Blanca Catalina Ramírez-Hernández

Heavy metal contamination in agricultural production is a significant public health issue in Mexico, as it directly impacts food safety and population exposure through dietary intake. Available scientific evidence indicates that vegetables and other plant-derived foods can serve as significant exposure pathways for toxic elements such as arsenic, cadmium, lead, chromium, and mercury. The consumption of contaminated foods may contribute to cumulative adverse health effects, including neurological, renal, and reproductive alterations, as well as an increased risk of chronic diseases. In Mexico, risk assessment is further constrained by methodological heterogeneity across studies and by difficulties in translating scientific evidence into concrete regulatory actions. Critically, the national regulatory framework lacks specific standards establishing maximum permissible limits for heavy metals in fresh fruits, vegetables, and grains, despite their central role in the population’s diet. Regulations focus primarily on drinking water quality and selected processed foods, creating a regulatory gap in the direct control of contaminants in crops. The findings underscore the urgent need to strengthen public policies by establishing crop-specific regulatory standards, implementing systematic monitoring programs, and integrating food safety considerations more effectively into environmental, agricultural, and public health policies in Mexico.

El artículo analiza la relación entre la percepción social de la contaminación atmosférica y la bioacumulación de metales pesados en frutos como la guayaba y el guamúchil de árboles urbanos, así como los riesgos asociados para la salud en el Área Metropolitana de Guadalajara. A través de encuestas se encontró que el 71 % percibe el aire contaminado, 85 % reconoce la capacidad de los árboles para acumular metales pesados y 64 % consume frutos de guamúchil o guayaba, pese a que 63 % manifiesta preocupación por su posible contaminación. El análisis químico mostró que, en comparación con los frutos de guayaba, los de guamúchil presentan concentraciones significativamente más altas de Mn, Cr, Pb, Zn y Ni (132.77, 82.14, 40.34, 33.01 y 22.41 mg kg⁻¹, respectivamente) superando el índice de riesgo no cancerígeno total (THQ < 1) en mujeres (1.26) y hombres (1.13). Asimismo, el riesgo cancerígeno total fue elevado con valores de 2.45 × 10⁻³ en mujeres y 2.20 × 10⁻³ en hombres, clasificados por la Agencia de Protección Ambiental (EPA, por sus siglas en inglés) como nivel de riesgo alto. Estos resultados respaldan la necesidad de implementar programas de comunicación basados en evidencia científica para informar a la población sobre el consumo de frutos de árboles urbanos según la calidad ambiental del entorno.

Lake Chapala is the main freshwater reservoir in Mexico and faces notable environmental pressure associated with urban, industrial, and agricultural activities, with documented evidence of heavy metal contamination. Thus, the artisanal fishers from Lake Chapala occupy a strategic position for understanding the socio-environmental dynamics of this lacustrine system. The objective of this study was to analyze their perceptions of pollution in Lake Chapala and the health risks associated with heavy metal contamination, with particular emphasis on the consumption of charal (Chirostoma spp.). Based on the results, 70% of fishers agreed that Lake Chapala is polluted, and 50% identified solid waste as the main source of contamination. Regarding water quality, 41% considered that it had not changed in recent years, while 37% perceived that it had deteriorated. With respect to heavy metals, 50% reported being aware of their presence in the lake; however, slightly more than 50% expressed concern about the possibility that charal could be contaminated. Fishers acknowledged the environmental pressure faced by Lake Chapala but prioritized risks based on visibility and their everyday experiences. Incorporating the perceptions of key stakeholders is essential for addressing socio-environmental problems, strengthening environmental communication and public health strategies, and effectively managing this lacustrine system.

This study evaluated heavy metal accumulation in bird feathers across four contrasting environments in Jalisco, Mexico (urban, semi-urban, agricultural, and semi-natural). We analyzed 370 feather samples from 58 species spanning seven trophic guilds using XRF spectrometry. Fifteen metals were quantified, with zinc (Zn) showing the highest concentrations overall. Multivariate analyses identified trophic guild as the strongest predictor of metal variation, while spatial differences were present but less pronounced. CUAltos was the only site consistently distinct from the others, mainly due to lower concentrations of several metals. Despite quantitative differences among guilds, their proportional metal profiles were similar—dominated by Zn, Y, Mo, and Hf—suggesting broad regional exposure rather than guild-specific accumulation. Redundancy Analysis indicated that atmospheric pollutants (COV and PM10) were the main environmental drivers of spatial variation, especially in Guadalajara’s urban sites. Agricultural variables, including agave cover, showed minor and non-significant effects. Neither sex nor migratory status influenced metal loads, consistent with feathers reflecting exposure during feather growth at the molt site, while potentially also incorporating locally deposited external contaminants. Overall, this study demonstrates the effectiveness of feathers as a non-invasive biomonitoring tool and highlights air quality as a key determinant of regional heavy metal contamination.

Heavy metal pollution in urban environments and public understanding of these contaminants pose major challenges for air-quality management. Urban trees have been proposed as tools to mitigate air pollution; however, evidence integrating biophysical assessments and social perception is still limited in the Guadalajara Metropolitan Area (AMG), Mexico. This study evaluated Cd and Pb accumulation in the leaves of five common urban tree species and assessed residents’ perceptions of air pollution and the role of urban trees. Significant interspecific differences were found, with Citrus × aurantium L. showing the highest Cd concentration (2.60 mg kg⁻¹) and Bauhinia variegata L. the highest Pb content (7.45 mg kg⁻¹). Socially, 62% of respondents found the AMG to be one of the most polluted metropolitan areas in the country, and >90% acknowledged direct or indirect health impacts associated with air pollution; nevertheless, a marked knowledge gap persisted about specific contaminants such as Cd and Pb. This “perception paradox” highlights an opportunity to strengthen risk communication and environmental education and suggests that urban-tree biomonitoring can provide locally meaningful evidence to support public engagement and policy actions. Taken together, the environmental and social findings provide an interpretive, metropolitan-scale synthesis that informs air quality management and public health protection in the AMG.

