Monday, December 01, 2025

Everyday repellent, global pollutant

Biochar Editorial Office, Shenyang Agricultural University

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The impact of N,N-diethyl-m-toluamide in aquatic environments: occurrence, fate, and ecological risk
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Credit: Yan Zhao, Jingwei Wang, Quan Jia, Qiao Ma, Hongliang Jia & Song Cui

N,N-diethyl-m-toluamide, better known as DEET, is one of the world’s most widely used insect repellents – and it is now turning up in rivers, lakes, groundwater and even drinking water around the globe, according to a new review by an international research team. The authors warn that while DEET helps protect millions of people from mosquito-borne diseases, its growing footprint in aquatic environments raises questions about long‑term ecological and health risks.

“We shouldn’t wait for a crisis”

“DEET has been a public‑health success story for decades, but our analysis shows it is also becoming a quiet, global water contaminant,” said lead author Yan Zhao of Dalian Maritime University. “We shouldn’t wait for a crisis; it is time to treat DEET as an emerging pollutant that requires better monitoring and smarter management.”

Co‑corresponding author Song Cui added that the goal is not to scare people away from using repellents, but to inform regulators and the public. “Vector‑borne diseases like dengue and malaria are still major threats, especially in tropical and subtropical regions, so repellents remain essential,” Cui said. “The question is how to control DEET’s environmental release while preserving its public‑health benefits.”

Everyday repellent, global pollutant

DEET was originally developed for military use and is now a staple ingredient in commercial mosquito and tick repellents worldwide. Beyond personal care products, it is also used in agriculture as a feeding deterrent, in pharmaceuticals as a skin‑penetration enhancer, and in materials science as a plasticizer and specialty solvent, broadening its routes into the environment.

The review reports that the global insect repellent market was valued at about 6.27 billion US dollars in 2024 and is projected to nearly double by 2033, with DEET‑based products dominating many national markets. In some countries, such as Argentina, more than three‑quarters of registered repellents contain DEET, underscoring the chemical’s central role in current mosquito control strategies.

How DEET reaches water

Most DEET entering the aquatic environment comes from everyday consumer use, the authors found. When people swim, shower, or wash DEET‑treated clothing, the compound is washed off into sewers or directly into surface waters, and a fraction absorbed through the skin is later excreted in urine.

Because conventional wastewater treatment plants only partially remove DEET – with reported removal efficiencies ranging from about 10% to 90% – significant amounts pass through into rivers, lakes and coastal waters. Additional inputs come from agricultural use, urban runoff and landfill leachate, where discarded consumer products break down and release DEET that can migrate into nearby groundwater and surface waters.

Where and how much is found

Monitoring data compiled in the paper show that DEET is now detected on every continent surveyed, in a wide range of aquatic systems. In surface waters, concentrations typically fall in the nanogram‑per‑liter to microgram‑per‑liter range, with higher levels in densely populated or tourism‑intensive areas and in rivers receiving large volumes of treated wastewater.

Landfill leachate stands out as the most polluted water matrix, with DEET concentrations frequently reaching microgram‑per‑liter and in some cases milligram‑per‑liter levels, far above those measured in rivers or lakes. Groundwater in highly impacted regions can also be heavily contaminated: in one Indian city, DEET was found in 96% of sampled wells, with average concentrations around 30 micrograms per liter and a maximum of 92 micrograms per liter.

Ecological and health concerns

Laboratory studies summarized in the review indicate that even at relatively low concentrations, DEET can harm sensitive aquatic organisms. Algae exposed to high levels show reduced cytochrome content and irreversible cellular damage, while fish and invertebrates exhibit impaired growth and disrupted nervous‑system function.

The authors also highlight emerging evidence that DEET can alter the composition and activity of aquatic microbial communities, including microbes involved in key processes such as nitrification. Although DEET is not considered strongly bioaccumulative, it has been detected in mussels from the Great Lakes and in bees and honey in Mexico, suggesting that trophic transfer and accumulation in some food webs are possible.

