The preparation route is deceptively simple and deliberately scalable. Lignin is impregnated with ferric chloride at a concentration of 0.125 mol/L and then calcined at 800 °C. During this thermal treatment, the iron salt decomposes into iron oxide nanodomains dispersed across the carbonaceous matrix derived from the lignin, while the high pyrolysis temperature simultaneously develops the aromatic carbon structure and pore network characteristic of biochar. The resulting composite is magnetic, which matters practically because spent adsorbent particles can be pulled out of suspension with a simple magnet rather than requiring energy-intensive filtration. When tested against sulfamethazine, a sulfonamide antibiotic widely used in livestock production and frequently detected in manure-amended soils, surface waters, and groundwater, the Fe@LBC achieved an adsorption capacity of 39.92 ± 0.14 mg/g within 360 minutes. That figure is approximately 2.6 times the capacity of the unmodified lignin biochar (LBC) prepared under otherwise comparable conditions, a difference the team attributes primarily to the introduced iron oxide phase rather than to any large change in surface area alone.

Why does the iron oxide make such a difference? The mechanistic answer, teased apart through a battery of experiments and computational modeling, centers on coordination chemistry. Sulfamethazine is an ionizable molecule with a sulfonamide functional group, a heterocyclic pyrimidine ring containing nitrogen atoms, and amine substituents, all of which carry lone pairs capable of donating electron density to Lewis-acidic metal centers on a surface. On pristine biochar, adsorption typically relies on weaker, pH-sensitive interactions: π–π stacking between the aromatic drug and the carbon lattice, hydrophobic partitioning, and hydrogen bonding, all of which fluctuate dramatically as solution pH changes the protonation state of the antibiotic. Sulfamethazine, like other sulfonamides, speciates across its pKa values, existing as neutral, cationic, or anionic forms depending on the surrounding acidity. Consequently, conventional biochars show pH-dependent sorption, performing well in some windows and poorly in others, which is a serious liability in real wastewater whose pH varies continuously. Fe@LBC sidesteps this problem: the Fe₂O₃ coordination sites bind the drug molecule through the nitrogen and oxygen donors regardless of whether the molecule is protonated or deprotonated, so the adsorption remains essentially stable across a broad pH range of 3 to 9.

The team backed this mechanistic picture with both spectroscopy and quantum chemistry. X-ray photoelectron spectroscopy (XPS) revealed shifts in the binding energies of nitrogen and oxygen signals after sulfamethazine adsorption, consistent with electron donation from these atoms into coordination bonds with surface iron. Complementing the experimental spectra, density functional theory (DFT) calculations simulated the interaction geometries and binding energies between sulfamethazine and Fe₂O₃ surface sites, confirming that the Fe₂O₃ complexation pathway is thermodynamically favored and is the dominant driver of selective sulfonamide binding. In other words, the iron oxide does not merely add roughness or charge to the surface; it creates chemically specific docking sites that recognize a structural motif common to sulfonamide antibiotics. Kinetic modeling indicated that the process is dominated by chemisorption-related surface interactions, with intraparticle diffusion contributing to the overall transport of molecules into the pore network. Isotherm and thermodynamic analyses completed the picture, characterizing the affinity, capacity, and energetic favorability of the uptake.

Selectivity is arguably the most consequential property demonstrated in the study. Real wastewater is a chemical free-for-all: it contains competing salts, natural organic matter such as humic substances, surfactants, and countless other trace organics that typically poison or outcompete adsorption sites. The researchers deliberately challenged Fe@LBC with coexisting salts and organic matter and found that the material showed superior tolerance to these interferences, maintaining its adsorption performance where the plain lignin biochar faltered. Moreover, in competitive scenarios, Fe@LBC exhibited preferential selectivity toward sulfonamide antibiotics over other solutes. This discrimination arises from the coordination chemistry described above: sulfonamides present the particular arrangement of heteroatom donors that the Fe₂O₃ sites bind most avidly, while many co-solutes lack this geometry and are adsorbed only weakly. A material that works selectively in a messy matrix is far more valuable at the treatment-plant scale than one that only performs in clean, single-solute laboratory solutions.

