Levels of persistent organic pollutants in cane toads (Rhinella marina) differ among sites with varying industrial and agricultural activities.

In this study, we captured cane toads (Rhinella marina) in four sites located in different regions affected by anthropogenic activities in Mexico. Subsequently we analyzed liver tissue for the presence of organochlorine pesticides (OCs) and polychlorinated biphenyls (PCBs) The levels of these POPs in the toads' livers ranged from 863.2 to 3109.6 ng/g of lipid weight across all sites. A multivariate statistical analysis highlighted two sites with the highest POPs levels, with the most polluted site displaying a high level of PCBs, suggesting influence of industrial activities. The second most polluted site displayed significant amounts of OCs, linking this location to agricultural activity. Additionally, we found pesticide metabolites and isomers that allowed us to distinguish past and recent exposure events. Our observations indicate that R. marina is suitable bioindicator of sites impacted by anthropogenic activities.

Ecotoxicological perspectives of microplastic pollution in amphibians.

Microplastics (MPs) are contaminants widely distributed in the environment and biota. Previously, most studies focused on identifying and characterizing microplastics in the marine environment, while their impact on freshwater ecosystems remains to be determined. This review summarizes recent findings regarding MPs physiological, immunological, and genetic effects on amphibians based upon the biological relevance of this species as indicators of freshwater pollution. Data demonstrated that MPs contamination may potentially alter various physiological processes in aquatic animals, mainly in the embryonic stages. It is worthwhile noting that adverse effects might be enhanced in synergy with other pollutants. However, amphibians might counteract the effect of MPs and other pollutants through microbiota present both in the intestine and on the skin. In addition, amphibian microbial composition might also be altered by MPs themselves in a manner that leads to unpredicted health consequences in amphibians.

Profile of urinary exosomal microRNAs and their contribution to diabetic kidney disease through a predictive classification model.

AIM: Evaluate the expression of exomiRs-126, -146, and -155 in urinary exosomes of patients with T2DM and diabetic kidney disease to establish a predictive classification model with exomiRs and clinical variables in order to determine their contribution to DKD. METHODS: The study group included 92 subjects: 64 patients diagnosed with T2DM subclassified into two groups with albuminuria (T2DM with albuminuria, n = 30) and without albuminuria (TD2M, n = 34) as well as 28 healthy, non-diabetic participants. Exosomes were isolated from urine and identified by TEM and flow cytometry. Profile expression of exomiRs-126, -146 and -155 was evaluated by RT-qPCR. Data were analysed by permutational multivariate analysis of variance (PERMANOVA), similarity percentage (SIMPER), principal coordinate analysis (PCO), and canonical analysis of principal coordinates (CAP). RESULTS: T2DM patients with and without albuminuria showed higher levels of miR-155 and miR-146 compared with controls. In addition, T2DM patients with albuminuria presented a significant increase in miR-126 contrasted to controls and patients without albuminuria. PCO analysis explained 34.6% of the total variability of the data (PERMANOVA; p < .0001). Subsequently, SIMPER analysis showed that miR-146, miR-155, and miR-126 together, with some clinical parameters, contributed to 50% of the between-group significance. Finally, the CAP analysis developed showed a correct classification of 89.01% with the analysed parameters. CONCLUSION: A platform using a combination of clinical variables and exomiRs could be used to classify individuals with T2D as risk for developing DKD.

Evaluation of in situ biosurfactant production by inoculum of P. putida and nutrient addition for the removal of polycyclic aromatic hydrocarbons from aged oil-polluted soil.