Moderate risk, big data gaps

To gauge overall environmental risk, the team used a “weighted average risk quotient” that combines information on exposure levels and species sensitivity across different water types. Using a conservative protective threshold for aquatic life, they estimated that DEET currently poses a moderate ecological risk globally, with the highest concern in landfill leachate, followed by groundwater and then surface waters.

However, the authors stress that this assessment is limited by major data gaps. Many low‑ and middle‑income countries in tropical and subtropical regions – where mosquito repellents are used most intensively – lack systematic monitoring data on DEET in rivers, groundwater or drinking water, making it difficult to evaluate local risks.

Can treatment plants keep up?

The review points to promising advances in water‑treatment technologies that can more effectively remove DEET. Advanced oxidation processes that generate highly reactive radicals, optimized ozonation systems, and hybrid treatment trains combining physical, chemical and biological steps have all shown improved performance compared with conventional treatment alone.

Biological approaches are also emerging, including specialized bacteria, fungi and enzyme‑rich waste materials capable of degrading DEET or transforming it into less persistent compounds. Yet the authors caution that some advanced treatments can produce unwanted by‑products, and that full mineralization of DEET and its transformation products must be verified to ensure net environmental benefit.

Call for monitoring and smarter regulation

The paper concludes that DEET should be treated as a priority emerging contaminant in water management and regulatory frameworks. The authors call for expanded, globally coordinated monitoring – especially in disease‑endemic regions – together with refined ecological risk assessments that reflect local species and long‑term, low‑dose exposure.

“Mosquito repellents are here to stay, but the way society manages their lifecycles can and should change,” said co‑author Jingwei Wang. “By combining better monitoring, improved treatment technologies and risk‑based regulation, it is possible to protect both public health and freshwater ecosystems at the same time.”

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Journal Reference: Zhao Y, Wang J, Jia Q, Ma Q, Jia HL, et al. 2025. The impact of N,N-diethyl-m-toluamide in aquatic environments: occurrence, fate, and ecological risk. Agricultural Ecology and Environment 1: e009

https://www.maxapress.com/article/doi/10.48130/aee-0025-0009

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About Agricultural Ecology and Environment:

Agricultural Ecology and Environment is a multidisciplinary platform for communicating advances in fundamental and applied research on the agroecological environment, focusing on the interactions between agroecosystems and the environment. It is dedicated to advancing the understanding of the complex interactions between agricultural practices and ecological systems. The journal aims to provide a comprehensive and cutting-edge forum for researchers, practitioners, policymakers, and stakeholders from diverse fields such as agronomy, ecology, environmental science, soil science, and sustainable development.

DOI

10.48130/aee-0025-0009

Method of Research

Literature review

Subject of Research

Not applicable

Article Title

The impact of N,N-diethyl-m-toluamide in aquatic environments: occurrence, fate, and ecological risk

DE-GLOBALIZATION

Indian IT professionals bear unseen costs of multinational companies’ shift to home-based working

New study reveals hidden strain of remote work in the Global South

University of Bath

Research from the University of Bath exposes the overlooked burdens of remote working in the Global South, revealing how it transfers economic, physiological and emotional strain to Indian IT workers supporting global firms.

Drawing on in-depth interviews with 51 Indian IT professionals*, the research reveals how remote work demands adaptations going far beyond setting up a home office or managing work-life boundaries.

Workers are balancing the needs of multigenerational households in small living spaces, adjusting daily routines, managing frequent power outages and unreliable internet connectivity, navigating pervasive surveillance technologies, and sharing constrained internet bandwidth among several family members.

The research shows that while organisations benefit from reduced operational costs, they often transfer infrastructural responsibilities to employees, without adequate support. Workers even reported installing industrial-grade power backups in regions with unreliable power.

“In the Global South, where infrastructure is volatile and homes are often shared with extended family, the burden of making remote work viable falls disproportionately on entire households,” said Professor Vivek Soundararajan, from the University of Bath’s School of Management, who led the study.

