1
|
Bharatiya M, Austin C, Arora M, Feeney RNM, Leonard ND, Low-Choy S, Paul B, Soficaru AD, Zhao JX, Smith TM. Tracking Childhood Lead Exposure in Early Industrial Romanians. CHEMOSPHERE 2024; 364:142947. [PMID: 39067821 DOI: 10.1016/j.chemosphere.2024.142947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2024] [Revised: 07/08/2024] [Accepted: 07/24/2024] [Indexed: 07/30/2024]
Abstract
Childhood lead exposure has been linked to severe adverse health outcomes throughout life. Measurements of lead in teeth have established that individuals living in contaminated environments show higher levels compared to individuals living further away, although less is known about when individuals are most susceptible to these exposures. We examined lead (Pb208) concentrations (ppm) in teeth over the first 2.5 years of life in 16 children born in the late 19th to early 20th century throughout Romania. This period of intense industrialization was characterized by increases in mining, coal burning, and oil refining-activities that contaminate air, water, and food with Pb. We hypothesized the distance from an operational mine or oil refinery, or being born in a city, would be positively associated with cumulative dentine Pb exposure (CDPE). We also predicted that Pb exposures would peak in the first six months of life when gastrointestinal (GI) absorption of Pb is likely highest. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) of sectioned tooth dentine followed by Bayesian statistical analyses revealed that living 30 km or more from a mine or oil refinery did not explain CDPE. However, being born in a city explained 42% of CDPE. All individuals showed maximum Pb exposures after six months of age, likely due to contaminated solid food and/or non-milk liquids. This research demonstrates how tooth formation can be coupled with comprehensive elemental mapping to analyse the context and timing of early-life neurotoxicant exposures, which may be extended to well-preserved teeth from clinical and historic populations.
Collapse
Affiliation(s)
- Maya Bharatiya
- Griffith Centre for Social and Cultural Research, Griffith University, Queensland, Australia; Australian Research Centre for Human Evolution, Griffith University, Queensland, Australia.
| | - Christine Austin
- Department of Environmental Medicine and Climate Science, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Manish Arora
- Department of Environmental Medicine and Climate Science, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Robin N M Feeney
- UCD School of Medicine, University College Dublin, Dublin, Ireland
| | - Nicole D Leonard
- Radiogenic Isotope Facility, School of the Environment, The University of Queensland, Queensland, Australia
| | - Samantha Low-Choy
- Griffith Institute of Educational Research, Griffith University, Queensland, Australia; Centre of Planetary Health and Food Security, Griffith University, Nathan, Queensland, Australia
| | - Bence Paul
- School of Geography, Earth and Atmospheric Sciences, University of Melbourne, Victoria, Australia; Elemental Scientific Lasers, LLC., Montana, USA
| | - Andrei D Soficaru
- "Francisc I. Rainer" Institute of Anthropology, Romanian Academy, Bucharest, Romania
| | - Jian-Xin Zhao
- Radiogenic Isotope Facility, School of the Environment, The University of Queensland, Queensland, Australia
| | - Tanya M Smith
- Griffith Centre for Social and Cultural Research, Griffith University, Queensland, Australia; Australian Research Centre for Human Evolution, Griffith University, Queensland, Australia
| |
Collapse
|
2
|
Specht AJ, Adesina KE, Read DE, Weisskopf MG. Benchtop x-ray fluorescence to quantify elemental content in nails non-destructively. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 918:170601. [PMID: 38309346 PMCID: PMC10923075 DOI: 10.1016/j.scitotenv.2024.170601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 01/29/2024] [Accepted: 01/29/2024] [Indexed: 02/05/2024]
Abstract
Metals continue to impose health issues among world populations. A non-invasive alternative biomarker for assessment of metals and other elements has been explored in other studies using toenail samples. Some benefits of using toenails as biomarkers over blood samples include cost efficiency, ease of collection, and a longer biological half-life within samples. The objective of this study was to employ desktop XRF for the purpose of measuring metal concentrations in human nail samples, thus conducting a non-destructive assessment. These benefits paired with comparable accuracy in exposure detection could prove toenail samples to be a preferred biomarker for many studies. Current elemental quantification techniques in toenail samples could be improved. The standard practice for measuring metal exposure in toenails, inductively coupled plasma mass spectrometry (ICP-MS), has a counterpart in x-ray fluorescence. While maintaining similar quantification capabilities, x-ray fluorescence could provide decreased cost, preservation of samples, and ease of operation. Portable XRF machines have been tested for measuring toenail samples, but they have drastically increased detection limits in comparison to ICP-MS. New benchtop XRF systems should give comparable detection limits to ICP-MS. This study compares the benchtop XRF measurements of lead (Pb), copper (Cu), iron (Fe), and Selenium (Se) levels to that of ICP-MS measurements of toenail samples and calculates estimated detection limits for 23 other elements. We found strong correlations for the toenail lead (R2 = 0.92), copper (R2 = 0.95), selenium (R2 = 0.60), and iron (R2 = 0.77) comparison between desktop XRF and ICP-MS measurements. Median minimum detection limits over the 23 elements were found to be 0.2 μg/g using a 7.5-min measurement. Benchtop XRF provides a lower detection limit than previously studied portable XRF machines, which gives it the capability of accurately detecting almost any desired element in nail samples. Benchtop XRF provides a non-destructive alternative to ICP-MS in surveillance of nail samples.
