Clouds: A Neglected Reservoir of Pesticides

and other trending science

While perusing the medical literature this morning, two newly published papers stood out as very important.

I have written a synopsis explaining why each is important, followed by the abstract itself.

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Are Clouds a Neglected Reservoir of Pesticides?

Environ Sci Technol . 2025 Oct 14;59(40):21579-21588.

doi: 10.1021/acs.est.5c03787. Epub 2025 Sep 8.

Synposis: This paper takes a step back and asks a deceptively simple question. Where do pesticides actually go after we spray them? The answer, it turns out, is not just soil and water. The authors point to clouds as an overlooked reservoir. Pesticides can evaporate, hitch a ride on atmospheric particles, and end up in cloud water, where they persist and undergo chemical changes. From there, they do not just disappear. They can be transported long distances and eventually fall back to earth in rain, effectively redistributing agricultural chemicals far beyond where they were originally applied.

What makes this important is the implication. We tend to think of pesticide exposure as local and controllable. This work suggests it is far more diffuse and dynamic. The atmosphere is not just a passive conduit. It is an active chemical environment that can transform these compounds and extend their reach. In practical terms, that means ecosystems and populations far removed from direct agricultural use may still be exposed. It is a reminder that once these chemicals are released, they do not respect boundaries, and our current models of exposure may be underestimating both the scale and the persistence of the problem.

Abstract (from the paper)

Pesticide contamination is a growing and alarming concern for both the environment and human health. Widely used in agriculture to control pests and disease carriers, pesticides undergo extensive long-range atmospheric transport in the gas phase, in aerosols, and, as shown here, in clouds. We measured the concentration of 32 pesticides at the puy de Dôme observatory (France) in the sub μg L^-1 to μg L^-1 range in cloud water, largely arising from regional to long-range transport that also involves pesticides currently banned for agricultural use in France. Half of the samples showed a total concentration of pesticides of over 0.5 μg L^-1, which is the European drinking water limit. If 2,4-dinitrophenol, which can also be produced by photochemical reactions, is excluded, two samples still present a total concentration of over 0.5 μg L^-1. The frequent detection of pesticides in rainwater may thus depend on their presence in clouds as well as atmospheric washout. Estimates of pesticides’ quantity in clouds over France, ranging from 6.4 ± 3.2 to 139 ± 75 tons, suggest that their amounts in the cloud aqueous phase are potentially high and that these compounds would affect areas that are not directly impacted by agricultural activities.

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Modifiable risk factors and risk of schizophrenia and bipolar disorder across severities of genetic risk

J Affect Disord. 2026 Apr 13:407:121800.

DOI: 10.1016/j.jad.2026.121800 , Online ahead of print.

Synopsis: This study tackles a question that comes up again and again in psychiatry: how much of serious mental illness is “genetic destiny,” and how much is influenced by the way we live? The authors looked at schizophrenia and bipolar disorder, and instead of treating genetics as all-or-nothing, they stratified people by genetic risk using polygenic scores. Then they asked a very practical question. Do modifiable factors still matter if your genetic risk is high? The answer, in short, is yes. Across the board, lifestyle and environmental factors such as metabolic health, substance use, and other behavioral risks were associated with increased odds of developing these disorders, and that relationship held even in people with higher genetic susceptibility.

What makes this work important is that it pushes back on a fatalistic narrative. Genetic risk is real, but it is not a fixed sentence. The data suggest that modifiable exposures can either amplify or mitigate that baseline risk. In other words, the trajectory toward schizophrenia or bipolar disorder appears to be shaped by an interaction between biology and environment, not dictated by DNA alone. For clinicians and patients, that is a meaningful shift. It implies that prevention and risk reduction are not theoretical. They are actionable, even in those who carry a heavier genetic load.

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Abstract (from the paper)

Background: Schizophrenia (SCZ) and bipolar disorder (BD) are severe, globally prevalent mental illnesses, influenced by genetic and modifiable risk factors. The brain care score (BCS) is a validated tool comprising 12 modifiable factors across physical, lifestyle, and social-emotional domains, each linked to brain health. This study examines how BCS relates to SCZ or BD risk across different genetic risk levels, quantified by polygenic risk scores (PRS).

Methods: Using UK Biobank data, we calculated BCS and PRS scores, and identified incident SCZ and BD cases. Cox proportional hazards models evaluated associations between BCS and SCZ or BD risk. Interaction and stratified analyses assessed how this association varies across genetic risk levels. Contributions of BCS domains were also evaluated.

Results: Among 299,665 participants, 331 SCZ and 787 BD cases were identified over a median 13.7-year follow-up. In low-PRS individuals, higher BCS significantly reduced SCZ risk, particularly in lifestyle (HR = 0.87, P = 0.027) and social-emotional domains (HR = 0.47, P < 0.001). In high-PRS individuals, no overall BCS-SCZ association was observed, though the social-emotional domain remained protective (HR = 0.56, P < 0.001). For BD, low-PRS groups showed stronger BCS protection, especially in lifestyle (HR = 0.91, P = 0.017) and social-emotional domains (HR = 0.44, P < 0.001). In high-PRS groups, BCS protection was attenuated, but remained significant in the social-emotional domain (HR = 0.50, P < 0.001). Sensitivity analysis supported these findings.

Conclusion: Improving lifestyle and social-emotional health can significantly reduce SCZ and BD risk, with effects influenced by genetic risk. Enhancing social emotional health provides protective effects across all genetic risk levels, highlighting it as a key preventive measure.

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JGM

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