Assessment of photo electro-Fenton and solar photo electro-Fenton processes for the efficient degradation of asulam herbicide.

The degradation of asulam herbicide by photo electro-Fenton (PEF) and solar photo electro-Fenton (SPEF) processes was studied using an undivided electrochemical BDD/carbon-felt cell to generate H2O2 continuously. A central composite design combined with response surface methodology was applied to determine the optimal operating conditions of current intensity = 0.30 A, [Fe2+] = 0.3 mM, and [Na2SO4] = 0.11 M at pH 3 to achieve the complete degradation of asulam by electro-Fenton. Subsequently, the SPEF process was more efficient treatment compared to PEF, achieving a complete degradation of asulam and 98% of mineralization in 180 min. Moreover, 4-aminobenzenesulfonamide, 4-aminophenol, and 4-benzoquinone were detected as aromatic intermediates, whereas acetic acid, oxalic acid, and NO3- ions were identified as final degradation by-products. Thus, the SPEF process is an efficient alternative for the complete degradation and mineralization of herbicide asulam in an aqueous solution under natural sunlight.

The situation of chlorpyrifos in Mexico: a case study in environmental samples and aquatic organisms.

Chlorpyrifos (CPF) is one of the most commonly used organophosphate pesticides. Because CPF was described as a toxic compound without safe levels of exposure for children, certain countries in Latin America and the European Union have banned or restricted its use; however, in Mexico it is used very frequently. The aim of this study was to describe the current situation of CPF in Mexico, as well as its use, commercialization, and presence in soil, water, and aquatic organisms in an agricultural region of Mexico. Structured questionnaires were applied to pesticide retailers to determine the sales pattern of CPF (ethyl and methyl); in addition, monthly censuses were conducted with empty pesticide containers to assess the CPF pattern of use. Furthermore, samples of soil (48 samples), water (51 samples), and fish (31 samples) were collected, which were analyzed chromatographically. Descriptive statistics were performed. The results indicate that CPF was one of the most sold (3.82%) and employed OP (14.74%) during 2021. Only one soil sample was found above the CPF limit of quantification (LOQ); in contrast, all water samples had CPF levels above the LOQ (x̄ = 4614.2 ng/L of CPF). In the case of fish samples, 6.45% demonstrated the presence of methyl-CPF. In conclusion, the information obtained in this study indicates the need for constant monitoring in the area, since the presence of CPF in soil, water, and fish constitutes a threat to the health of wildlife and humans. Therefore, CPF should be banned in Mexico to avoid a serious neurocognitive health problem.

Environmental Levels, Sources, and Cancer Risk Assessment of PAHs Associated with PM2.5 and TSP in Monterrey Metropolitan Area.

In this work, the content of polycyclic aromatic hydrocarbons (PAHs) in total suspended particles and particulate matter with an aerodynamic diameter ≤ 2.5 µm (PM2.5) was analyzed using gas chromatography-mass spectrometry. In addition, a sequential chemical analysis of C-rich particles was performed through the parallel coupling of micro-Raman spectroscopy and scanning electron microscopy with X-ray scattering detection. Samples were collected at four sites in the Monterrey metropolitan area, Mexico. A total of 13 PAHs were quantified; indeno(1,2,3-cd)pyrene, chrysene, and benzo(a)anthracene were the most abundant. The total PAH concentrations at the four sampling sites ranged from 1.34 to 8.76 µg/m3. The diagnostic relation of the PAHs indicates that these compounds were emitted by the burning of gasoline and diesel and by the burning of charcoal and biomass. The sequential analysis correlated the morphology and the elemental/molecular composition of the C-rich particles, associated with the PAHs, with their possible emission sources. The estimated lifetime excess cancer risk for inhalation was higher than that established by the World Health Organization, which clearly makes this a potential health risk for the population.

Pesticide residues in orange fruit from citrus orchards in Nuevo Leon State, Mexico.

Some international organisations established maximum residue limits (MRLs) in food to protect human health. Mexico lacks regulations in this matter, affecting national and international trade from agroindustry. The aim of this study was to diagnose pesticide residues in oranges from Nuevo Leon, México, in citrus orchards. In May 2014, 100 orange fruit samples were taken randomly from orchards and subjected to analysis for 93 pesticides at residual level by GC/QQQ-MS and LCQ-TOF-MS. Results showed the presence of 15 pesticide residues in the samples. The comparison of the residual levels of pesticides found in orange samples among the MRLs allowed by USA, EU and Japanese regulations demonstrated that all samples were below MRLs issued by USA and Japan. Some orange samples were above MRLs issued by the EU. This provides a basis to establish strategies in order to satisfy International Standards to protect human health and encourage Food Safety in Mexico.

