan et al. (2022) and Daniels et al. (2020).

With the growing popularity of cost-effective functionalized magnetic nanoparticle (MNP) adsorbents for pollutant analysis, Wu et al. (2021) examined their applications in detecting trace organic contaminants in environmental water based on publications during 2015-2019. They comprehensively analyzed the advancements in MNP-sorbent selectivity, stability, and reusability by integrating various functional materials, further delving into their synthetic pathways, modification materials, and mechanisms. Factors that impact extraction efficiency along with improvement strategies were also discussed. To optimize extraction efficiency, future research should target novel MNPs, refined detection methods, technique integration, and automation.

Guan et al. (2022) reviewed the diffusive gradients in thin-films (DGT) technique in soil analysis. They concluded that DGT offers greater accuracy than traditional extraction-based methods in assessing organic pollutant uptake by plants from limited soil supplies. They summarized recent development of DGT applications and grouped them into four key areas including chemical speciation, bioavailability measurement, desorption kinetic modeling, and interfacial process mapping of nutrients and contaminants.

In chromatography-based spectrometry analyses of organic pollutants, the efficient extraction of target chemicals is imperative to achieve optimal sensitivity. Daniels et al. (2020) offered a comprehensive picture of current extraction methods for trace levels of pharmaceuticals in water samples. They covered conventional SPE, and emerging miniaturized and online procedures with an emphasis on the advancement of large-volume injections without sample enrichment. Meanwhile, Pulleyblank et al. (2019) broadened the discourse by assessing extraction methods for oxygenated polycyclic aromatic hydrocarbons (PAHs) in diverse matrices. They contrasted traditional solvent extraction and SPE techniques with emerging techniques like sportive extraction, miniaturization, and automation methods, highlighting the potential of emerging methods in improving efficiency. In short, the future of extraction methods research hinges on instrumental sensitive and selective development, as well as the standardization of compound-specific extraction methodologies.

3. Fate, transport, and risk assessment

The fate and transport of organic pollutants in the environment are crucial as they determine pollution exposure and potential impacts (Crone et al., 2019; Keerthanan et al., 2021). Some hydrophobic pollutants are known to persist in soils and sediments for decades and bioaccumulate up the food chain. In contrast, other pollutants, like many PPCPs may degrade more readily. However, their continuous release into the environment and resistance to standard wastewater treatments still pose a significant concern. Upon release into the environment, organic pollutants undergo various processes such as advection, diffusion, sorption, volatilization, photolysis, hydrolysis, and degradation. Their transport and transformation are influenced by a complex interplay of these processes along with environmental factors such as temperature, pH, and the presence of other substances.

As industries evolve and introduce novel organic compounds into the environment, it is necessary to update research focuses, coupled with advancements in scientific methodologies, to address both traditional and emerging organic pollutants. In this context, CREST’s contribution is notable with 19 reviews over the past four years on the fate and transport, and risk assessment of six major groups of organic pollutants and other chemicals of concern, reflecting the progressing state of research on the fate and risk assessment for several organic pollutant groups, including PFAS (Liu et al., 2022; Xie et al., 2021), PPCPs (Bonnot et al., 2023; Keerthanan et al., 2021; Liu et al., 2021), organophosphate easter (Hu et al., 2023; Lao et al., 2023; Yang et al., 2022), pesticides (Moreira-Santos et al., 2019; Villamar-Ayala et al., 2019), PAHs (Ali et al., 2021; Liu et al., 2023; Mo et al., 2022), disinfect byproducts (Gao et al., 2019; Jasemizad et al., 2022), and other organic pollutants (de Campos et al., 2022; Kennedy et al., 2022; Stroski et al., 2019; Xiong et al., 2022a).

3.1. Per- and polyfluoroalkyl substances

PFAS, notable for their widespread usage and environmental persistence, result in unavoidable exposure, particularly accumulating in mothers and subsequently transferring to infants via the placenta and breastfeeding, posing potential health threats. Liu et al. (2022) provided valuable insight into both prenatally and postnatally maternal transfer of PFAS to offspring. Their transfer efficiencies are affected by alkyl chain length, the presence of functional groups, and the position of molecular branching. Although serum-to-breast milk transfer efficiency is comparatively lower than transplacental transfer, infant exposure to PFAS through breastfeeding in the first month surpasses that from transplacental transfer during gestation. Given the updated reference doses, such exposure could represent substantial health risks to infants.