The study, published in the Journal of Economic Geography, highlights five key dimensions of how IT workers have to adapt their households at multiple levels to sustain professional work, namely space, time, technical, surveillance, and emotional.

“Remote work's big promise was that talent could work from anywhere but it didn’t eliminate workplace inequality, it just moved it into the home," said Professor Soundararajan.

"Indian IT professionals - doing identical jobs to their counterparts in London or New York- spend their salaries on industrial backup power systems, negotiate with apartment associations over equipment installations, and coordinate elaborate family schedules just to stay online.”

India’s IT sector employs 5.80 million professionals. They supply remote services to multinational clients across finance, healthcare, retail and government.

“Our findings call for a rethink of remote work policies, one that integrates home as an integral component of productive work,” said co-author Dr Pankhuri Agarwal. “Organisations and policymakers must recognise that home/remote working is not inherently equitable or flexible.

“Family structure and housing arrangements are completely different to the Global North and pose very different remote working challenges. Companies must better understand the realities on the ground for remote work if they want to protect worker wellbeing.”

The researchers say that while 'infrastructural volatility' is a condition endemic to the Global South it is increasingly relevant worldwide, as climate change and economic pressures strain infrastructure globally, including the UK.

The research was supported by a UKRI Future Leaders Fellowship and contributes to emerging debates on the geography of work, digital capitalism, and the future of labour in post-pandemic economies https://embed-dignity.com/.

Remote work and reorganisation of household infrastructure in the Global South: insights from the Indian Information Technology industry is published in the Journal of Economic Geography.

Journal

Journal of Economic Geography

DOI

10.1093/jeg/lbaf052

Method of Research

Case study

Subject of Research

People

Evidence from professional golf shows political divides undermine focus and hurt performance at work

University of California - Berkeley Haas School of Business

By Scott Morrison, UC Berkeley Haas

Few workers face more scrutiny than professional athletes. Every movement is measured, every outcome quantified, and every performance evaluated against objective standards. So when UC Berkeley Haas researcher Tim Sels wondered how America’s deepening political polarization was affecting workers’ performance, he turned to one of the most comprehensive data sets on individual human performance: the PGA Tour.

What he discovered on golf courses—where random assignments and precise metrics make the invisible visible—was that professional golfers perform significantly worse when randomly grouped with competitors holding opposing political views. Even more striking, this performance gap nearly triples during periods of heightened national political polarization—and it translates directly into lower winnings.

The implications of his study, co-authored by Balázs Kovács of Yale School of Management, extend far beyond the fairway. The same dynamic may be undermining productivity in open-plan offices, on trading floors, in sales teams, and anywhere workers find themselves in close proximity with colleagues holding opposing political views.

“Political differences can create a more stressful and less psychologically safe environment, reducing focus and leading to reduced individual performance,” explains Tim Sels, a post-doctoral researcher at UC Berkeley’s Haas School of Business and lead author of the study published in Management Science.

“Political differences can create a more stressful and less psychologically safe environment, reducing focus and leading to reduced individual performance.”
—Tim Sels, postdoctoral researcher, UC Berkeley Haas

Random team assignments

The study, conducted by Sels and Balázs Kovács of Yale University’s School of Management, analyzed over 25,000 player-tournament-rounds from more than 700 PGA Tour tournaments between 1997 and 2022. The researchers painstakingly identified the political affiliations of 360 players—82 Democrats and 278 Republicans—through voter registration records, campaign donations, social media activity, and public statements. They then examined how these golfers performed when randomly assigned to play alongside political allies versus opponents during the first two rounds of tournaments.

The advantage of the PGA Tour as a research setting lies in its randomization. Unlike most workplace situations where people self-select into teams or are deliberately paired, PGA Tour officials use a computer program to randomly assign golfers to groups for the opening rounds. This random assignment provides the scientific gold standard for establishing causal relationships—a rare find in social science research.

