Exposure Assessment to Environmental Chemicals in Children from Ciudad Juarez, Chihuahua, Mexico

The development of rapid immunoassays for the urinary analysis of 1-hydroxypyrene glucuronide facilitate both laboratory and on-site polycyclic aromatic hydrocarbon biomonitoring

Polycylic Aromatic Hydrocarbons (PAHs) are produced during the incomplete burning of organic materials. PAH sources include vehicle exhaust, tobacco smoke and waste incineration. Environmental and occupational exposures to PAHs are known to occur. Cancer is a significant endpoint of PAH exposure and several occupations associated with high PAH exposure have been classified by IARC as carcinogenic to humans (Group 1). Pyrene is a common component of PAH mixtures and metabolism of pyrene leads to the excretion of 1-hydroxypyrene glucuronide (1-OHPyrG) in urine. Laboratory measurement of urinary 1-OHPyrG is employed in occupational and environmental biomonitoring programmes. The production of an anti-1-OHPyrG monoclonal antibody would allow the development of a PAH biomonitoring ELISA facilitating large scale laboratory screening and routine testing. The development of a lateral flow immunoassay and the production of a field test (point of use test) would greatly increase the value of biomonitoring. A novel Lateral Flow has been developed which employs an anti-1-OHPyrG sheep monoclonal antibody (Mab) to capture the PAH metabolite. The captured metabolite is visualised through a second Mab raised against the Mab-1-OHPyrG immune complex. This sandwich assay provides a positive correlation between the assay signal and biomarker concentration. A Smartphone camera allows signal measurement and a carefully considered 'app' provides result interpretation and data analysis. Results are provided in an exposed/not-exposed format. Performance of the lateral flow was confirmed through a comparative study and field trial. The development of a lateral flow test provides "real-time" analysis to occupational health professionals. On-site screening allows the immediate confirmation of safe working practice, provides immediate reassurance to those involved in potentially hazardous activities and greatly increases the efficacy of biomonitoring.

A comprehensive analysis of children's blood lead levels in Latin America and the Caribbean over the last eight years: Progress and recommendations

In 2017 we published a review on blood lead levels (BLL) in children from Latin America and the Caribbean (LAC) for data available up to 14th of March 2014 and recommended the identification and control of "lead hot spots". In the present study, an evaluation of progress toward reducing BLL in the region was carried out. A systematic review of the latest literature on lead exposure in the LAC region held on the PubMed, Web of Science and LILACS databases (January 2014 to March 2022) was conducted using the PRISMA methodology. Only original papers published in peer-reviewed English, Spanish, or Portuguese journals were eligible. A total of 558 papers were retrieved, 77 of which met the selection criteria and 31 (40.25 %) were carried out in Mexico. The prevalence of children with BLL above 10 μg. dL-1 was 22.08 % in the previous review versus 6.78 % in the current study. In the present review, the prevalence of children with BLL above 5 μg. dL-1 was 29.62 %, and only one study reported a BLL prevalence rate between 3.3 and 5 μg. dL-1. The highest BLLs were associated with well-known sources or occupational exposures. The number of countries (n = 13) that published data on BLL in children was lower compared to the previous review (n = 16). Most studies were conducted in areas with known lead exposure sources, similar to the earlier review. The percentage of children at risk of lead poisoning in the region remains unknown because few studies have published data on environmental exposure levels and most samples were relatively small. The recommendation to identify and control sources of lead exposure was maintained, while further suggestions for establishing a systematic public health surveillance system for lead were proposed to help reduce the knowledge gap and inform public health policy-making in LAC.

Biomarkers for polycyclic aromatic hydrocarbons in human excreta: recent advances in analytical techniques-a review

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental pollutants that are generated by the incomplete combustion of organic materials. The main anthropogenic sources of PAHs are the combustion of solid fuels for heating purposes, illegal waste incineration, road transport and industries based on fossil fuels. PAHs can easily enter the body because they are present in all elements of the environment, including water, soil, air, and food. Due to their ubiquitous presence, PAHs, may exert a harmful effect on human health. Assessing PAH exposure through biomonitoring mostly involve techniques to measure the concentration of 1-hydroxypyrene in human urine. Nevertheless, through recent progress in analytical techniques, other common metabolites of PAHs in human biospecimens can be detected. A scientific literature search was conducted to determine which hydroxy derivatives of PAHs are markers of PAHs exposure and to reveal the leading sources of these compounds. Techniques for analyzing biological samples to identify OH-PAHs are also discussed. The most frequently determined OH-PAH in human urine is 1-hydroxypyrene, the concentration of which reaches up to a dozen ng/L in urine. Apart from this compound, the most frequently determined biomarkers were naphthalene and fluorene metabolites. The highest concentrations of 1- and 2-hydroxynaphthalene, as well as 2-hydroxyfluorene, are associated with occupational exposure and reach approximately 30 ng/L in urine. High molecular weight PAH metabolites have been identified in only a few studies. To date, PAH metabolites in feces have been analyzed only in animal models for PAH exposure. The most frequently used analytical method is HPLC-FLD. However, compared to liquid chromatography, the LOD for gas chromatography methods is at least one order of magnitude lower. The hydroxy derivatives naphthalene and fluorene may also serve as indicators of PAH exposure.