Collapse
Affiliation(s)
- Aaron J Specht
- School of Health Sciences, Purdue University, West Lafayette, IN 47906, United States of America; Harvard T.H. Chan School of Public Health, Boston, MA 02115, United States of America.
| | - Kolawole E Adesina
- School of Health Sciences, Purdue University, West Lafayette, IN 47906, United States of America
| | - Daniel E Read
- School of Health Sciences, Purdue University, West Lafayette, IN 47906, United States of America
| | - Marc G Weisskopf
- Harvard T.H. Chan School of Public Health, Boston, MA 02115, United States of America
| |
Collapse
|
3
|
Validity of Geolocation and Distance to Exposure Sources from Geographical Information Systems for Environmental Monitoring of Toxic Metal Exposures Based on Correlation with Biological Samples: a Systematic Review. Curr Environ Health Rep 2022; 9:735-757. [PMID: 36447111 DOI: 10.1007/s40572-022-00383-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/05/2022] [Indexed: 12/05/2022]
Abstract
PURPOSE OF REVIEW In epidemiologic studies, biomarkers are the best possible choice to assess individual exposure to toxic metals since they integrate all exposure sources. However, measuring biomarkers is not always feasible, given potential budgetary and time constraints or limited availability of samples. Alternatively, approximations to individual metal exposure obtained from geographic information systems (GIS) have become popular to evaluate diverse metal-related health outcomes. Our objective was to conduct a systematic review of epidemiological studies that evaluated the validity of GIS-based geolocation and distance to pollutant sources as an approximation of individual metal exposure based on correlation with biological samples. RECENT FINDINGS We considered 11 toxic metals: lead (Pb), cadmium (Cd), antimony (Sb), aluminum (Al), arsenic (As), chromium (Cr), nickel (Ni), mercury (Hg), tungsten (W), uranium (U), and vanadium (V). The final review included 12 manuscripts which included seven metals (Pb, Cd, Al, As, Cr, Hg, and Ni). Many studies used geolocation of the individuals to compare exposed (industrial, urban, agricultural, or landfill sources) and unexposed areas and not so many studies used distance to a source. For all metals, except lead, there was more animal than human biosampling to conduct biological validation. We observed a trend towards higher levels of Cd, Cr, Hg, and Pb in biosamples collected closer to exposure sources, supporting that GIS-based proxies for these metals might approximate individual exposure. However, given the low number and heterogeneity of the retrieved studies, the accumulated evidence is, overall, not sufficient. Given the practical benefits and potential of modern GIS technologies, which allow environmental monitoring at a reasonable cost, additional validation studies that include human biosampling are needed to support the use of GIS-based individual exposure measures in epidemiologic studies.
Collapse
|
4
|
Egan KB, Dignam T, Brown MJ, Bayleyegn T, Blanton C. Using Small Area Prevalence Survey Methods to Conduct Blood Lead Assessments among Children. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19106151. [PMID: 35627688 PMCID: PMC9141915 DOI: 10.3390/ijerph19106151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 05/10/2022] [Accepted: 05/12/2022] [Indexed: 12/04/2022]
Abstract
Introduction: Prevalence surveys conducted in geographically small areas such as towns, zip codes, neighborhoods or census tracts are a valuable tool for estimating the extent to which environmental risks contribute to children’s blood lead levels (BLLs). Population-based, cross-sectional small area prevalence surveys assessing BLLs can be used to establish a baseline lead exposure prevalence for a specific geographic region. Materials and Methods: The required statistical methods, biological and environmental sampling, supportive data, and fieldwork considerations necessary for public health organizations to rapidly conduct child blood lead prevalence surveys at low cost using small area, cluster sampling methodology are described. Results: Comprehensive small area prevalence surveys include partner identification, background data collection, review of the assessment area, resource availability determinations, sample size calculations, obtaining the consent of survey participants, survey administration, blood lead analysis, environmental sampling, educational outreach, follow-up and referral, data entry/analysis, and report production. Discussion: Survey results can be used to estimate the geographic distribution of elevated BLLs and to investigate inequitable lead exposures and risk factors of interest. Conclusions: Public health officials who wish to assess child and household-level blood lead data can quickly apply the data collection methodologies using this standardized protocol here to target resources and obtain assistance with these complex procedures. The standardized methods allow for comparisons across geographic areas and over time.
