Accumulation of arsenic, lead, copper, and zinc, and synthesis of phytochelatins by indigenous plants of a mining impacted area.

Several native plants, able to grow in an unconfined mining impacted area that is now in close vicinity with urban areas, were evaluated for their ability to accumulate heavy metals. The main soil contaminants were As, Pb, Cu, and Zn. Sampling of the rhizospheric metal polluted soil showed that Euphorbia prostrata Aiton, Parthenium incanum Kunth, and Zinnia acerosa (DC.) A. Gray were able to grow in the presence of high amounts of mixtures of these elements. The plants accumulated the metals in the above ground parts and increased the synthesis of thiol molecules. E. prostrata showed the highest capacity for accumulation of the mixture of elements (588 µg g DW(-1)). Analysis of the thiol-molecules profile showed that these plants synthesized high amounts of long-chain phytochelatins, accompanied by low amounts of monothiol molecules, which may be related to their higher resistance to As and heavy metals. The three plants showed translocation factors from roots to leaves >1 for As, Pb, Cu, and Zn. Thus, by periodically removing aerial parts, these plants could be useful for the phytoremediation of semi-arid and arid mining impacted areas, in which metal hyper-accumulator plants are not able to grow.

Factors related to health outcomes and health risk behaviors of adolescents with lead exposure: A pilot study / Factores relacionados con el estado de salud y conductas de riesgo para la salud de adolescentes con exposición a plomo: Un estudio piloto

This pilot study was an approach to determine the health outcomes (nutritional status, cognitive status, mental health and educational status), and the presence of health risk behaviors (aggressive behavior/ delinquency, hazardous/harmful drinking, substance use/abuse and tobacco use) of adolescents who have been exposed all their lives to lead. Besides, we could identify individual, familial and social factors, such as lead exposure, that were related to them. The sample included 40 adolescents (25 females and 15 males), aged 12-19 years, who participated as children in the Childhood Lead Exposure Surveillance Program (CLESP), conducted in a metallurgical area of Mexico. The 100% of the participants were reported neurologically healthy by medical clinical examination. The 15% were below 70 points of the Full Scale Intelligence Quotient, higher than the expected percentage in the general Mexican population. Moreover, we detected the presence of health risk behaviors. The protective factors identified were mean cell volume, adolescent education, father education and living in an apartment. Risk factors identified were: sleep hours, mono-parental family, positive family history of substance use/abuse, residents by household, having social security, tibia bone lead, and childhood blood lead (p<0.05). The gender and exercise variables were accounted for both risk and protection. The health problems that we found were mostly related to individual factors, followed by familial and social factors. The lead exposure explained, in minor proportions, the multivariate models; however, for every 1 pg lead/g bone mineral increased in the tibia and 1 pg/dL increase in blood lead during childhood; the Perceptual Organization/Perceptual Reasoning Index and Processing Speed Index are decreased by 1.21 and 1.11~points, respectively. The detection of protective and risk factors enable the design of an intervention program as an extension of CLESP. The health of these adolescents can be improved by avoiding some risk factors and fostering protective factors at individual, family and community levels.

Este estudio piloto fue una aproximación para determinar el estado de salud (nutricional, cognitivo, salud mental y educacional) y las conductas de riesgo para la salud (agresión/delincuencia, consumo riesgoso/ dañino de alcohol, uso/ abuso de sustancias y consumo de tabaco) de adolescentes que han estado expuestos toda su vida al plomo. Se identificaron factores individuales, familiares y sociales; así como la exposición al plomo, que estuvieran relacionados con ellos. Se incluyeron 40 adolescentes (25 mujeres y 15 hombres) de 12 a 19 años de edad, quienes participaron siendo niños en el Programa de Vigilancia Infantil de Exposición a Plomo (PVIEP), conducido en un área metalúrgica de México. El 100% estaba neurológicamente sano por examen médico. El 15% obtuvo menos de 70 puntos en la Escala Total del Coeficiente Intelectual, porcentaje mayor al esperado en la población general mexicana. Además se detectó la presencia de conductas de riesgo. Los factores protectores identificados fueron volumen corpuscular medio, educación del adolescente, educación del padre y vivir en departamento. Los factores de riesgo fueron horas de sueño, familia monoparental, familia con antecedentes de uso/abuso de sustancias, número de residentes en la vivienda, tener seguridad social, plomo en tibia y plomo en sangre durante la infancia (p<0.05). El género y el ejercicio fueron variables tanto de riesgo como de protección. Los problemas de salud encontrados estuvieron mayormente asociados a factores individuales, seguidos por factores familiares y sociales. La exposición a plomo explicó en menor proporción los modelos multivariados, sin embargo, por cada 1 ug plomo/g de hueso mineral incrementado en tibia y 1 ug/dL de plomo incrementado en sangre durante la infancia, el Indice de Organización Perceptual/Razonamiento Perceptual e Indice de Velocidad de Procesamiento, disminuyeron 1.21 y 1.11 ~puntos, respectivamente. La detección de factores de riesgo y protección permitirá el diseño de un programa de intervención como parte del PVIEP. La salud de estos adolescentes puede ser mejorada aminorando algunos factores de riesgo y fomentando factores de protección, desde el nivel individual, familiar y/o comunitario.