This work aimed to conduct a laboratory study to evaluate the use of Pseudomonas putida CB-100 and nutrient addition for the removal of PAHs from an aged oil-polluted soil of Veracruz, Mexico. Pseudomonas putida is a biosurfactant-producing bacterium capable of metabolizing polycyclic aromatic hydrocarbons (PAHs), which are toxic compounds with low water solubility, high melting, and boiling points, and low vapor pressure; characteristics that increase as their molecular weight increases and make them more recalcitrant. The methodology consisted in sampling the long-term oil-polluted soil and testing the use of Gamma irradiation (25 kGy) for the sterilization of the soil for abiotic control. We evaluated serological bottles containing 20 g of 35% moist soil (irradiated and non-irradiated) with the following treatments: the addition of nutrients (NH4Cl, NaNO3, KH2PO4, and K2HPO4), an inoculum of P. putida, and both P. putida and nutrients. The parameters assessed were pH, organic matter, humidity, available phosphorus, total nitrogen, cultivable heterotrophic microorganisms, CO2 production, rhamnolipids, surface tension, and the removal of eleven PAHs. The non-irradiated soil added with P. putida was the most efficient in the removal of PAHs; the pattern was: Benzo(a)anthracene > Phenanthrene > Fluoranthene > Benzo(k)fluoranthene > Chrysene > Pyrene > Anthracene > Acenaphthylene > Benzo(b)fluoranthene. In conclusion, P. putida in the non-irradiated soil produced in situ biosurfactants (1.55 mg/kg of rhamnolipids and an 11.9 mN/m decrease in surface tension) and removed PAHs in 10 days.

Giant Toads (Rhinella marina) From the Industrial Zones of Low Basin of the Coatzacoalcos River (Veracruz, MX) Presents Genotoxicity in Erythrocytes.

The lower basin of Coatzacoalcos River is one of the most polluted regions of the southern Gulf of Mexico. Organochlorine compounds, polybrominated diphenyl ethers, polycyclic aromatic hydrocarbons, and heavy metals have been registered in this region. In the present study, genotoxicity was evaluated in the blood of giant toads (Rhinella marina) from Coatzacoalcos' rural and industrial zones, and compared with laboratory toads. Determination of the frequency of micronucleus and erythrocyte nuclear abnormalities by the light microscope and cell cycle and apoptosis by flow cytometry were used as biomarkers of genotoxicity. We found more variability in micronucleus and more nuclear buds in toads from industrial zones. Also, cell cycle alterations and an increase of apoptosis in erythrocytes were found in toads from rural and industrial zones. Multivariate statistics show that the toads from the industrial zone were more affected than toads from laboratory and rural zones.

Holistic health risk assessment in an artisanal mercury mining region in Mexico.

Mexico is one of the world's leading mercury producers and exporters. However, mercury mining is carried out using artisanal procedures, which highly impact ecosystems. In the municipality of Pinal de Amoles, Queretaro, Mexico, artisanal mercury mining (AMM) is practiced in a region that has been categorized as a Biosphere Reserve. Therefore, a holistic health risk assessment for mercury was performed in the region, including environmental monitoring (air, water, and soil) and mercury exposure in both humans (children, women, and miners) and biota (plants, rodents, and worms). The atmospheric mercury determination was carried out using the JEROME® J405 analyzer, whereas total mercury in environmental and biological samples was determined by atomic absorption spectrophotometry/cold vapor. Results showed that mercury concentrations in the environmental and biological matrices exceeded their respective reference values. These results demonstrate the direct influence of AMM in the increasing levels of mercury in all the components of the studied ecosystem. Therefore, comprehensive intervention strategies must be implemented to reduce and prevent human health and ecological risks due to the presence of mercury. In this regard, the Minamata Convention for mercury control should include biomonitoring programs not only for humans but also for critical ecological receptors in polluted ecosystems.

Nondestructive biomarkers in giant toad (Rhinella marina) to assess the effect of complex mixture of pollutants in Coatzacoalcos River, Mexico.

