Persistent Organic Pollutants and Heavy Metal Concentrations in Soil from the Metropolitan Area of Monterrey, Nuevo Leon, Mexico

Environmental and biological monitoring of organochlorine pesticides in the city of Salamanca, Mexico

The former Tekchem Industrial Unit located in the city of Salamanca, Mexico, constitutes an environmental liability in which the presence of high levels of organochlorine pesticides (OCPs) has been reported. In the present study, levels of OCPs were quantified using gas chromatography-mass spectrometry in 52 soil samples and in 88 blood samples from school-age children in the city of Salamanca. A median concentration of 70.6 ng/g (6.93-3299) was obtained for total OCPs in soil, while for the total sum of dichlorodiphenyltrichloroethane (DDT) the value was 49.6 ng/g (6.93-3276). In children, the median level of the total sum of OCPs was 390 ng/g lipid (7.34-14,895), and for the total sum of DDT was 175 ng/g lipid (< LOD-14,802). The OCPs that resulted in highest concentrations in soil were DDT and its metabolites, as well as aldrin and heptachlor epoxide, while in blood the highest levels corresponded to 4,4'-dichlorodiphenyltrichloroethane (4,4'-DDT) and its metabolites, followed by heptachlor and heptachlor epoxide. The spatial distribution of the concentrations of OCPs in soil shows that the facilities of Tekchem may be a significant potential source for the dispersion of these compounds toward the metropolitan area of Salamanca. The results obtained in the present study demonstrate the presence of OCPs in soil and in child population, providing important bases to study the problem from a broader perspective, while reiterating the importance of continuing efforts to generate resolute and precautionary measures with respect to the environmental liability of Tekchem.

Heavy metals and metalloids accumulation in common beans (Phaseolus vulgaris L.): A review

This review focuses on evaluating the accumulation and translocation of As, Cd, Hg, and Pb in Phaseolus vulgaris L. plants and on the possible effects of these elements on the growth of Phaseolus vulgaris L. in soil contaminated with these elements. Heavy metals (HMs) and metalloids (Ms) such as arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) represent serious environmental threats due to their wide abundance and high toxicity. HMs and Ms contamination in water and soils from natural or anthropogenic sources, is of great concern in agricultural production due to their toxic effects on plants, adversely affecting food safety and plant growth. The uptake of HMs and Ms by Phaseolus vulgaris L. plants depends on several factors including soil properties such as pH, phosphate, and organic matter. High concentrations of HMs and Ms could be toxic to plants due to the increased generation of ROS such as (O₂^•-), (^•OH), (H₂O₂), and (¹O₂) and oxidative stress due to an imbalance between ROS generation and antioxidant enzyme activity. To minimize the effects of ROS, plants have developed a complex defense mechanism based on the activity of antioxidant enzymes such as SOD, CAT, GPX, etc., and phytohormones, especially salicylic acid (SA) that can reduce the toxicity of HMs and Ms in the factors that affect the uptake of these elements by bean plants, and in addition, defense mechanisms under oxidative stress caused by the presence of As, Cd, Hg, and Pb.

Expression levels and network analysis of inflammamiRs in peripheral blood mononuclear cells exposed to DDE "in vitro"

Recent studies have demonstrated that dichlorodiphenyldichloroethylene (DDE) induced a pro-inflammatory condition in peripheral blood mononuclear cells (PBMC). However, the molecular mechanisms implicated in this condition are poorly understood. Therefore, this study aimed to evaluate miR-155, miR-126, and miR-21 expression levels in PBMC exposed "in vitro" to DDE. PBMC were dosed with increasing concentrations of DDE (10-80 µg mL^-1) at different treatment times (0-24 h). The results showed an up-regulation in the expression levels of assessed miRNAs (miR-155, miR-146, and miR-21) after PBMCs were exposed to DDE. Besides, bioinformatic analysis was performed to understand the biological roles of assessed miRNAs. The bioinformatic analysis shows that assessed miRNAs are associated with regulating signaling pathways involved in cancer, apoptosis, cell cycle, inflammation, metabolism, etc. These findings offer new insights into the molecular mechanisms related to the inflammatory processes and their regulation induced by DDE in PBMC exposed "in vitro".

