Environmental and biological monitoring of organochlorine pesticides in the city of Salamanca, Mexico.

The former Tekchem Industrial Unit located in the city of Salamanca, Mexico, constitutes an environmental liability in which the presence of high levels of organochlorine pesticides (OCPs) has been reported. In the present study, levels of OCPs were quantified using gas chromatography-mass spectrometry in 52 soil samples and in 88 blood samples from school-age children in the city of Salamanca. A median concentration of 70.6 ng/g (6.93-3299) was obtained for total OCPs in soil, while for the total sum of dichlorodiphenyltrichloroethane (DDT) the value was 49.6 ng/g (6.93-3276). In children, the median level of the total sum of OCPs was 390 ng/g lipid (7.34-14,895), and for the total sum of DDT was 175 ng/g lipid (< LOD-14,802). The OCPs that resulted in highest concentrations in soil were DDT and its metabolites, as well as aldrin and heptachlor epoxide, while in blood the highest levels corresponded to 4,4'-dichlorodiphenyltrichloroethane (4,4'-DDT) and its metabolites, followed by heptachlor and heptachlor epoxide. The spatial distribution of the concentrations of OCPs in soil shows that the facilities of Tekchem may be a significant potential source for the dispersion of these compounds toward the metropolitan area of Salamanca. The results obtained in the present study demonstrate the presence of OCPs in soil and in child population, providing important bases to study the problem from a broader perspective, while reiterating the importance of continuing efforts to generate resolute and precautionary measures with respect to the environmental liability of Tekchem.

Exposure to arsenic and lead in children from Salamanca México, effects on telomeric lengthening and mitochondrial DNA.

Levels of urinary arsenic and levels of lead in blood were measured in children attending elementary schools located in an industrial zone in Salamanca, México. Its possible effects using telomere length and mitochondrial DNA copy number as biomarkers of genomic disequilibrium by oxidative stress were studied. Eighty-eight children (6-15 years old) were included and urine samples were collected for quantification of arsenic, while lead was measured in blood samples using inductively coupled plasma mass spectrometry (ICP-MS). DNA was isolated from peripheral blood and relative telomere length and the mitochondrial DNA copy number were determined by real-time PCR. The geometric mean of urinary arsenic was 54.16 µg/L (11.7-141.1 µg/L). Ninety-eight percent of the children were above 15 µg/L (biomonitoring equivalent value). With respect to the concentration of lead in blood, the mean was 3.78 µg/dL (LOD-22.61), where 24.5% of the participants had equal or above the reference value (5 µg/dL; Mexican Official Norm NOM-199-SSA1-2000, 2017). A positive association between urinary arsenic and telomere length was found (ß = 0.161; 95% CI: 0.12; 0.301; P = 0.034), while lead blood concentrations were negatively associated with mitochondrial DNA copy number (ß = - 0.198; 95% CI: - 2.81; - 0.17; P = 0.019), after adjusting by age, sex, and total white blood cell count. Differences in the mitochondrial DNA content were observed in children with lead blood levels from 2.5 µg/dL, (P ≤ 0.001), suggesting an effect at lead exposure levels considered acceptable (< 5 µg/dL). In conclusion, children living in an industrial area in Salamanca showed an exposure to arsenic and lead and an impact on telomere length and mitochondrial DNA content associated with arsenic and lead exposure, respectively.

Dosis de exposición a fluoruros por el consumo de diferentes tipos de leche en residentes de una zona con hidrofluorosis endémica en México / Level of exposure to fluorides by the consumption of different types of milk in residents from an area of Mexico with endemic hydrofluorosis

Introducción: Diversos estudios han demostrado la presencia de fluorosis (FD) en la dentición primaria, lo que puede indicar una exposición a los fluoruros (F-) en la primera infancia. La leche materna se recomienda como alimento exclusivo hasta los 6 meses de edad. Aunque se menciona que solo una pequeña cantidad de F- puede eliminarse por leche materna, estudios han demostrado la presencia de este elemento en leche de mujeres residentes de zonas contaminadas, así como en leche de fórmulas comerciales. El objetivo del proyecto fue evaluar la dosis de exposición a F- a través de leche en niños residentes de una zona con hidrofluorosis endémica. Metodología: Un total de 110 niños de entre 6 y 36 meses de edad del municipio de Lagos de Moreno, Jalisco, México, participaron en el estudio. Se colectaron muestras de agua de los hogares, leche y orina. Las muestras se cuantificaron con el electrodo de ion selectivo. Se calculó la dosis de exposición a F- a través del programa Oracle Crystal Ball. Resultados: Se observaron dosis superiores a la dosis de referencia para FD en la leche de fórmula reconstituida con agua de abastecimiento público, de vaca pasteurizada (entera) y de vaca sin tratamiento sanitario (cruda) en el percentil 90, 70 y 50, respectivamente, así como una correlación entre los niveles de F- en leche y F- en orina (r = 0,41; p < 0,001). Conclusiones: La identificación de fuentes de F- en etapas tempranas del desarrollo infantil podría reducir el riesgo de presentar FD