In this study, we evaluated the usefulness of nondestructive biomarkers approach in giant toads (Rhinella marina). We obtained blood samples and the residual condition index of toads from rural and industrial zones from Coatzacoalcos River, Mexico (COA). In the blood samples, we determined the activity of enzymes, lipid peroxidation, and the presence of cell death (apoptosis). We found that the activity of the enzyme delta-aminolevulinic dehydratase was lower. Still, the glutathione s-transferase activity and the percentage of apoptosis in erythrocytes were higher in the toads of COA than laboratory toads. Meanwhile, some biomarkers in toads showed differences when compared between Industrial and Rural zones. These results and correlations between biomarkers showed how the response changed in the toads living near the industrial zones. We demonstrate that a nondestructive biomarkers approach can be useful in environmental studies with anuran amphibians.

Patterns in utilization of carbon sources in soil microbial communities contaminated with mine solid wastes from San Luis Potosi, Mexico.

In San Luis Potosí, Mexico, the exploitation of minerals has historically been carried out as an activity that has left in its path environmental liabilities, with high concentrations of heavy metals. These metals have undergone weathering by rain and wind and have moved closer to inhabited locations as is the case of Cerro de San Pedro (CSP) and Villa de la Paz (VDP). The objective of this study is to show the biological alteration of soils due to the presence of heavy metals and metalloids like Cadmium (Cd), Copper (Cu), Lead (Pb) and Arsenic (As) and to find the relationship between contamination and risk indexes. Soil samples were obtained from sites with historical records of mining activity and their surroundings. Several analyses were performed, such as pH levels, organic matter, electrical conductivity, clays, heavy metals and As. Moreover, Community Level Physiological profiling (CLPP) were conducted. The obtained evidence showed high levels of contamination by As and heavy metals in both sites (CSP: 6485.1 mg/Kg of Pb and pH of 4.4; VDP: 7188.2 mg/Kg of As and pH of 7.8). According to the Metal Pollution Index (MPI), 607.0 in CSP and 1050.5 in VDP, presented a high environmental risk, apart from, risk to human health (SQGQI) 35.8 in CSP and 131.5 in VDP. At the same time, CLPPs showed that microbiological communities were selective in taking up substrate groups, in the following order: Carbohydrates > Polymers > Carboxylic acids > Amino acids > Amines/Amides. However, a positive correlation in CSP was only found between both indexes and Amines/Amides (r = 0.46, p < 0.05), and in VDP the D-Galactonic acid-γ-Lactone with the MPI (r = 0.49, p < 0.05), and with the SQGQI (r = 0.45, p < 0.05). Although this behavior was not homogeneous, it was possible to find negative correlations between both indexes and the AWCD with other substrates, influenced by the physicochemical characteristics presented in each studied site. Consequently, according to our findings, a combined effect between the physicochemical characteristics, As, and heavy metals took place, on the metabolic activity, causing alterations to soil functions.

Identification of metabolic markers in patients with type 2 Diabetes by Ultrafast gas chromatography coupled to electronic nose. A pilot study.

Metabolomics is a potential tool for the discovery of new biomarkers in the early diagnosis of diseases. An ultra-fast gas chromatography system equipped to an electronic nose detector (FGC eNose) was used to identify the metabolomic profile of Volatile Organic Compounds (VOCs) in type 2 diabetes (T2D) urine from Mexican population. A cross-sectional, comparative, and clinical study with translational approach was performed. We recruited twenty T2D patients and twenty-one healthy subjects. Urine samples were taken and analyzed by FGC eNose. Eighty-eight compounds were identified through Kovats's indexes. A natural variation of 30% between the metabolites, expressed by study groups, was observed in Principal Component 1 and 2 with a significant difference (p < 0.001). The model, performed through a Canonical Analysis of Principal coordinated (CAP), allowed a correct classification of 84.6% between healthy and T2D patients, with a 15.4% error. The metabolites 2-propenal, 2-propanol, butane- 2,3-dione and 2-methylpropanal, were increased in patients with T2D, and they were strongly correlated with discrimination between clinically healthy people and T2D patients. This study identified metabolites in urine through FGC eNose that can be used as biomarkers in the identification of T2D patients. However, more studies are needed for its implementation in clinical practice.

Integrated probabilistic risk assessment in sites contaminated with arsenic and lead by long-term mining liabilities in San Luis Potosi, Mexico.

