Leticia Carrizales-Yáñez

Epigenetic markers of exposure to polycyclic aromatic hydrocarbons in Mexican brickmakers: A pilot study

A pilot cross-sectional study was carried out in a group of 39 male brick manufacturers in San Luis Potosi, Mexico to identify epigenetic biomarkers of exposure to polycyclic aromatic hydrocarbons (PAHs). A questionnaire was used to compile the smoking and drinking habits, clinical history, working time, and socioeconomic characteristics of the participants. 1-Hydroxypyrene (1-OHP) levels were measured from urine samples using high-performance liquid chromatography, and genomic DNA was isolated from blood samples for methylation analysis using pyrosequencing. The mean 1-OHP level was 0.18 μg g(-1) creatinine (range 0.023-1.11), which was below the expected occupational exposure level. After adjusting for potential confounders, the 1-OHP urine concentration was negatively associated with DNA methylation of the interleukin 12 (β=-1.57; 95% CI: -2.9 to -0.23; p=0.02) and p53 gene promoters (β=-2.7; 95% CI: -5.46-0.06; p=0.055). Suggestive negative associations were also found for the TNF-α gene (β=-3.9; 95% CI:-8.28-0.48; p=0.08) and Alu sequences (β=-0.55; 95% CI:-1.25-0.16; p=0.12). Although the individual exposures to PAHs as estimated by urinary 1-OHP concentrations were low, changes in specific and global DNA methylation were observed.

Genotoxic and Hematological Effects in Children Exposed to a Chemical Mixture in a Petrochemical Area in Mexico

Children living in Coatzacoalcos, Veracruz, and in nearby surrounding areas are exposed to a mixture of pollutants from different sources. Previous studies in the area have reported genotoxic and haematotoxic compounds, such as lead (Pb), benzene, toluene, and polycyclic aromatic hydrocarbons (PAHs), in environmental and biological samples. The final toxic effects of these compounds are unknown because the toxic behaviour of each compound is modified when in a complex mixture. This is the first study on the exposure and effect of chemical mixtures on children who live near a petrochemical area. The aim of this study was to evaluate genotoxicity and haematological effects in children environmentally exposed to such mixtures and to determine whether the final effect was modified by the composition of the mixture composition. Biomarkers of exposure to Pb, benzene, toluene, and PAHs were quantified in urine and blood samples of 102 children. DNA damage was evaluated using comet assay, and haematological parameters were determined. Our results show that Pb and toluene did not surpass the exposure guidelines; the exposure was similar in all three localities (Allenede, Mundo Nuevo, and López Mateos). In contrast, exposure to PAHs was observed at three levels of exposure: low, medium, and high. The most severe effects of these mixtures were strictly related to coexposure to high levels of PAHs.

Diseño y aplicación de un Programa de Comunicación de Riesgos para la salud ambiental infantil en un sitio contaminado con plomo y arsénico

A metallurgical industry in San Luis Potosi city, Mexico, has contaminated the zone by lead (Pb) and arsenic (As). Since 1989 were reported by our group high concentrations of Pb in blood (PbB) and As in urine (AsU) in the local children. In present work, a Risk Communication Program (RCP) was generated to inform the children about the environmental risks of the site where they live, and to change conducts to diminish the exposure to Pb and As. We worked with 170 children (5 to 7 years) of the zone. The RCP was applied and the evaluation was realized by means of analysis of drawings, questionnaires and biological monitoring. In drawings of the children appeared toxic elements such as Pb, contaminated soil, cigarettes, among others. In the questionnaires applied to the children and family parents it was possible to estimate a change in the knowledge and in some conducts with regard to the pollutants, their effects and their exposure. There was not a decrease in the levels of PbB and in the levels of AsU. These were due probably because the principal route of exposure is not only the soil that had been contemplated previously.

Human health risks associated with heavy metals in soil in different areas of San Luis Potosí, México

ABSTRACT The aim of this study was to develop a health risk assessment in different areas of San Luis Potosí, México. Four heavy metals (arsenic, mercury, cadmium, and lead) were analyzed in soil from communities assessed. The mean arsenic concentration was significantly higher (p < .05) in the city of San Luis Potosí (51.85 mg/kg) compared to the other assessed areas (5.52–8.43 mg/kg). For cadmium, the mean concentration was significantly higher (p < .05) in Santa Maria Picula (7.46 mg/kg) than in the other areas (3.72–4.15 mg/kg). Regarding mercury levels, a significantly higher (p < .05) mean concentration was found in Mezquitic (1.54 mg/kg) compared to other areas (0.56–0.81 mg/kg). Lastly, when comparing the mean lead concentration in the city of San Luis Potosí (108 mg/kg), it was found to be significantly lower (p < .05) than in other areas (219–227 mg/kg). Subsequently, a probabilistic health risk assessment was performed, ingestion was the major exposure pathway for all four metals. Maximum cumulative hazard index (HI) values showed higher risk in all sampled locations (HIs > 1.0), suggesting that these sites can pose a non-carcinogenic risk to the populations (children) living in those areas. This study highlights the necessity of establishing a biomonitoring program for the surveillance of the child populations living in the assessed locations.

DNA methylation changes in Mexican children exposed to arsenic from two historic mining areas in San Luis potosí

Arsenic is a carcinogen and epimutagen that threatens the health of exposed populations worldwide. In this study, we examined the methylation status of Alu and long interspersed nucleotide elements (LINE‐1) and their association with levels of urinary arsenic in 84 Mexican children between 6 and 12 years old from two historic mining areas in the State of San Luis Potosí, Mexico. Urinary arsenic levels were determined by atomic absorption spectrophotometry and DNA methylation analysis was performed in peripheral blood leukocytes by bisulfite‐pyrosequencing. The geometric mean of urinary arsenic was 26.44 µg/g Cr (range 1.93–139.35). No significant differences in urinary arsenic or methylation patterns due to gender were observed. A positive correlation was found between urinary arsenic and the mean percentage of methylated cytosines in Alu sequences (Spearman correlation coefficient r = 0.532, P < 0.001), and a trend of LINE‐1 hypomethylation was also observed (Spearman correlation coefficient r = −0.232, P = 0.038) after adjustment for sex and age. A linear regression model showed an association with log‐normalized urinary arsenic for Alu (β = 1.05, 95% CI: 0.67; 1.43, P < 0.001) and LINE‐1 (β = −0.703, 95% CI: −1.36; −0.38, P = 0.038). Despite the low‐level arsenic exposure, a subtle epigenetic imbalance measured as DNA methylation was detected in the leukocytes of Mexican children living in two historic mining areas. Environ. Mol. Mutagen. 57:717–723, 2016.