Regeneration and reuse, the practical test that determines whether an adsorbent is a lab curiosity or a genuine candidate for deployment, were also addressed. The regeneration experiments showed that Fe@LBC retained satisfactory adsorption capacity over multiple adsorption–desorption cycles, demonstrating reproducibility and recyclability. Combined with its magnetic separability, this cyclability reduces both operating cost and secondary waste. The economics of the feedstock reinforce the case: lignin is generated in enormous quantities as a by-product of pulping and biorefinery operations, is often burned simply for low-grade heat, and is cheap. Turning it into an engineered adsorbent is a textbook example of valorization—converting a disposal liability into a functional material for environmental remediation.

The stakes of the problem being addressed are worth spelling out. Sulfonamide antibiotics are among the most frequently detected pharmaceutical classes in rivers, groundwater, and effluents worldwide, because a large fraction of administered doses passes unmetabolized through animals and humans and conventional wastewater treatment plants are not designed to strip such trace organics. Chronic exposure of microbial communities to sub-inhibitory antibiotic concentrations is a recognized driver of antibiotic resistance gene dissemination, a public health threat that transcends borders. Epidemiological studies cited by the team have also associated antibiotic exposure with adverse health outcomes, underscoring that these are not benign trace contaminants. Because adsorption is one of the few treatment technologies that is simple, cheap, and deployable at scale, a robust and selective adsorbent for sulfonamides fills a genuine gap in the water treatment toolbox.

The study also situates itself within a fast-moving research landscape on engineered biochars. Previous work has shown that iron-impregnated biochars, metal-doped frameworks, and other functionalized carbon materials can enhance uptake of sulfonamides such as sulfamethoxazole and sulfadiazine, but pH dependence and poor selectivity have remained recurring limitations. Prior investigations of sulfamethazine sorption on biochars documented strong sensitivity to dissolved organic matter and to the ionization state of the molecule. What distinguishes the present work is the combination of these strands: a waste-derived, magnetically separable substrate; iron oxide coordination sites engineered deliberately by a one-step impregnation and calcination protocol; and, critically, direct mechanistic proof from XPS and DFT that coordination is responsible for both the pH independence and the selectivity. The mechanistic attribution, in other words, is not inferred from performance alone but demonstrated at the molecular level.

From an engineering standpoint, the parameters reported provide a starting recipe for scale-up. The optimal FeCl₃ impregnation concentration of 0.125 mol/L balances iron loading against the risk of pore blockage by excessive oxide deposition, and the 800 °C calcination temperature ensures both good graphitization of the carbon and crystallization of the iron oxide phase. The 360-minute equilibration time reflects chemisorption kinetics, which are slower than purely physical adsorption but yield far stronger, more stable binding. The thermodynamic signatures reported indicate the spontaneity and endothermic character of the uptake, guiding practitioners on temperature optimization. None of these numbers are exotic; they involve commodity chemicals and standard pyrolysis equipment, which strengthens the argument that the material could be produced at industrial scale.

Looking forward, the study opens several avenues. The same Fe₂O₃ coordination strategy could, in principle, be tuned to target other ionizable pollutant classes whose donor atoms match metal-oxide Lewis-acid sites, and testing the adsorbent in continuous-flow columns and in real wastewater matrices would be the natural next steps before pilot deployment. The research also contributes to the broader circular-economy agenda in environmental engineering, where waste streams from one industry become remediation tools for another. For now, the Nanjing team’s work stands as a compelling demonstration that a wood-derived waste, an iron salt, and a furnace can yield a smart, selective, pH-proof scavenger for one of the world’s most pervasive antibiotic pollutants—and that the key to that selectivity lies in the subtle electron-sharing chemistry between a drug molecule and a rusty-looking oxide nanoparticle.

Conventional wastewater treatment plants were never designed to strip out recalcitrant organic micropollutants such as pharmaceuticals, and trace amounts routinely slip through into receiving waters. Advanced oxidation processes (AOPs) attack these stubborn compounds by generating highly reactive free radicals that fragment contaminant molecules. But chemical degradation alone does not guarantee safety. As contaminants break down, they spawn transformation products (TPs) that can, in some cases, be as toxic as—or more toxic than—the parent compounds. The research team, led by Lucas Gustavo da Costa and Alam Gustavo Trovó of the Federal University of Uberlândia, together with collaborators at the Oswaldo Cruz Institute, set out to answer a deceptively simple question: does measurable chemical removal of micropollutants actually translate into reduced biological harm?

