Congenital heart defects, or CHDs, are structural abnormalities of the heart and great vessels present at birth. They affect roughly 8 to 10 out of every 1,000 newborns globally, with prevalence varying widely by geography, from about 2.3 per 1,000 in Africa to about 9.3 per 1,000 in Asia. They are the most common form of congenital malformation and a leading cause of perinatal mortality, imposing a heavy medical and emotional burden on families. In China, where the new study was conducted, CHDs rank first among all birth defects, with a prevalence of roughly 6 to 8 per 1,000. While genetics clearly plays a role, researchers have long suspected that environmental exposures during pregnancy, from air pollution to heavy metals, contribute to the malformations, which arise when the embryonic heart fails to form correctly during a narrow window of development.

Antimony is a toxic trace element with chemical properties similar to arsenic, and it is ubiquitous in the modern environment. It is used in flame retardants, automotive brake friction materials, and lubricants, and it is abundant in airborne particulate matter. Fossil fuel and waste combustion, computer-chip manufacturing, and electronic-waste recycling all release antimony into the environment, and plastic containers used to store mineral water can leach measurable amounts of the element into their contents. People accumulate antimony through inhalation, dietary intake, and dermal contact. Previous research has linked antimony exposure to vascular inflammation, oxidative stress, and hypertension, but epidemiological evidence connecting it specifically to heart defects in newborns had remained scarce, which is precisely the gap the new study set out to fill.

The investigation was a nested case-control study conducted within a birth cohort established jointly by Gansu Provincial Maternity and Child Care Hospital and Yale University. The researchers enrolled 291 women: 97 who gave birth to infants with congenital heart defects, and 194 controls drawn from the same cohort and matched to cases at a 2-to-1 ratio by maternal age, within two years, and by residential community. All controls delivered singleton, full-term newborns of normal birth weight with no congenital malformations. Maternal whole blood samples were collected during prenatal hospitalization before delivery, and antimony concentrations were measured using inductively coupled plasma mass spectrometry, a highly sensitive technique with a detection limit of just 0.008 micrograms per liter. Laboratory staff performing the measurements were fully blinded to whether each specimen came from a case or a control, minimizing assessment bias.

The results were striking. Mean maternal blood antimony was 13.05 micrograms per liter in the control group compared with 20.30 micrograms per liter in the CHD group, a statistically significant difference. Using receiver operating characteristic curve analysis, the team identified a cutoff of roughly 20 micrograms per liter to split participants into high- and low-exposure groups. Women in the high-exposure group had 4.455 times the odds of having an infant with a heart defect compared with the low-exposure group, with a 95 percent confidence interval spanning 2.029 to 9.782. For isolated CHDs, meaning cases with a single malformation rather than multiple defects, the association was even stronger, with an odds ratio of 12.648.

The study also uncovered what appears to be a threshold effect. For each incremental increase of 6 micrograms per liter in maternal blood antimony, the risk of CHDs in offspring rose by 38.9 percent. Restricted cubic spline analysis revealed an inverted L-shaped relationship: at maternal blood antimony levels between zero and 18.409 micrograms per liter, the risk of heart defects remained low and stable, but once concentrations exceeded that threshold, risk climbed steadily with rising antimony levels. This pattern suggests that danger emerges only above a certain exposure concentration rather than across the entire range, a finding the authors note has important implications for identifying safe exposure limits.

Subgroup analyses strengthened the overall signal. Elevated antimony was associated with higher risk for several common CHD subtypes, including malformations of the great arteries such as patent ductus arteriosus, septal defects such as atrial and ventricular septal defects, and atrial septal defects specifically. The associations held across maternal age groups, gestational weight change, preconception health education, employment status, and the timing of folic acid supplementation. The study also found a significant interaction between antimony and household income: compared with women who had low antimony and high income, those with high antimony and low income faced a 65.4 percent higher risk of having a child with a heart defect, suggesting that socioeconomic disadvantage may compound the biological burden of the exposure.

The biological plausibility of these findings is supported by a growing body of laboratory evidence. In zebrafish larvae, exposure to high concentrations of antimony significantly altered heart rate, induced developmental delay, elevated reactive oxygen species, and depleted glutathione, a key cellular antioxidant. Antimony exposure also disrupted the expression of immune-related genes in the larvae. In mouse studies, antimony triggered endoplasmic reticulum stress by disrupting calcium homeostasis, activating signaling pathways that lead to cardiomyocyte death, and produced visible mitochondrial swelling and cristae fracture in heart tissue. Cellular experiments have shown that both trivalent and pentavalent antimony suppress ATP production and impair mitochondrial function in cardiac cells. Proposed mechanisms include antimony’s irreversible binding to intracellular sulfhydryl groups, interference with DNA methylation during embryonic development, and the induction of oxidative DNA damage and lipid peroxidation.

The authors are careful to frame their work as an observational study that provides epidemiological clues rather than proof of causation. Blood samples were collected before delivery, whereas the critical window for fetal cardiac morphogenesis occurs at gestational weeks 3.5 to 8, so the measured concentrations may reflect cumulative gestational exposure rather than exposure during that specific period. The total number of cases was also limited, reducing statistical precision for individual subtypes, and residual confounding cannot be excluded despite adjustment for maternal ethnicity, body mass index, smoking, gestational hypertension, and supplementation habits. The team calls for larger multicenter prospective cohort studies with repeated blood measurements across gestation to validate the findings and pinpoint the exposure window with greater precision.

Still, the public health implications are considerable. Drinking water standards currently cap antimony at 5 micrograms per liter in China and 6 micrograms per liter in the United States, and the study’s risk threshold of roughly 18.4 micrograms per liter in blood suggests that exposure well above these environmental benchmarks corresponds to meaningful increases in congenital heart defect risk. The researchers argue that the prenatal living environment may be a modifiable target for CHD prevention, and that raising awareness of maternal environmental risks, adopting healthier lifestyles, and minimizing exposure to antimony-containing sources, from polluted air to contaminated water and plastic food containers, could help reduce the incidence of the world’s most common birth defect. As industrial development continues to reshape the chemical environments in which pregnancies unfold, studies like this one make clear that the invisible contaminants accumulating in expectant mothers’ blood may carry consequences that last a lifetime.