The Influence of Environmental Polycyclic Aromatic Hydrocarbons (PAHs) Exposure on DNA Damage among School Children in Urban Traffic Area, Malaysia

This study aimed to investigate the association between particulate PAHs exposure and DNA damage in Malaysian schoolchildren in heavy traffic (HT) and low traffic (LT) areas. PAH samples at eight schools were collected using a low volume sampler for 24 h and quantified using Gas Chromatography-Mass Spectrometry. Two hundred and twenty-eight buccal cells of children were assessed for DNA damage using Comet Assay. Monte-Carlo simulation was performed to determine incremental lifetime cancer risk (ILCR) and to check the uncertainty and sensitivity of the estimated risk. Total PAH concentrations in the schools in HT area were higher than LT area ranging from 4.4 to 5.76 ng m^-3 and 1.36 to 3.79 ng m^-3, respectively. The source diagnostic ratio showed that PAHs in the HT area is pyrogenic, mainly from diesel emission. The 95th percentile of the ILCR for children in HT and LT area were 2.80 × 10^-7 and 1.43 × 10^-7, respectively. The degree of DNA damage was significantly more severe in children in the HT group compared to LT group. This study shows that total indoor PAH exposure was the most significant factor that influenced the DNA damage among children. Further investigation of the relationship between PAH exposure and genomic integrity in children is required to shed additional light on potential health risks.

The questionnaire design process in the European Human Biomonitoring Initiative (HBM4EU)

BACKGROUND

Designing questionnaires is a key point of epidemiological studies assessing human exposure to chemicals. The lack of validated questionnaires can lead to the use of previously developed and sub-optimally adapted questionnaires, which may result in information biases that affect the study's validity. On this ground, a multidisciplinary group of researchers developed a series of tools to support data collection within the HBM4EU initiative. The objective of this paper is to share the process of developing HBM4EU questionnaires, as well as to provide researchers with harmonized procedures that could help them to design future questionnaires to assess environmental exposures.

METHODS

In the frame of the work package on survey design and fieldwork of the HBM4EU, researchers carried out procedures necessary for the development of quality questionnaires and related data collection tools. These procedures consisted of a systematic search to identify questionnaires used in previous human biomonitoring (HBM) studies, as well as the development of a checklist and evaluation sheet to assess the questionnaires identified. The results of these evaluations were taken into consideration for the development of the final questionnaires.

RESULTS

The main points covered by each of the sections included in HBM4EU questionnaires are described and discussed in detail. Additional tools developed for data collection in the HBM4EU (e.g. non-responder questionnaire, satisfaction questionnaire, matrix-specific questionnaire) are also addressed. Special attention is paid to the limitations faced and hurdles overcome during the process of questionnaire development.

CONCLUSIONS

Designing questionnaires for use in HBM studies requires substantial effort by a multidisciplinary team to guarantee that the quality of the information collected meets the study's objectives. The process of questionnaire development described herein will contribute to improve the harmonization of HBM studies within the social and environmental context of the EU countries.

A Systematic Review of Studies on Genotoxicity and Related Biomarkers in Populations Exposed to Pesticides in Mexico

In agricultural activities, pest control is essential, and the most effective method is the use of chemical agents that also represent an important source of exposure to potentially toxic compounds. Pesticides constitute a heterogeneous group of compounds designed specifically to control different pests. Besides measuring their levels or that of their metabolites in air, plasma, serum, blood, urine, etc., some studies reported increased DNA damage levels after occupational or environmental pesticides exposure, evidenced by several cytogenetic biomarkers such as chromosomal aberrations (CA), sister chromatid exchanges (SCE), micronuclei frequency (MN) together with other nuclear abnormalities (NA), alkaline comet assay, but also changes in oxidative stress parameters and miRNA levels. Single or combined, these techniques have also been used in genotoxic biomonitoring studies of workers occupationally exposed to pesticides in Mexico. Despite being a country with great agricultural activity and reported excessive pesticide use, genotoxic studies have been relatively few and, in some cases, contradictory. A review was made of the studies available (published until the end of 2020 on PubMed, Web of Science, Redalyc and Scielo, both in English and Spanish) in the scientific literature that evaluated occupational exposure of human samples to pesticides assessed with DNA damage and related biomarkers in Mexico.