Polybrominated diphenyl ethers in the environment: a wake-up call for concerted action in India

Polybrominated diphenyl ethers (PBDEs) are a class of persistent organic pollutants (POPs) used as flame retardants in the products utilized in day-to-day life. Their bioaccumulation, low volatility, and high persistence in the environment have led to their global spread even to remote and distant regions. The present study identifies gaps in the investigation of the neurotoxic potential of PBDEs, their effects on brain development, toxicokinetic, and their potential as a carcinogen. In India, to date, only human breast milk was assessed for levels of PBDEs, and it is suggested that other human tissues can also be explored. No data on the reproductive toxicity of PBDEs are reported from Indian cohorts. Long-range transport and deposition of PBDEs in colder regions necessitates monitoring of Himalayan regions in India. An inventory of PBDEs is required to be made for addressing the worrisome situation of the unregulated import of E-waste from the developed countries in India. The study also emphasizes providing guidelines for the articulation of policies regarding sound surveillance and management of PBDE production, consumption, and release in the Indian context. It is recommended that a separate cell for monitoring and follow-up of PBDEs should be established in India. Also, the development of better alternatives and environment-friendly remediation technologies for PBDEs is the need of the hour.

Composition and diversity of butterflies (Lepidoptera, Papilionoidea) along an atmospheric pollution gradient in the Monterrey Metropolitan Area, Mexico

This study compares the variation of richness, abundance and diversity of butterfly species along an atmospheric pollution gradient and during different seasons in the Monterrey Metropolitan Area, Mexico. Likewise, we analyse the influence of environmental variables on the abundance and richness of butterfly species and quantify the indicator species for each atmospheric pollution category. Based on spatial analysis of the main atmospheric pollutants and the vegetation cover conditions, four permanent sampling sites were delimited. The sampling was carried out monthly in each of the sites using aerial entomological nets and ten Van Someren-Rydon traps during May 2018 to April 2019. A total of 8,570 specimens belonging to six families and 209 species were collected. Both species richness and abundance were significantly different between all sites, except for the comparison between the moderate contamination site and the high contamination site; diversity decreased significantly with increasing levels of contamination. The seasonality effect was absent on species richness; however, for species abundance the differences between dry season and rainy season were significant in each site excepting the moderate contamination site. Regarding diversity, the seasonal effect showed different distribution patterns according to each order. Relative humidity, vegetation cover and three pollution variables were highly correlated with both abundance and species richness. From the total number of species found, only 47 had a significant indicator value. This study constitutes the first faunistic contribution of butterflies as indicators of the environmental quality of urban areas in Mexico, which will help in the development of strategies for the management, planning and conservation of urban biodiversity.

Polybrominated diphenyl ethers in soils from Tianjin, North China: distribution, health risk, and temporal trends

Available information is still insufficient for a comprehensive understanding of the global distribution of polybrominated diphenyl ethers (PBDEs) in the environment. In particular, little is known about the changing trend of their distribution in urban soils. We conducted a survey of 21 PBDEs in urban soils from Tianjin, China. The chemicals were widely present in the area and summed concentrations ranged from 0.65 to 108 ng/g in soil, indicating low to moderate levels of pollution relative to other areas. BDE-209 was the predominant congener, contributing 88.9% of the concentrations of total soil PBDEs. Source assessment indicated that soil PBDEs in the area were mainly derived from the release of commercial deca-BDE from local industrial production processes and consumer products. We found that the soil concentrations of PBDEs appear to have declined in recent years, compared with other previous reports in this region. However, more studies are needed on this possible change trend of PBDE pollution, especially its impact on human health, although their calculated non-carcinogenic health risks in this study were low.

Roles of mtDNA damage and disordered Ca2+ homeostasis in the joint toxicities of cadmium and BDE209

Cadmium, a typical heavy metal, causes serious toxicities on many organs and tissues. As the last partially controlled class of polybrominated diphenyl ethers (PBDEs), BDE209 can also induce various health issues. Although apoptosis mediated by mitochondria has been known to be a key player in inducing toxicities by cadmium, the detailed mechanisms are incompletely understood. Moreover, co-existence of cadmium and PBDEs has been found in various environment context and human body. However, studies on the joint toxicity of cadmium and PBDEs are still limited with largely unknown mechanisms. In the present study, we investigated the adverse effects and mechanisms of single or combined treatment of CdCl₂ and BDE209 on hepatocytes. We observed that apoptosis were significantly induced by CdCl₂, and the combined treatment of CdCl₂ and BDE209 greatly promoted the progression of apoptosis. BDE209 induced mild apoptosis. Mitochondria was the pivot of several mechanisms to induce apoptosis, including ROS production, decreased mitochondrial membrane potential (MMP), mtDNA damage and disordered calcium (Ca²⁺) homeostasis. However, we found that mtDNA damage and disordered Ca²⁺ homeostasis were the main mechanisms for CdCl₂-induced apoptosis while ROS production played important roles in BDE209-induced apoptosis. Less mtDNA damage occurred in BDE209-treated cells. In the cells with combined treatment, CdCl₂ and BDE209 exhibited a complementary pattern for the underlying mechanisms of apoptosis, leading to the joint toxicities, in which CdCl₂ showed more contributions. In a conclusion, our results demonstrated that combined exposure to cadmium and BDE209 causes joint adverse effects on hepatocytes through diverse mechanisms as mediated by mitochondria.