Subject of Research: Association between prenatal antimony exposure and congenital heart defects in offspring

Article Title: Association between maternal antimony exposure and offspring congenital heart defects: findings from a large birth cohort study

Article References: Shao, Y., Cao, L., Lin, R., Ran, J., Liu, Q., & Mao, B. (2026). Association between maternal antimony exposure and offspring congenital heart defects: findings from a large birth cohort study. Frontiers in Public Health, 14, Article 1957018. https://doi.org/10.3389/fpubh.2026.1957018

Image Credits: AI Generated

DOI: 10.3389/fpubh.2026.1957018

Keywords: antimony, congenital heart defects, pregnancy, heavy metals, birth cohort, environmental health, ICP-MS, oxidative stress, patent ductus arteriosus, septal defects, drinking water, pollution

Antimony was originally developed by the systems biology community to solve a simple but persistent problem. SBML, the XML-based format used to exchange models between software tools, is precise and machine-friendly, but its nested tags make it cumbersome for researchers to write or inspect by hand. Antimony offered an alternative: a concise syntax in which a scientist can define species, compartments, reactions, and parameters in a few lines of text, then convert seamlessly back and forth between that text and standards-compliant SBML. The idea proved popular, and Antimony became embedded in widely used tools across the field, including the popular simulation environment Tellurium.

But software standards do not stand still. Since Antimony’s original release, SBML itself has evolved significantly, most notably with the introduction of SBML Level 3 and a growing family of extension packages that add capabilities the original specification lacked. Modeling practice has evolved too, with researchers increasingly combining kinetic reaction models with constraint-based approaches, attaching statistical uncertainty to parameters, and demanding publication-quality visualizations of their networks. Antimony’s developers recognized that the language needed a formal, comprehensive update to keep pace, and Antimony 3 is the result: a version that consolidates years of cumulative improvements and extends the language’s reach into the newest corners of the SBML ecosystem.

The headline technical advance in Antimony 3 is its expanded support for SBML Level 3 Core and several of its most important packages. The update covers the Flux Balance Constraints package, known as FBC, which underpins flux balance analysis, a technique that uses stoichiometric constraints to predict metabolic fluxes in genome-scale models. It also supports the Distributions package, which allows modelers to represent parameters as probability distributions rather than fixed numbers, capturing uncertainty in experimental measurements. The Layout and Render packages round out the list, enabling models to carry structured spatial diagrams and visual styling information alongside their mathematical content.

The practical significance of that package support is that Antimony 3 allows modelers to combine capabilities that previously required separate tools or manual file editing. A single plain-text model specification can now mix kinetic reactions with flux balance analysis, represent uncertain parameters using probability distributions, add biological context through annotations, and define publication-ready visualizations, all in one unified format. For researchers who build, share, and reuse models across laboratories and software platforms, this means fewer format conversions, fewer opportunities for error, and a single readable document that captures the full richness of a modern computational model.

Under the hood, Antimony 3 is delivered as a lightweight C/C++ library with a stable C API, a design choice that makes it easy to embed in other applications. The library ships with official bindings for three major scripting ecosystems: Python, Julia, and JavaScript compiled to WebAssembly. The WebAssembly support is particularly notable, because it means Antimony can run directly inside a web browser, opening the door to browser-based modeling tools that require no installation at all. The developers have also released a cross-platform desktop graphical interface, so researchers who prefer point-and-click workflows can use the language without touching a command line.

This multi-platform delivery reflects a broader trend in computational biology, where the same model may need to live in a Jupyter notebook, a desktop application, and a web service. By providing a stable C API at its core and consistent bindings above it, Antimony 3 ensures that a model written once behaves identically across all of these environments. The library is released as open-source software under the permissive BSD 3-Clause License, and the source code is freely available on GitHub, allowing anyone to inspect, modify, or integrate it into their own projects without licensing barriers.

For the systems biology community, the release addresses a growing pain point. As models have grown larger and more sophisticated, the burden of maintaining them in machine-oriented formats has grown with them. Genome-scale metabolic models, for example, can contain thousands of reactions, and constraint-based analyses increasingly sit alongside dynamic kinetic simulations in the same research workflow. A human-readable language that spans both worlds lowers the barrier for experimentalists who want to check what a model actually says, for students learning to build their first networks, and for reviewers who need to verify that a published model matches its description in a paper.

The emphasis on uncertainty representation also speaks to a maturing field. Point estimates for kinetic parameters are often optimistic, since experimental measurements carry noise and biological variability. By supporting the SBML Distributions package, Antimony 3 lets modelers encode that variability directly in the model definition, making uncertainty an explicit part of the shared artifact rather than a footnote in the accompanying text. Combined with annotation support for biological context, the language pushes models toward becoming self-describing documents that carry their evidence, their mathematics, and their visual presentation together.

Antimony 3 is available now at the project’s GitHub repository, and the developers describe it as a formalization of the language’s cumulative evolution rather than a departure from it. Existing users should find their models carry forward, while gaining access to the extended SBML Level 3 features. As computational models take on ever larger roles in drug discovery, metabolic engineering, and basic biological research, tools that make those models easier to write, read, and trust are likely to matter more with every passing year. With this release, the community’s answer to machine-only modeling formats has caught up with the state of the art.

