Luis E. Fernandez

Climate change, toxic pollution, and social inequities are converging to create new risks for workers and communities, particularly in the Global South. Yet occupational and environmental health research and policy still tend to address these stressors in isolation, not considering their interactions. To synthesize the main messages of the COP30 side event, “Amazon and Heat: Community-First Climate–Environment–Health Action from the Amazon Basin to Africa and Europe”, presented in the context of the LIMA2025 Conference on Occupational Medicine, and to propose a framework for integrated climate–environment–health action in work and community settings. This conference report and policy perspective are based on a narrative synthesis of presentations and discussions delivered during the COP30 side event and subsequently presented at LIMA2025 by researchers, Indigenous leaders, occupational health practitioners and civil society organizations from the Amazon Basin, Africa and Europe. Contributions were grouped into thematic domains: (1) climate and toxic exposures in the Amazon; (2) work and heat in African and Southern European settings; and (3) cross-cutting challenges and policy opportunities. The analysis followed a qualitative thematic approach. Across regions, participants described intersecting exposures to heat, toxic chemicals, air pollution, deforestation and psychosocial stress, disproportionately affecting workers, Indigenous peoples, traditional populations, pregnant women and children. Evidence from cohort studies, intervention projects, and remote-sensing analyses highlighted: (i) elevated mercury exposure and increasing microplastics and diesel contamination in Amazonian communities, alongside climate-sensitive food-system vulnerabilities; (ii) growing heat-related health risks among children and pregnant women in African cities; and (iii) dehydration, kidney dysfunction, and cardiometabolic risks among agricultural and construction workers in Southern Europe. Cross-cutting themes included exposure mixtures, inequities in access to care and justice, persistent data gaps, and the need for locally owned technologies, capacity building, and sustainable solutions. The side event catalyzed the development of an Amazon Climate–Environment–Health Consortium and a shared policy agenda. Integrated, equity-focused action on heat, toxic exposures, and work is essential for a just climate transition.

1. Heavy metals are pervasive environmental contaminants that can impair the health of organisms globally. As the largest anthropogenic source of the potent neurotoxin mercury (Hg), gold mining has amplified these threats throughout the tropics. Consequently, there is a mounting need to monitor Hg contamination of the richest biological communities on Earth. Venous whole blood provides a reliable, nonlethal measurement of recent dietary and site-derived contamination, but collecting and cold-storing samples can be impractical in field conditions. 2. To overcome these challenges, we developed and evaluated a method to assay Hg exposure in vascular organisms by measuring the volume of dried blood spots (DBS) in the field, which can be stored at ambient temperatures until analysis. We explored the method's precision and accuracy in estimating whole blood Hg concentrations by collecting paired whole blood and DBS aliquots from birds ( n = 527 individuals, 140 species) along a trophic gradient (i.e., granivores to piscivores) in Belize and Peru. 3. Using a Bayesian linear mixed-effects model, we found a highly precise and unbiased relationship between DBS and whole blood total Hg concentrations that was centered at perfect unity ( R ² = 0.99; β = 1.00 ± 0.03; 95% CrI: 0.95–1.05). Agreement between individual paired aliquots was more variable, in which approximately 12% of DBS containing at least 1 ng THg differed from whole blood by more than ±20%. However, DBS accuracy increased at higher THg concentrations, suggesting that disagreement at low concentrations is an expected consequence of higher measurement error near the analytical limit of detection of our instruments. 4. Compared to whole-blood collection and analysis workflows, DBS offer substantial logistical advantages by eliminating cold-chain dependence and reducing transport burden, laboratory handling time, and overall operational costs. Consequently, volume-measured DBS provide a practical and highly reliable alternative for monitoring Hg contamination in both humans and wildlife, particularly for ecological and population-level applications in remote and resource-limited environments.

