Iván N. Pérez-Maldonado

Assessment of DDT levels in selected environmental media and biological samples from Mexico and Central America.

Taking into account the environmental persistence and the toxicity of DDT, the Pan American Health Organization (PAHO) organized a surveillance program in Mesoamerica which included the detection of residual DDT in environmental (soil) and biological samples (fish tissue and childrens blood). This program was carried out in communities from Mexico, Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica and Panama. This paper presents the first report of that program. As expected, the results show that the levels for [summation operator] DDT in soil (outdoor or indoor) and fish samples in the majority of the locations studied are below guidelines. However, in some locations, we found children with high concentrations of DDT as in Mexico (mean level 50.2 ng/mL). Furthermore, in some communities and for some matrices, the DDT/DDE quotient is higher than one and this may reflect a recent DDT exposure. Therefore, more efforts are needed to avoid exposure and to prevent the reintroduction of DDT into the region. In this regard it is important to know that under the surveillance of PAHO and with the support of UNEP, a regional program in Mesoamerica for the collection and disposal of DDT and other POPs stockpiles is in progress.

Exposure assessment of polybrominated diphenyl ethers (PBDEs) in Mexican children.

Flame retardants (FRs) constitute a group of compounds that are added to materials in order to suppress, reduce, or delay fire. At present the most used FRs are the polybrominated diphenyl ethers (PBDEs), and diverse studies have found individuals exposed to them. However, few studies have reported data in children. The objective of this report was to assess PBDEs levels in children of six communities in México. During the year 2006 we analyzed a total of 173 healthy children (aged 6-13 years old). Plasma samples were taken and quantified (gas chromatography/mass spectrometer) for PBDEs. Six PBDEs congeners (BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, and BDE-209) were quantified in blood serum. We detected exposure to PBDEs in all the communities. The total PBDEs levels ranged from no detectable (nd) to 43.4 ng g(-1) lipid, the dominant PBDE congener was BDE-47, followed by BDE-100, BDE-99 and BDE-153, whereas the levels of BDE-209 were below LOD. Children living in an industrial and urban area (Cd. Juarez, Chih) had the highest levels of PBDEs, approximately two times that of children living in El Refugio, S.L.P. (a rural area) or in Milpillas, S.L.P. (municipal landfill) and 4-5 times higher than levels found in children living in San Luis Potosi, S.L.P. (urban area), in Chihuahua, Chih. (urban area), and San Juan Tilapa, Edo. Mex. (municipal landfills). Results cannot be generalized since the communities selected are not representative of the Mexican population. However, they do indicate that Mexican children are exposed to PBDEs.

Exposure to indoor air pollutants (polycyclic aromatic hydrocarbons, toluene, benzene) in Mexican indigenous women.

UNLABELLED Indoor air pollution is considered to be a serious public health issue in Mexico; therefore, more studies regarding this topic are necessary. In this context, we assessed exposure to polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds in: (i) women who use firewood combustion (indoor) for cooking and heating using traditional open fire; (ii) women who use firewood combustion (outdoor) for cooking and heating using traditional open fire; and (iii) women who use LP gas as the principal energy source. We studied 96 healthy women in San Luis Potosi, México. Urine samples were collected, and analyses of the following urinary exposure biomarkers were performed by high-performance liquid chromatography: 1-hydroxypyrene (1-OHP), trans, trans-muconic acid, and hippuric acid (HA). The highest levels of 1-OHP, trans, trans-muconic acid, and HA were found in communities where women were exposed to indoor biomass combustion smoke (or products; geometric mean ± s.d., 3.98 ± 5.10 μmol/mol creatinine; 4.81 ± 9.60 μg/l 1-OHP; 0.87 ± 1.78 mg/g creatinine for trans, trans-muconic acid; and 1.14 ± 0.91 g/g creatinine for HA). Our findings indicate higher exposure levels to all urinary exposure biomarkers studied in women who use indoor firewood combustion for cooking and heating (using traditional open fire). PRACTICAL IMPLICATIONS High mean levels of 1-hydroxypyrene, t,t-muconic acid, and hippuric acid were found in women who use firewood combustion (indoor) for cooking and heating using traditional open fire and taking into account that millions of women and children in Mexico are living in scenarios similar to those studied in this report, the assessment of health effects in women and children exposed to polycyclic aromatic hydrocarbons and volatile organic compounds is urgently needed. Moreover, it is immediately necessary an intervention program to reduce exposure.