DNA damage in earthworms by exposure of Persistent Organic Pollutants in low basin of Coatzacoalcos River, Mexico

Persistent Organic Pollutants (POPs) are stable organic chemicals that represent a potential risk for ecosystems due to their high toxicity, persistence and biomagnification through food chains. Bioindicators in ecosystems have emerged to assess the effect of environmental pollutants. Earthworms are some of the most common bioindicator organisms in terrestrial ecosystems. The main objective of this study was to evaluate the geontoxicity of POP exposure in wild earthworms captured at different levels of urbanization throughout the lower basin of the Coatzacoalcos River (industrial, urban and rural areas). POP soil and earthworm tissue concentrations were measured via Gas-Mass Chromatography, and earthworm DNA damage was evaluated through the comet assay. The greatest concentrations of ΣPOPs, DDT and HCH were found in soil from industrial sites, followed by urban and rural areas (504.68, 383.10, 298.16; 22.6, 4.6, 2.6 and 433.7, 364, 255.6 mg/kg, respectively). Unlike other pollutants, mean ΣPCBs values were highest for industrial soil samples, followed by those from rural and urban areas (41.10, 33.97 and 12.44 mg/kg respectively). For all earthworm tissue POP analyses, the highest concentrations were found in individuals from industrial sites, followed by the urban and rural areas. Furthermore, the highest levels of DNA damage were registered in the industrial area, followed by the urban and rural areas. These assays suggest a strong links among regional soil contamination, POPs bioavailability and the potential risk of detrimental health effects for organisms that inhabit surface soil (soil life). Earthworms contribute vital ecosystem services that could be affected by these results. This work provides evidence of the potential ecological risk that exists in the Lower Basin of the Coatzacoalcos River.

Multi-component determination of atmospheric semi-volatile organic compounds in soils and vegetation from Tarragona County, Catalonia, Spain

Tarragona County (Spain) is home to the most important chemical/petrochemical industrial complex in Southern Europe, which raises concerns about the presence and effects of the numerous environmental contaminants. In order to assess the levels and patterns of five classes of semi-volatile organic compounds (SVOCs) - polycyclic aromatic hydrocarbons (PAHs), synthetic musks (SMs), polychlorinated biphenyls (PCBs), brominated flame retardants (BFRs) and one organochlorine pesticide, hexachlorobenzene (HCB), 27 samples of soil and vegetation (Piptatherum L.) from different areas (petrochemical, chemical, urban/residential, and background) of Tarragona County were analysed. The results show that PAHs levels in soils ranged from 45.12 to 158.00ng/g and the urban areas presented the highest concentrations, mainly associated with the presence of a nearby highway and several roads with heavy traffic. PAHs levels in vegetation samples ranged from 42.13 to 80.08ng/g, where the greatest influence came from the urban and petrochemical areas. In the case of SMs, levels in soils and vegetation samples ranged from 5.42 to 10.04ng/g and from 4.08 to 17.94ng/g, respectively, and in both cases, background areas (at least 30km away from the main SVOCs emission sources) showed the highest levels, suggesting an influence of the personal care products derived from beach-related tourism in the coast. PCBs (from 6.62 to 14.07ng/g in soils; from 0.52 to 4.41ng/g in vegetation) prevailed in the chemical area in both matrices, probably associated with the presence of two sub-electrical stations located in the vicinities. In general terms, BFRs and HCB values recorded in soil and vegetation samples were quite similar between matrices and sampling areas.

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

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).