Introduction: Several studies have shown the presence of fluorosis (DF) in primary dentition, suggesting an exposure to fluorides (F-) in early childhood. Breast milk is recommended as an exclusive food until 6 months of age. Although it is mentioned that only a small amount of F- can be eliminated by breast milk, studies have shown the presence of this element in milk of women living in contaminated areas, as well as in infant formulas. The objective of this project was to evaluate the exposure level to F- through milk in children living in an area with endemic hydrofluorosis. Methodology: The study included 110 children between 6 and 36 months of age from the municipality of Lagos de Moreno, Jalisco. Water samples were collected from the homes, as well as samples of milk (maternal, formula, whole or raw), and urine. Measurments were made with a selective ion electrode. The exposure level of F- for milk intake was calculated using the Oracle Crystal Ball package. Results: Levels greater than the reference level for DF were observed in infant formula reconstituted with public supply water, pasteurised cow's milk (whole) and untreated cow's milk treatment (raw) in the 90th, 70th, and 50th percentile, respectively, with a correlation being found between the levels of F- in milk and F- in urine (r = 0.41, P < .001)

[Level of exposure to fluorides by the consumption of different types of milk in residents from an area of Mexico with endemic hydrofluorosis]. / Dosis de exposición a fluoruros por el consumo de diferentes tipos de leche en residentes de una zona con hidrofluorosis endémica en México.

INTRODUCTION: Several studies have shown the presence of fluorosis (DF) in primary dentition, suggesting an exposure to fluorides (F-) in early childhood. Breast milk is recommended as an exclusive food until 6 months of age. Although it is mentioned that only a small amount of F- can be eliminated by breast milk, studies have shown the presence of this element in milk of women living in contaminated areas, as well as in infant formulas. The objective of this project was to evaluate the exposure level to F- through milk in children living in an area with endemic hydrofluorosis. METHODOLOGY: The study included 110 children between 6 and 36 months of age from the municipality of Lagos de Moreno, Jalisco. Water samples were collected from the homes, as well as samples of milk (maternal, formula, whole or raw), and urine. Measurments were made with a selective ion electrode. The exposure level of F- for milk intake was calculated using the Oracle Crystal Ball package. RESULTS: Levels greater than the reference level for DF were observed in infant formula reconstituted with public supply water, pasteurised cow's milk (whole) and untreated cow's milk treatment (raw) in the 90th, 70th, and 50th percentile, respectively, with a correlation being found between the levels of F- in milk and F- in urine (r=0.41, P<.001). CONCLUSIONS: The identification of sources of F- in the early stages of child development could reduce the risk of developing DF.

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.

Trace element contents in fine particulate matter (PM2.5) in urban school microenvironments near a contaminated beach with mine tailings, Chañaral, Chile.

Air quality in schools is an important public health issue because children spend a considerable part of their daily life in classrooms. Particulate size and chemical composition has been associated with negative health effects. We studied levels of trace element concentrations in fine particulate matter (PM2.5) in indoor versus outdoor school settings from six schools in Chañaral, a coastal city with a beach severely polluted with mine tailings. Concentrations of trace elements were measured on two consecutive days during the summer and winter of 2012 and 2013 and determined using X-ray fluorescence. Source apportionment and element enrichment were measured using principal components analysis and enrichment factors. Trace elements were higher in indoor school spaces, especially in classrooms compared with outdoor environments. The most abundant elements were Na, Cl, S, Ca, Fe, K, Mn, Ti, and Si, associated with earth's crust. Conversely, an extremely high enrichment factor was determined for Cu, Zn, Ni and Cr; heavy metals associated with systemic and carcinogenic risk effects, whose probably origin sources are industrial and mining activities. These results suggest that the main source of trace elements in PM2.5 from these school microenvironments is a mixture of dust contaminated with mine tailings and marine aerosols. Policymakers should prioritize environmental management changes to minimize further environmental damage and its direct impact on the health of children exposed.