Perfluoroalkyl compounds (PFCs), a subset of the broader group of PFAS, have garnered some attention as potential endocrine disruptors. Xie et al. (2021) reviewed the toxic effects of PFCs in vitro and in vivo, underscoring their associations with thyroid dysfunction and cancer induction. The general population, including those with occupational exposure and other high-risk groups like pregnant women and neonates, are among the exposed. PFCs disrupt endocrine function, often seen as thyroid malfunction or hormonal imbalance, especially in pregnant women, and are linked to chemicals like perfluorooctane sulfonic acid (Xie et al., 2021). Despite these findings, there is no consistent correlation between PFC exposure and thyroid hormone alterations or thyroid cancer risk.

3.2. Pharmaceuticals and personal care products

PPCPs can enter agricultural soils via wastewater, compost, and manure application. As plants absorb such emerging pollutants, they become a primary vector for human exposure to PPCPs through consumption, possibly leading to harmful health effects. Keerthanan et al. (2021) aggregated literature on the occurrence of PPCPs and provided a detailed account of plant uptake and translocation under greenhouse and field conditions, along with the mechanism of their plant uptake. They summarized factors influencing these processes such as biological characteristics of plants (lipid and carbohydrate content of plant roots), physiochemical properties of PPCPs (molecular size, Kow, and pKa), and environmental conditions of media. Their risks to humans from consuming contaminated vegetables are considerably lower than the permissible intake threshold. The authors emphasized the need for further research on personal care products, whereas the impact of pharmaceuticals has been more extensively studied.

Bonnot et al. (2023) analyzed the transformation pathways and the reactions undergone in specific matrices based on the parent compound chemical structures to better understand the transformation processes of PPCPs. The transformation of 116 PPCPs led to 1371 transformation products formed by biotic (630), abiotic (568), and both biotic and abiotic (61) reactions in natural and/or synthetic matrices. Eleven main transformation reactions can describe the transformation products dataset, with hydroxylation as the major reaction occurring at 28% followed by dehydrogenation (13%), and cleavage (11%). While predominant studies utilize synthetic media, insights into transformation reactions in environmental matrices, particularly soils and sediments, remain limited.

Polycyclic musks (PCMs) are synthetic fragrance compounds that permeate the environment in myriad ways due to their extensive production and use. Their lipophilic and persistent nature leads to their bioaccumulation and potential toxic effects in organisms, triggering severe ecological risks given their prolonged low-dose environmental presence. Liu et al. (2021) reviewed current knowledge of the concentrations, distribution, and determination methods of PCMs, with a specific focus on their ecotoxicology and environmental behavior, to raise awareness about minimizing PCM introduction into the environment. They further contemplated prospective research concerning micro-interface effects, advanced molecular mechanisms, and bioremediation of PCM-contaminated areas.

3.3. Organophosphate easter

Organophosphate esters (OPEs) are pervasive in the environment and have been consistently detected in human specimens, leading to mounting concerns about their adverse health impacts.

Lao et al. (2023) mapped the prevalence of OPEs across a decade in diverse microenvironments such as residences, vehicles, and offices, shedding light on age-specific exposures. Meanwhile, Yang et al. (2022) reviewed profiles of OPE and OPE metabolites (mOPEs) occurrence in human samples like urine, blood, and milk, and associated health risks. Among various exposure pathways, dietary intake has emerged as the primary exposure route (Lao et al., 2023; Yang et al., 2022). Varied concentrations of mOPEs have been observed across regions, with the USA registering higher levels than Europe and Asia (Yang et al., 2022). A notable pattern in OPE concentrations in different environments was discerned, with in-vehicle and office spaces showing higher concentrations than residences and outdoors (Lao et al., 2023). For exposure assessment, given the differential metabolic activities of OPEs across these matrices, urinary mOPE concentrations offer insights into short-term OPE exposure, while matrices like hair and nails capture long-term exposure trends (Yang et al., 2022). Even though overall health risks are deemed low for all age groups, the vulnerability of infants to OPE exposure primarily due to breast milk ingestion highlights future research (Lao et al., 2023).