The performance gaps were striking and economically meaningful. Golfers playing in politically mixed groups scored 0.2 strokes worse per round, ranked approximately 2.5 positions poorer, and faced a 5.3% reduced probability of making the tournament cut—the critical threshold separating those who earn prize money from those who go home empty-handed. These performance differences translated into a financial loss of approximately $13,000 to $23,400 in each of the PGA’s 47 tournaments, in which prize pools typically range from $10 million to $20 million.

“In professional sports, tiny differences in performance can make a huge difference in rankings or earnings,” says Sels.

Psychological tension

The study’s most revealing findings came from examining when these performance gaps emerged. Using detailed shot-level data, Sels and Kovács discovered that being in a politically mixed group primarily affected performance during driving and putting, moments when golfers stand closest to their playing partners. During the “approach to the green” and “around the green” stages, when players are more dispersed across the course, the political composition of the group had no significant effect.

This proximity pattern points to the underlying mechanism: anxiety triggered by the mere presence of political opponents. “We’re not talking about heated political debates on the course,” Sels emphasizes. “Professional golfers maintain silence during shots. But simply being aware of politically different others in shared spaces creates psychological tension that disrupts performance.”

“Professional golfers maintain silence during shots. But simply being aware of politically different others in shared spaces creates psychological tension that disrupts performance.”
—Tim Sels

Higher polarization boosts performance gap

Sels and Kovács also found that this tension waxes and wanes with the national political climate. During periods of high polarization, measured by the Partisan Conflict Index tracking political disagreement among U.S. politicians in major newspapers, the performance gap nearly tripled to 0.55 strokes per round. During calmer political periods, the gap virtually disappeared, dropping to just 0.02 strokes.

The researchers ran an extensive array of tests to rule out other explanations. They controlled for age, race, nationality, language, religion, education, hobbies, and numerous other individual attributes. They tested whether friendship ties, residential proximity, or prior playing history explained the effects (they didn’t). They examined whether being a political minority in the group mattered (it didn’t). And still, the core finding remained: political heterogeneity impairs performance primarily through proximity-based anxiety.

Workplace implications

What’s happening on the golf course is likely happening in other workplaces, too. The study identifies specific workplace conditions where political differences are most likely to harm individual performance: when political ideology is noticeable, when colleagues’ political views are known, when people work in close physical proximity, and when individual performance is tracked and rewarded. Open-plan offices, trading floors, sales environments with side-by-side representatives, and collaborative workspaces all fit this profile.

Numerous studies have examined how demographic diversity affects team outcomes, with mixed findings about when it helps or harms performance. But political heterogeneity has remained understudied—despite the fact that recent surveys show more than a quarter of U.S. workers discuss politics with colleagues, with in-person workers (30%) more likely to engage in such discussions than hybrid (24%) or remote workers (19%).

“Political affiliation signals shared values and beliefs more directly than demographics,” Kovács notes. “It creates in-groups and out-groups that influence psychological security even without explicit interaction.”

“Political affiliation signals shared values and beliefs more directly than demographics. It creates in-groups and out-groups that influence psychological security even without explicit interaction.”
—Balázs Kovács, Yale School of Management

Practical solutions

Importantly, the researchers caution against simplistic solutions. “We’re not advocating for organizational homogeneity,” Sels stresses. “Diversity can be very beneficial when you’re being creative.” Instead, they suggest practical solutions such as:

giving workers more space during politically charged periods.
enhancing psychological safety through inclusive practices
encouraging diversity in creative areas while giving people room to work independently when the work demands concentration.

Unfortunately, political polarization remains high—the Partisan Conflict Index has trended sharply upward since the early 2000s, with particular spikes during the 2013 government shutdown and following the 2016 Trump-Clinton election. For organizations, that means mounting pressure to address a force that can quietly erode productivity. The PGA Tour findings suggest these divisions have real implications for working Americans, even if the economic toll is harder to quantify. Recognizing these costs is the first step toward managing political differences more effectively.