Boron and Coumaphos Residues in Hive Materials Following Treatments for the Control of Aethina tumida Murray.

In the search of alternatives for controlling Aethina tumida Murray, we recently proposed the BAA trap which uses boric acid and an attractant which mimics the process of fermentation caused by Kodamaea ohmeri in the hive. This yeast is excreted in the feces of A. tumida causing the fermentation of pollen and honey of infested hives and releasing compounds that function as aggregation pheromones to A. tumida. Since the boron is the toxic element in boric acid, the aim of this article is to assess the amount of boron residues in honey and beeswax from hives treated with the BAA trap. For this aim, the amount of bioaccumulated boron in products of untreated hives was first determined and then compared with the amount of boron of products from hives treated with the BAA trap in two distinct climatic and soil conditions. The study was conducted in the cities of Padilla, Tamaulipas, and Valladolid, Yucatan (Mexico) from August 2014 to March 2015. The quantity of boron in honey was significantly less in Yucatan than in Tamaulipas; this agrees with the boron deficiency among Luvisol and Leptosol soils found in Yucatan compared to the Vertisol soil found in Tamaulipas. In fact, the honey from Yucatan has lower boron levels than those reported in the literature. The BAA treatment was applied for four months, results show that the BAA trap does not have any residual effect in either honey or wax; i.e., there is no significant difference in boron content before and after treatment. On the other hand, the organophosphate pesticide coumaphos was found in 100% of wax samples and in 64% of honey samples collected from Yucatan. The concentration of coumaphos in honey ranges from 0.005 to 0.040 mg/kg, which are below Maximum Residue Limit (MRL) allowed in the European Union (0.1 mg/kg) but 7.14% of samples exceeded the MRL allowed in Canada (0.02 mg/kg).

DDE and PCB 153 independently induce aryl hydrocarbon receptor (AhR) expression in peripheral blood mononuclear cells.

Recent studies have demonstrated that compounds inducing pro-inflammatory cytokines enhance AhR expression. The aim of this study was 2-fold: (1) to determine if two pro-inflammatory compounds, dichlorodiphenyldichloroethylene (DDE) and 2,2',4,4',5,5'-hexa-chlorobiphenyl (PCB 153), independently affect AhR gene expression in peripheral blood mononuclear cells (PBMC); and (2) if affected, to determine whether the mechanism involved was due to AhR activation or to a pro-inflammatory effect of the chemicals. PBMC isolated from healthy individuals were incubated in the presence of DDE (10 µg/ml) and PCB 153 (20 ng/ml) over time and AhR and CYP1A1 expression was assessed with a real-time PCR technique. The results indicated there was over-expression of the AhR mRNA in PBMC when the cells were treated with DDE and PCB 153. No changes in expression levels of CYP1A1 mRNA were found. Importantly, when the cells were exposed to DDE and PCB 153 in the presence of an antagonist of tumor necrosis factor (TNF)-α, the over-expression of AhR was abolished; as expected, the expression of CYP1A1 was unaffected. In conclusion, these studies demonstrated for the first time an increment of AhR expression "in vitro" in PBMC treated with two pro-inflammatory environmental pollutants, DDE and PCB153. Moreover, the over-expression of AhR was dependent of TNFα induced by DDE and PCB 153 and was independent of AhR activation.

DDT, DDE, and 1-hydroxypyrene levels in children (in blood and urine samples) from Chiapas and Oaxaca, Mexico.

The aim of this study was to evaluate the DDT, DDE, and 1-hydroxypyrene exposure levels of children living in communities located in southeastern Mexico. The study communities were Lacanja and Victoria in Chiapas state and Ventanilla in Oaxaca state. Children living in Lacanja had total blood DDT levels (mean ± SD, 29,039.6 ± 11,261.4 ng/g lipid) that were significantly higher than those of children in Victoria (10,220.5 ± 7,893.1 ng/g lipid) and Ventanilla (11,659.7 ± 6,683.7 ng/g lipid). With respect to the 1-hydroxypyrene levels in urine samples, the levels in Lacanja (4.8 ± 4.1 µg/L or 4.5 ± 3.9 µmol/mol creatinine) and Victoria (4.6 ± 3.8 µg/L or 3.9 ± 3.0 µmol/mol Cr) were significantly higher than levels found in Ventanilla (3.6 ± 1.4 µg/L or 2.5 ± 0.5 µmol/mol Cr). In conclusion, our data indicate high levels of exposure in children living in the communities studied in this work. The evidence found in this study could be further used as a trigger to revisit local policies on environmental exposures.

p,p'-DDE, a DDT metabolite, induces proinflammatory molecules in human peripheral blood mononuclear cells "in vitro".