Collapse
Affiliation(s)
- Kathryn B. Egan
- Division of Environmental Health Science and Practice, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA;
- Office of Community Health and Hazard Assessment, Agency for Toxic Substances and Disease Registry, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA
- Correspondence: ; Tel.: +404-718-5778
| | - Timothy Dignam
- Office of the Director, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA;
| | - Mary Jean Brown
- Department of Social and Behavioral Sciences, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA;
| | - Tesfaye Bayleyegn
- Division of Environmental Health Science and Practice, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA;
| | - Curtis Blanton
- Division of Global Health Protection, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA;
| |
Collapse
|
5
|
Brown MJ, Patel P, Nash E, Dikid T, Blanton C, Forsyth JE, Fontaine R, Sharma P, Keith J, Babu B, Vaisakh TP, Azarudeen MJ, Riram B, Shrivastava A. Prevalence of elevated blood lead levels and risk factors among children living in Patna, Bihar, India 2020. PLOS GLOBAL PUBLIC HEALTH 2022; 2:e0000743. [PMID: 36962532 PMCID: PMC10021519 DOI: 10.1371/journal.pgph.0000743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 08/15/2022] [Indexed: 03/26/2023]
Abstract
Childhood lead exposure remains a key health concern for officials worldwide, contributing some 600,000 new cases of intellectually disabled children annually. Most children affected by high exposure to lead live in low- and middle-income countries. The leaded gasoline phase out in India was completed in 2000. Yet, in 2020, an estimated 275 million children aged 0 to 9 years had blood lead levels (BLLs) ≥ 5 μg/dL known to adversely affect intelligence and behavior. Lead sources reported in India include spices, cookware, paint, traditional medicines and cosmetics, and lead-acid battery recycling and repair. However, their relative contribution has not been characterized. More than 200 lead pollution sites related to battery recycling and repair activities were identified in Bihar and Jharkhand, India. Ninety percent of the recycling sites had soil lead concentrations exceeding the US Environmental Protection Agency's standards. We compared blood and environmental lead levels in two groups of children in Patna, Bihar. Households in proximity to battery recycling operations (Proximal n = 67) versus households distal to these operations (Distal n = 68). The average age of children was 40 months; 46% were female. Overall, the geometric mean (GM) BLL was 11.6 μg/dL. GM BLLs of children in Proximal and Distal households were not significantly different (10.2 μg/dL vs. 13.1 μg/dL respectively; p≤0.07). About 87% children, 56 Proximal and 62 Distal had BLLs ≥5 μg/dl. Lead concentrations in environmental samples were significantly higher in Proximal households (soil mean 9.8 vs. 1.6 μg/ft2; dust mean 52.9 vs. 29.9 μg/ft2 p<0.001; Proximal vs. Distal respectively) whereas concentrations in all spices were higher in Distal households (mean 46.8 vs 134.5 ppm p<0.001; Proximal vs. Distal respectively), and turmeric (mean 59.4 vs. 216.9 ppm Proximal vs. Distal respectively). In multivariate analyses for all children lead in spices and turmeric and number of rooms in the house were significant while for the Proximal group only lead in spices remained in the model. The predictive value of these models was poor. For the Distal group, a model with lead concentration in spices, turmeric and soil and number of rooms in the house was a much better fit. Of the 34 water samples collected, 7 were above the Indian standard of 10 ppb for lead in drinking water (2 in the Proximal area, 5 in the Distal area). Children in Patna, Bihar, India are exposed to multiple sources of lead, with lead levels in house dust and loose, locally sourced spices the most likely to increase blood lead levels. A holistic approach to blood lead testing and source identification and remediation are necessary to prevent lead exposure.
Collapse
Affiliation(s)
- M J Brown
- Department of Social and Behavioral Sciences, Harvard Chan School of Public Health, Boston, Massachusetts, United States of America
| | - P Patel
- National Center for Disease Control India, New Delhi, India
| | - E Nash
- Pure Earth, New York, New York, United States of America
| | - T Dikid
- National Center for Disease Control India, New Delhi, India
| | - C Blanton
- Division of Global Health Protection, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - J E Forsyth
- Stanford Woods Institute for the Environment, Stanford University, Stanford, California, United States of America
| | - R Fontaine
- Division of Global Health Protection, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - P Sharma
- Pure Earth, New York, New York, United States of America
| | - J Keith
- Pure Earth, New York, New York, United States of America
| | - B Babu
- National Center for Disease Control India, New Delhi, India
| | - T P Vaisakh
- National Center for Disease Control India, New Delhi, India
| | - M J Azarudeen
- National Center for Disease Control India, New Delhi, India
| | - B Riram
- National Center for Disease Control India, New Delhi, India
| | - A Shrivastava
- National Center for Disease Control India, New Delhi, India
| |
Collapse
|
6
|
Wu Z, Chen Y, Han Y, Ke T, Liu Y. Identifying the influencing factors controlling the spatial variation of heavy metals in suburban soil using spatial regression models. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 717:137212. [PMID: 32062284 DOI: 10.1016/j.scitotenv.2020.137212] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 01/29/2020] [Accepted: 02/07/2020] [Indexed: 05/16/2023]
Abstract
Determining the factors that control the spatial variation of heavy metals in suburban soil is important in identifying and preventing pollution sources. Soil intrinsic factors combined with environmental variables can effectively explain the spatial distribution of heavy metals. Compared with classical statistical methods, such as multiple linear regression (MLR) models, spatial regression models that can cope with the spatial dependence of heavy metals have greater potential in establishing an accurate relationship between influencing factors and heavy metals. This study aims to identify the factors that influence the spatial variation of lead (Pb) and cadmium (Cd) in 138 topsoil samples from the suburbs of Wuhan City, China, by using spatial regression models with MLR as the reference. Moran's I values reveal the spatial autocorrelation of Pb and Cd. The spatial lag model (SLM) outperforms MLR and has higher R2 and lower spatial dependence of residuals. The significant coefficients of the spatial lag term in SLMs indicate that the spatial variation of Pb and Cd depends on their surrounding observations. SLM results show that Pb content depends on the distance from the nearest industrial enterprises and suggest that industrial pollution is the main source of Pb. Cd content depends on pH, soil organic matter, and the topographic wetness index, indicating that intrinsic and topographical factors contribute to the spatial variation of Cd. Parent materials and application of phosphorus fertilizer are the most likely sources of Cd. The findings highlight the spatial autocorrelation of heavy metals and the effects of intrinsic factors and environmental variables on the spatial variation of such metals. Moreover, this study reveals the effectiveness of spatial regression models in identifying the influencing factors of heavy metals.