A review on the analytical procedures of halogenated flame retardants by gas chromatography coupled with single quadrupole mass spectrometry and their levels in human samples

Halogenated flame retardants (HFRs) market is continuously evolving and have moved from the extensive use of polybrominated diphenyl ether (PBDE) to more recent introduced mixtures such as Firemaster 550, Firemaster 680, DP-25, DP-35, and DP-515. These substitutes are mainly composed of non-PBDEs HFRs such as 2-ethyl-hexyl tetrabromobenzoate (TBB), bis(2-ethylhexyl) tetrabromophthalate (TBPH), 1,2-bis-(2,4,6-tribromophenoxy) ethane (BTBPE) and decabromodiphenyl ethane (DBDPE). Other HFRs commonly being monitored include Dechlorane Plus (DP), Dechlorane 602 (Dec602), Dechlorane 603 (Dec603), Dechlorane 604 (Dec604), 5,6-dibromo-1,10, 11, 12,13,13-hexachloro- 11-tricyclo[8.2.1.02,9]tridecane (HCDBCO) and 4,5,6,7-tetrabromo-1,1,3-trimethyl-3-(2,3,4,5-tetrabromophenyl)-2,3-dihydro-1H-indene (OBTMPI). This review aims at highlighting the advances in the past decade (2010-2020) on both the analytical procedures of HFRs in human bio-specimens using gas chromatography coupled with single quadrupole mass spectrometry and synthesizing the information on the levels of these HFRs in human samples. Human specimen included in this review are blood, milk, stool/meconium, hair and nail. The review summarizes the analytical methods, including extraction and clean-up techniques, used for measuring HFRs in biological samples, which are largely adopted from those for analysing PBDEs. In addition, new challenges in the analysis to include both PBDEs and a wide range of other HFRs are also discussed in this review. Review of the levels of HFRs in human samples shows that PBDEs are still the most predominant HFRs in many cases, followed by DP. However, emerging HFRs are also being detected in human despite of the fact that both their detection frequencies and levels are lower than PBDEs and DP. It is clearly demonstrated in this review that people working in the industry or living close to the industrial areas have higher HFR levels in their bodies.

Effect of gene-environment interaction (arsenic exposure - PON1 Q192R polymorphism) on cardiovascular disease biomarkers in Mexican population

Cardiovascular diseases (CVDs) are the primary cause of death worldwide. However, little is known about how the interaction between risk factors affects CVDs. Therefore, the aim of this study was to evaluate the effect of the gene-environment interaction (arsenic exposure x PON1 Q192R polymorphism) on serum levels of CVDs biomarkers in Mexican women. Urinary arsenic levels (UAs) ranged from 5.50-145 μg/g creatinine. The allele frequency was 0.38 and 0.62 for the Q and R alleles, respectively. Moreover, significant associations (p<0.05) were detected between UAs and CVDs biomarkers (ADMA, FABP4, and miR-155). Comparable data were found when CVDs biomarkers were evaluated through PON1 genotype, significant (p<0.05) higher serum concentrations of CVDs biomarkers were identified in R allele carriers compared to levels found in Q allele carriers. Besides, a gene-environment interaction was documented. The results of this study we believe should be of significant interest to regulatory authorities worldwide.

Spatial and temporal distribution of p,p'-DDE (1‑dichloro‑2,2‑bis (p‑chlorophenyl) ethylene) blood levels across the globe. A systematic review and meta-analysis

BACKGROUND

Although p,p'‑DDT (1,1,1‑trichloro-2,2‑bis (p‑chlorophenyl)‑ethane) has been banned for decades in most countries, its major metabolite p,p'-DDE (1‑dichloro‑2,2‑bis (p‑chlorophenyl) ethylene) is still detected in the vast majority of human blood samples.

OBJECTIVES

The purpose of this study was to quantitatively estimate the geographical distribution of DDE blood levels and record time-trends for specific countries and continents, exploiting available data from the scientific literature.

METHODS

A literature search was performed in SCOPUS and PUBMED databases. Studies were screened at 2 levels applying different sets of inclusion/exclusion criteria. Blood levels of DDE along with other variables of interest were extracted, and a meta-analysis of random effects was conducted, by using the package metafor within the statistical programming language R. Results were expressed as pooled geometric means (GM [95% confidence intervals, CIs]).