DNA damage and decreased DNA repair in peripheral blood mononuclear cells in individuals exposed to arsenic and lead in a mining site.

The aim of this study was to evaluate DNA damage and the capacity for DNA repair in children exposed to arsenic and lead. During 2006, we studied a total of 85 healthy children (aged 4-11 years) who were residents of Villa de la Paz (community A), Matehuala (community B), and Soledad de Graciano Sanchez (community C) in San Luis Potosi, Mexico. The quantification of arsenic in urine (AsU) and lead in blood (PbB) was performed by atomic absorption spectrophotometry. The alkaline comet assay was used to evaluate DNA damage and DNA repair. The highest levels of AsU and PbB in children were found in community A (44.5 µg/g creatinine for arsenic and 11.4 µg/dL for lead), followed by community B (16.8 µg/g creatinine for arsenic and 7.3 µg/dL for lead) and finally by children living in community C (12.8 µg/g creatinine for arsenic and 5.3 µg/dL for lead). When DNA damage was assessed, children living in community A had the highest DNA damage. Analysis of these same cells 1 h after a challenge with H(2)O(2) 10 µM showed a dramatic increase in DNA damage in the cells of children living in community B and community C, but not in the cells of children living in community A. Moreover, significantly higher levels of DNA damage were observed 3 h after the challenge ended (repair period) in cells from individuals living in community A. Our results show that children exposed to metals might be more susceptible to DNA alterations.

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.

Decreased intelligence in children and exposure to fluoride and arsenic in drinking water.

Recent evidence suggests that fluoride (F) and arsenic (As) may adversely affect intelligence quotient (IQ) scores. We explore the association between exposure to F and As in drinking water and intelligence in children. Three rural communities in Mexico with contrasting levels of F and As in drinking water were studied: Moctezuma (F 0.8+/-1.4 mg/L; As 5.8+/-1.3 microg/L); Salitral (F 5.3+/-0.9 mg/L; As 169+/-0.9 microg/L) and 5 de Febrero (F 9.4+/-0.9 mg/L; As 194+/-1.3 microg/L). The final study sample consisted of 132 children from 6 to 10 years old. After controlling for confounders, an inverse association was observed between F in urine and Performance, Verbal, and Full IQ scores (beta values = -13, -15.6, -16.9, respectively). Similar results were observed for F in drinking water (beta values = -6.7, -11.2, -10.2, respectively) and As in drinking water (beta values= -4.30, -6.40, -6.15, respectively). The p-values for all cases were < 0.001. A significant association was observed between As in urine and Full IQ scores (beta = -5.72, p = 0.003). These data suggest that children exposed to either F or As have increased risks of reduced IQ scores.

Decreased intelligence in children and exposure to fluoride and arsenic in drinking water

Recent evidence suggests that fluoride (F) and arsenic (As) may adversely affect intelligence quotient (IQ) scores. We explore the association between exposure to F and As in drinking water and intelligence in children. Three rural communities in Mexico with contrasting levels of F and As in drinking water were studied: Moctezuma (F 0.8±1.4mg/L; As 5.8±1.3µg/L); Salitral (F 5.3±0.9mg/L; As 169±0.9µg/L) and 5 de Febrero (F 9.4±0.9mg/L; As 194±1.3µg/L). The final study sample consisted of 132 children from 6 to 10 years old. After controlling for confounders, an inverse association was observed between F in urine and Performance, Verbal, and Full IQ scores (beta values = -13, -15.6, -16.9, respectively). Similar results were observed for F in drinking water (beta values = -6.7, -11.2, -10.2, respectively) and As in drinking water (beta values= -4.30, -6.40, -6.15, respectively). The p-values for all cases were < 0.001. A significant association was observed between As in urine and Full IQ scores (beta = -5.72, p = 0.003). These data suggest that children exposed to either F or As have increased risks of reduced IQ scores.