In vitro study on the joint hepatoxicity upon combined exposure of cadmium and BDE-209

Joint toxicity is an important issue during the risk assessment of environmental pollutants. Contamination of heavy metals and persistent organic pollutants (POPs) under the environmental and biological settings poses substantial health risk to humans. Although previous studies demonstrated the co-occurrence of cadmium and decabrominated diphenyl ether (BDE-209) in environmental mediums, food chains and even human body, their potentially joint toxicities remain elusive thus far. Our investigation here with respect to the hepatotoxicity in vitro clearly demonstrated that combined exposure of cadmium and BDE-209 aggravated the injuries in hepatocytes, which was evidenced by the additive effects on the induction of remarkable morphological alternations, LDH release, cell apoptosis and necrosis, impairment of mitochondrial activity and transmembrane potential. Enhanced ROS production was one of the mechanisms for cell apoptosis and death upon joint treatment. Additionally, more cadmium-treated cells underwent apoptosis than BDE-209-treated cells while more ROS was generated with BDE-209 treatment, indicating that other mechanisms might be involved in cadmium-induced apoptosis. Our results would be helpful for evaluating the joint-hepatotoxicity upon combined exposure of cadmium and BDE-209 as well as investigating the underlying mechanisms.

Urinary trans-trans muconic acid (exposure biomarker to benzene) and hippuric acid (exposure biomarker to toluene) concentrations in Mexican women living in high-risk scenarios of air pollution

This study aimed to determine t,t-muconic acid (t,t-MA; exposure biomarker for benzene) and hippuric acid (HA; exposure biomarker for toluene) concentrations in the urine of women living in Mexico. In a cross-sectional study, apparently healthy women (n = 104) were voluntarily recruited from localities with a high risk of air pollution; t,t-MA and HA in urine were quantified using a high-performance liquid chromatography (HPLC) technique. Mean urinary levels of t,t-MA ranged from 680 to 1,310 μg/g creatinine. Mean values of HA ranged from 0.38 to 0.87 g/g creatinine. In conclusion, compared to data recently reported in literature, we found high urinary levels of t,t-MA and HA in assessed women participating in this study. We therefore deem the implementation of a strategy aimed at the reduction of exposure as a necessary measure for the evaluated communities.

Artificial neural networks to evaluate organic and inorganic contamination in agricultural soils

The assessment of organic and inorganic contaminants in agricultural soils is a difficult challenge due to the large-scale dimensions of the areas under investigation and the great number of samples needed for analysis. On-site screening techniques, such as Field Portable X-ray Fluorescence (FPXRF) spectrometry, can be used for inorganic compounds, such as heavy metals. This method is not destructive and allows a rapid qualitative characterization, identifying hot spots from where to collect soil samples for analysis by traditional laboratory techniques. Recently, fast methods such as immuno-assays for the determination of organic compounds, such as dioxins, furans and PCBs, have been employed, but several limitations compromise their performance. The aim of the present study was to find a method able to screen contaminants in agricultural soil, using FPXRF spectrometry for metals and a statistical procedure, such as the Artificial Neural Networks technique, to estimate unknown concentrations of organic compounds based on statistical relationships between the organic and inorganic pollutants.

Critical review of soil contamination by polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (NBFRs); concentrations, sources and congener profiles

Polybrominated diphenyl ethers (PBDEs) have been used in a broad array of polymeric materials such as plastics, foams, resins and adhesives to inhibit the spread of fires since the 1970s. The widespread environmental contamination and well documented toxic effects of PBDEs have led to bans and voluntary withdrawals in many jurisdictions. Replacement novel brominated flame retardants (NBFRs) have, however, exhibited many of the same toxic characteristics as PBDEs and appear to share similar environmental fate. This paper presents a critical review of the scientific literature regarding PBDE and NBFR contamination of surface soils internationally, with the secondary objective of identifying probable pollution sources. An evaluation of NBFR distribution in soil was also conducted to assess the suitability of the newer compounds as replacements for PBDEs, with respect to their land contamination potential. Principle production of PBDEs and NBFRs and their consequent use in secondary polymer manufacture appear to be processes with strong potential to contaminate surrounding soils. Evidence suggests that PBDEs and NBFRs are also released from flame retarded products during disposal via landfill, dumping, incineration and recycling. While the land application of sewage sludge represents another major pathway of soil contamination it is not considered in this review as it is extensively covered elsewhere. Both PBDEs and NBFRs were commonly detected at background locations including Antarctica and northern polar regions. PBDE congener profiles in soil were broadly representative of the major constituents in Penta-, Octa- and Deca-BDE commercial mixtures and related to predicted market place demand. BDE-209 dominated soil profiles, followed by BDE-99 and BDE-47. Although further research is required to gain baseline data on NBFRs in soil, the current state of scientific literature suggests that NBFRs pose a similar risk to land contamination as PBDEs.

