Sandra Teresa Orta-García

Concentrations of persistent organic pollutants (POPs) in human blood samples from Mexico City, Mexico.

Studies in Mexico have demonstrated exposure to persistent organic pollutants (POPs) in people living in different sites through the country. However, studies evaluating exposure to POPs in people living in Mexico City (one of most contaminated places in the world) are scarce. Therefore, the aim of this study was to assess the levels of polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and its metabolite dichlorodiphenyldichloroethylene (DDE) in the blood as exposure biomarkers in people living in Mexico City. A total of 123 participants (blood donors aged 20-60 years) were recruited during 2010 in Mexico City. Quantitative analyses of blood samples were performed using gas chromatography coupled with mass spectrometry. Levels of the assessed compounds ranged from non-detectable (<LOD) to 350 ng/g lipid; from 8.20 to 91.0 ng/g lipid and from <LOD to 34.0 ng/g lipid for total PBDEs, total PCBs and total DDT, respectively. The current study indicates POP exposure in the people assessed and highlights the need for further biomonitoring studies of these POPs in the region. In this regard, biomonitoring of toxins on a global scale may be the first step towards the prevention of toxin-induced illnesses in the population.

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

Abstract 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.

Analysis of cytotoxic effects of silver nanoclusters on human peripheral blood mononuclear cells 'in vitro'.

The antimicrobial properties of silver nanoparticles (AgNPs) have made these particles one of the most used nanomaterials in consumer products. Therefore, an understanding of the interactions (unwanted toxicity) between nanoparticles and human cells is of significant interest. The aim of this study was to assess the in vitro cytotoxicity effects of silver nanoclusters (AgNC, < 2 nm diameter) on peripheral blood mononuclear cells (PBMC). Using flow cytometry and comet assay methods, we demonstrate that exposure of PBMC to AgNC induced intracellular reactive oxygen species (ROS) generation, DNA damage and apoptosis at 3, 6 and 12 h, with a dose‐dependent response (0.1, 1, 3, 5 and 30 µg ml–1). Advanced electron microscopy imaging of complete and ultrathin‐sections of PBMC confirmed the cytotoxic effects and cell damage caused by AgNC. The present study showed that AgNC produced without coating agents induced significant cytotoxic effects on PBMC owing to their high aspect ratio and active surface area, even at much lower concentrations (<1 µg ml–1) than those applied in previous studies, resembling what would occur under real exposure conditions to nanosilver‐functionalized consumer products. Copyright

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.

DDT and DDE concentrations in the blood of Mexican children residing in the southeastern region of Mexico.

The aim of this study was to assess the levels of dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE) in the blood of children living in the southeastern region of Mexico. In this study, we found high levels of DDT and its principal metabolite (DDE) in the blood of children residing in the communities studied. The levels of total DDT found in our study ranged from 4,676.4 ng/g lipid to 64,245.2 ng/g lipid. All of the children in the study had detectable levels of DDT and/or DDE. In conclusion, our data indicate that children living within the study areas are exposed to high levels of DDT and DDE. Moreover, these results can be used as a trigger to revisit local policies on environmental exposures.

Effect of polychlorinated biphenyls 118 and 153 on Th1/Th2 cells differentiation

The objective of this study was evaluate the effect of coplanar polychlorinated biphenyls (PCB) 118-congener (PCB like-dioxin) and noncoplanar PCB 153-congener (PCB no like-dioxin) on differentiation of humans T-CD4+ lymphocytes into Th1 or Th2 subpopulations. Peripheral blood mononuclear cells (PBMC) were isolated from healthy volunteers (aged 25–30 years); T-CD4+ lymphocytes were separated from PBMC. Then, the differentiation of T-CD4+ cells into Th1 or Th2 subpopulation was performed and the intracellular cytokines analyses were assessed. No effect on IFNγ (produced by Th1 cells) production was observed when the cells were treated with both PCBs congeners. However, the PCB 118-congener induced an increase of IL-4-producing T-CD4 cells (produced by Th2 cells), PCB153 not exerted any effect on IL-4 production. The clinical significance of our data is uncertain, therefore, more studies are necessary in order to elucidate the effects generated in exposed human individual.

Polybrominated diphenyl ethers (PBDEs) concentration in soil from San Luis Potosi, Mexico: levels and ecological and human health risk characterization

The aim of this study was to assess the levels of polybrominated diphenyl ethers (PBDEs) in soils from the city of San Luis Potosi in Mexico and perform an ecological and human health risk characterization. In order to confirm the presence of PBDEs, outdoor surface soil samples were collected and the concentrations of PBDEs in urban, industrial, agricultural, and brick kiln industry areas were determined. The mean total PBDEs levels obtained in the study sites were 25.0 ± 39.5 μg/kg (geometric mean ± standard deviation) in the brick kiln industry zone; 34.5 ± 36.0 μg/kg in the urban zone; 8.00 ± 7.10 μg/kg in the industrial zone and 16.6 ± 15.3 μg/kg in the agricultural zone. The ecological and human health risk characterization showed relatively low-hazard quotient values. However, the moderately high PBDEs levels found in soils highlight the necessity to establish a systematic monitoring process for PBDEs in environmental and biological samples.