Collapse
Affiliation(s)
- Zihao Wu
- School of Resource and Environmental Science, Wuhan University, Wuhan 430079, China
| | - Yiyun Chen
- School of Resource and Environmental Science, Wuhan University, Wuhan 430079, China; Collaborative Innovation Center of Geospatial Technology, Wuhan University, Wuhan 430079, China; Key Laboratory of Geographic Information System of Ministry of Education, Wuhan University, Wuhan 430079, China
| | - Yiran Han
- School of Resource and Environmental Science, Wuhan University, Wuhan 430079, China
| | - Tan Ke
- School of Resource and Environmental Science, Wuhan University, Wuhan 430079, China
| | - Yaolin Liu
- School of Resource and Environmental Science, Wuhan University, Wuhan 430079, China; Collaborative Innovation Center of Geospatial Technology, Wuhan University, Wuhan 430079, China; Key Laboratory of Geographic Information System of Ministry of Education, Wuhan University, Wuhan 430079, China.
| |
Collapse
|
7
|
Early-life Pb exposure as a potential risk factor for Alzheimer’s disease: are there hazards for the Mexican population? J Biol Inorg Chem 2019; 24:1285-1303. [DOI: 10.1007/s00775-019-01739-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 10/25/2019] [Indexed: 12/30/2022]
|
8
|
Ashrap P, Sánchez BN, Téllez-Rojo MM, Basu N, Tamayo-Ortiz M, Peterson KE, Meeker JD, Watkins DJ. In utero and peripubertal metals exposure in relation to reproductive hormones and sexual maturation and progression among girls in Mexico City. ENVIRONMENTAL RESEARCH 2019; 177:108630. [PMID: 31421446 PMCID: PMC6734930 DOI: 10.1016/j.envres.2019.108630] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Revised: 07/23/2019] [Accepted: 08/04/2019] [Indexed: 05/08/2023]
Abstract
There is increasing evidence that several metals are endocrine disrupting chemicals (EDCs). In utero development and adolescence are critical windows of susceptibility to EDC exposure. With the exception of a few heavy metals, few human studies have evaluated the impact of metal exposure on pubertal development. Our aim was to investigate measures of in utero and peripubertal metal exposure in relation to reproductive hormone levels and sexual maturation and progression among girls from the Early Life Exposure in Mexico to Environmental Toxicants (ELEMENT) cohorts. We measured urinary concentrations of aluminum (Al), arsenic (As), barium (Ba), cadmium (Cd), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), antimony (Sb), selenium (Se), and zinc (Zn) in samples collected from women during their third trimester of pregnancy and from their female children at 8-13 years (n = 132). We measured serum testosterone, estradiol, dehydroepiandrosterone sulfate (DHEA-S), inhibin B, and sex hormone-binding globulin (SHBG) at age 8-13, and assessed Tanner stages for sexual maturation (breast, pubic hair development, and menarche status), at two time points (8-13, 14-18 years). We used linear regression to independently examine in utero and peripubertal metal concentrations as predictors of peripubertal hormones. In a longitudinal analysis using generalized estimation equations, we evaluated Tanner stage and menarche progression in relation to individual in utero and peripubertal metal concentrations. We found that higher in utero Zn was associated with increased inhibin B. Several metals at 8-13 years were associated with higher DHEA-S and estradiol, while Ni was positively but Cu was negatively associated with testosterone. In utero Ni, Al, and Cd were associated with slower progression of breast development after adjustment for child age and BMI z-score. For example, an IQR increase in in utero Al exposure was associated with 0.82 times lower odds of progressing to a higher Tanner stage for breast development per year (95% CI: 0.68, 0.99). Peripubertal concentrations of Ba and Al were also associated with being at a higher pubic hair Tanner stage and menarche at 8-13, but lower odds of progressing to the next stage at 14-18 years. We used Bayesian kernel machine regression (BKMR) to model the joint effect of multiple metals while accounting for correlated exposures, as well as potential non-linear relationships between metals and outcomes of interest, which yielded results similar to individual analyses. These findings suggest that female reproductive development may be vulnerable to the effects of metal exposure, and using both Tanner stages and hormone levels may provide clues about underlying mechanisms in two sensitive periods of development.
Collapse
Affiliation(s)
- Pahriya Ashrap
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, United States
| | - Brisa N Sánchez
- Department of Biostatistics, University of Michigan School of Public Health, Ann Arbor, MI, United States
| | - Martha M Téllez-Rojo
- Center for Nutrition and Health Research, Instituto Nacional de Salud Pública, Cuernavaca, Morelos, Mexico
| | - Niladri Basu
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec, Canada
| | - Marcela Tamayo-Ortiz
- Center for Nutrition and Health Research, Instituto Nacional de Salud Pública, Cuernavaca, Morelos, Mexico; Mexican Council for Science and Technology, Mexico City, Mexico
| | - Karen E Peterson
- Department of Nutritional Sciences, University of Michigan School of Public Health, Ann Arbor, MI, United States
| | - John D Meeker
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, United States
| | - Deborah J Watkins
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, United States.