Subject of Research: A human-readable modeling language for SBML Level 3 systems biology models

Article Title: Antimony 3: Extending human-readable model definitions for SBML Level 3 Core and Packages

Article References: Heydarabadipour, A., Smith, L. P., Hellerstein, J. L., & Sauro, H. M. (2026). Antimony 3: Extending human-readable model definitions for SBML Level 3 Core and Packages. PLOS Computational Biology, 22(10), e1014207. https://doi.org/10.1371/journal.pcbi.1014207

Image Credits: AI Generated

DOI: 10.1371/journal.pcbi.1014207

Keywords: Antimony, SBML Level 3, systems biology, flux balance analysis, FBC package, Distributions package, computational modeling, open-source software, biochemical networks, model interchange, WebAssembly, PLOS Computational Biology

Persistence is a phenomenon familiar to microbiologists from bacterial studies, in which small subpopulations of cells enter a non-dividing or slow-growing state and thereby survive antibiotic exposures that kill their proliferating siblings. In Leishmania, persisters have been suspected as a major driver of treatment failure and clinical relapse, but the molecular mechanisms governing their formation remained poorly understood. The new work set out to change that by building an experimental model of persistence in Leishmania mexicana, a species widely used in laboratory studies of the parasite’s biology. The central question was deceptively simple: what, at the level of gene expression, distinguishes a parasite that survives a lethal drug challenge from one that does not?

To answer it, the team first had to isolate the survivors. They exposed promastigote parasites, the motile form of Leishmania grown in culture, to potassium antimonyl tartrate, or PAT, a laboratory stand-in for the antimony-containing drugs used clinically. The dose was deliberately harsh: it killed roughly 80 percent of the parasite population. The remaining viable parasites were then enriched using Ficoll density gradient centrifugation, a technique that separates cells by their physical properties and allowed the researchers to concentrate the persister-like subpopulation. When these survivors were placed back into drug-free medium, they displayed the hallmark behavior of persisters: their growth was delayed compared with untreated parasites, and when they were challenged with the drug again, they proved markedly more tolerant than parasites that had never been exposed.

With a reliable population of persister-like cells in hand, the researchers turned to transcriptomic profiling, sequencing the RNA of the parasites across three distinct phases: the acute stress of drug exposure, a drug-free recovery period, and a rechallenge with PAT. The results revealed a global remodeling of gene expression in the persister-like cells under all tested conditions. Rather than a narrow, targeted response, the parasites appeared to reorganize broad swaths of their biology. Induction of the persister state was characterized by the downregulation of numerous biological processes, paired with a robust upregulation of nucleolar pathways. The nucleolus is the cellular compartment where ribosomes, the molecular machines that build proteins, are assembled, and its prominence in the persister signature points toward epitranscriptomic changes, chemical modifications of RNA molecules themselves, during the formation of the persister-like state.

One of the most striking observations came when the drug was removed. The persister transcriptional profile did not linger; it reverted rapidly, initiating a program of ribosome biogenesis that allowed the parasites to exit their latent state and resume proliferation. During this resuscitation phase, the researchers detected active protein synthesis and the upregulation of biological processes associated with metabolic and mitochondrial functions. In other words, the persister state is not a one-way door. It is a dynamic, reversible condition with its own entry program and its own exit program, each executed with apparent precision. This reversibility is precisely what makes persisters so dangerous in a clinical setting: they can survive a course of treatment and then repopulate the infection once the drug pressure subsides.

The rechallenge experiments provided perhaps the most revealing window into the persister lifestyle. When the enriched persister-like parasites were exposed to PAT a second time, they did not respond the way their parental counterparts did. Instead, they rapidly implemented a highly conserved, coordinated survival reprogramming in which 316 genes were uniquely downregulated and 241 genes were upregulated. The downregulated genes were concentrated in mitochondrial function and protein synthesis, driving the parasites into a dormant state that minimizes the drug’s targets and conserves energy. The upregulated genes, by contrast, were enriched for drug-response and stress-tolerance functions, equipping the cells to withstand the immediate chemical toxicity. The parental parasites, facing the same drug for the first time, mounted a broad and disorganized response, a molecular scramble that contrasts sharply with the rehearsed efficiency of the persisters.

Intriguingly, the rechallenged persisters also exhibited transcriptomic features that transiently phenocopy stable genetic resistance. This pre-adapted state was characterized by the targeted upregulation of epigenetic and epitranscriptomic modulators, heavy metal transporters, and catabolic enzymes, all of which help maintain viability under drug pressure. Heavy metal transporters are particularly noteworthy in the context of antimony therapy, because antimony is a metalloid and pumping it out of the cell is a classic mechanism of resistance. The fact that persisters transiently ramp up these systems without any permanent genetic change suggests that the persister state may serve as a proving ground, a way for parasites to test and rehearse the molecular tools that, if later locked in by mutation or gene amplification, would constitute full-blown resistance.

This framing carries significant evolutionary weight. The authors argue that drug persistence in Leishmania is not merely a metabolic collapse but a sophisticated survival strategy involving active transcriptome remodeling, downregulation of translation, and epigenetic and epitranscriptomic changes. If the transient persister state constitutes an initial evolutionary step toward permanent drug resistance, then the population of persisters surviving each treatment cycle represents a reservoir of pre-adapted cells from which resistant lineages can emerge. That would help explain the familiar clinical trajectory of leishmaniasis: initial response to antimonial therapy, followed by relapse, and in some cases the eventual failure of the drug altogether. It also aligns with a broader theme in infectious disease research, in which phenotypic tolerance is increasingly recognized as a stepping stone to genotypic resistance across many microbial species.

The study also highlights new molecular vulnerabilities that could be exploited therapeutically. If persisters depend on specific nucleolar pathways, epigenetic modulators, and coordinated transcriptional programs to establish and maintain their tolerant state, then drugs that interfere with those programs could sensitize the cells to antimony and prevent the survival of the subpopulation that seeds relapse. Combination therapies that pair conventional antimonials with agents targeting the persister machinery are an obvious avenue for future investigation, although translating findings from cultured promastigotes to the intracellular amastigote stage that infects human patients will require further work. The experimental model developed by the research team, combining lethal drug exposure, density gradient enrichment, and time-resolved transcriptomics, provides a platform for such studies.