Association between Q192R paraoxonase 1 polymorphism and serumadipocyte-fatty acid binding protein (FABP4) levels in Mexican women

Abstract Aim: This study aimed to evaluate the genetic effects of PON1 Q192R polymorphism on serum FABP4 levels in Mexican women. Methods: PON1 Q192R polymorphism was genotyped using a TaqMan allelic discrimination assay and serum FABP4 concentration was measured using an enzyme-linked immunosorbent assay. Results: The distribution of genotype frequencies in the assessed women (PON1 Q192R polymorphism) was QQ = 20%, QR = 48% and RR = 32%. Significantly higher serum FABP4 levels were found in women with genotype QR/RR (20.6 ± 2.20 ng/mL), when compared with the levels found in the QQ group (12.8 ± 1.70 ng/mL) (p = .004). After, the odds ratio (OR) was calculated by binomial logistic regression analysis and a significantly higher OR was found in the QR/RR group when compared with the QQ group (OR = 3.45; 95% CI = 1.80–16.50; p < .05). Conclusion: The results support an association between 192R-allele of the PON1 polymorphism (Q192R) and increased serum FABP4 levels (suggested as an early biomarker of CVDs risk) in assessed Mexican women.

DDT and Its Metabolites in Mexico

DDT (dichlorodiphenyltrichloroethane) was first synthesized in 1874, and its insecticidal properties were discovered in 1939 by Paul Hermann Muller (Stapleton 1998). The U.S. military began using DDT extensively for mosquito control in 1944, particularly in the Pacific, where much of the action of World War II took place in highly malarious areas (Stapleton 1998). In 1955, the World Health Organization (WHO) started a global malaria control program with DDT; by 1958, 75 countries had joined and, at the peak of the campaign, 69,500 tons of pesticides mainly DDT [1,1,1-trichloro-2,2-bis(pchlorophenyl)ethane] were applied to 100 million dwellings each year (Wijeyaratne, 1993). For the control of malaria, houses were sprayed twice a year with DDT wettable powder to kill resting mature Anopheles mosquito. Later, the Stockholm Convention on Persistent Organic Pollutants, which came into force on 17 May 2004, outlawed the use of 12 chemicals including DDT (UNEP, 2004). However, one exemption clause allows malaria-endemic nations to use DDT, strictly for disease vector control. The United Nations Environment Program estimates that about 25 countries will use DDT under exemptions from the DDT pesticide ban (POPs, 2009). Thus, in regard to presence of DDT around the world can be divided into three scenarios: Sites where DDT is still in use; sites where the presence is due to DDT sprayed several years ago, and sites where the presence of DDT is the result of a long-range transport of the insecticide to areas where it was never used like the Antarctic. In Mesoamerica (Mexico, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua and Panama) DDT was used until the year 2000, Mexico and Nicaragua being the last nations that applied the insecticide in agriculture and for the control of malaria. Table 1 lists the period and the total amount of DDT used in each Mesoamerican country by the malaria control programs. The amount used (approximately 85,000 tons between 1946 and 1999) together with the high environmental persistence of DDT and its metabolites, provide the necessary conditions for DDT to become a contaminant of concern for this region of the world (ISAT, 2002). Taking into account the environmental persistence and the toxicity of DDT, a program for the control of malaria without using insecticides in Mesoamerica was developed between 2004 and 2007, with assistance from the Pan American Health Organization [PAHO; (Chanon et al., 2003; PAHO, 2008)]. The phase-out of DDT in Costa

Polybrominated diphenyl ethers (PBDEs) levels in blood samples from children living in the metropolitan area of Guadalajara, Jalisco, Mexico

Abstract The aim of this study was to perform a polybrominated diphenyl ethers (PBDEs) exposure assessment using blood samples collected from children living in the metropolitan area of Guadalajara, Jalisco, Mexico (GDL). Five congeners of PBDEs were analyzed using a gas chromatography/mass spectrometry technique. The blood concentrations of total PBDEs ranged from 5.50 to 169 ng/g lipid (42.0 ± 18.0 ng/g lipid; mean ± standard deviation). Regarding BDE congeners, the main congener (highest blood levels) was BDE99 (14.5 ± 5.50 ng/g lipid), followed by BDE100 (9.80 ± 3.40 ng/g lipid) and BDE154 (9.80 ± 5.90 ng/g lipid), and finally BDE153 (5.80 ± 2.30 ng/g lipid) and BDE47 (2.20 ± 1.20 ng/g lipid). In conclusion, blood PBDEs concentrations of concern were detected in this study, as blood levels were similar to the ones found in North America (the highest worldwide).