| |
Collapse
|
9
|
Dong C, Taylor MP, Zahran S. The effect of contemporary mine emissions on children's blood lead levels. ENVIRONMENT INTERNATIONAL 2019; 122:91-103. [PMID: 30509512 DOI: 10.1016/j.envint.2018.09.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 09/11/2018] [Accepted: 09/12/2018] [Indexed: 06/09/2023]
Abstract
BACKGROUND Broken Hill is home to Australia's oldest silver-zinc-lead mine. However, the precise source of childhood blood lead (PbB) exposures has been subject to considerable debate. Lead sources include natural soil Pb enrichment, legacy deposition, contemporary mining emissions, and Pb-based paint. OBJECTIVE To test whether contemporary mining emissions independently affect childhood PbB in Broken Hill. METHODS Children's (<5 years old) PbB measures from 2011 to 2015 (n = 4852), obtained from Broken Hill Child & Family Health Centre, were analyzed using generalised linear regression models, including covariates of household soil Pb, city dust Pb concentrations (PbD), demographic factors and Pb ore production. Two natural experiments involving wind direction and the 2009 dust storm were examined to test whether the PbB-distance gradient from the mining operations was influenced by contemporary emissions. The influence of contemporary emissions was further interrogated by examining the effect of ore production on PbB and PbD. RESULTS Children living downwind and proximate to the mine had substantially higher PbB outcomes than children similarly distant but upwind. Dust Pb deposition increased significantly with proximity to mining operations as well to Pb production (1991-2013). Average annual PbB correlated with Pb ore production (p < 0.01) with all subsets of children PbB levels responding with near unit elasticity to Pb ore production (p < 0.01). Pre- and post-analysis of the dust storm showed the PbB-distance gradient remained statistically unaltered further confirming contemporary emissions as a source of exposure. CONCLUSIONS Contemporary mining emissions influence children's PbB measures independent of other sources and need to be remediated to facilitate reductions in harmful exposure.
Collapse
Affiliation(s)
- Chenyin Dong
- Department of Environmental Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales, Australia.
| | - Mark Patrick Taylor
- Department of Environmental Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales, Australia; Energy and Environmental Contaminants Research Centre, Macquarie University, Sydney, New South Wales, Australia
| | - Sammy Zahran
- Department of Economics, Centre for Disaster and Risk Analysis, Colorado State University, Fort Collins, CO, USA
| |
Collapse
|
10
|
Kordas K, Ravenscroft J, Cao Y, McLean EV. Lead Exposure in Low and Middle-Income Countries: Perspectives and Lessons on Patterns, Injustices, Economics, and Politics. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2018; 15:E2351. [PMID: 30356019 PMCID: PMC6266944 DOI: 10.3390/ijerph15112351] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 10/19/2018] [Accepted: 10/21/2018] [Indexed: 01/15/2023]
Abstract
Lead exposure is a legacy issue that continues to affect vulnerable population groups globally, but particularly in low and middle-income countries (LMICS). We take a multi-disciplinary approach to examine the patterns of lead exposure in these countries, discuss the underlying injustices and socio-political causes, and the economic costs that are associated with exposure. We conclude with some lessons we drew from our discussion of lead across the disciplines and advocate for a number of approaches to solving this ongoing issue. These include (i) biomonitoring that could be integrated into existing health surveys or public health programs targeting young children; (ii) greater civic engagement to push for solutions; and, (iii) environmental control policies that represent a continuum of local, context-specific to broad, national-level, and even global approaches.
Collapse
Affiliation(s)
- Katarzyna Kordas
- Department of Epidemiology and Environmental Health, University at Buffalo, Buffalo, NY 14214, USA.
| | - Julia Ravenscroft
- Department of Epidemiology and Environmental Health, University at Buffalo, Buffalo, NY 14214, USA.
| | - Ying Cao
- Division of Health Services Policy and Practice, Department of Epidemiology and Environmental Health, University at Buffalo, Buffalo, NY 14214, USA.
| | - Elena V McLean
- Department of Political Science, University at Buffalo, Buffalo, NY 14260, USA.
| |
Collapse
|
11
|
Martins AC, Gallimberti M, de Oliveira Souza VC, Rocha BA, Barbosa F. Biomonitoring for uranium exposure among young children living in nineteen states across five regions of Brazil. J Radioanal Nucl Chem 2018. [DOI: 10.1007/s10967-018-5964-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
12
|
Etiang' NA, Arvelo W, Galgalo T, Amwayi S, Gura Z, Kioko J, Omondi G, Patta S, Lowther SA, Brown MJ. Environmental Assessment and Blood Lead Levels of Children in Owino Uhuru and Bangladesh Settlements in Kenya. J Health Pollut 2018; 8:180605. [PMID: 30524854 PMCID: PMC6239056 DOI: 10.5696/2156-9614-8.18.180605] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 05/04/2018] [Indexed: 05/25/2023]
Abstract
BACKGROUND Lead exposure is linked to intellectual disability and anemia in children. The United States Centers for Disease Control and Prevention (CDC) recommends biomonitoring of blood lead levels (BLLs) in children with BLL ≥5 μg/dL and chelation therapy for those with BLL ≥45 μg/dL. OBJECTIVES This study aimed to determine blood and environmental lead levels and risk factors associated with elevated BLL among children from Owino Uhuru and Bangladesh settlements in Mombasa County, Kenya. METHODS The present study is a population-based, cross-sectional study of children aged 12-59 months randomly selected from households in two neighboring settlements, Owino Uhuru, which has a lead smelter, and Bangladesh settlement (no smelter). Structured questionnaires were administered to parents and 1-3 ml venous blood drawn from each child was tested for lead using a LeadCare ® II portable analyzer. Environmental samples collected from half of the sampled households were tested for lead using graphite furnace atomic absorption spectroscopy. RESULTS We enrolled 130 children, 65 from each settlement. Fifty-nine (45%) were males and the median age was 39 months (interquartile range (IQR): 30-52 months). BLLs ranged from 1 μg/dL to 31 μg/dL, with 45 (69%) children from Owino Uhuru and 18 (28%) children from Bangladesh settlement with BLLs >5 μg/dL. For Owino Uhuru, the geometric mean BLL in children was 7.4 μg/dL (geometric standard deviation (GSD); 1.9) compared to 3.7 μg/dL (GSD: 1.9) in Bangladesh settlement (p<0.05). The geometric mean lead concentration of soil samples from Owino Uhuru was 146.5 mg/Kg (GSD: 5.2) and 11.5 mg/Kg (GSD: 3.9) (p<0.001) in Bangladesh settlement. Children who resided <200 m from the lead smelter were more likely to have a BLL ≥5 μg/dL than children residing ≥200 m from the lead smelter (adjusted odds ratio (aOR): 33.6 (95% confidence interval (CI): 7.4-153.3). Males were also more likely than females to have a BLL ≥5 μg/dL (39, 62%) compared to a BLL<5 μg/dL [aOR: 2.4 (95% CI: 1.0-5.5)]. CONCLUSIONS Children in Owino Uhuru had significantly higher BLLs compared with children in Bangladesh settlement. Interventions to diminish continued exposure to lead in the settlement should be undertaken. Continued monitoring of levels in children with detectable levels can evaluate whether interventions to reduce exposure are effective. PARTICIPANT CONSENT Obtained. ETHICS APPROVAL Scientific approval for the study was obtained from the Ministry of Health, lead poisoning technical working group. Since this investigation was considered a public health response of immediate concern, expedited ethical approval was obtained from the Kenya Medical Research Institute and further approval from the Mombasa County Department of Health Services. The investigation was considered a non-research public health response activity by the CDC. COMPETING INTERESTS The authors declare no competing financial interests.