For a disease in which the therapeutic arsenal has remained narrow for decades, the demonstration that Leishmania persisters are active participants in their own survival, rather than passive casualties of slowed metabolism, is a conceptual advance with practical implications. It suggests that the battle against leishmaniasis is not only fought at the level of parasite killing but also at the level of parasite decision-making, in the regulatory networks that allow a subset of cells to rewrite their gene expression and wait out the storm. Intercepting that rewrite, before it hardens into permanent resistance, may prove to be one of the most promising strategies for preventing the relapses that have made this ancient disease so difficult to cure.

Subject of Research: Transcriptomic mechanisms of antimony-induced drug tolerance and persistence in Leishmania parasites

Article Title: Active transcriptome remodeling underlies antimony-induced drug tolerance in persister-like Leishmania parasites

Article References: Quiceno, E., Rodríguez-Almonacid, C. C., Omeir, K., Ancira, J., Phillips, C., & Karamysheva, Z. N. (2026). Active transcriptome remodeling underlies antimony-induced drug tolerance in persister-like Leishmania parasites. PLOS Pathogens, 22(10), e1014682. https://doi.org/10.1371/journal.ppat.1014682

Image Credits: AI Generated

DOI: 10.1371/journal.ppat.1014682

Keywords: Leishmania, leishmaniasis, drug tolerance, persister cells, antimony, transcriptomics, PLOS Pathogens, drug resistance, epitranscriptomics, ribosome biogenesis, parasitology, treatment relapse

The study, published in Communications Earth & Environment, was led by Degao Zhai of the State Key Laboratory of Geological Processes and Mineral Resources at China University of Geosciences in Beijing, together with Gang Zhao, Qingfei Wang and Jiajun Liu from the same institution, and an international team including Anthony E. Williams-Jones of McGill University, Runsheng Yin of the Chinese Academy of Sciences in Guiyang, Ryan Mathur of Juniata College, Manuel Keith of Ludwig-Maximilians-Universität München, Jian-Feng Gao and Di Chen, and Junwei Xu of the Geophysical and Geochemical Survey Institute of Hunan. Their work addresses a stubborn problem in economic geology: for large, low-temperature hydrothermal deposits, direct tracers of metal sources have remained frustratingly limited.

Antimony is far more familiar to most people than they realize. The element is a critical ingredient in flame retardants, lead-acid batteries, semiconductors and a range of military and industrial applications, which is why many governments now classify it as a strategic raw material. China dominates global production, and the South China belt—with world-famous districts such as Xikuangshan—sits at the heart of that dominance. Understanding where its metal comes from is therefore not just an academic puzzle; it directly shapes how exploration geologists decide where to drill next.

The traditional difficulty is that antimony deposits in South China formed from relatively cool hydrothermal fluids, typically far below the temperatures associated with magmatic ore systems. In hotter systems, geochemists can often link ores to specific intrusions or volcanic rocks using a battery of tracers. In these low-temperature systems, however, the fluids traveled long distances, interacted with many different rocks along the way, and left behind few unambiguous fingerprints of their ultimate origin. Competing models have variously invoked the Precambrian basement, sedimentary sequences, or deep crustal and mantle reservoirs, but the evidence has never been decisive.

Zhai and colleagues attacked the problem with a novel strategy: measuring the isotopic compositions of antimony itself, in tandem with mercury, in stibnite—the antimony sulfide mineral that makes up the ores. Isotopes are atoms of the same element with different masses, and their ratios in a mineral act like a chemical passport, recording the reservoir from which the element was derived. Antimony isotope analysis is a young technique, and this study represents one of its most ambitious applications to ore-forming systems. Mercury isotopes, by contrast, are better established, and they bring a special advantage: the mass-independent fractionation signature of mercury, denoted Δ199Hg, is largely unaffected by the ordinary chemical processing that happens as fluids move through the crust, making it an unusually faithful recorder of whether material passed through surface environments or came from the deep Earth.

The results are remarkable for their sheer variability. The measured δ123Sb values of the ores span from −0.64 to +0.69 per mil, the δ202Hg values range from −1.86 to +2.08 per mil, and the Δ199Hg values extend from −0.20 to +0.14 per mil. In isotope geochemistry, such wide spreads are not noise; they are a message. A single, uniform source would produce a narrow cluster of values. Instead, the data point to a mixing relationship between two isotopically distinct reservoirs that contributed metal to the ore-forming fluids in varying proportions across the belt.

The first reservoir is the Precambrian basement, the ancient metamorphic rocks that underlie much of southern China. Metamorphic devolatilization—the process by which heat and pressure drive fluids and volatile elements out of deeply buried rocks—can liberate antimony and mercury from these crustal rocks and release them into circulating hydrothermal systems. The isotopic signatures of the ores that align with this reservoir indicate that the old basement was not a passive bystander but an active supplier of metal to the belt.

The second reservoir is far more dramatic: a deep, recycled mantle-related source. Mercury’s mass-independent signatures in particular carry information about whether the element once cycled through Earth’s surface environment—oceans and atmosphere—before being dragged back into the interior by subduction and later returned through deep fluids. The data support a model in which some of the antimony in the South China belt was ultimately derived from material that had been recycled into the mantle and was released again from depth, a conclusion that connects these shallow, cool ore systems to the planet’s grandest geochemical conveyor belt.

This dual-source picture resolves a long-standing tension in the literature. Earlier debates often treated the question as either-or: either the metal came from the crust or from depth. The coupled isotope approach shows that the answer is both, with the relative contributions varying from deposit to deposit. That insight matters for exploration, because deposits fed predominantly by one reservoir or the other may occur in different structural and geological settings, and the isotopic composition of ore minerals could in principle serve as a vectoring tool, helping geologists assess the character of a system from early-stage samples.