RESULTS

A total of 418 papers were included in the quantitative synthesis that contained data for 854 population subgroups, and analyzed a total of 195,595 samples. Overall global DDE concentrations dropped from 5207 (95% CI: 3616-7499) ng/g lipids during 1951-1969 to 207 (95% CI: 159-269) ng/g lipids for studies reporting sampling after 2000. Analyses for studies published from 2001 and onward revealed geographical differences regarding DDE burden.

DISCUSSION

The significant decline in DDE blood levels after its restriction is demonstrated in our results. Differences in decrease trends were observed in different parts of the globe, which can be explained by deferred implementation of environmental policies. In some countries DDE concentrations remain high, and systematic biomonitoring is proposed.

Internal exposure levels of polycyclic aromatic hydrocarbons in children and adolescents: a systematic review and meta-analysis

Polycyclic aromatic hydrocarbons (PAHs) are widely found in the environment, and comparing to adults, children are more vulnerable to PAHs exposure. Urinary metabolites of PAHs are used as preferred biomarkers to estimate the PAHs exposure. Systematic review on the internal exposure level of children and adolescents is rare. We aimed to calculate the internal exposure levels of PAHs in children and adolescents and compare the levels of PAHs internal exposure in various children groups. We searched PubMed, OVID, Web of Science, EBSCO, ACS, and four Chinese databases, and all studies examining the urinary concentrations of PAHs in children and adolescent were identified. The total exposure level of 11 PAHs metabolites were pooled. Standard mean difference (SMD) and 95% confidence intervals (CIs) of PAHs urinary concentration were calculated and pooled by RevMan5.3 to compare the exposure levels of different children groups. We found that 1-OHPyr, 2-OHNap, 2-OHFlu, 3-OHPhe, and 4-OHPhe were five PAHs metabolites most commonly studied in existing studies in children, and their total exposure levels were 0.38 ± 0.98, 2.32 ± 4.83, 0.81 ± 1.54, 0.09 ± 0.14, 0.03 ± 0.10 μmol/mol creatinine, respectively. The meta-analysis showed that the levels of 1-OHPyr were higher in higher environmental exposure group (SMD = 0.21, 95% CI = 0.03~0.40), ETS exposure group (SMD = 0.31, 95% CI = 0.08~0.54), and 6~11 years group (SMD = 0.16, 95% CI = 0.09~0.24); the level of 2-OHNap (SMD = 0.27, 95% CI = 0.01~0.53) was higher in higher environmental exposure group; however, the levels of 3-OHPhe (SMD = - 0.34, 95% CI = - 0.57~- 0.12) and 4-OHPhe (SMD = - 0.48, 95% CI = - 0.69~- 0.28) were higher in lower environmental exposure group. The levels of 1-OHPyr (SMD = - 0.01, 95% CI = - 0.11~0.10) and 2-OHNap (SMD = 0.01, 95% CI = - 0.20~0.22) were not statistically different between boys and girls. In conclusions, we found that the internal diversity of PAHs existed in children and adolescents, and the level of 1-OHPyr in children and adolescents was in higher status compared with non-occupational people who do not smoke.

Collaborative response to arsenic-contaminated soil in an Appalachian Kentucky neighborhood

The aim of this study was to identify factors associated with an increased exposure to arsenic-contaminated soil in a Kentucky neighborhood as part of collaborative public health response. An exposure assessment survey was administered to residents and toenail clippings and soil samples analyzed for arsenic concentration. The associations between exposure variables and arsenic concentrations were evaluated using a multivariate-generalized estimating equation. An ecological assessment of cancer incidence in the community was also conducted using standardized incidence ratio maps. Median toenail arsenic was 0.48 micrograms/gram (µg/g), twice the expected regional level of 0.2 µg/g. Mean residence surface soil arsenic level was 64.8 ppm. An increase of 1 ppm of residence concentration was significantly associated with a 0.003 µg/g rise in toenail levels. Concentrations for respondents who engaged in digging were 0.68 µg/g significantly higher compared to individuals who did not. No significantly elevated rates of lung or bladder cancer were observed in the affected ZIP codes. Living in areas with high soil arsenic contamination might lead to (1) increased exposure; (2) elevated residence soil arsenic concentrations and (3) the action of digging in the soil was associated with elevated toenail arsenic levels. Based upon elevated soil levels identified, residents were recommended to move from the contaminated environment until remediation was complete. Additional recommendations included regular health-care follow-up.