Human Health Risks Assessment Associated with Polychlorinated Biphenyls (PCBs) in Soil from Different Contaminated Areas of Mexico

Recent studies have documented environmental contamination by PCBs in soil from different areas in Mexico (industrial, mining, and urban sites). However, the real significance of that soil contamination has not been established. Therefore, the aim of this study was to perform a human health risk assessment (Monte Carlos simulation) to evaluate the probable toxic effects of soils contaminated with PCBs on children in four sites in Mexico. A high non-carcinogenic risk (total nHQ = 1.1E+01; if nHQ ≥1, hazardous health effects cannot be ruled out) was found in Alpuyeca, Morelos, Mexico. Moreover, the total CR (cancer risk) found in Alpuyeca, Morelos is of concern (total CR = 5.1E-03), being that a cut-point of 1.0E-06 has been suggested as a safe level for cancer risk. Taking into consideration the data shown in this research, we conclude that a strategy to protect human health is necessary for the assessed sites.

Assessment of DDT and Metabolites in Soil and Sediment of Potentially Contaminated Areas of Belém, Amazon Region, Brazil

The aim of this study was to evaluate the distribution of DDT and metabolites in surface soils and soil profiles from two areas containing deposits of obsolete pesticides in Belém, Amazon Region, Brazil. DDT and metabolites were extracted by microwave assisted extraction and analyzed by gas chromatography with electron capture detection. Concentrations of total DDT in surface soil samples ranged from 64.22 mg kg^-1 in area 1 (A1) to 447.84 mg kg^-1 in area 2 (A2). Lower levels were found in soil profiles than at the surface (6.21-21.17 mg kg^-1 in A1 and 36.13-113.66 mg kg^-1 in A2). pp'-DDT, pp'-DDE and pp'-DDD were detected in sediments at levels of 2.01, 0.96 and 0.35 mg kg^-1, respectively. The ratio (DDE + DDD)/ΣDDT was low indicating the recent introduction of DDT to the environment in the two study areas, through the volatilization and atmospheric deposition of the obsolete pesticides.

Organochlorine pesticides in residential soils and sediments within two main agricultural areas of northwest Mexico: Concentrations, enantiomer compositions and potential sources

The agricultural Mexicali and Yaqui valleys (MV, YV) in northwest Mexico were heavily treated with organochlorine pesticides in the past. Residential soils and agricultural drain sediments were sampled in 2008-2009 and analyzed for DDTs (o,p'- and p,p'- isomers of DDE, DDD and DDT); hexachlorocyclohexanes (α-, β-, γ- and δ-HCH) and chlordanes (trans-chlordane, cis-chlordane, heptachlor and heptachlor exo-epoxide). Geometric means (GMs) (ng g^-1 dry weight) were: MV soils (n = 27) ΣDDT 22, ΣHCH 0.80, ΣCHL 0.88; YV soils (n = 25) ΣDDT 5.0, ΣHCH 0.23, ΣCHL 0.67; MV sediments (n = 3) ΣDDT 5.0, ΣHCH 0.23, ΣCHL 0.53; YV sediments (n = 8) ΣDDT 2.6, ΣHCH 0.12, ΣCHL 0.090. GMs were significantly higher (p < 0.05) in MV than YV soils for ΣDDT and ΣHCH, but not for ΣCHL. Comparison to worldwide regulatory guideline values (RGVs) for residential soils showed all compounds below mean or GM RGVs, but above the lowest RGV in some cases. Low p,p'-DDT/(p,p'-DDT + p,p'-DDE) in most soils indicated aged residues. Lack of p,p'-DDT metabolism might account for its dominance in a few soils. HCH isomer profiles suggested aged technical HCH in the YV, and technical HCH + lindane in the MV. Heptachlor dominated the ΣCHL, probably from application of technical heptachlor as well as chlordane. Chiral compounds were nonracemic in soils and sediments and indicated enantioselective microbial degradation of (+)α-HCH, (-)trans-chlordane, (-)cis-chlordane and (+)o,p'-DDT. Depletion of (+)o,p'-DDT in soils may account for similar enantiomer signatures previously reported in air of northwest Mexico.

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. © 2016 Wiley Periodicals, Inc.