Beyond the immediate implications for antimony, the study demonstrates the broader power of a technique that is only now coming of age. Coupled antimony and mercury isotope analysis offers a potentially powerful tool for identifying metal sources in ore deposits worldwide, the authors argue, and its application may help refine deposit models globally. It also opens a window onto the dynamic interplay between Earth’s interior and crustal metal cycling—the slow, planet-scale circulation that moves elements between the mantle, the crust and the surface over hundreds of millions of years.

For a metal that has become a centerpiece of supply-chain security debates, the new results carry practical weight. If the giant South China belt owes its wealth to a combination of ancient basement rocks and deeply recycled mantle material, then exploration models built on shallow crustal processes alone may be missing part of the story. The isotopic fingerprints locked inside stibnite crystals now suggest that some of the world’s most important antimony ores are, quite literally, gifts from the deep Earth—delivered upward through fluids that connected the planet’s interior to its crust in ways geologists are only beginning to decode.

Subject of Research: Metal sources of the South China antimony belt traced with coupled antimony and mercury isotopes

Article Title: Coupled Sb-Hg isotopes reveal mixed basement and deeply recycled mantle-related metal sources for the South China antimony belt

Article References: Zhai, D., Zhao, G., Williams-Jones, A. E., Yin, R., Mathur, R., Keith, M., Wang, Q., Liu, J., Chen, D., Gao, J.-F., & Xu, J. (2026). Coupled Sb-Hg isotopes reveal mixed basement and deeply recycled mantle-related metal sources for the South China antimony belt. Communications Earth & Environment. https://doi.org/10.1038/s43247-026-04108-4

Image Credits: AI Generated

DOI: 10.1038/s43247-026-04108-4

Keywords: antimony, mercury isotopes, South China, ore deposits, economic geology, geochemistry, Precambrian basement, mantle recycling, stibnite, hydrothermal fluids, metal sources, critical metals

The mines at Crocette and Pestarena tell a story that stretches back to the end of the thirteenth century, when the first official documents recorded underground gold mining in the valley. Operations continued into the mid-twentieth century, ending at Pestarena in 1961 as ore grades declined and costs rose. The gold was locked in quartz-carbonate veins hosted in paragneisses and micaschists at Pestarena and in orthogneisses at Crocette, where it occurred alongside sulfide minerals, chiefly pyrite and arsenopyrite, with lesser galena, sphalerite, pyrrhotite and chalcopyrite. Extraction relied on mercury amalgamation and, from the late 1880s, cyanidation, both of which generated enormous quantities of waste rock and fine-grained tailings that were dumped around the processing plants with little regard for the consequences.

That carelessness left a lasting mark. Sulfide minerals in the exposed waste oxidize when they meet air and water, generating acid or neutral mine drainage that mobilizes potentially toxic elements into soils, groundwater and streams. Previous investigations had already documented alarming conditions: soils near Crocette with arsenic concentrations ranging from 145 to more than 40,000 milligrams per kilogram, a natural background value for the area calculated at 477 milligrams per kilogram against an Italian regulatory threshold of just 20 to 50, and surface waters in the most contaminated samples reaching 279 micrograms of arsenic per liter, far above the Italian limit of 10. A 2025 study by members of the same team found that three quarters of groundwater and surface water samples at the two sites were contaminated with arsenic, with other elements exceeding thresholds in groundwater downstream of the tailings.

To build a complete picture, the researchers merged decades of earlier geochemical and mineralogical data with a new sampling campaign conducted in May and July 2024, collecting 28 fresh samples of waste rock, tailings, soil and sediment from depths of up to 30 centimeters. The new material was analyzed at an accredited laboratory using a four-acid digestion followed by inductively coupled plasma emission spectroscopy and mass spectrometry, covering more than fifty elements, while mineralogy was resolved with X-ray powder diffraction and scanning electron microscopy. Because decades of erosion and dispersion have blurred the boundary between waste and native soil, the team classified every sample under two scenarios: a conservative one counting only material clearly located on waste dumps, and a broader one that also included adjacent, vegetation-free or chemically distinctive material, mirroring the distinction between indicated and inferred resources in resource estimation.

The mineralogical work revealed the fingerprints of intense chemical weathering. Alongside the dominant quartz, feldspars and micas inherited from the host rocks, the waste contains secondary minerals that record the breakdown of the original sulfides: scorodite, formed from the alteration of arsenopyrite; jarosite, precipitated as pyrite and pyrrhotite oxidize; and alunite, produced during the alteration of aluminosilicates. Electron microscopy also identified grains of monazite-(Ce), a phosphate mineral that can carry up to seventy percent rare earth oxides, dominated by cerium with significant lanthanum, praseodymium and neodymium, along with traces of residual arsenopyrite, ilmenite, zircon and barite. Scheelite, a calcium tungstate and one of the world’s principal tungsten ores, appeared among the minor minerals, a hint of the critical metals hiding in plain sight.

When the researchers normalized their measured concentrations against the composition of the upper continental crust, the scale of the enrichment became striking. At Pestarena, arsenic in the waste is a median of roughly 1,700 to 2,000 times more abundant than in average crustal rock, while bismuth, tungsten and antimony show median enrichments of about 100, 35 and 15 respectively, with slight enrichment of beryllium and of the light rare earth elements lanthanum, cerium, praseodymium and neodymium. At Crocette the picture is even more dramatic: arsenic reaches a median enrichment of around 4,000 times crustal values, followed by tungsten at 50, antimony at 40 and bismuth at 26. These figures matter because arsenic, bismuth, antimony and tungsten all appear on the European Union’s list of critical raw materials, the strategic elements underpinning semiconductors, photovoltaics, clean energy technologies and defense applications.