Collapse
Affiliation(s)
- Nancy A Etiang'
- Ministry of Health, Kenya
- Jomo Kenyatta University of Agriculture and Technology, Kenya
| | - Wences Arvelo
- Division of Global Health Protection, Center for Global Health, Centers for Disease Control and Prevention, USA
| | - Tura Galgalo
- Division of Global Health Protection, Center for Global Health, Centers for Disease Control and Prevention, Kenya
| | | | | | | | | | - Shem Patta
- Mombasa County Department of Health Services, Kenya
| | - Sara A Lowther
- Division of Global Health Protection, Center for Global Health, Centers for Disease Control and Prevention, USA
| | | |
Collapse
|
13
|
Lewis RC, Meeker JD, Basu N, Gauthier AM, Cantoral A, Mercado-García A, Peterson KE, Téllez-Rojo MM, Watkins DJ. Urinary metal concentrations among mothers and children in a Mexico City birth cohort study. Int J Hyg Environ Health 2018; 221:609-615. [PMID: 29703512 PMCID: PMC6197859 DOI: 10.1016/j.ijheh.2018.04.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2017] [Revised: 04/13/2018] [Accepted: 04/16/2018] [Indexed: 10/17/2022]
Abstract
Personal care product use is a potential source of metals exposure among children, but studies have been limited. We measured urinary concentrations of 10 metals (aluminum, arsenic [As], barium [Ba], cadmium, cobalt [Co], lead [Pb], manganese [Mn], molybdenum [Mo], nickel, and zinc [Zn]) in third trimester pregnant women (n = 212) and their children at 8-14 years of age (n = 250). Demographic factors (child sex, age, socioeconomic status, and maternal education), body mass index (BMI) z-score, and child personal care product use in the 24 h prior to urine collection were examined as predictors of urinary metal concentrations. Metals were detected in 80-100% of urine samples, with significant differences in maternal versus childhood levels. However, metal concentrations were not strongly correlated within or between time points. In linear regression models including all demographic characteristics, BMI z-score, and specific gravity, age was associated with higher Co (6% [95% CI: 2, 10]), while BMI z-score was associated with lower Mo (-6% [95% CI: -11, -1). In addition, significantly higher metal concentrations were observed among users of colored cosmetics (Mo: 42% [95% CI: 1, 99]), deodorant (Ba: 28% [3, 58]), hair spray/hair gel (Mn: 22% [3, 45]), and other toiletries (As: 50% [9, 108]), as well as with an increasing number of personal care products used (As: 7% [3, 11]) after adjustment for child sex, age, total number of products used, and specific gravity. However, significantly lower metal concentrations were noted for users of hair cream (As and Zn: -20% [-36, -2] and -21% [-35, -2], respectively), shampoo (Pb: -40% [-62, -7]), and other hair products (Pb: -44% [-65, -9]). We found that personal care product use may be a predictor of exposure to multiple metals among children. Further research is recommended to inform product-specific exposure source identification and related child health risk assessment efforts.
Collapse
Affiliation(s)
- Ryan C Lewis
- Center for Health Sciences, Exponent, Inc., Oakland, CA, USA
| | - John D Meeker
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA
| | - Niladri Basu
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, QC, Canada
| | | | - Alejandra Cantoral
- Center for Nutrition and Health Research, National Institute of Public Health, Cuernavaca, MOR, Mexico
| | - Adriana Mercado-García
- Center for Nutrition and Health Research, National Institute of Public Health, Cuernavaca, MOR, Mexico
| | - Karen E Peterson
- Department of Nutritional Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA
| | - Martha Maria Téllez-Rojo
- Center for Nutrition and Health Research, National Institute of Public Health, Cuernavaca, MOR, Mexico
| | - Deborah J Watkins
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA.