Estudios recientes sugieren que el flúor (F) y el arsénico (As) pueden tener efectos adversos sobre el coeficiente intelectual (CI). En este estudio exploramos la asociación entre el F y el As y la inteligencia en niños expuestos a estas sustancias a través del agua. Tres comunidades rurales de México con diferentes niveles de F y As fueron estudiadas: Moctezuma (F 0,8±1,4mg/L; As 5,8±1,3µg/L); Salitral (F 5,3±0,9mg/L; As 169±0,9µg/L) y 5 de Febrero (F 9,4±0,9mg/L; As 194±1,3µg/L). La muestra final fue de 132 niños de 6 a 10 años de edad. Después de controlar por confusores, se obtuvieron asociaciones inversas entre F en orina y las puntuaciones de los CI (Desempeño, Verbal y Total) (valores beta = -13, -15,6, -16,9, respectivamente) p < 0,001 en todos los casos. Resultados similares se obtuvieron con F en agua (valores beta = -6,7, -11,2, -10,2, respectivamente) y con As en agua (valores beta = -4,30, -6,40, -6,15, respectivamente). En todos los casos p < 0,001. Para As en orina, se obtuvo una asociación inversa con las puntuaciones del CI total (beta= -5,72; p = 0,003). Estos datos sugieren que los niños expuestos al F o al As tienen mayor riesgo de tener disminución en las puntuaciones del CI.

DDT induces apoptosis in human mononuclear cells in vitro and is associated with increased apoptosis in exposed children.

The aim of the present work was to investigate whether DDT and its metabolites are able to induce apoptosis of human peripheral blood mononuclear cells (PBMC) both in vitro and in vivo. Cells isolated from healthy individuals were incubated in the presence of increasing concentrations of p'p-DDT, p'p-DDE, or p'p-DDD (0-150 microg/mL) for different intervals. Apoptosis was then determined by flow cytometry (DNA cell content analysis) and fluorescence microscopy (Hoechst staining). A significant level of apoptosis was induced by DDT, DDD, and DDE at 80 microg/mL compared to controls, reaching a maximum effect at 100 microg/mL. We began to detect apoptosis at 12h, with a maximum effect at 24h of incubation. These results were confirmed using the TUNEL assay in cells treated with the three compounds tested as well as with o'p-DDT at 100 microg/mL and 24h of incubation. Our data demonstrate that DDT and its metabolites are able to induce apoptosis of human PBMC in vitro. Therefore, we performed a preliminary study in children exposed to this insecticide. When compared to a control population, the exposed children had higher levels of DDT, DDD, and DDE in blood and also had a higher frequency of apoptosis. In the exposed children, a weak positive association was found between the frequency of apoptosis and the exposure to DDT and DDE. Our results showed that more studies are needed in people exposed to DDT, as apoptosis may cause serious public health effects such as immunosuppression.

DNA damage in blood cells from children exposed to arsenic and lead in a mining area.

In this work, we studied the frequency of DNA damage in children living in Villa de la Paz, Mexico, a mining site contaminated with arsenic and lead. DNA damage in blood cells was assessed using the Comet assay, and the results were compared to those found in children living in a less exposed town (Matehuala). In Villa de la Paz, high concentrations of arsenic and lead in surface soil and household dust were found. All of the soil samples had concentrations above 100 mg/kg of arsenic, and 58% of the samples were higher than 400 mg/kg of lead (these concentrations are used as intervention guidelines by the United States Environmental Protection Agency). In agreement with the environmental results, urinary arsenic in children living in Villa de la Paz (geometric mean 136 microg/g creatinine) was significantly higher than that found in children living in Matehuala (34 microg/g creatinine). Blood lead levels were also significantly higher in children from Villa de la Paz (11.6 microg/dL) than in children from Matehuala (8.3 microg/dL). The results of the Comet assay showed that the tail length and the tail moment in children living in Villa de la Paz were higher than those observed for children in Matehuala (P<0.05). Taking all the data into account, our study has shown increased DNA damage in children exposed to arsenic and lead in the mining site of Villa de la Paz.

Overview of human health and chemical mixtures: problems facing developing countries.

In developing countries, chemical mixtures within the vicinity of small-scale enterprises, smelters, mines, agricultural areas, toxic waste disposal sites, etc., often present a health hazard to the populations within those vicinities. Therefore, in these countries, there is a need to study the toxicological effects of mixtures of metals, pesticides, and organic compounds. However, the study of mixtures containing substances such as DDT (dichlorodiphenyltrichloroethane, an insecticide banned in developed nations), and mixtures containing contaminants such as fluoride (of concern only in developing countries) merit special attention. Although the studies may have to take into account simultaneous exposures to metals and organic compounds, there is also a need to consider the interaction between chemicals and other specific factors such as nutritional conditions, alcoholism, smoking, infectious diseases, and ethnicity.