The same waste that concentrates these valuable elements also drives the environmental damage, and the team quantified that damage using standard contamination indices. River sediments collected away from the mine workings proved uncontaminated, but sediments from the drainage channels of the mine tunnels and the tailings outflows showed heavy to extreme arsenic contamination, moderate to heavy lead contamination and high ecological risk, driven overwhelmingly by arsenic. In the surrounding soils, the geo-accumulation index placed Pestarena in the heavily to extremely contaminated category for arsenic, with a mean value of 3.5 and individual samples exceeding 5.0, alongside moderate lead contamination, while Crocette soils fell in the moderately to heavily contaminated range. The potential ecological risk index, which weights each element by its toxicity, averaged 296.4 at Pestarena and 251.1 at Crocette, both within the moderate risk category, with arsenic contributing the dominant share, followed by lead and cobalt.

What elevates the study beyond a conventional contamination survey is its economic framing. By estimating the volumes of waste rock and tailings at each site from field observations and stratigraphic data, and applying bulk densities of 1.5 grams per cubic centimeter for waste rock and 1.8 for tailings, the researchers calculated the residual quantities of arsenic, bismuth, antimony and tungsten still locked in the dumps. They then multiplied these quantities by plausible recovery rates of 60 to 80 percent, consistent with efficiencies of 77 to 99 percent reported for tungsten, 81 to 99 percent for arsenic, up to 98 percent for antimony and 76 to 99 percent for bismuth in comparable secondary resources, and by average market prices from 2000 to 2021. Arsenic emerges as the most abundant target, with bismuth, antimony and tungsten present in significant quantities, although the authors stress that these preliminary estimates cannot by themselves establish economic feasibility, since remediation, processing and residue disposal costs must all be weighed against revenues.

The technical pathways for such recovery already exist. Published case studies describe arsenic and antimony extraction from antimony flotation waste by acid leaching, the recovery of antimony and bismuth from copper smelter flue dusts through acid chloride leaching and selective precipitation, the stabilization of arsenic as crystalline scorodite during copper electrorefining, and the recovery of tungsten and arsenic from tungsten-bearing residues using alkaline leaching with pressure oxidation, deep eutectic solvents paired with electrodialysis, or acid leaching followed by solvent extraction. Arsenic occupies a paradoxical position in this landscape: it is both a valuable resource, essential for gallium arsenide semiconductors and electronic technologies, and one of the world’s most notorious poisons, capable of causing severe chronic health effects through contaminated water and food. Any recovery scheme must therefore be paired with safe long-term management of the arsenic left behind, for example by precipitation as scorodite or vitrification, to prevent the problem simply migrating from one waste heap to another.

The broader message is one of reframing. Within the European Union, mining and quarrying generated nearly 500 million tonnes of waste in 2022, the second largest share of any economic activity, and the Circular Economy Action Plan together with the Critical Raw Materials Act now explicitly encourages treating old waste heaps as anthropogenic deposits rather than burdens. The Anzasca Valley study suggests that remediation and resource recovery need not be opposing goals: excavating and processing contaminated waste can simultaneously reduce ecological risk, clean up soils and water, and supply strategic materials that Europe currently imports at geopolitical peril. The authors caution that further work is needed to characterize the materials more precisely, optimize treatment processes and evaluate the full economic and environmental sustainability of recovery strategies. But their central conclusion is clear: the mountains of waste left behind by a thousand years of Alpine gold mining may yet prove to be among the most valuable things those mines ever produced.

Subject of Research: Environmental impact assessment and critical raw material recovery from abandoned gold mining waste in the Western Alps

Article Title: From environmental burden to resource potential: environmental impact evaluation and Critical Raw Materials recovery from abandoned gold mining waste in the Western Alps (NW Italy)

Article References: Zaniboni, L., Cavallo, A., De Luca, D. A., Lasagna, M., Padoan, E., Martin, M., & Dino, G. A. (2026). From environmental burden to resource potential: environmental impact evaluation and Critical Raw Materials recovery from abandoned gold mining waste in the Western Alps (NW Italy). Environmental Science and Pollution Research. https://doi.org/10.1007/s11356-026-38241-6

Image Credits: AI Generated

DOI: 10.1007/s11356-026-38241-6

Keywords: critical raw materials, arsenic, gold mining, mine waste, tailings, circular economy, environmental contamination, ecological risk, Western Alps, Italy, tungsten, antimony

The research team, led by Xiaoyan Liu and Yirong Wang of the School of Minerals Processing and Bioengineering at Central South University in Changsha, China, together with colleagues including corresponding author Hongchang Liu and Zhenyuan Nie, designed a 42-day experiment with a 2 × 2 × 2 factorial structure. That means they independently varied three factors: the mineral composition, with and without pyrite mixed into the stibnite; the light conditions, running parallel treatments under illumination and in complete darkness; and the biological conditions, with and without a community of acidophilic microorganisms of the kind that thrive in acidic mine drainage. By crossing these factors, the team could separate the contribution of each variable and, crucially, detect the interactions between them that simpler experiments would miss.

The analytical arsenal deployed in the study was correspondingly broad. The researchers tracked solution chemistry over the entire incubation, examined the chemical composition of mineral surfaces using X-ray photoelectron spectroscopy, characterized the structure of the microbial communities that developed in each treatment, measured the electrochemical behavior of the mineral pairs, and monitored signals of hydroxyl radicals, the ferociously reactive species denoted ·OH that can oxidize sulfide minerals and their dissolved products. This combination allowed the group to link macroscopic dissolution rates to molecular-scale interfacial processes, a connection that has long been difficult to establish for mixed sulfide mineral systems in mining environments.

The headline result concerns galvanic coupling. When two minerals with different electrochemical potentials are in electrical contact in an electrolyte, they behave like a short-circuited battery: the mineral with the lower rest potential becomes the anode and dissolves preferentially, while the more noble mineral acts as the cathode. Electrochemical analyses in the study confirmed that in pyrite–stibnite mixtures, pyrite assumes the cathodic role and stibnite the anodic one. In practical terms, the presence of pyrite accelerates the anodic dissolution of stibnite, effectively wiring the antimony ore into a corrosion cell that keeps pushing electrons out of the stibnite lattice. The authors identify this pyrite–stibnite galvanic coupling as the primary electrochemical process driving stibnite biodissolution in their experiments, which explains why pyrite emerged as the dominant factor among all the variables tested.