| |
Collapse
|
14
|
Ericson B, Landrigan P, Taylor MP, Frostad J, Caravanos J. The Global Burden of Lead Toxicity Attributable to Informal Used
Lead-Acid Battery Sites. Ann Glob Health 2017; 82:686-699. [DOI: 10.1016/j.aogh.2016.10.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
|
15
|
Torres-Sánchez L, López-Carrillo L, Rosado JL, Rodriguez VM, Vera-Aguilar E, Kordas K, García-Vargas GG, Cebrian ME. Sex differences in the reduction of arsenic methylation capacity as a function of urinary total and inorganic arsenic in Mexican children. ENVIRONMENTAL RESEARCH 2016; 151:38-43. [PMID: 27450997 DOI: 10.1016/j.envres.2016.07.020] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 07/13/2016] [Accepted: 07/14/2016] [Indexed: 06/06/2023]
Abstract
Chronic arsenic (As) exposure decreases adult and children's ability to methylate inorganic As (iAs); however, few studies have examined children's sex differences. We measured urinary concentrations of iAs, monomethylarsonic (MMA), and dimethylarsinic (DMA) acids, and calculated the primary (PMI: MMA/iAs) and secondary (SMI: DMA/MMA) methylation capacity indexes in 591 children 6-8 years in Torreón, Mexico. We determined iAs, MMA, and DMA by hydride generation cryotrapping AAS. Lineal regression models estimated associations between methylation capacity and total As (TAs) or iAs. Interactions with sex were tested at p<0.10. Boys had significantly higher TAs levels, (58.4µg/L) than girls (46.2µg/L). We observed negative associations between TAs and PMI (β=-0.039; p<0.18) and SMI (β=-0.08; p=0.002) with significant sex differences; PMI reduction was significant in boys (β=-0.09; p=0.02) but not in girls (β=0.021; p=0.63), p for interaction=0.06. In contrast, SMI reduction was significantly more pronounced in girls. Furthermore, negative associations PMI (β=-0.19; p<0.001) and SMI (β=-0.35; p<0.001) were a function of urinary iAs levels, independently of TAs; however, the reduction in PMI was more pronounced in boys (β=-0.24; p<0.001; girls β=-0.15; p<0.001), p for interaction=0.04. A significant negative association was observed between SMI and iAs levels without significant sex differences. TAs and iAs associations with metabolite percentages were in good agreement with those observed with methylation indexes. Our results suggest that iAs plays an important role in reducing As methylation ability and that significant sex differences are present in As metabolism. These differences merit further investigation to confirm our findings and their potential implications for arsenic toxicity in children.
Collapse
Affiliation(s)
| | | | - Jorge L Rosado
- Escuela de Ciencias Naturales, Universidad Autónoma del Estado de Querétaro, Querétaro, Mexico
| | - Valentina M Rodriguez
- International Exchange Program for Minority Students, Mount Sinai School of Medicine, New York, NY, USA
| | - Eunice Vera-Aguilar
- Departamento de Farmacología, Centro de Investigación y de Estudios Avanzados del IPN, México City, Mexico
| | - Katarzyna Kordas
- School of Social and Community Medicine, University of Bristol, Bristol, UK
| | - Gonzalo G García-Vargas
- Facultad de Medicina, Universidad Juárez del Estado de Durango, Gómez Palacio, Durango, Mexico
| | - Mariano E Cebrian
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del IPN, México City, Mexico.
| |
Collapse
|
16
|
Hinwood AL, Stasinska A, Callan AC, Heyworth J, Ramalingam M, Boyce M, McCafferty P, Odland JØ. Maternal exposure to alkali, alkali earth, transition and other metals: Concentrations and predictors of exposure. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2015; 204:256-263. [PMID: 25984984 DOI: 10.1016/j.envpol.2015.04.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 04/26/2015] [Indexed: 06/04/2023]
Abstract
Most studies of metals exposure focus on the heavy metals. There are many other metals (the transition, alkali and alkaline earth metals in particular) in common use in electronics, defense industries, emitted via combustion and which are naturally present in the environment, that have received limited attention in terms of human exposure. We analysed samples of whole blood (172), urine (173) and drinking water (172) for antimony, beryllium, bismuth, cesium, gallium, rubidium, silver, strontium, thallium, thorium and vanadium using ICPMS. In general most metals concentrations were low and below the analytical limit of detection with some high concentrations observed. Few factors examined in regression models were shown to influence biological metals concentrations and explained little of the variation. Further study is required to establish the source of metals exposures at the high end of the ranges of concentrations measured and the potential for any adverse health impacts in children.
Collapse
Affiliation(s)
- A L Hinwood
- Centre for Ecosystem Management, Edith Cowan University, Western Australia, Australia.
| | - A Stasinska
- School of Population Health, University of Western Australia, Australia
| | - A C Callan
- Centre for Ecosystem Management, Edith Cowan University, Western Australia, Australia; School of Medical Sciences, Edith Cowan University, Western Australia, Australia
| | - J Heyworth
- School of Population Health, University of Western Australia, Australia
| | - M Ramalingam
- Centre for Ecosystem Management, Edith Cowan University, Western Australia, Australia; Department of Chemistry Malaysia, Jalan Sultan, Petaling Jaya, 46661 Selangor, Malaysia
| | - M Boyce
- Centre for Ecosystem Management, Edith Cowan University, Western Australia, Australia
| | - P McCafferty
- ChemCentreWA, PO Box 1250, Bentley, WA 6983, Australia
| | - J Ø Odland
- Department of Community Medicine, University of Tromsø, N-9037 Tromsø, Norway
| |
Collapse
|
17
|
Said S, Hernandez GT. Environmental exposures, socioeconomics, disparities, and the kidneys. Adv Chronic Kidney Dis 2015; 22:39-45. [PMID: 25573511 DOI: 10.1053/j.ackd.2014.09.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 08/30/2014] [Accepted: 09/09/2014] [Indexed: 12/27/2022]
Abstract
Kidney disease disproportionately affects racial and ethnic minority populations, the poor, and the socially disadvantaged. The excess risk of kidney disease among minority and disadvantaged populations can only be partially explained by an excess of diabetes, hypertension, and poor access to preventive care. Disparities in the environmental exposure to nephrotoxicants have been documented in minority and disadvantaged populations and may explain some of the excess risk of kidney disease. High-level environmental and occupational exposure to lead, cadmium, and mercury are known to cause specific nephropathies. However, there is growing evidence that low-level exposures to heavy metals may contribute to the development of CKD and its progression. In this article, we summarize the excess risk of environmental exposures among minority and disadvantaged populations. We also review the epidemiologic and clinical data linking low-level environmental exposure to lead, cadmium, and mercury to CKD and its progression. Finally, we briefly describe Mesoamerican nephropathy, an epidemic of CKD affecting young men in Central America, which may have occupational and environmental exposures contributing to its development.