The centerpiece of their work is the H₂O₂/S₂O₈²⁻/UVC process, a hybrid system that combines hydrogen peroxide and persulfate with short-wave ultraviolet C radiation. UVC photons cleave both oxidants simultaneously, generating hydroxyl radicals (HO•) and sulfate radicals (SO₄•⁻) in the same reaction volume. This dual-radical strategy outperforms systems relying on either oxidant alone, or on peroxymonosulfate (HSO₅⁻), which is costlier and demands more energy for activation. The hybrid route also resists interference from inorganic species commonly found in real effluents, making it an economically attractive candidate for deployment at full-scale treatment plants. The process had already been chemically optimized in the team’s earlier work using multivariate mixture design and rotatable central composite design experiments; the new study is its first integrated biological stress test.

The experiments used real municipal effluent from a wastewater treatment plant in Uberlândia, Minas Gerais, sampled after the plant’s final tertiary treatment stage of coagulation-flocculation with ferric chloride and flotation. The effluent was enriched with three pharmaceuticals representing different therapeutic classes: colchicine (COL, an antimitotic agent), nitazoxanide (NTZ, an antiparasitic), and sulfamethoxazole (SMX, a widely detected antibiotic), each at 325 nmol L⁻¹—equivalent to 130, 100, and 82 micrograms per liter, respectively. That concentration was deliberately chosen as high enough for direct HPLC–DAD analysis without preconcentration, yet low enough to be environmentally representative. Treatment was carried out in an amber glass reactor irradiated by two 8-watt UVC mercury lamps emitting at 254 nm, with a measured irradiance of 4.9 W m⁻². Residual oxidants were neutralized with sodium thiosulfate before any biological testing, ensuring that observed effects could not be attributed to leftover peroxide chemistry.

The ecotoxicological battery spanned multiple trophic levels and levels of biological organization. Oxidative stress was assessed in the earthworm Eisenia andrei by measuring malondialdehyde (MDA), a marker of lipid peroxidation, and protein carbonylation, an irreversible oxidative modification of proteins. Phytotoxicity was evaluated using lettuce (Lactuca sativa) seeds and a growth index combining germination rate and root elongation. Cytotoxicity and genotoxicity were quantified in onion (Allium cepa) root meristems through the mitotic index and the frequency of chromosomal and nuclear aberrations—micronuclei, chromosome breaks, stickiness, bridges, and nuclear buds—across 5,000 cells per sample. Finally, growth inhibition was tested in two environmentally relevant microbes: Azospirillum brasilense, a plant growth-promoting bacterium used in soybean cultivation, and Saccharomyces cerevisiae, a yeast that persists in soils and fermentative niches.

The untreated enriched effluent told a worrying story. It exhibited substantial genotoxicity in onion cells—21%, approaching the 24% seen with the positive control, methyl methanesulfonate—and severe phytotoxicity, with lettuce growth indices far below the 80% threshold that signals absence of toxicity. Even the unspiked effluent itself suppressed lettuce growth, achieving a growth index of only 47%, evidence that bioactive compounds survive conventional treatment. In earthworms, individual aqueous solutions of NTZ and SMX raised MDA levels by 37.2% and 23.5% respectively, while the three-compound mixture increased lipid peroxidation by 38.0%, pointing to additive or synergistic oxidative stress mechanisms involving reactive oxygen species and Fenton-type chemistry within cells.

The picture changed decisively after oxidation. Following 10 minutes of UVC-driven treatment—the point at which 80% chemical degradation had been achieved, matching the minimum removal target proposed in the European Union’s COM(2022)541 directive—genotoxicity fell to 10%, and after 20 minutes, corresponding to the limit of quantification for the parent compounds, it dropped further to 6%, a statistically significant reduction. The plant growth index climbed above 80%, crossing from toxic territory into biocompatibility. The mitotic index in onion cells remained statistically indistinguishable from the deionized-water control (around 39–40% versus 40%), demonstrating that the process generated no cytotoxic byproducts capable of arresting cell division. And crucially for agricultural applications, neither the treated effluent nor its transformation products inhibited growth of A. brasilense or S. cerevisiae.