The microbial dimension of the study adds a second, complementary layer to the mechanism. Under biotic conditions, pyrite did more than serve as a passive cathode. Its dissolution released iron and sulfur species into solution, and these products sustained microbial iron and sulfur cycling. Acidophilic microorganisms, notably iron oxidizers of the kind well known from bioleaching systems, oxidize ferrous iron to ferric iron, and ferric iron is itself a powerful oxidant that attacks sulfide minerals. By feeding this cycle, pyrite-derived Fe and S species enabled continuous Fe3+ regeneration, maintaining an oxidizing environment that supported ongoing stibnite dissolution even as the experiment progressed over six weeks. In other words, the microbes and the minerals form a self-reinforcing loop: pyrite supplies the chemical fuel, microbes regenerate the oxidant, and stibnite pays the price by dissolving.

Light, the third experimental variable, played a more subtle but chemically elegant role. Pyrite is a semiconductor, and illumination can promote electrons across its band gap, altering the way charge transfers at the mineral–water interface. The X-ray photoelectron spectroscopy results quantify this effect vividly. On mineral surfaces exposed to light, the relative proportion of sulfate, the fully oxidized end product of sulfide oxidation, rose from 29.80 percent in the dark to 63.89 percent under illumination. Meanwhile, residual sulfide on the surfaces fell from 50.33 percent to just 15.55 percent. These numbers indicate that light substantially accelerated the surface oxidation of the sulfide minerals, shifting the interfacial chemistry toward more complete oxidation. The study concludes that light mainly affected interfacial electron transfer rather than acting as the primary driver of dissolution in its own right.

Accompanying the photochemical effect was a change in reactive oxygen chemistry. The pyrite-bearing biotic system exposed to light displayed stronger hydroxyl radical signals than its dark counterpart. Hydroxyl radicals are among the most potent oxidants in aqueous chemistry, and previous work has shown that pyrite surfaces can generate them through reactions involving oxygen, water, and intermediate hydrogen peroxide. The new findings tie this radical production into the broader dissolution picture: in systems containing both pyrite and stibnite under illumination, interfacial electron transfer and radical-mediated oxidation reinforce one another, deepening the oxidative transformation of the mineral surfaces and, by extension, the mobilization of antimony.

Why does this matter beyond the laboratory? Antimony contamination around mining districts is a serious environmental and public health issue, and the mobility of antimony in water depends strongly on its oxidation state and speciation. Understanding what controls the rate at which stibnite weathers is therefore essential for predicting how antimony spreads from mine waste into rivers, sediments, and groundwater. The study’s finding that a seemingly inert companion mineral can electrochemically accelerate ore dissolution means that risk assessments based on stibnite alone may substantially underestimate release rates in pyrite-rich ores, which are common in nature. The work also resonates with earlier research showing that pyrite-induced hydroxyl radicals can oxidize antimonite, the reduced form of antimony, hinting that the galvanic and radical pathways may jointly shape antimony speciation in the field.

The research also carries implications for the industrial side of the antimony story. Bioleaching, the use of acidophilic microbes to extract metals from sulfide ores, relies on precisely the same chemistry that mobilizes antimony in the environment. If pyrite–stibnite galvanic coupling is the dominant dissolution mechanism, then process designers could exploit it deliberately, tuning mineral blends, ferric iron regeneration, and even illumination to enhance metal recovery from refractory antimony ores and metallurgical residues. Conversely, in remediation scenarios, suppressing the galvanic contact or interrupting microbial iron cycling could slow antimony release from tailings. The same electrochemical insight thus cuts in two directions, offering both a hazard model and a process lever.

What makes the study conceptually satisfying is its synthesis of three traditionally separate perspectives on sulfide mineral weathering: electrochemistry, microbiology, and photochemistry. Rather than treating these as competing explanations, the factorial design reveals them as nested layers of one system. Pyrite sets the electrochemical stage by forming a corrosion couple with stibnite; the microbial community maintains the oxidizing atmosphere by cycling iron and sulfur species; and light modulates the rate of interfacial electron transfer while amplifying hydroxyl radical production. For anyone tracking the environmental fate of antimony, from mine-site hydrologists to geochemists modeling critical raw material flows, the message is that the invisible wiring between minerals, microbes, and photons deserves as much attention as the ore itself. The full study is available in Environmental Geochemistry and Health under DOI 10.1007/s10653-026-03484-2.

Subject of Research: Pyrite-driven galvanic and microbial mechanisms controlling stibnite biodissolution under light and dark conditions

Article Title: The influence mechanism of pyrite on the biodissolution of stibnite under light/darkness conditions

Article References: Liu, X., Wang, Y., Wu, D., Chen, L., Liu, H., Yang, W., Muhammad, A., Lai, J., & Nie, Z. (2026). The influence mechanism of pyrite on the biodissolution of stibnite under light/darkness conditions. Environmental Geochemistry and Health, 48(14), Article 581. https://doi.org/10.1007/s10653-026-03484-2

Image Credits: AI Generated

DOI: 10.1007/s10653-026-03484-2

Keywords: antimony, stibnite, pyrite, galvanic corrosion, biodissolution, acidophilic microorganisms, iron cycling, sulfur cycling, hydroxyl radicals, mine drainage, photochemistry, Environmental Geochemistry and Health

The study examined 1,400 Maui adults, measuring concentrations of 24 different metals in urine samples while simultaneously assessing pulmonary function through standardized breathing tests conducted at the same visit. When researchers compared the results against national biomonitoring reference data from the United States, the disparities were striking. Participants showed antimony concentrations nearly 40 times higher than U.S. reference values, manganese at 3.8 times, barium at 2.3 times and arsenic at 2.2 times the national benchmarks. These are not trace deviations; they represent a population carrying a metal burden far beyond what typical American residents experience.