Urinary levels of 1-hydroxypyrene and health risk assessment in children living in Mexican communities with a high risk of contamination by polycyclic aromatic hydrocarbons (PAHs)

Health complications have been associated with polycyclic aromatic hydrocarbons (PAHs) exposure, a widespread environmental pollutants family. Therefore, the objective of this investigation was to develop a probabilistic health risk evaluation (using Monte-Carlo simulation) in an infantile population living in areas with a high risk of pollution by PAHs (indoor wood combustion, brick kiln industry, municipal landfill, and low and high vehicular traffic) in Mexico. Urine samples were obtained from Mexican children (n = 135) and urinary 1-OHP concentrations (used as a PAHs biomarker) were quantified. Highest urinary 1-OHP concentrations were detected in children living in areas that use wood combustion as the principal indoor fuel (3.50 ± 0.95 µg/L). Nevertheless, estimated hazard quotients (HQ) lower than 1 were found in all assessed sites after Monte-Carlo analysis. Although HQ <1.0 (a toxic effect is not expected), more data are necessary to determine the real impact of PAHs exposure on children health status.

Impact of arsenic exposure on clinical biomarkers indicative of cardiovascular disease risk in Mexican women

An appropriate and precise identification of high-risk individuals to develop cardiovascular diseases (CVD) is of high importance to reduce these kinds of diseases, a major health concern worldwide. Therefore, the aim of this research was to evaluate prognostic CVD biomarkers in Mexican women exposed to inorganic arsenic via drinking water. Then, a cross-sectional study including 190 women was achieved. Urinary arsenic (UAs) levels were analyzed as exposure biomarker to that metalloid. While, plasma asymmetric dimethylarginine (ADMA), adipocyte fatty acid-binding protein (FABP4), adiponectin, and chemerin levels, hypertriglyceridemic waist (HW) phenotype, atherogenic index of plasma (AIP), and Framingham risk score (FRS) were assessed as prognostic CVD biomarkers. Mean UAs level detected in the evaluated urinary samples was 45.0 ± 40.0 μg/g creatinine. In addition, mean plasma ADMA, FABP4, chemerin and adiponectin levels were 0.68 µmol/L, 20.3 ng/mL, 12.5 μg/mL, and 255 ng/mL, correspondingly. Approximately, 54% of women participants displayed an HW phenotype. Regarding AIP and FRS values, 0.12 ± 0.15 and 7.50 ± 8.00 were found, respectively. Besides, strong and significant associations (p < 0.05) between UAs and AIP, ADMA, and FABP4 were distinguished. Also, after a multivariate analysis, the association between those variables persisted after adjustment for traditional risk factors of CVD. In conclusion, according to the results found in this research, the most sensible CVD biomarkers distinguished in this study were AIP, ADMA, and FABP4. Nevertheless, more studies are necessary to confirm the results found in this investigation.

Children environmental exposure to particulate matter and polycyclic aromatic hydrocarbons and biomonitoring in school environments: A review on indoor and outdoor exposure levels, major sources and health impacts

Children, an important vulnerable group, spend most of their time at schools (up to 10 h per day, mostly indoors) and the respective air quality may significantly impact on children health. Thus, this work reviews the published studies on children biomonitoring and environmental exposure to particulate matter (PM) and polycyclic aromatic hydrocarbons (PAHs) at school microenvironments (indoors and outdoors), major sources and potential health risks. A total of 28, 35, and 31% of the studies reported levels that exceeded the international outdoor ambient air guidelines for PM₁₀, PM_2.5, and benzo(a)pyrene, respectively. Indoor and outdoor concentrations of PM₁₀ at European schools, the most characterized continent, ranged between 7.5 and 229 μg/m³ and 21-166 μg/m³, respectively; levels of PM_2.5 varied between 4 and 100 μg/m³ indoors and 6.1-115 μg/m³ outdoors. Despite scarce information in some geographical regions (America, Oceania and Africa), the collected data clearly show that Asian children are exposed to the highest concentrations of PM and PAHs at school environments, which were associated with increased carcinogenic risks and with the highest values of urinary total monohydroxyl PAH metabolites (PAH biomarkers of exposure). Additionally, children attending schools in polluted urban and industrial areas are exposed to higher levels of PM and PAHs with increased concentrations of urinary PAH metabolites in comparison with children from rural areas. Strong evidences demonstrated associations between environmental exposure to PM and PAHs with several health outcomes, including increased risk of asthma, pulmonary infections, skin diseases, and allergies. Nevertheless, there is a scientific gap on studies that include the characterization of PM fine fraction and the levels of PAHs in the total air (particulate and gas phases) of indoor and outdoor air of school environments and the associated risks for the health of children. There is a clear need to improve indoor air quality in schools and to establish international guidelines for exposure limits in these environments.