Environmental Health Assessment of Deltamethrin in a Malarious Area of Mexico: Environmental Persistence, Toxicokinetics, and Genotoxicity in Exposed Children

We reported previously that children are exposed to deltamethrin in malarious areas. In the present work we explored the levels of this insecticide in soil samples and also obtained relevant toxico-kinetic data of deltamethrin in exposed children. Results show that, after spraying, indoor levels of deltamethrin in soil samples were higher than outdoor levels. The mean half-life estimated with these data was 15.5 days for outdoor samples and 15.4 days for indoor samples. Children’s exposure to deltamethrin was assessed using as biomarkers the urinary concentrations of the metabolites 3-phenoxybenzoic acid (3-PBA) and cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (Br2CA). The mean level of both biomarkers reached a peak within the first 24 hr postexposure; 6 months after the initial exposure, urinary levels of 3-PBA and Br2CA were found at levels observed before exposure. Approximately 91% of the total 3-PBA or Br2CA was excreted during the first 3 days after exposure. Therefore, we estimated a half-life for this period, the values for 3-PBA and Br2CA being almost identical (13.5 vs. 14.5 hr). Finally, considering reports about the genotoxicity of deltamethrin, we assessed DNA damage in children before and 24 hr after indoor spraying of deltamethrin; we found no differences in the comet assay end points. In conclusion, we observed exposure to deltamethrin in children, but we did not find any relationship between soil concentrations of deltamethrin and urinary levels of the metabolites. At least for genotoxicity, the exposed children appeared not to be at risk.

DNA damage in Mexican children living in high-risk contaminated scenarios

The aim of this study was to evaluate the deoxyribonucleic acid (DNA) damage (as a biomarker of biological effects) in children living in areas at high risk of contamination in Mexico using the comet assay. The alkaline comet assay was performed in order to assess DNA damage levels in blood cells of 276 children living in eleven communities in four states of Mexico. Moreover, levels of arsenic and 1-hydroxypyrene (1-OHP) in urine and lead and total DDT [sum of 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene (DDE) and 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT)] in blood were quantified. We found urinary 1-OHP levels between <LOD and 14.5 μmol/mol creatinine; for arsenic, the urinary levels were 3.5-180 μg/g creatinine (range). Lead levels in blood ranged from 0.5 to 24 μg/dL and finally, the levels of total DDT (DDE and DDT) ranged from <LOD to 32,000 ng/g lipid. Regarding DNA damage (comet assay), the most important finding in our study was that children exposed to a chemical mixture [high levels of exposure to polycyclic aromatic hydrocarbons (PAHs) and DDT were found] had the significant highest DNA damage level (p<0.05) in their blood cells (olive tail moment=7.5±3.5), when compared with DNA damage levels in children living in the other scenarios assessed in this work. Finally, significant correlations were observed between urinary arsenic levels (r=0.32, p<0.05); urinary 1-OHP levels (r=0.65, p<0.01); total DDT in blood levels (r=0.59, p<0.01) and DNA damage. In conclusion, the data indicates that children living in areas which are at high risk of contamination showed high levels of biomarkers of exposure in urine or blood. Moreover, the exposure levels contribute to DNA damage and suggest an increased health risk in studied sites at risk of great pollution.

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.

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.

Use of the Rey-Osterrieth Complex Figure Test for neurotoxicity evaluation of mixtures in children.

The aim of this study was to assess the value of the childrens version of the Rey-Osterrieth Complex Figure Test as a screening test in a population exposed to different mixtures of neurotoxicants. Copy and Immediate Recall scores were evaluated through the test. Children were recruited from three sites; an area with natural contamination by fluoride and arsenic (F-As), a mining-metallurgical area with lead and arsenic contamination (Pb-As) and a malaria zone with the evidence of fish contaminated with dichlorodiphenyltrichloroethane (DDT) and polychlorinated biphenyls (PCBs). Children aged 6-11 years old, living in one of the three polluted sites since birth were recruited (n=166). The exposure was evaluated as follows: fluoride and arsenic in urine, lead in blood and DDT, dichlorodiphenyldichloroethylene (DDE) and PCBs in serum. To evaluate the test performance, z-scores for Copy and Immediate Recall were calculated. The proportion of children by residence area with performance lower than expected by age (below -1 SD) for Copy and Immediate Recall was in the F-As area (88.7% and 59%) and in the DDT-PCBs area (73% and 43.8%), respectively. In the Pb-As area, the proportion was 62% for both tests. After adjustment, Copy correlated inversely with fluoride in urine (r=-0.29; p<0.001) and Immediate Recall correlated inversely with fluoride in urine (r=-0.27; p<0.05), lead in blood (r=-0.72; p<0.01), arsenic in urine (r=-0.63; p<0.05) and DDE (r=-0.25; p<0.05). This study provided evidence that children included in this research are living in high risk areas and were exposed to neurotoxicants. Poor performance in the test could be explained in some way by F, Pb, As or DDE exposure, however social factors or the low quality of school education prevalent in the areas could be playing an important role.

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.

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.