The pulmonary findings may prove even more consequential. Across three complementary statistical approaches, higher combined metal exposure was consistently associated with several measures of abnormal lung function. Arsenic, cadmium, copper and antimony emerged as the metals contributing most strongly to those patterns. Each of these substances has well-documented toxicological profiles: arsenic and cadmium are established carcinogens, antimony is a metalloid used in flame retardants and electronics, and copper in excess can damage respiratory tissue. The convergence of elevated body burdens and measurable respiratory impairment in the same individuals points to a public health problem that outlasts the emergency phase of a disaster by many months.

The researchers are careful, however, not to attribute the entire burden to the fires alone. Because no pre-wildfire biomonitoring data exist for these residents, the study cannot determine precisely how much of the measured metal load came directly from the August 2023 disaster versus chronic, persistent or other ongoing exposures. Hawaiʻi’s geology, a long history of agricultural and industrial land use, diet and other environmental factors may all have contributed to exposures that predated the fires. The disaster may then have introduced entirely new contaminants while simultaneously disturbing and remobilizing pollutants already locked in soil, dust and the built environment. Disentangling those pathways, the team says, will require longitudinal biomonitoring and environmental sampling over years.

What makes the Maui situation scientifically distinct is the nature of the fire itself. Much of the existing knowledge about wildfire health effects derives from studies of smoke generated by burning vegetation. But the Lahaina fire belonged to a different and increasingly common category: the wildland–urban interface disaster, in which flames sweep through neighborhoods rather than forests. Such fires consume homes, vehicles, electronics, treated lumber and electrical systems, generating complex chemical mixtures that bear little resemblance to wood smoke. At the same time, they disturb pollutants accumulated in soil from decades of earlier agricultural, industrial or other land uses, redistributing them across the landscape during cleanup and recovery.

Those materials can remain in ash, settled dust, soil and debris long after the flames are extinguished, creating continued exposure pathways that include resuspended fine particles, direct contact with contaminated dust and debris, and indirect environmental exposure even when the air looks clear. This is the mechanism the MauiWES team believes explains why metal burdens remained elevated in residents’ bodies many months after the disaster. When a fire burns through an entire community, it can fundamentally alter how contaminants move through the environment, transforming a static contamination landscape into a dynamic and prolonged source of human exposure.

The geographic patterns uncovered by the study add another layer of complexity. Exposure was not confined to Lahaina, the town most closely associated with the disaster. Lahaina residents did show a distinct metal profile, including relatively elevated concentrations of arsenic and cadmium, but Wailuku and Kahului residents recorded the highest median concentrations of copper, iron and molybdenum. Kula and Kihei displayed different metal profiles as well, underscoring that no single uniform exposure pattern existed across the island. Pulmonary impairment varied in parallel: among interpretable breathing test results, Wailuku and Kahului exhibited some of the highest prevalence of abnormal lung-function measures, while Lahaina also showed substantial impairment and Kula generally showed the lowest burden.

These spatial differences suggest that the post-disaster exposure landscape is far more complicated than a simple comparison between people inside and outside a burn zone. The researchers believe the measured metal mixtures reflect overlapping contributions from wildfire-generated material, contaminants remobilized by the disaster, historically contaminated soils, local land use, geology and other ongoing environmental sources. Determining the relative contribution of each pathway is now a central focus of the research program, and the answer will shape how communities recovering from urban fires should be monitored and protected.

The implications extend well beyond Hawaiʻi. As destructive fires increasingly reach developed communities across the American West, Australia, the Mediterranean and elsewhere, the Maui findings suggest that disaster-response systems may need to look beyond short-term measurements of smoke and particulate matter. Future responses, the researchers argue, could include longer-term environmental monitoring, human biomonitoring, respiratory surveillance and targeted assessment of soil, ash and settled dust, particularly in places with histories of agricultural or industrial contamination. In September 2026, the National Institute of Environmental Health Sciences awarded the team a five-year, $3.6 million grant to investigate pollutants left behind by decades of agricultural and industrial activity in Hawaiʻi and to examine whether wildfires and other disasters can remobilize those contaminants into new pathways of human exposure.

That new project, led by MauiWES co-directors Alika Maunakea and Ruben Juarez together with Alison Lee of the Icahn School of Medicine at Mount Sinai, will follow approximately 1,000 Hawaiʻi residents over five years, combining environmental measurements, biological samples and cardiopulmonary assessments. Its goal is to distinguish persistent background exposures, legacy contamination and disaster-related exposures while examining how each contributes to heart and lung health over time. Together, the studies shift the scientific question from simply asking what a wildfire released to a broader and more consequential one: how a disaster transforms an existing environmental contamination landscape and changes what people are exposed to in the months and years that follow.

The research team has also emphasized that the study was designed not merely to document harm but to connect participants with information and care. MauiWES participants receive access to their individual health results, opportunities to discuss those findings with the research team, and referrals when screening identifies potential health concerns. The study will continue following families over time to understand how health evolves during Maui’s recovery. Juarez acknowledged that the findings may be difficult for families who have already endured so much, but stressed that the team’s responsibility extends beyond publishing the science to returning information to the community, connecting people with care when they need it, and continuing to learn alongside Maui as the island rebuilds. For now, the central lesson stands: exposure may not end when the smoke clears, and the next scientific challenge is to understand which exposures persist, where they come from and what they mean for long-term health.

Subject of Research: Persistent toxic metal exposure and pulmonary impairment among residents affected by the 2023 Maui wildfires

Article Title: EMBARGOED: Toxic metals found in Maui residents months after 2023 wildfires, UH study finds

Article References: EMBARGOED: Toxic metals found in Maui residents months after 2023 wildfires, UH study finds. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: Maui wildfires, Lahaina, toxic metals, biomonitoring, lung function, arsenic, cadmium, antimony, wildland-urban interface, environmental health, University of Hawaii, PNAS