Mining environmental liabilities (MEL) in San Luis Potosi are the result of more than 450 years of mining activity, which has contaminated the soil mainly with arsenic (As) and lead (Pb) in several areas. Risk assessments are used to estimate the possibility of the occurrence of adverse effects on human health or on ecological receptors; and the most accessible way of performing them is through probabilistic estimates such as the Latin Hypercube Sampling (LHS) model. Therefore, the aim of this study was to carry out an Integrated Probabilistic Environmental Risk Assessment (IPERA) for the estimation of health risks in infants and rodents. The mean concentrations of As and Pb in soil were significantly higher (p<0.05) in all contaminated sites than in their respective reference sites. Villa de la Paz was the site with the highest mean concentration of As (1374 mg/kg), while Charcas was the one with the highest level of Pb (12,929 mg/kg). The Hazard Quotient (HQ) was calculated and Villa de la Paz had the highest values of As in both rodents (11.994) and children (39.32), and Charcas showed the highest values of Pb in both (24.971 and 31.668 for rodents and children respectively). The cumulative hazard Index (HI) reveals there is a very significant health risk due to As and Pb exposure for both rodents and children in contaminated areas of these mining communities.

Ultrafast gas chromatography coupled to electronic nose to identify volatile biomarkers in exhaled breath from chronic obstructive pulmonary disease patients: A pilot study.

An analytical method to identify volatile organic compounds (VOCs) in the exhaled breath from patients with a diagnosis of chronic obstructive pulmonary disease (COPD) using a ultrafast gas chromatography system equipped with an electronic nose detector (FGC eNose) has been developed. A prospective study was performed in 23 COPD patients and 33 healthy volunteers; exhalation breathing tests were performed with Tedlar bags. Each sample was analyzed by FCG eNose and the identification of VOCs was based on the Kovats index. Raw data were reduced by principal component analysis (PCA) and canonical discriminant analysis [canonical analysis of principal coordinates (CAP)]. The FCG eNose technology was able to identify 17 VOCs that distinguish COPD patients from healthy volunteers. At all stages of PCA and CAP the discrimination between groups was obvious. Chemical prints were correctly classified up to 82.2%, and were matched with 78.9% of the VOCs detected in the exhaled breath samples. Receiver operating characteristic curve analysis indicated the sensitivity and specificity to be 96% and 91%, respectively. This pilot study demonstrates that FGC eNose is a useful tool to identify VOCs as biomarkers in exhaled breath from COPD patients. Further studies should be performed to enhance the clinical relevance of this quick and ease methodology for COPD diagnosis.

DNA damage in different wildlife species exposed to persistent organic pollutants (POPs) from the delta of the Coatzacoalcos river, Mexico.

The delta of the Coatzacoalcos river is a priority region for the biological conservation in the Gulf of Mexico. Environmental studies in the area have detected a complex mixture of contaminants where the presence of Persistent organic compounds (POPs) is highlighted. Deoxyribonucleic acid (DNA) integrity of biological populations are global concerns due to their ecological implications. The purpose of this study was to measure the exposure to POPs and DNA damage in nine species residing in the Coatzacoalcos river classified by taxonomic group, type of habitat and feeding habits. Total POPs concentrations (minimum and maximum) detected for all species were from 22.7 to 24,662.1 ng/g l.w; and the values of DNA damage (minimum and maximum) varied from 0.7 to 20.5 and from 6.5 to 56.8 µm (Olive tail moment and tail length respectively). Broadly speaking, reptiles, species residing in the wetland and the ones with a carnivorous diet showed higher levels of POPs and DNA damage. This study provides us with a baseline of the state of POPs contamination and shows the degree of environmental stress to which the different components of the ecosystem of the Coatzacoalcos river delta are subject to.

DNA damage in earthworms by exposure of Persistent Organic Pollutants in low basin of Coatzacoalcos River, Mexico.