In a recent study, our group demonstrated that when peripheral blood mononuclear cells (PBMCs) were treated "in vitro" with p,p'-DDE, a DDT metabolite, an antioxidant response and biomarkers of inflammation were induced at the mRNA level, indicating a proinflammatory state. Thus, the aim of this study was to evaluate the induction of proinflammatory molecules at the protein level in PBMCs exposed to p,p'-DDE "in vitro". The main finding was that "in vitro" exposure to p,p'-DDE enhanced the expression of proinflammatory cytokines (TNF-α, IL-1ß, IL-6) at the protein level in PBMCs. We also observed COX-2 induction at the protein level. Considering that p,p'-DDE has been identified as a persistent metabolite and is frequently found in the population, it is important to evaluate early inflammation biomarkers in populations exposed to DDT and to estimate the true risk of inflammatory disease development.

Antitumor and immunomodulatory effects of Justicia spicigera Schltdl (Acanthaceae).

ETHNOPHARMACOLOGICAL RELEVANCE: Medicinal plants are an important source of antitumor compounds. This study evaluated the acute toxicity in vitro and in vivo, as well as the cytotoxic, antitumor and immunomodulatory effects of ethanolic extracts of Justicia spicigera leaves (JSE). MATERIALS AND METHODS: The in vitro and in vivo toxicity of JSE was evaluated with comet assay in peripheral blood mononuclear cells (PBMC) and acute toxicity in mice, according to the Lorke procedure, respectively. The apoptotic effect of JSE on human cancer cells and human noncancerous cells was evaluated using flow cytometry with annexin-Alexa 488/propidium iodide. Also, different doses of JSE were injected intraperitoneally daily into athymic mice bearing tumors of HeLa cells during 18 days. The growth and weight of tumors were measured. The in vitro immunomodulatory effects of JSE were evaluated estimating the effects of JSE on the phagocytosis of the yeast Saccharomyces cerevisiae, NO production and H(2)O(2) release in macrophages, as well as the proliferation of splenocytes and NK activity. RESULTS: The comet assay showed that only JSE tested at 200 and 1000 µg/ml induced a significantly DNA damage in PBMC, compared to untreated cells, whereas the LD(50) was >5000 mg/kg by intraperitoneal route (i.p.) and by oral route. JSE showed pro-apoptotic (Annexin/PI) effects by 35% against HeLa cells, but lack toxic effects against human normal cells. JSE administrated at 10, 50 and 100 mg/kg i.p. inhibited the tumor growth by 28%, 41% and 53%, respectively, in mice bearing HeLa tumor. JSE stimulated, in a concentration dependent manner, the phagocytosis of Saccharomyces cerevisiae yeasts, the NO production and H(2)O(2) release by human differentiated macrophages. In addition, JSE stimulated the proliferation of murine splenocytes and induced the NK cell activity. CONCLUSION: Justicia spicigera shows low toxic effects in vitro and in vivo, exerts apoptotic effects on HeLa cells, has antitumor effects in mice bearing HeLa tumor and induces immunomodulatory activities in vitro.

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.

Variability in DDT-induced apoptosis in Mexican indigenous populations.

CONTEXT: In previous studies, we showed that DDT and its metabolites are able to induce apoptosis of peripheral blood mononuclear cells (PBMC) "in vitro" and "in vivo", by a mechanism involving oxidative stress. OBJECTIVE: The objective of this study was to evaluate the mechanism by which DDT induces apoptosis in PBMC in children exposed to DDT and its metabolites. MATERIALS AND METHODS: Eligibility criteria included children who: (1) have lived in the selected community since birth, (2) were between 6 and 14 years of age at the time of the study, (3) had not been exposed to medicaments or tobacco smoke, and (4) had had no infectious diseases in the month prior to the study. DDT and its metabolites were quantified using gas chromatography with an electron capture detector, PBMC apoptosis was measured using the TUNEL assay, DNA damage and oxidative damage were studied using the comet assay. RESULTS: Apoptosis correlated to DDE exposure (p=0.040), as previously found. DNA damage also correlated to DDT (p=0.005) and DDE (p=0.004) levels. However, neither exposure to DDT or DDE and oxidative damage, nor oxidative damage and apoptosis, were significantly correlated. Children living in Lacanja, Chiapas, one of the communities studied in this work, had the highest levels of exposure to DDT and its metabolites, yet had the lowest percentage of apoptosis. CONCLUSION: Resistance to DDE-induced apoptosis was found in children from one community. Further studies are needed in order to understand the mechanism involved in this apoptosis resistance.

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.