Health Risk Assessment and Urinary Excretion of Children Exposed to Arsenic through Drinking Water and Soils in Sonora, Mexico

Environmental arsenic exposure is associated with increased risk of non-cancerous chronic diseases and a variety of cancers in humans. The aims of this study were to carry out for the first time a health risk assessment for two common arsenic exposure routes (drinking water and soil ingestion) in children living in the most important agricultural areas in the Yaqui and Mayo valleys in Sonora, Mexico. Drinking water sampling was conducted in the wells of 57 towns. A cross-sectional study was done in 306 children from 13 villages in the valleys. First morning void urine samples were analyzed for inorganic arsenic (InAs) and monomethyl and dimethyl arsenic (MMA and DMA) by HPLC/ICP-MS. The results showed a wide range of arsenic levels in drinking water between 2.7 and 98.7 μg As/L. Arsenic levels in agricultural and backyard soils were in the range of < 10-27 mg As/kg. The hazard index (HI) = ∑hazard quotient (HQ) for drinking water, agricultural soil, and backyard soil showed values > 1 in 100% of the study towns, and the carcinogenic risk (CR) was greater than 1E-04 in 85%. The average of arsenic excreted in urine was 31.7 μg As/L, and DMA had the highest proportion in urine, with averages of 77.8%, followed by InAs and MMA with 11.4 and 10.9%, respectively, percentages similar to those reported in the literature. Additionally, positive correlations between urinary arsenic levels and HI values were found (r = 0.59, P = 0.000). These results indicated that this population is at high risk of developing chronic diseases including cancer.

Urinary biomarkers of polycyclic aromatic hydrocarbons in pre- and peri-pubertal girls in Northern California: Predictors of exposure and temporal variability

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs), a class of chemicals produced as combustion by-products, have been associated with endocrine disruption. To understand exposure in children, who have been less studied than adults, we examined PAH metabolite concentrations by demographic characteristics, potential sources of exposure, and variability over time, in a cohort study of pre- and peri-pubertal girls in Northern California.

METHODS

Urinary concentrations of ten PAH metabolites and cotinine were quantified in 431 girls age 6-8 years at baseline. Characteristics obtained from parental interview, physical exam, and linked traffic data were examined as predictors of PAH metabolite concentrations using multivariable linear regression. A subset of girls (n = 100) had repeat measures of PAH metabolites in the second and fourth years of the study. We calculated the intraclass correlation coefficient (ICC), Spearman correlation coefficients, and how well the quartile ranking by a single measurement represented the four-year average PAH biomarker concentration.

RESULTS

Eight PAH metabolites were detected in ≥ 95% of the girls. The most consistent predictors of PAH biomarker concentrations were cotinine concentration, grilled food consumption, and region of residence, with some variation by demographics and season. After adjustment, select PAH metabolite concentrations were higher for Hispanic and Asian girls, and lower among black girls; 2-naphthol concentrations were higher in girls from lower income households. Other than 1-naphthol, there was modest reproducibility over time (ICCs between 0.18 and 0.49) and the concentration from a single spot sample was able to reliably rank exposure into quartiles consistent with the multi-year average.

CONCLUSIONS

These results confirm diet and environmental tobacco smoke exposure as the main sources of PAHs. Controlling for these sources, differences in concentrations still existed by race for specific PAH metabolites and by income for 2-naphthol. The modest temporal variability implies adequate exposure assignment using concentrations from a single sample to define a multi-year exposure timeframe for epidemiologic exposure-response studies.

Potential Co-exposure to Arsenic and Fluoride and Biomonitoring Equivalents for Mexican Children

BACKGROUND

Mexico is included in the list of countries with concurrent arsenic and fluoride contamination in drinking water. Most of the studies have been carried out in the adult population and very few in the child population. Urinary arsenic and urinary fluoride levels have been accepted as good biomarkers of exposure dose. The Biomonitoring Equivalents (BE) values are useful tools for health assessment using human biomonitoring data in relation to the exposure guidance values, but BE information for children is limited.

METHODS

We conducted a systematic review of the reported levels of arsenic and fluoride in drinking water, urinary quantification of speciated arsenic (inorganic arsenic and its methylated metabolites), and urinary fluoride levels in child populations. For BE values, urinary arsenic and fluoride concentrations reported in Mexican child populations were revised discussing the influence of factors such as diet, use of dental products, sex, and metabolism.

RESULTS

Approximately 0.5 and 6 million Mexican children up to 14 years of age drink water with arsenic levels over 10 μg/L and fluoride over 1.5 mg/L, respectively. Moreover, 40% of localities with arsenic levels higher than 10 μg/L also present concurrent fluoride exposure higher than 1.5 mgF/L. BE values based in urinary arsenic of 15 μg/L and urinary fluoride of 1.2 mg/L for the environmentally exposed child population are suggested.