Persistent Organic Pollutants (POPs) are stable organic chemicals that represent a potential risk for ecosystems due to their high toxicity, persistence and biomagnification through food chains. Bioindicators in ecosystems have emerged to assess the effect of environmental pollutants. Earthworms are some of the most common bioindicator organisms in terrestrial ecosystems. The main objective of this study was to evaluate the geontoxicity of POP exposure in wild earthworms captured at different levels of urbanization throughout the lower basin of the Coatzacoalcos River (industrial, urban and rural areas). POP soil and earthworm tissue concentrations were measured via Gas-Mass Chromatography, and earthworm DNA damage was evaluated through the comet assay. The greatest concentrations of ΣPOPs, DDT and HCH were found in soil from industrial sites, followed by urban and rural areas (504.68, 383.10, 298.16; 22.6, 4.6, 2.6 and 433.7, 364, 255.6 mg/kg, respectively). Unlike other pollutants, mean ΣPCBs values were highest for industrial soil samples, followed by those from rural and urban areas (41.10, 33.97 and 12.44 mg/kg respectively). For all earthworm tissue POP analyses, the highest concentrations were found in individuals from industrial sites, followed by the urban and rural areas. Furthermore, the highest levels of DNA damage were registered in the industrial area, followed by the urban and rural areas. These assays suggest a strong links among regional soil contamination, POPs bioavailability and the potential risk of detrimental health effects for organisms that inhabit surface soil (soil life). Earthworms contribute vital ecosystem services that could be affected by these results. This work provides evidence of the potential ecological risk that exists in the Lower Basin of the Coatzacoalcos River.

Mercury Levels and Risk Implications Through Fish Consumption on the Sinaloa Coasts (Gulf of California, Northwest Mexico).

Fish consumption is the major source of mercury to humans. Fetuses and children are the most sensitive groups of populations to the effects of mercury. Consequently, fish consumption by pregnant women, children, and women of childbearing age is of concern because of the effects of mercury exposure on human health. To assess mercury exposure in a population in northwest Mexico, the allowed daily consumption of fish (which indicates the maximum daily amount of fish that can be consumed without causing adverse noncarcinogenic effects) was calculated for the general population (GP) and fishing-related population (FRP). The studied groups for both sectors of the population were children A (3-10 years old), children B (11-15 years old), women of childbearing age (16-40 years old), and the rest of the population (men ≥16 years old, and women ≥41 years old). Mercury content in canned and frozen tuna, smoked marlin, tilapia, Pacific sierra, dolphinfish, and bullseye puffer ranged from 0.01 to 0.23 µg/g wet weight; none of the values were above the limit set by Mexico. Regarding mercury concentrations and rates of fish consumption, the GP consumes 1.7-2.7 times the allowed daily consumption, and the FRP consumes 1.6-3.9 that limit. The risk analysis showed the children A and B groups from the GP and adults of FRP to be the highest percentage of the population at risk (approximately 35%). These results highlight the need for adequate strategies that consider mercury exposure as part of public health policies associated with fish consumption in Mexico.

Plasma asymmetric dimethylarginine (ADMA) levels in Mexican women exposed to polycyclic aromatic hydrocarbons (PAHs): A preliminary study.

Recent studies indicate that exposure to environmental pollutants (as polycyclic aromatic hydrocarbons) is a very important risk factor for development of cardiovascular diseases (CVDs). Correspondingly, in recent times asymmetric dimethylarginine (ADMA) has been proposed as a new and meaningful biomarker predictor for the risk of CVDs. Therefore, the objective of this study was to evaluate plasma ADMA concentrations in Mexican women (n=155) exposed to polycyclic aromatic hydrocarbons (PAHs). Urinary 1-hydroxypyrene [(1-OHP), exposure biomarker for PAHs] levels were quantified using a high performance liquid chromatography (HPLC) technique and plasma ADMA concentrations were analyzed using a commercially available ELISA kit. Urinary 1-OHP levels in all women assessed ranged from

Using urinary 1-hydroxypyrene concentrations to evaluate polycyclic aromatic hydrocarbon exposure in women using biomass combustion as main energy source.