Artisanal and small-scale gold mining (ASGM) is the largest global anthropogenic mercury (Hg) source and is widespread in the Peruvian Amazon. Consuming Hg-laden foods exposes people to this potent neurotoxin. While numerous studies have examined fish Hg content near ASGM, Hg accumulation in other commonly consumed animal-and plant-based foods from terrestrial environments is often overlooked. In this study, we aim to address understudied dietary Hg exposures. To understand Hg exposure from food staples in the Peruvian Amazon, we measured total and methyl Hg in local crops, fish, chicken meat, chicken feathers, and eggs from ASGM-impacted and upstream (reference) communities. Diet surveys were used to estimate probable weekly Hg intake from each food. Fish and chicken stable carbon and nitrogen isotope signatures were analyzed to evaluate trophic magnification. Though few crops exceeded food safety recommendations, rice methyl Hg proportions were high (84%). Trophic level was an expected key predictor of fish Hg content. 81% (17 of 21) of local carnivorous fish exceeded WHO and EPA recommendations. Compared to upstream communities, mining-impacted communities demonstrated elevated total Hg in crops (1.55 (interquartile ranges (IQR): 0.60–3.03) μg kg⁻¹ upstream versus 3.38 (IQR: 1.62–11.58) in mining areas), chicken meats (2.69 (IQR: BDL–9.96) μg kg⁻¹ versus 19.68 (IQR: 6.33–48.1)), and feathers (91.20 (IQR: 39.19–216.13) μg kg⁻¹ versus 329.99 (IQR: 173.22–464.99)). Chicken meats from mining areas exhibited over double the methyl Hg concentrations of those upstream. Methyl Hg fractions in chicken muscle tissue averaged 93%. Egg whites and livers exceeded Hg recommendations most frequently. Proximity to mining, but not trophic position, was a predictor of chicken Hg content. Our results demonstrate that terrestrial and aquatic foods can accumulate Hg from mining activity, introducing additional human Hg exposure routes. However, locally sourced carnivorous fish was the largest contributor to an estimated three-fold exceedance of the provisional tolerable weekly Hg intake.

Mercury contamination from artisanal and small-scale gold mining (ASGM) currently accounts for 37% of the global total, often affecting tropical regions where regulations, if they exist, are often poorly enforced. Ingestion by people and other animals damages the nervous, reproductive, and cognitive systems. Despite the efforts of many organizations and governments to curb mercury releases from ASGM, it is increasing globally. There are many possible interventions, all with significant complexity and cost. Therefore, we recommend taking an established systematic approach to articulate the current situation and construct theories of change (ToC) for different possible interventions for any government or organization trying to solve this problem. Here we present a high-level situation analysis and generic ToC to support a more coordinated approach that explicitly builds upon previous experience to identify organization- and situation-appropriate engagement on this issue. We then illustrate the use of these generic models to construct a specific ToC with a policy-focused entry point. This includes interventions through (1) engagement with the global Minamata Convention on Mercury; (2) support for existing national laws and policies connected to ASGM and mercury contamination; and (3) engagement of indigenous people and local communities with governments to meet the governments’ legal obligations. By methodically articulating assumptions about interventions, connections among actions, and desired outcomes, it is possible to create a more effective approach that will encourage more coordination and cooperation among governments and other practitioners to maximize their investments and support broad environmental and socio-political outcomes necessary to address this pernicious problem.

El servicio ecosistémico hídrico (SEH) se identifica como el principal servicio que se debe conservar, proteger y gestionar adecuadamente para asegurar su calidad, cantidad y disposición. El objetivo del presente trabajo fue desarrollar una propuesta metodológica para la identificación de los Mecanismos de Retribución por Servicios Ecosistémicos Hídricos (MERESE-H) en el departamento de Madre de Dios, Perú. Se procedió a desarrollar talleres con actores locales claves, para la identificación de actividades humanas actuales que ocasionan cambios de uso de suelo en el área de estudio. Adicionalmente se desarrolló un estudio diagnóstico a nivel socio económico para conocer la situación del servicio de saneamiento de los operadores de agua en las áreas rurales y pequeñas ciudades en la Amazonía de Madre de Dios. Como secuencia metodológica, se utilizó la herramienta “Integrated Valuation of Ecosystem Services and Tradeoffs” (InVEST) para calcular el Índice de Servicio Hidrológico (ISH) para las cuencas priorizadas, mostrando el estado actual de sus servicios hídricos. Estos datos fueron usados para contrastar la problemática de administración de operación y el mantenimiento del servicio junto a las deficiencias proyectadas del ISH de las cuencas en estudio; resultando en una seria deficiencia en el servicio a nivel de calidad y cantidad de agua para su uso adecuado como servicio básico. Finalmente, con la metodología propuesta, se han identificado cinco sitios que cumplen con los criterios para un adecuado diseño, implementación y gestión de un MERESE-H. Este resultado se visualiza en una tabla “semáforo” para la intervenciòn en un corto y mediano plazo en áreas rurales y pequeñas ciudades amazónicas. La herramienta InVEST, como parte del proceso de valoración, es recomendada para la evaluación de los servicios hidrológicos de las microcuencas a trabajar; pero para obtener resultados más cercanos a la realidad, es necesario contar con datos actualizados, principalmente sobre el uso de suelo y climatológicos (precipitación y evapotranspiración).