The mechanistic details are instructive. In the untreated enriched effluent, micronuclei—membrane-bound DNA fragments expelled from the nucleus during flawed cell division—were among the most frequent aberrations, indicating clastogenic and aneugenic damage. Colchicine exposure predictably produced C-metaphase accumulation, a signature of its tubulin-binding, spindle-disrupting mechanism first described in Allium nearly a century ago. SMX depressed the mitotic index and induced chromosomal damage, consistent with prior findings in Vicia faba. NTZ, whose genotoxicity had never before been reported, produced chromosome breaks, stickiness, and nuclear buds. After oxidation, the overall aberration burden fell sharply, particularly micronuclei and stickiness, although a few bridges and polyploid cells persisted even at 20 minutes—a reminder that some transformation products or resistant residuals may linger.

The microbial results came with a subtlety. Reduced A. brasilense growth after treatment initially looked like a red flag, but the team attributes it to depletion of assimilable organic matter, which serves as radical scavenger during oxidation and as a nutrient source afterward—not to toxicity. The negative control likewise grew slowly. This distinction matters because AOPs are designed to mineralize organic carbon, and a nutrient-poorer medium should not be misread as a more toxic one. For S. cerevisiae, no inhibition occurred at any stage of treatment, although NTZ alone significantly depressed yeast optical density, reinforcing the compound’s cell-cycle interference potential even at nanomolar-scale exposures.

The study’s broader significance lies in its methodological stance. By adopting an “effect-driven approach,” the team evaluated the toxicity of whole reaction mixtures without needing to isolate and identify individual transformation products—an impractical task given that many degradation byproducts are not commercially available. Their findings align with a growing consensus that treatment efficacy must be judged not merely by parent-compound removal but by the nature and reactivity of the resulting transformation products. Biochemical biomarkers such as MDA and protein carbonylation detected sublethal disturbances that mortality-based endpoints would have missed entirely, providing early warnings of cellular distress at environmentally relevant concentrations.

One caveat deserves attention: while lipid peroxidation declined after treatment, protein carbonylation rose slightly—1.05-fold above control—suggesting some transformation products may still provoke protein oxidation even as lipid damage subsides. The authors flag this discrepancy and call for future identification of the specific TPs responsible, alongside expanded organism panels, longer-term exposure studies, and pilot-scale validation across different environmental matrices.

The regulatory context sharpens the urgency. The EU’s proposed urban wastewater treatment directive mandates at least 80% removal of specified organic micropollutants and microbiological control for agricultural reuse, yet it conspicuously omits eco-compatibility assessment of the treated water itself. This study supplies exactly that missing dimension, showing that a process satisfying the chemical benchmark also delivers measurable biological benefit—lower genotoxicity, restored plant growth, intact cell division, and unharmed beneficial microbes. As water scarcity intensifies globally and reuse becomes less optional, the Brazilian team’s integrated bioassay framework offers a template for ensuring that the water farmers irrigate with is not merely chemically compliant, but genuinely ecologically safe.

Brazil nut shells, often regarded as agricultural waste, are abundant in regions where the Brazil nut tree thrives. Instead of being discarded or incinerated, these shells are now being explored for their potential to adsorb harmful contaminants from wastewater. The project highlights a sustainable method of waste utilization, transforming what would otherwise contribute to environmental degradation into a valuable resource for combating water pollution.

The cornerstone of the study lies in the synthesis of porous carbon from Brazil nut shells. This process involves carbonization, wherein the shells are subjected to high temperatures in an inert atmosphere. The result is a highly porous carbon material that possesses an impressive surface area, making it an ideal candidate for adsorbing contaminants such as pharmaceuticals from aqueous solutions. The transformation of waste into functional materials is a key focus area in environmental remediation, and this research exemplifies that potential.

One of the unique aspects of this research is the examination of both the single and simultaneous adsorption capacities of the synthesized porous carbon for ibuprofen and diclofenac. Both substances are widely used pharmaceuticals that can persist in the environment and pose substantial risks to aquatic ecosystems and human health. Their presence in water bodies necessitates the development of effective treatment methods to remove these contaminants and safeguard public health.

The authors meticulously conducted a series of laboratory experiments to evaluate the adsorption efficiency of the porous carbon. They investigated parameters such as contact time, initial concentration of pollutants, and temperature, ensuring a comprehensive understanding of the material’s performance. The results revealed a significant capacity of the carbon derived from Brazil nut shells to adsorb ibuprofen and diclofenac, with optimal conditions identified to maximize removal efficiency. Such findings illuminate the path towards innovative strategies for treating pharmaceutical-laden wastewater.