CONTEXT: The use of solid fuels for cooking and heating is likely to be the largest source of indoor air pollution on a global scale. OBJECTIVE: The aim of this study was to investigate the urinary excretion of 1-hydroxypyrene (1-OHP) in women living in a rural community, where biomass combustion is used as main energy source during a working day. MATERIALS AND METHODS: The study was performed on urine samples collected in 2012, of 30 healthy women who were residents of a rural community in San Luis Potosi, Mexico. Urine was collected from each woman at three time points (morning, post-lunch and evening) during a working day. The analysis of urinary 1-OHP was performed using high-performance liquid chromatography (HPLC). Also, a health-risk assessment was conducted. RESULTS: The highest levels of 1-OHP in this study were found in the samples taken in the evening (geometric mean ± SD; 0.36 ± 0.13 µg/g creatinine). However, no significant differences among 1-OHP concentrations in the evening and post-lunch samples (0.27 ± 0.10 µg/g creatinine; 0.58 ± 0.67 µg/L) were observed. But, the 1-OHP levels (0.17 ± 0.13 µg/g creatinine; 0.19 ± 0.21 µg/L) found in samples collected in the morning were significantly lower than the 1-OHP levels found in samples collected during post-lunch and evening time. DISCUSSION AND CONCLUSION: The data shown in this study demonstrated an increment in the exposure levels to PAHs in women across the shift. However, no health risk was found in this study.

Assessment of the polychlorinated biphenyls (PCBs) levels in soil samples near an electric capacitor manufacturing industry in Morelos, Mexico.

In Mexico, polychlorinated biphenyls (PCBs) were principally used as heat transfer chemicals in electric transformers and capacitors as well as hydraulic fluids and lubricants in heavy electrical equipment since the early 1940s. However, although PCBs have been banned in Mexico, their past and present improper disposal has resulted in environmental contamination. Therefore, the aim of this study was to evaluate the PCBs levels in soil samples in the immediate area of an electric capacitor manufacturing industry, which was established several years ago in Alpuyeca, Morelos, Mexico. To confirm the presence of PCBs, surface soil samples (1-5 cm in depth) were collected from the vicinity of the industry. We determined the concentrations of 40 PCB congeners in soil samples using gas chromatography/mass spectrometry. The total PCBs levels in the soil samples ranged from 6.2 to 108460.6 µg kg(-1). Moreover, when we analyzed the results of the congeners (non-dioxin-like PCBs and dioxin-like PCBs), the levels of non-dioxin-like PCB congeners ranged from 5.7 to 103469 µg kg(-1) and the levels of dioxin-like PCB congeners ranged from 0.5 to 4992 µg kg(-1). Considering that soil is an important pathway of exposure in humans, analysis of PCBs levels in blood (as a biomarker of exposure) is necessary in individuals living in Alpuyeca, Morelos.

Effect of mining activities in biotic communities of Villa de la Paz, San Luis Potosi, Mexico.

Mining is one of the most important industrial activities worldwide. During its different stages numerous impacts are generated to the environment. The activities in the region have generated a great amount of mining residues, which have caused severe pollution and health effects in both human population and biotic components. The aim of this paper was to assess the impact of mining activities on biotic communities within the district of Villa de la Paz. The results showed that the concentrations of As and Pb in soil were higher than the national regulations for urban or agricultural areas. The bioavailability of these metals was certified by the presence of them in the roots of species of plants and in kidneys and livers of wild rodents. In regard to the community analysis, the sites that were located close to the mining district of Villa de la Paz registered a lower biological diversity, in both plants and wild rodents, aside from showing a change in the species composition of plant communities. The results of this study are evidence of the impact of mining on biotic communities, and the need to take into account the wildlife in the assessment of contaminated sites.