Polluted water in the Chapala–Santiago basin (CSB) contains several genotoxic substances that present risks to human health, particularly among residents of communities surrounding Lake Chapala and the Santiago River, where a high prevalence of cancer has been documented. For this reason, it is necessary to study the genotoxic activity of these waters and the genetic damage in inhabitants of the surrounding populations. This study assessed the genotoxicity of water in various communities in the CSB and evaluated DNA damage to lymphocytes in residents of nearby locations. The alkaline comet assay was employed to evaluate water genotoxicity and DNA damage to lymphocytes in residents living near these waters. A standardized questionnaire was distributed to participants of this study to evaluate their exposure to polluted water. Significant genotoxic activity (p < 0.05) was observed in the lymphocytes of individuals exposed to contaminated water (tail length in Puente Grande 27.88 ± 5.4 compared to 3.77 ± 1.64 of negative control), along with notable DNA damage (p ≤ 0.05) to the lymphocytes of residents living in proximity to these waters (tail length in Juanacatlán 12.3 ± 3.4 compared to 1.4 ± 0.74 of negative control). The waters of the CSB possess the capacity to cause DNA damage; meanwhile, genotoxicity increases from Chapala to El Salto due to the additional input of genotoxic contaminants, thereby elevating the cancer risk for the exposed population. The comet test proved to be a useful tool that allowed data to be obtained quickly and reliably.

The Trans-Mexican Volcanic Belt (TMVB) in its western section possesses a high biodiversity, resulting from its environmental heterogeneity. However, this biological richness is threatened by diverse anthropogenic pressures, such as deforestation and land use change. With the objective of evaluating the taxonomic diversity of birds in the western TMVB, this study was carried out in two localities of Jalisco: Sierra de Quila Flora and Fauna Protection Area and a sustainable avocado production zone in Zapotlán el Grande. Sampling was carried out in different vegetation types during the years 2021 to 2024, using mist nets and point counts. To evaluate taxonomic diversity, the analysis of taxonomic distinctness was employed. A total of 202 bird species were recorded, where it was observed that the most important taxonomic unit was the order level, with Passeriformes being the most diverse order. Among the different vegetation types, the tropical deciduous forest presented the greatest species richness. Although migration increased bird richness in general, taxonomic diversity decreased. The results also showed that secondary vegetation and agricultural zones have a high taxonomic diversity, which is consistent with the intermediate disturbance hypothesis, which suggests that a moderate disturbance can increase habitat heterogeneity and promote the coexistence of multiple species.

Humic substances and beneficial microorganisms are key biostimulants for sustainable agriculture and global food security in the face of climate change. Marine bacteria are emerging as a promising source of plant-beneficial microbes, tapping into a microbial diversity as immense as the oceans themselves. However, their potential, limitations, and mechanisms of action––especially in combination with other biostimulants––remain largely unexplored. In this study, we isolated the Streptomyces sp. LAP3 strain from the giant limpet Scutellastra mexicana. We evaluated the efficacy of the marine bacterium, applied alone or in combination with the humic product Leonardite hydrolate (L), in enhancing tomato performance under field conditions. Treatments included: (1) marine Streptomyces (MS), (2) Leonardite hydrolate (L), (3) both biostimulants (MS + L), and (4) a control (CTRL). We assessed growth, photosynthetic performance, antioxidant responses, and fruit yield and quality. Both biostimulants individually improved plant performance, but their combination had a significant synergistic effect, markedly boosting tomato productivity, thermotolerance, and resilience during a heatwave. Enhanced photosynthetic efficiency and antioxidant enzyme activity were associated with improved agronomic traits. These results highlight the potential of combining Streptomyces sp. LAP3 and Leonardite hydrolate as an eco-friendly strategy to increase crop productivity, strengthen stress resilience, promote sustainable agriculture, and reduce reliance on agrochemicals.

The bioaccumulation of heavy metals, such as Cr, Cd, Pb, and As, in vegetables irrigated with contaminated water represents a risk to human health. The objective of this study was to evaluate the Cr concentration in chayote fruits in sites irrigated with contaminated water from Lake Chapala and to assess the potential risk to human health using the estimated daily intake (EDI), objective risk quotient (THQ), and carcinogenic risk quotient (TCR). In parallel, interviews were conducted with local producers to understand their perceptions of the quality of irrigation water and their willingness to adopt more sustainable agricultural practices. In two of the sites and seasons, Cr concentrations exceeded the FAO-WHO limit of 2.3 mg·kg⁻¹ (from 2.49 to 4.82 mg·kg⁻¹). In all, 90% of producers used water from Lake Chapala to irrigate their crops, although most did not perform water quality analyses, despite 32% being aware that the water was contaminated. The results highlight the need to implement strategies to increase awareness of the quality of irrigation water, as well as the need for comprehensive public policies that combine technical assessments and producer perceptions to reduce the risks associated with the use of contaminated irrigation water to promote sustainable agricultural production.