Moreover, the study utilized various adsorption models to interpret the data collected during experiments. This analytical approach provided insights into the mechanisms governing the adsorption process, contributing to the broader scientific understanding of how porous carbons function in environmental remediation settings. By detailing the adsorption kinetics and equilibrium, the researchers painted a clearer picture of the interactions between the carbon material and the pharmaceutical contaminants.

The implications of this research extend beyond merely addressing pollutant removal. By promoting the sustainable use of Brazil nut shells, the study also supports local economies that rely on agricultural practices. It encourages the development of circular economy concepts, where waste materials can be repurposed for beneficial uses, fostering both environmental and economic sustainability.

In a world grappling with mounting water pollution issues, solutions that incorporate waste valorization are increasingly vital. The synthesis of porous carbon from Brazil nut shells demonstrates an effective avenue for reducing pharmaceutical pollutants while simultaneously providing a practical use for agricultural waste. Such research builds the foundation for future innovations in the field of environmental science and engineering, promoting materials that are both functional and derived from renewable sources.

The researchers also addressed potential challenges in scaling this process for commercial applications. While laboratory results are promising, practical implementation requires careful consideration of cost-effectiveness and material availability. Future studies should aim to explore the feasibility of large-scale production of porous carbons from agro-industrial waste, ensuring that these advancements can be realized at an industrial level.

As the study progresses, it stands as a testament to the intersection of environmental sustainability and innovation. The brave exploration of converting Brazil nut shells into valuable adsorbents provides a refreshing perspective on waste management and pollution control. The findings could inspire similar approaches utilizing other types of agro-industrial waste, paving the way for extensive research on sustainable materials in environmental remediation.

As we await further developments in this exciting field, the contributions of da Silva and his colleagues remind us that solutions to environmental challenges can indeed be found within the very waste we generate. The potential for agricultural by-products to play a crucial role in combating pollution emphasizes the importance of innovative research and its impact on future sustainability efforts.

In conclusion, the valorization of Brazil nut shells into porous carbon not only addresses the immediate concerns surrounding pharmaceutical residues in water but also represents a paradigm shift towards a more sustainable approach in managing agricultural waste. The findings of this study will undoubtedly spark further inquiry, pushing the boundaries of what is possible when we rethink waste and pollution management strategies.

Subject of Research: Valorization of agro-industrial waste (Brazil nut shells) for porous carbon synthesis and adsorption of pharmaceutical contaminants.

Article Title: Valorization of agro-industrial waste (Brazil nut shells) for porous carbon synthesis: single and simultaneous adsorption of ibuprofen and diclofenac from aqueous solutions.

Article References:

da Silva, J.P.S., da Silva, M.G.C., Vieira, M.G.A. et al. Valorization of agro-industrial waste (Brazil nut shells) for porous carbon synthesis: single and simultaneous adsorption of ibuprofen and diclofenac from aqueous solutions. Environ Sci Pollut Res (2025). https://doi.org/10.1007/s11356-025-37115-7

Image Credits: AI Generated

DOI: https://doi.org/10.1007/s11356-025-37115-7

Keywords: Brazil nut shells, porous carbon, ibuprofen, diclofenac, wastewater treatment, adsorption, environmental sustainability, agro-industrial waste.

Research led by Dias, Mourão, and de Souza focuses on the potential of supercritical water technology as a solution for the degradation of antibiotics in water environments. The study’s findings suggest that this innovative method could efficiently eliminate pharmaceutical contaminants while offering a sustainable alternative to conventional wastewater treatment processes. Recognizing the dangers posed by antibiotic pollution, the researchers emphasize the pressing need for technologies capable of breaking down these hazardous substances effectively.

Supercritical water is a state of water attained at high temperatures and pressures, where it exhibits unique solvent properties. In this supercritical phase, water behaves differently than in its liquid or vapor forms, allowing for enhanced chemical reactions. The researchers explain that this state enables water to dissolve various organic compounds, making it a powerful medium for the degradation of complex pollutants, such as antibiotics. The ability to operate under high-pressure conditions increases the reaction rates and improves the decomposition of these harmful substances, ensuring a higher degree of mineralization and reduced toxicity.