Aryl OPEs, used extensively in industrial and consumer goods, are identified as emerging endocrine disruptors. Focusing on representative aryl OPEs, including triphenyl phosphate, 2-ethylhexyl diphenyl phosphate, tricresyl phosphate, and isomers of mono-, di-, and tri-isopropylated triaryl phosphates, Hu et al. (2023) delved into the endocrine and metabolic disrupting toxicities of aryl OPEs, detailing the signaling pathways involved. In essence, aryl OPEs meddle with hormonal balance and function as agonists/antagonists for multiple hormone receptors. They also interfere with lipid homeostasis and bind with liver X receptor and peroxisome proliferator-activated receptor γ, thereby affecting the cardiovascular system and liver. By drawing comparisons between the structures of emerging aryl OPEs and their legacy counterparts, Hu et al. (2023) postulated the potential endocrine-disrupting toxicity of newer aryl OPEs, yet future research is essential to validate this and understand the underlying molecular level mechanisms in the environment.

3.4. Pesticides

Pesticides, instrumental in optimizing crop yields, have unintended ecological implications. For instance, while targeting specific pests, they can inadvertently displace non-target species from their habitats, leading to potential risks to the agricultural ecosystem. As regulations evolve, research on pesticide formulations adapts, addressing emergent challenges and reducing environmental impact.

Glyphosate, a key herbicide, has a propensity to migrate to water bodies due to its physicochemical properties. Villamar-Ayala et al. (2019) reviewed the formulations of glyphosate and its toxic effects on aquatic life, spanning from protozoans to secondary consumers. For example, marine protozoans demonstrated more sensitivity to glyphosate compared to freshwater counterparts, while many fish species showed increased sensitivity, especially during early life stages. With concerns about the bioaccumulation of glyphosate in secondary consumers, efforts to treat and mitigate its presence have intensified, encompassing both conventional and innovative approaches. While advanced oxidation processes emerge as a promising solution, combining biological and physicochemical processes may be more feasible in agricultural settings.

Moreira-Santos et al. (2019) highlighted the knowledge gap stems from conventional toxicity tests of pesticides, in both single and multi-species studies, which impose forced exposure, thereby neglecting the potential for pesticides to disrupt or fragment habitats. With existing information on pesticide-induced migration in aquatic animals, they presented conditions under which avoidance becomes ecologically significant and provided evidence from diverse studies suggesting that traditional methods might underestimate the ecological risks of certain pesticides. Hence, integrating non-forced exposure tests into ecotoxicology might offer a more holistic ecological risk assessment for pesticides.

3.5. Polycyclic aromatic hydrocarbons

PAHs are complex organic pollutants prevalent in the environment, stemming primarily from incomplete combustion processes. Their interactions with carriers like colloids or nanoparticles can amplify potential health risks. Furthermore, the intricacies of PAH dissipation in soils and the transgenerational effects of certain PAHs highlight the multifaceted challenges they present to environmental and public health.

Black carbon and PAHs are primary aerosol byproducts of various combustion processes. Due to its potent sorption efficiency, black carbon acts as a vital carrier for the more toxic and carcinogenic PAHs in our environment, spanning mediums such as air, water, and soil. Ali et al. (2021) reviewed the sources of these pollutants and the health impacts of PAHs associated with black carbon. The primary contributors include the burning of fossil fuels, biomass, industrial activities, and vehicular emissions. The health implications of this coexistence encompass a broad spectrum, from acute respiratory problems and aggravated bronchitis to severe long-term conditions like heart diseases and lung cancer. Despite the environmental ubiquity of black carbon and its decisive role in determining the fate of other organic pollutants, especially PAHs, the comprehensive health and environmental risks posed by black carbon in tandem with PAHs remain inadequately explored.