Blood lead levels, δ-ALAD inhibition, and hemoglobin content in blood of giant toad (Rhinella marina) to assess lead exposure in three areas surrounding an industrial complex in Coatzacoalcos, Veracruz, Mexico.

The Coatzacoalcos Region in Veracruz, Mexico houses one of the most important industrial complexes in Mexico and Latin America. Lead is an ubiquitous environmental pollutant which represents a great risk to human health and ecosystems. Amphibian populations have been recognized as biomonitors of changes in environmental conditions. The purpose of this research is to measure exposure to lead and evaluate hematological and biochemical effects in specimens of giant toads (Rhinella marina) taken from three areas surrounding an industrial complex in the Coatzacoalcos River downstream. Lead levels in toads' blood are between 10.8 and 70.6 µg/dL and are significantly higher in industrial sites. We have found a significant decrease in the delta-aminolevulinic acid dehydratase (δ-ALAD) activity in blood from 35.3 to 78 % for the urban-industrial and industrial sites, respectively. In addition, we have identified a strong inverse relationship between the δ-ALAD activity and the blood lead levels (r = -0.84, p < 0.001). Hemoglobin and mean corpuscular hemoglobin levels, as well as the condition factor, are found to be lower at industrial sites compared with the reference sites. Our results suggest that the R. marina can be considered a good biomonitor of the δ-ALAD activity inhibition and hematological alterations at low lead concentrations.

Exposición infantil al plomo en sitios contaminados / Children exposure to lead in contaminated sites

OBJETIVO: Determinar el grado de la exposición infantil al plomo en diversos tipos de sitios contaminados. MATERIAL Y MÉTODOS: El estudio se realizó de junio 2008 a diciembre 2009 en cuatro sitios de México: metalúrgica de Ávalos, Chihuahua.; metalúrgica de Morales, San Luis Potosí (SLP); zona alfarera en La Trinidad, Tlaxcala, y sitio minero en Cedral, SLP. Se cuantificó plomo en polvo y se realizó un biomonitoreo humano en niños de la comunidad. RESULTADOS: Los valores obtenidos de plomo en polvo exterior superaron el límite establecido de 400 mg/kg para suelos residenciales en un intervalo de valores para los cuatro sitios de 62 a 5 187 mg/kg. En cuanto al monitoreo biológico, todas las poblaciones presentaron valores extremos, desde los 22 µg/dL en Cedral, 31 µg/dL en Morales, y 32 µg/dL en Ávalos, hasta los 52 µg/dL en La Trinidad. Es importante señalar que encontramos una correlación positiva y significativa entre los valores de plomo en polvo y plomo en sangre en todos los sitios de estudio (p<0.001). CONCLUSIÓN: Estos sitios son un ejemplo de los riesgos en salud relacionados con la exposición a plomo en México; por consiguiente, se requiere de un programa nacional de salud pública dirigido a reducir la exposición a este metal en poblaciones vulnerables.

OBJECTIVE: To assess the exposure to lead in children living in various types of contaminated sites. MATERIALS AND METHODS: The study was conducted from June 2008 to December 2009 at four sites in Mexico: Avalos metallurgical, Chihuahua; Morales metallurgical, San Luis Potosí (SLP); Trinidad pottery area, Tlaxcala and Cedral mine site, SLP. These sites contain different sources of lead. The metal levels were quantified in outdoor dust and in peripheral blood of children. RESULTS: Lead dust concentrations exceed the National Guidelines for residential soils (400 mg/kg) in a range of values for the four sites from 62 to 5 187 mg/kg. Regarding biological monitoring, the studied children showed maximum lead blood levels of 22 µg/dL in Cedral, 31 µg/dL in Morales, 32 µg/dL in Avalos, and 52 µg/dL in Trinidad. It is important to mention that in all the studied sites, a significative positive correlation was found between blood lead levels and the lead concentrations in dust. CONCLUSION: These sites are an example of the health risks related to lead exposure in Mexico; therefore, there is an urgent need for a national public health program aimed at reducing lead exposure in vulnerable populations.