Mercury (Hg) endangers human and wildlife health globally, primarily due to its release from artisanal small-scale gold mining (ASGM). During gold extraction, Hg is emitted into the environment and converted to highly toxic methylmercury by microorganisms. In Madre de Dios (MDD), Peru, ASGM dominates the economy and has transformed rainforests into expansive deforested areas punctuated by abandoned mining ponds. The aim of this study was to evaluate the use of bats as bioindicators for mercury pollution intensity in tropical terrestrial ecosystems impacted by ASGM. We collected 290 bat fur samples from three post-ASGM sites and one control site in Madre de Dios. Our results showed a wide Hg distribution in bats (0.001 to 117.71 mg/kg) strongly influenced by feeding habits. Insectivorous and piscivorous bats from ASGM sites presented elevated levels of Hg surpassing the mercury small mammal threshold for small mammals (10 mg/kg). We observed the highest reported fur mercury concentrations for insectivorous Neotropical bats reported to date (Rhynchonycteris naso, 117 mg/kg). Our findings further confirm that Hg emissions from ASGM are entering local food webs and exposing wildlife species at several trophic levels to higher levels of Hg than in areas not impacted by mining. We also found that three bat genera consistently showed increased Hg levels in ASGM sites relative to controls indicating potential usefulness as bioindicators of mercury loading in terrestrial ecosystems impacted by artisanal and small-scale gold mining.

Increasing gold and mineral mining activity in rivers across the global tropics has degraded ecosystems and threatened human health^1,2. Such river mineral mining involves intensive excavation and sediment processing in river corridors, altering river form and releasing excess sediment downstream². Increased suspended sediment loads can reduce water clarity and cause siltation to levels that may result in disease and mortality in fish^3,4, poor water quality⁵ and damage to human infrastructure⁶. Although river mining has been investigated at local scales, no global synthesis of its physical footprint and impacts on hydrologic systems exists, leaving its full environmental consequences unknown. We assemble and analyse a 37-year satellite database showing pervasive, increasing river mineral mining worldwide. We identify 396 mining districts in 49 countries, concentrated in tropical waterways that are almost universally altered by mining-derived sediment. Of 173 mining-affected rivers, 80% have suspended sediment concentrations (SSCs) more than double pre-mining levels. In 30 countries in which mining affects large (>50 m wide) rivers, 23 ± 19% of large river length is altered by mining-derived sediment, a globe-spanning effect representing 35,000 river kilometres, 6% (±1% s.e.) of all large tropical river reaches. Our findings highlight the ubiquity and intensity of mining-associated degradation in tropical river systems.

The Matsigenka people living traditional lifestyles in remote areas of the Amazon rely on a fish-based diet that exposes them to methylmercury (MeHg) at levels that have been associated with decreased IQ scores. In this study, the association between Hg levels and working memory was explored using the framework of the Multicomponent Model. Working memory tasks were modified to fit the culture and language of the Matsigenka when needed and included measures for verbal storage (Word Span) visuospatial storage (Corsi Block Task) and a measure of executive functions, the Self-Ordered Pointing Task (SOPT). An innovation of the Trail Making Tests A & B (TMT A & B) was pilot tested as another potential measure of executive functions. The mean hair Hg levels of 30 participants, ages 12 to 55 years, from three different communities (Maizal, Cacaotal and Yomibato) was 7.0 ppm (sd = 2.40), well above the World Health Organization (WHO) limit for hair of 2.0 ppm and ranged from 1.8 to 14.2 ppm, with 98% of a broader sample of 152 individuals exceeding the WHO limit. Hair Hg levels showed significant associations with cognitive performance, but the degree varied in magnitude according to the type of task. Hg levels were negatively associated with executive functioning performance (SOPT errors), while Hg levels and years of education predicted visuospatial performance (Corsi Block accuracy). Education was the only predictor of Word Span accuracy. The results show that Hg exposure is negatively associated with working memory performance when there is an increased reliance on executive functioning. Based on our findings and the review of the experimental research, we suggest that the SOPT and the Corsi Block have the potential to be alternatives to general intelligence tests when studying remote groups with extensive cultural differences.