CONCLUSIONS

An actual risk map of Mexican children exposed to high levels of arsenic, fluoride, and both arsenic and fluoride in drinking water was generated. Mexican normativity for maximum contaminant level for arsenic and fluoride in drinking water should be adjusted and enforced to preserve health. BE should be used in child populations to investigate exposure.

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).

Serum Concentrations of New Predictive Cardiovascular Disease Biomarkers in Mexican Women Exposed to Lead

The purpose of this study was to evaluate lead exposure and its relationship with serum levels of predictive CVD biomarkers [asymmetric dimethylarginine (ADMA), adipocyte fatty acid-binding protein (FABP4), adiponectin, and chemerin] in women living in San Luis Potosi, Mexico. A mean blood lead level (BLL) of 11.5 ± 9.00 μg/dL (mean ± standard deviation) was found after all blood samples were analyzed. Regarding serum predictive CVD biomarkers, mean serum level of 0.68 ± 0.38 μmol/L, 20.5 ± 16.5 ng/mL, 12.5 ± 3.30 μg/mL, and 255 ± 130 ng/mL were found for ADMA, FABP4, adiponectin, and chemerin, respectively. Simple significant associations (Pearson´s correlations) between BLL and ADMA (r = 0.17; p = 0.04) and FABP4 (r = 0.23; p = 0.03) were found. Furthermore, a multivariate linear regression model showed that BLL was a significant predictor of serum ADMA (β = 0.06; p = 0.001) and FABP4 (β = 1.75; p = 0.0004) concentrations after adjusting by confounders. For serum chemerin and adiponectin levels, no associations were found with BLL. In conclusion, high serum ADMA and FABP4 (predictive CVD biomarkers) levels were found in women exposed to lead. Consequently, this research can be used as a point of departure for the prevention of CVD events in populations living in sites environmentally impacted with lead.

Evaluation of epigenetic alterations (mir-126 and mir-155 expression levels) in Mexican children exposed to inorganic arsenic via drinking water

Recently, a great number of epidemiological studies have shown evidence that exposure to inorganic arsenic could have harmful effects on the cardiovascular system of humans. However, the underlying mechanisms through which arsenic induces cardiovascular toxic effects remain unclear. In this regard, epigenetic mechanisms have emerged as a probable connection between environment and disease phenotypes, including cardiovascular diseases. Therefore, this study aimed to evaluate epigenetic changes related to cardiotoxicity (miR-126 and miR-155 expression levels) in children from San Luis Potosi, Mexico exposed to inorganic arsenic. From 2014 to 2015, in a cross-sectional study, children (aged 6-12 years; n = 73) attending public schools at the studied sites were enrolled to take part in this study. Urinary arsenic was used as an exposure biomarker and analyzed by an atomic absorption spectrophotometry technique. On the other hand, miR-126 and miR-155 expression levels were evaluated by qRT-PCR. A mean urinary arsenic level of 30.5 ± 25.5 μg/g of creatinine was found. Moreover, the data showed a significant negative association (p < 0.05) between urinary arsenic concentrations and plasma miR-126 levels. However, an association between urinary arsenic concentrations and plasma miR-155 levels was not found (p > 0.05). In this regard, some investigations have shown an association between diminished plasma miR-126 levels and cardiovascular illnesses. The results found in this study are of concern. However, more similar studies including a larger sample size are necessary in order to clarify the real significance of the data.

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.

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.

Mercury in Children: Current State on Exposure through Human Biomonitoring Studies

Mercury (Hg) in children has multiple exposure sources and the toxicity of Hg compounds depends on exposure routes, dose, timing of exposure, and developmental stage (be it prenatal or postnatal). Over the last decades, Hg was widely recognized as a threat to the children’s health and there have been acknowledgements at the international level of the need of a global policy intervention—like the Minamata treaty—aimed at reducing or preventing Hg exposure and protecting the child health. National human biomonitoring (HBM) data has demonstrated that low levels of exposure of Hg are still an important health concern for children, which no one country can solve alone. Although independent HBM surveys have provided the basis for the achievements of exposure mitigation in specific contexts, a new paradigm for a coordinated global monitoring of children’s exposure, aimed at a reliable decision-making tool at global level is yet a great challenge for the next future. The objective of the present review is to describe current HBM studies on Hg exposure in children, taking into account the potential pathways of Hg exposure and the actual Hg exposure levels assessed by different biomarkers.