Liu et al. (2023) explored the dissipation of PAHs in soils through abiotic processes, particularly photodegradation and mineral-catalyzed oxidation. The PAH transformation dynamics are predominantly influenced by clay minerals, metal oxides/hydroxides, and soil organic matter. Beyond direct and indirect photodegradation, PAHs undergo oxidation facilitated by metal compounds like MnO₂, Fe_xO_y, and various clay minerals. The transformation effectiveness hinges on several factors: the electron properties of minerals, pH levels, temperature, moisture, and oxygen content. Future research must bridge the gap between laboratory findings and field applications, exploring the broader implications of natural attenuation rooted in abiotic processes.

Benzo[a]pyrene, a pervasive environmental pollutant of PAHs, has been scrutinized predominantly for its genotoxic and carcinogenic properties. Emerging data suggest that ancestral benzo[a]pyrene exposure may lead to transgenerational osteotoxic effects, even impacting unexposed the third generation of descendants. To understand the mechanisms behind transgenerational benzo[a]pyrene-induced bone harm, Mo et al. (2022) proposed the hereditary transmission of osteotoxic effects in fish due to ancestral benzo[a]pyrene exposure is primarily driven by epigenetic disruptions in bone miRNAs/genes. After DNA methylation alternation or histone modifications, the disruption can be attributed to two potential epigenetic pathways: bone miRNAs undergo dysregulation, subsequently influencing target gene function, and direct dysregulation of bone genes. They advocated for subsequent research to validate this mechanism, ensuring its relevance to humans, and uncovering the intricate mechanisms underlying transgenerational benzo[a]pyrene osteotoxicity.

3.6. Disinfect byproducts

Haloacetaldehydes, a prevalent group of disinfection by-products in drinking water, are recognized for their high cytotoxicity. Gao et al. (2019) reviewed haloacetaldehydes’ formation, occurrence, analysis, and control in various waters. They are predominantly found in surface waters during warm seasons, which infiltrate into source waters of drinking water treatment plants mainly through disinfectant recirculation. Among the identified haloacetaldehydes, chloroacetic acid has been the most examined, showing spatio-temporal variability dependent on climate and treatment types. Haloacetaldehyde formation, influenced by disinfection methods, precursors, and environmental conditions, can be managed with nanofiltration and reverse osmosis. Beyond drinking water, humans can also be exposed to haloacetaldehydes through skin contact and inhalation in recreational waters. Given haloacetaldehydes’ persistent formation and their significant impacts, further research is needed to understand the transformation between different haloacetaldehydes and the use of alternative disinfectants.

N-Nitrosamines, recognized human carcinogens, are widely known to form during the disinfection of waters containing amine compounds. Jasemizad et al. (2022) evaluated the precursors and occurrence of nitrosamines, and the disinfection processes related to their formation or removal. They emphasized the impacts of inorganic ion nitrosamine formation. While lower inorganic ion concentrations in source waters have limited impact, higher ion concentrations in wastewater could significantly affect disinfection processes. Besides, numerous studies on ozonation have found substantial levels of nitrosamines, similar to those observed in well-recognized chloramination processes. For controlling nitrosamines formation, pre-oxidation, and advanced oxidation processes emerged as the most promising mitigation strategies, due to extended exposure of precursors for effective mineralization. They highlighted the need for further studies on inorganic ions’ roles under real-world conditions, particularly concerning waters with high inorganic ion loads.

3.7. Other organic pollutants

In addition to well-known pollutant groups, a spectrum of other organic pollutants, including oil dispersants, quinones, antifouling biocides, and cannabis byproducts are also covered. These studies are pivotal for evaluating environmental ramifications, informing regulatory frameworks, fostering the development of safer alternatives, and safeguarding both ecosystems and public health.