In the study, the authors evaluated the efficacy of SCWO using various antibiotics, analyzing parameters such as temperature, pressure, and reaction time. Their results demonstrated that increasing the operational temperature significantly enhances the degradation of antibiotic compounds. Furthermore, the research indicates that specific antibiotics exhibit varied resistance to degradation in supercritical water, necessitating tailored approaches for different pollutants. This finding opens the door for further research aimed at optimizing conditions to maximize the breakdown of resistant compounds.

Supercritical water technology operates efficiently under the right conditions and can be integrated into existing wastewater treatment infrastructures. This adaptability is crucial for municipalities struggling with antibiotic contamination, as implementing SCWO could significantly enhance current treatment processes. As antibiotic resistance continues to rise, the ability of SCWO to neutralize a diverse range of compounds while minimizing environmental impact presents a compelling argument for its widespread adoption.

One of the most remarkable aspects of SCWO technology is its potential to convert waste into energy. The process can yield useful energy outputs, such as heat and gas, through the degradation of organic materials in contaminated water. By utilizing the energy produced during treatment, facilities can reduce operational costs, promote sustainability, and make significant strides toward energy neutrality. This dual benefit emphasizes the integral role of SCWO in the broader framework of environmental remediation and sustainable practices.

The implications of the research extend beyond mere technical advancements; they touch upon urgent societal issues such as public health. The accumulation of antibiotics in water sources not only threatens aquatic creatures but poses risks to human health as well. As resistant bacteria proliferate, they compromise the efficacy of lifesaving treatments. The researchers urge governments and regulatory bodies to consider implementing supercritical water technology in the fight against pharmaceutical pollution.

Public awareness of antibiotic pollution is also a crucial element in the success of remediation efforts. Educating communities about the significance of proper medication disposal and the risks associated with contaminating water sources may help reduce the load on treatment facilities. Combined with innovative technologies such as SCWO, these educational initiatives could play a significant role in curbing the environmental impacts of antibiotic use in medical practices.

Looking ahead, the study’s authors acknowledge the need for further research to refine and optimize supercritical water technology for practical applications. They suggest that long-term studies addressing various operational parameters and their effects on antibiotic degradation should be prioritized. Such research would not only solidify the role of SCWO in wastewater treatment but also reinforce its position as a game-changing technology in environmental protection.

Furthermore, collaboration between academia, industry, and regulatory bodies will be essential for advancing supercritical water technology. Developing pilot projects and scaling these innovations will require investment and commitment from a myriad of stakeholders. The authors stress that fostering partnerships can expedite the transition from theoretical applications to mainstream practices, paving the way for more effective solutions to combat antibiotic pollution.

In conclusion, Dias, Mourão, and de Souza’s research shines a light on the transformative potential of supercritical water technology in addressing antibiotic contamination in aquatic environments. By promoting efficient and sustainable practices, this technology represents a valuable addition to the toolkit of environmental scientists and policymakers. As the ramifications of antibiotic pollution become increasingly critical, embracing innovative solutions like SCWO may well be a vital step toward preserving public health and safeguarding our ecosystems.

The fight against antibiotic resistance is not merely a scientific endeavor; it is a call to action for all sectors of society. Together, we must strive to implement technologies that address these challenges, fostering a healthier planet for future generations. The study highlights the pressing need for innovative solutions in environmental engineering and continues the discourse on improving public health through responsible antibiotic use and pollution prevention.

In an era where environmental degradation threatens both human health and ecosystems alike, the insights gained from this cutting-edge research pave the way for a more sustainable future. As we look toward implementing effective wastewater treatments, supercritical water technology emerges as a paramount tool in our ongoing battle against pollution and antibiotic resistance.

Subject of Research: Supercritical water technology for degradation of antibiotics in water.

Article Title: Supercritical water technology: a promising approach for degradation of antibiotics in water.

Article References:

Dias, I.M., Mourão, L.C., de Souza, G.B.M. et al. Supercritical water technology: a promising approach for degradation of antibiotics in water.
Environ Sci Pollut Res (2025). https://doi.org/10.1007/s11356-025-37107-7

Image Credits: AI Generated

DOI: https://doi.org/10.1007/s11356-025-37107-7

Keywords: Supercritical water technology, antibiotic degradation, environmental remediation, wastewater treatment, public health.