Read the full paper:

Political Heterogeneity and Societal Polarization Impair Individual Performance: Evidence from Random Assignment in Professional Golf

By Tim Sels, UC Berkeley Haas, and Balázs Kovács, Yale School of Management

Management Science

Journal

Management Science

DOI

10.1287/mnsc.2023.01798

Method of Research

Data/statistical analysis

Subject of Research

People

Article Title

Political Heterogeneity and Societal Polarization Impair Individual Performance: Evidence from Random Assignment in Professional Golf

Glossy flowers: an enticing call from afar, a mystery up close

University of Würzburg

The existence of glossy surfaces in the plant and animal world poses a mystery to science. This is because clear and consistent signals are advantageous for reliable communication, for example between flowers and pollinators. Glossiness contradicts this principle, as its appearance is highly dependent on the viewing angle and illumination conditions and is therefore variable.

A research team at Julius-Maximilians-Universität Würzburg (JMU) has now investigated this contradiction. Their study shows that gloss fundamentally changes the efficacy of the visual signal depending on the distance and viewing angle of the observer, therefore has both advantages and disadvantages.

The Surface Structure creates the Gloss

The study was conducted under the leadership of Dr. Johannes Spaethe at the Chair of Behavioral Physiology and Sociobiology at JMU; Dr. Casper J. van der Kooi, head of a research group at the University of Groningen and at that time a Humboldt Fellow visiting the University of Würzburg, and Alexander Dietz as part of his master's thesis were responsible for the study. The team has now published the results of its research in the journal Science Advances.

“The difference between matte and glossy flowers lies in their microscopic surface structure,” says Johannes Spaethe, explaining the background to the study. Most flowers have a matte surface formed by countless tiny, cone-shaped cells – snapdragons, for example. This structure scatters the incident light in all directions. The result is a stable color signal that looks the same to pollinators from almost every angle.

In contrast, glossy flowers, such as buttercups, have flat surface cells. These act like tiny mirrors that reflect bright, directional flashes of light. These reflections can overlap or even overlay the actual color signal caused by the flower pigments.

Behavioral Experiments with Artificial Flowers

To investigate the effect of gloss on pollinators, the research team conducted behavioral experiments with bumblebees (Bombus terrestris). Using artificial flower replicas that differed only in their surface texture – matte or glossy – they were able to precisely analyze the insects' reactions. Their results reveal a fundamental visual conflict of objectives.

“The advantage of glossy flowers is that they are more easily recognizable from a distance,” explains Alexander Dietz. The gloss effect makes a decisive difference, especially at the perception limit of bumblebees, at very small viewing angles between three and six degrees: shiny flowers were still visible to the insects, while matte flowers of the same color and size could no longer be recognized.

However, there is a downside: “The same shine that attracts from a distance makes it difficult to perceive colors at close range,” explains Casper van der Kooi. The experiments showed that bumblebees had significantly more difficulty distinguishing between similar colors at close range on shiny surfaces. “The light reflected from the flat cells interfered with the reliable interpretation of the color signal,” says the scientist.

This risk of confusion has noticeable ecological consequences: For bees, foraging on glossy flowers becomes less efficient because they have to spend more time and energy distinguishing the correct flowers. For the plants, in turn, there is an increased risk of so-called “interspecific pollen transfer” – i.e., the transfer of pollen between different species – which can reduce reproductive success.

LA REVUE GAUCHE - Left Comment

Monday, December 01, 2025

Everyday repellent, global pollutant

DOI

Method of Research

Subject of Research

Article Title

Journal

DOI

Method of Research

Subject of Research

Evidence from professional golf shows political divides undermine focus and hurt performance at work

Random team assignments

Psychological tension

Higher polarization boosts performance gap

Workplace implications

Practical solutions

Read the full paper:

Journal

DOI

Method of Research

Subject of Research

Article Title

Glossy flowers: an enticing call from afar, a mystery up close

The Surface Structure creates the Gloss

Behavioral Experiments with Artificial Flowers

More than just a Question of Appearance: Lessons from Evolution

Journal

DOI

Method of Research

Subject of Research

Article Title

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