Following a deepwater horizon spill, oil dispersant Corexit EC9500A has been extensively used both sub-surface and on the ocean’s surface. Stroski et al. (2019) summarized the new toxicological information on Corexit EC9500A and their potential impacts on the species studied. Though aquatic testing reveals its low toxicity to several crustaceans, corals, and fish, Corexit EC9500A exhibits heightened toxicity to plankton, daphnia, and the early life stages of various species. Human health studies have indicated minimal acute toxicities but suggest potential chronic effects upon substantial exposure. For risk assessment, the spill location, affected species, and product effectiveness all play essential roles. Before endorsing its widespread use in such systems, more comprehensive research is paramount.

Quinones can cause DNA damage, resulting in DNA adducts, by producing reactive oxygen species or directly binding to DNA, subsequently leading to gene mutations and increased cancer risks. Xiong et al. (2022a) summarized various DNA damages caused by quinones and the associated adducts. Beyond stable environmental quinones like naphthoquinone, certain pollutants like estrogen and benzo[a]pyrene can metabolically activate into quinones, further intensifying DNA adduct production. Crucially, the dione moiety in quinones plays a pivotal role in DNA adduct formation. LC-MS is the best detection tool for understanding DNA adducts to understand DNA damage dynamics and cancer-causing mechanisms. They offered a fresh look at quinone toxicity, proposing DNA adduct analysis strategies to gauge potential health threats from multiple DNA damages.

Historically, cannabis has been recognized for its psychoactive effects. Following its recent legalization, there has been an uptick in commercial cannabis products. Alarmingly, current wastewater treatments are inadequate in filtering cannabis’s bioactive components, risking contamination of aquatic ecosystems. Kennedy et al. (2022) proposed cannabis as pseudo-persistent due to constant replenishment and frequent detection in various water samples. Due to its bioaccumulation potential and potential impact on ecosystem as endocrine-disrupting chemicals, future study is needed to provide regulators and risk managers with information regarding the current and future safety (Kennedy et al., 2022).

With an extensive collation of toxicological and environmental data, de Campos et al. (2022) assessed the risk of 11 EU-sanctioned antifouling biocides to marine environments. Biocides such as diuron, chlorothalonil, and dichlorooctylisothiazolinone are notably toxic. Alarmingly, medetomidine and copper thiocyanate, show up to 400 times more toxicity to non-target versus target species. Based on ecotoxicological data, biocides vary in hazard, with zinc pyrithione being the most hazardous and tolylfluanid the least. Risk evaluations highlight biocides like dichlorooctylisothiazolinone, diuron, and chlorothalonil as high-risk to coastal ecosystems, emphasizing the need for regular coastal monitoring.

4. Conclusions

Organic pollutants mirror the evolving landscape of modern industry, scientific advancement, and regulatory efforts, with the selection of target chemicals dynamically responding to these changes to address the most pressing concerns of the time. Research into the fate and transport of organic pollutants helps predict their distributions and concentrations in different environmental compartments, inform risk assessments, and guide the development of effective remediation strategies. Based on the 30 publications during 2019-2023 in CREST, this collection highlights recent advancements in major types of monitoring technologies and examined the fates and risks of key groups of organic pollutants. We emphasized the importance of rigorous research in bridging the knowledge gap surrounding organic pollutant detection and their impacts on the ecosystem, the following research areas need further attention:

1. It is critical to accurately determine organic pollutant concentrations in the environment for proper risk assessment. Improved analytical techniques are needed to determine environmentally relevant concentrations of organic pollutants. Reducing cost and improving analysis efficiency in complex environmental samples are also required.

2. The reactivity and bioavailability of organic pollutants can be diminished under real environmental conditions by aggregation, chemical reactions, and adsorption of solutes and organics. This implies that the desired performance and risks of organic pollutants will change with spatial and temporal factors, but these effects still have not been fully quantified.

3. Mathematical models can also be calibrated and used to simulate the fate of organic pollutants in the environment, but our knowledge of controlling factors and processes, and our ability to characterize matrix effect, co-existing pollutants, and key environmental parameters are still incomplete, especially under field conditions.

4. Standardized approaches to determine the risks of organic pollutants to ecosystems and humans rapidly and comprehensively are still needed. Multi-omics (e.g., genomics, transcriptomics, proteomics, and metabolomics) and bioinformatic tools could be utilized for this purpose, but more research is needed on the individual and population levels.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.