Collapse
|
18
|
Zamoiski RD, Guallar E, García-Vargas GG, Rothenberg SJ, Resnick C, Andrade MR, Steuerwald AJ, Parsons PJ, Weaver VM, Navas-Acien A, Silbergeld EK. Association of arsenic and metals with concentrations of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D among adolescents in Torreón, Mexico. ENVIRONMENTAL HEALTH PERSPECTIVES 2014; 122:1233-8. [PMID: 25095279 PMCID: PMC4216165 DOI: 10.1289/ehp.1307861] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 08/01/2014] [Indexed: 05/19/2023]
Abstract
BACKGROUND Limited data suggest that lead (Pb), cadmium (Cd), and uranium (U) may disrupt vitamin D metabolism and inhibit production of 1,25-dihydroxyvitamin D [1,25(OH)2D], the active vitamin D metabolite, from 25-hydroxyvitamin D [25(OH)D] in the kidney. OBJECTIVES We evaluated the association between blood lead (BPb) and urine arsenic (As), Cd, molybdenum (Mo), thallium (Tl), and U with markers of vitamin D metabolism [25(OH)D and 1,25(OH)2D]. METHODS We conducted a cross-sectional study of 512 adolescents in Torreón, a town in Mexico with a Pb smelter near residential areas. BPb was measured using atomic absorption spectrometry. Urine As, Cd, Mo, Tl, and U were measured using inductively coupled plasma mass spectrometry. Serum 25(OH)D and 1,25(OH)2D were measured using a chemiluminescent immunoassay and a radioimmunoassay, respectively. Multivariable linear models with vitamin D markers as the outcome were used to estimate associations of BPb and creatinine-corrected urine As and metal concentrations with serum vitamin D concentrations, controlling for age, sex, adiposity, smoking, socioeconomic status, and time outdoors. RESULTS Serum 25(OH)D was positively associated with urine Mo and Tl [1.5 (95% CI: 0.4, 2.6) and 1.2 (95% CI: 0.3, 2.1) ng/mL higher with a doubling of exposure, respectively]. Serum 1,25(OH)2D was positively associated with urine As and U [3.4 (95% CI: 0.9, 5.9) and 2.2 (95% CI: 0.7, 3.7) pg/mL higher, respectively], with little change in associations after additional adjustment for serum 25(OH)D. Pb and Cd were not associated with 25(OH)D or 1,25(OH)2D concentrations. CONCLUSIONS Overall, our findings did not support a negative effect of As or metal exposures on serum 1,25(OH)2D concentrations. Additional research is needed to confirm positive associations between serum 1,25(OH)2D and urine U and As concentrations and to clarify potential underlying mechanisms.
Collapse
Affiliation(s)
- Rachel D Zamoiski
- Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
López-Santos A, Martínez-Santiago S. Use of two indicators for the socio-environmental risk analysis of Northern Mexico under three climate change scenarios. AIR QUALITY, ATMOSPHERE, & HEALTH 2014; 8:331-345. [PMID: 26246862 PMCID: PMC4519635 DOI: 10.1007/s11869-014-0286-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2014] [Accepted: 07/24/2014] [Indexed: 06/04/2023]
Abstract
The aims of this study were to (1) find critical areas susceptible to the degradation of natural resources according to local erosion rates and aridity levels, which were used as environmental quality indicators, and (2) identify areas of risk associated with the presence of natural hazards according to three climate change scenarios defined for Mexico. The focus was the municipality of Lerdo, Durango (25.166° to 25.783° N and 103.333° to 103.983° W), which has dry temperate and very dry climates (BSohw and BWhw). From the Global Circulation Models, downscaling techniques for the dynamic modeling of environmental processes using climate data, historical information, and three regionalized climate change scenarios were applied to determine the impacts from laminar wind erosion rates (LWER) and aridity indices (AI). From the historic period to scenario A2 (ScA2, 2010-2039), regarding greenhouse gas emissions, the LWER was predicted to reach 147.2 t ha-1 year-1, representing a 0.5 m thickness over nearly 30 years and a change in the AI from 9.3 to 8.7. This trend represents an increase in drought for 70.8 % of the study area and could affect 90 % of the agricultural activities and approximately 80 % of the population living in the southeastern Lerdense territory.
Collapse
Affiliation(s)
- Armando López-Santos
- Unidad Regional Universitaria de Zonas Áridas, Universidad Autónoma Chapingo, Km. 40 Carretera Gómez Palacio-Chihuahua, Bermejillo, Dgo CP 35230 Mexico
| | - Santos Martínez-Santiago
- Unidad Regional Universitaria de Zonas Áridas, Universidad Autónoma Chapingo, Km. 40 Carretera Gómez Palacio-Chihuahua, Bermejillo, Dgo CP 35230 Mexico
| |
Collapse
|