Assessment of exposure to polycyclic aromatic hydrocarbons in preschool children: Levels and impact of preschool indoor air on excretion of main urinary monohydroxyl metabolites

The present work aimed to assess exposure of preschool children to polycyclic aromatic hydrocarbons (PAHs) by environmental monitoring (eighteen compounds in air) and biomonitoring (six urinary biomarkers of exposure (OH-PAHs)). The impact of preschool indoor air on excretion of urinary monohydroxyl metabolites was also evaluated. Gaseous and particulate-bound PAHs were simultaneously collected indoors and outdoors in two Portuguese preschools. PAHs and OH-PAHs were quantified by high-performance liquid chromatography with fluorescence and photodiode array detection. Total air (gaseous+total suspended particles) levels of PAHs (ΣPAHs) were higher indoors than outdoors. Gaseous phase (composed by ≥98% of 2-3 rings compounds) and particulate-bound PAHs (90-99% of 5-6 rings) accounted for 93-95% and 5-7% of ΣPAHs in indoor air, respectively. Total (including probable/possible) carcinogenic PAHs represented 26-45% of ΣPAHs; naphthalene and dibenz[a,h]anthracene were the strongest contributors. A similar distribution profile was observed between airborne PAHs and urinary OH-PAHs. Urinary 1-hydroxynaphthalene+1-hydroxyacenaphthene represented more than 78% of ΣOH-PAHs, being followed by 2-hydroxyfluorene, 1-hydroxypyrene, and 1-hydroxyphenanthrene. 3-hydroxybenzo[a]pyrene (PAH biomarker of carcinogenicity) was not detected. Results suggest that children had preschool indoor air as their major exposure source of naphthalene and acenaphthene, while no conclusion was reached regarding fluorene, phenanthrene and pyrene.

Environmental exposure and effects on health of children from a tobacco-producing region

Children may be environmentally exposed to several hazards. In order to evaluate the health of children living in a tobacco-producing region, different biomarkers of exposure and effect, as well as hematological parameters, were evaluated. Biomarkers of exposure to the following xenobiotics were assessed: pesticides, nicotine, toxic elements, and organic solvents. Oxidative damage markers malondialdehyde (MDA) and protein carbonyls (PCO), vitamin C, microalbuminuria (mALB) levels, and N-acetyl-β-D-glucosaminidase (NAG) activity were also evaluated. Peripheral blood samples and urine were collected from 40 children (6-12 years), at two different crop periods: in the beginning of pesticide applications (period 1) and in the leaf harvest (period 2). The Wilcoxon signed-rank test for paired data was used to evaluate the differences between both periods. Biomarkers of exposure cotinine in urine and blood chromium (Cr) levels were increased in period 1 when compared to period 2. Moreover, a significant reduced plasmatic activity of butyrylcholinesterase (BuChE) was observed in period 2 in relation to period 1. Blood Cr levels were above the recommended by WHO in both evaluations. The biomarkers MDA and PCO as well as the kidney dysfunction biomarker, mALB, presented levels significantly increased in period 1. Additionally, decreased lymphocytes and increased basophils were also observed. Cotinine was positively associated with PCO, and Cr was positively associated with PCO and MDA. The increased Cr levels were associated with decreased lymphocytes and increased basophils. Our findings demonstrate that children environmentally exposed to xenobiotics in rural area may present early kidney dysfunction, hematological alterations, as well as lipid and protein damages, associated with co-exposure to different xenobiotics involved in tobacco cultivation.

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.

Plasma asymmetric dimethylarginine (ADMA) levels in Mexican women exposed to polycyclic aromatic hydrocarbons (PAHs): A preliminary study

Recent studies indicate that exposure to environmental pollutants (as polycyclic aromatic hydrocarbons) is a very important risk factor for development of cardiovascular diseases (CVDs). Correspondingly, in recent times asymmetric dimethylarginine (ADMA) has been proposed as a new and meaningful biomarker predictor for the risk of CVDs. Therefore, the objective of this study was to evaluate plasma ADMA concentrations in Mexican women (n=155) exposed to polycyclic aromatic hydrocarbons (PAHs). Urinary 1-hydroxypyrene [(1-OHP), exposure biomarker for PAHs] levels were quantified using a high performance liquid chromatography (HPLC) technique and plasma ADMA concentrations were analyzed using a commercially available ELISA kit. Urinary 1-OHP levels in all women assessed ranged from <LOD to 8.80μmol/mol creatinine. Regarding plasma ADMA concentrations, the mean levels ranged from 0.66 to 1.00μmol/L. Moreover, a significantly relationship was found between plasma ADMA concentrations and urinary 1-OHP levels (p=0.005; r=0.390). In conclusion, the results showed in this study demonstrated that the urinary 1-OHP levels were significant predictors of plasma ADMA concentrations in Mexican women exposed to PAHs. Although with due caution regarding the low representativeness of the present screening, it can be considered as a preliminary work to perform prospective studies including greater number of individuals and focusing in a more complete characterization of the effects produced by PAHs exposure on cardiovascular health.