Association of Leukocyte Telomere Length and Mitochondrial DNA Copy Number in Children from Salamanca, Mexico.

AIM: The purpose of this study was to determine if there is a correlation between telomere length (TL) and mitochondrial DNA copy number (mtDNAcn) in children. METHODS: Leukocyte TL and mtDNAcn were measured by real-time PCR in 98 Mexican children 6-12 years of age from Salamanca, México. RESULTS: A positive association was found between TL and mtDNAcn after a natural log transformation (Pearson correlation r = 0.72; p < 0.0001). No correlation between age and body mass index (BMI) biomarkers was found, and no differences according to sex were observed. After adjustment for these variables, a linear regression model showed an association between TL and mtDNAcn (ß = 0.739, 95% confidence interval 0.594; 0.885, p < 0.0001). CONCLUSIONS: A strong positive correlation between TL and mtDNAcn was found in the study population; age, sex, and BMI seemed to have no effect on this correlation.

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.

Apoptosis of peripheral blood mononuclear cells in children exposed to arsenic and fluoride.

In this study, we evaluated apoptosis induction in human immune cells in children exposed to arsenic (As) and fluoride (F). Children living in two areas in Mexico (Soledad de Graciano Sanchez (SGS) in San Luis Potosí and Colonia 5 de Febrero in Durango) were studied. Water, urine and blood samples were collected. Approximately 90% of the water samples in 5 de Febrero had As and F levels above the World Health Organization intervention guideline (10 µg/L and 1.5mg/L, respectively). In SGS, 0% of the water samples exceeded Mexican guidelines. Urinary As and F levels in children living in 5 de Febrero were significantly higher than the levels found in children living in SGS. In addition, the level of apoptosis was higher in children from the 5 de Febrero community when compared with the level of apoptosis in children living in SGS. Thus, in a worldwide context, our study demonstrates the health risks to children living in these regions.

Assessment of polychlorinated biphenyls and mercury levels in soil and biological samples from San Felipe, Nuevo Mercurio, Zacatecas, Mexico.

The aim of this work was to evaluate contamination by polychlorinated biphenyls and mercury in soil, and to assess exposure level to both contaminants in children living in San Felipe, Nuevo Mercurio, Zacatecas, Mexico. We found soil levels of total polychlorinated biphenyls ranging from non detectable (nd) to 190 µg/kg. Mercury soil levels ranged from 8.9 to 10215.0 mg/kg. Exposure levels of total polychlorinated biphenyls assessed in blood and urinary mercury in children living in the studied community were 1,600 ± 8,800 ng/g lipid and 4.2 ± 7.1 µg/g creatinine, respectively.

Exposure to persistent organic pollutants (POPs) and DNA damage as an indicator of environmental stress in fish of different feeding habits of Coatzacoalcos, Veracruz, Mexico.

The region of Coatzacoalcos, Veracruz hosts one of the largest and most important industrial areas of Mexico and Latin America. Industrial development and rapid population growth, have triggered a severe impact on aquatic ecosystems of the region. The aim of this study was to determine the levels of POPs in sediment and in muscle tissue of five fish species from different trophic levels in downstream residents of the Coatzacoalcos River, and their integration with DNA damage in the fish, evaluated with the comet assay in whole blood as a biological indicator of stress, in order to obtain a baseline of the ecological condition of the region. The compounds detected in sediment and in muscle tissue were hexachlorobenzene (HCB), α-, ß-, γ-hexachlorocyclohexane (HCH), dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethylene (DDE), mirex and polychlorinated biphenyls (PCBs). Sediment concentrations of these pollutants (except for mirex) exceeded the values of protection provided by international guidelines, suggesting a potential risk to aquatic life in the region. DNA damage recorded in the fish species is evidence of exposure to a mix of genotoxic pollutants, which combined with exposure to POPs, reflects the degree of environmental stress of aquatic organisms in the region. The results of this study show the importance of determining the presence of contaminants in the environment, the bioaccumulation in tissues and their effects on exposed organisms, providing an integrated approach in assessing the health of aquatic ecosystems.