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Jensen N, Terrell R, Ramoju S, Shilnikova N, Farhat N, Karyakina N, Cline BH, Momoli F, Mattison D, Krewski D. Magnetic resonance imaging T1 indices of the brain as biomarkers of inhaled manganese exposure. Crit Rev Toxicol 2022; 52:358-370. [PMID: 36412542 DOI: 10.1080/10408444.2022.2128719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Excessive exposure to manganese (Mn) is linked to its accumulation in the brain and adverse neurological effects. Paramagnetic properties of Mn allow the use of magnetic resonance imaging (MRI) techniques to identify it in biological tissues. A critical review was conducted to evaluate whether MRI techniques could be used as a diagnostic tool to detect brain Mn accumulation as a quantitative biomarker of inhaled exposure. A comprehensive search was conducted in MEDLINE, EMBASE, and PubMed to identify potentially relevant studies published prior to 9 May 2022. Two reviewers independently screened identified references using a two-stage process. Of the 6452 unique references identified, 36 articles were retained for data abstraction. Eligible studies used T1-weighted MRI techniques and reported direct or indirect T1 measures to characterize Mn accumulation in the brain. Findings demonstrate that, in subjects exposed to high levels of Mn, deposition in the brain is widespread, accumulating both within and outside the basal ganglia. Available evidence indicates that T1 MRI techniques can be used to distinguish Mn-exposed individuals from unexposed. Additionally, T1 MRI may be useful for semi-quantitative evaluation of inhaled Mn exposure, particularly when interpreted along with other exposure indices. T1 MRI measures appear to have a nonlinear relationship to Mn exposure duration, with R1 signal only increasing after critical thresholds. The strength of the association varied depending on the regions of interest imaged and the method of exposure measurement. Overall, available evidence suggests potential for future clinical and risk assessment applications of MRI as a diagnostic tool.
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Affiliation(s)
- N Jensen
- Risk Sciences International, Ottawa, Canada.,School of Epidemiology and Public Health, University of Ottawa, Ottawa, Canada
| | - R Terrell
- Risk Sciences International, Ottawa, Canada.,School of Epidemiology and Public Health, University of Ottawa, Ottawa, Canada
| | - S Ramoju
- Risk Sciences International, Ottawa, Canada
| | - N Shilnikova
- Risk Sciences International, Ottawa, Canada.,McLaughlin Centre for Population Health Risk Assessment, University of Ottawa, Ottawa, Canada
| | - N Farhat
- Risk Sciences International, Ottawa, Canada.,School of Epidemiology and Public Health, University of Ottawa, Ottawa, Canada.,School of Mathematics and Statistics, Carleton University, Ottawa, Canada
| | - N Karyakina
- Risk Sciences International, Ottawa, Canada.,McLaughlin Centre for Population Health Risk Assessment, University of Ottawa, Ottawa, Canada
| | - B H Cline
- International Manganese Institute, Paris, France
| | - F Momoli
- Risk Sciences International, Ottawa, Canada.,School of Epidemiology and Public Health, University of Ottawa, Ottawa, Canada
| | - D Mattison
- Risk Sciences International, Ottawa, Canada.,School of Epidemiology and Public Health, University of Ottawa, Ottawa, Canada.,Arnold School of Public Health, University of South Carolina, Columbia, SC, USA
| | - D Krewski
- Risk Sciences International, Ottawa, Canada.,School of Epidemiology and Public Health, University of Ottawa, Ottawa, Canada.,McLaughlin Centre for Population Health Risk Assessment, University of Ottawa, Ottawa, Canada.,School of Mathematics and Statistics, Carleton University, Ottawa, Canada
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Manganese Intoxication Recovery and the Expression Changes of Park2/Parkin in Rats. Neurochem Res 2021; 47:897-906. [PMID: 34839452 DOI: 10.1007/s11064-021-03493-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/18/2021] [Accepted: 11/17/2021] [Indexed: 10/19/2022]
Abstract
Occupational overexposure to manganese (Mn) produces Parkinson's disease-like manganism. Acute Mn intoxication in rats causes dopaminergic neuron loss, impairment of motor activity and reduction of the expression of Park2/Parkin. The expression of Park2/Parkin is also reduced. Whether these changes are reversible after cessation of Mn exposure is unknown, and is the goal of this investigation. Adult male rats were injected with Mn2+ at doses 1 mg/kg and 5 mg/kg in the form of MnCl2·4H2O, every other day for one-month to produce acute Mn neurotoxicity. For a half of rats Mn exposure was suspended for recovery for up to 5 months. Mn neurotoxicity was evaluated by the accumulation of Mn in blood and brain, behavioral activities, dopaminergic neuron loss, and the expression of Park2/Parkin in the blood cells and brain. Dose-dependent Mn neurotoxicity in rats was evidenced by Mn accumulation, rotarod impairments, reduction of tyrosine hydroxylase (TH)-positive neurons in the substantia nigra, decreased level of Park2 mRNA in the blood and brain, and decreased Parkin protein in the brain. After cessation of Mn exposure, the amount of Park2 mRNA in the blood started to increase one month after the recovery. After 5-month of recovery, blood and brain Mn returned to normal, rotarod activity recovered, the reduction of TH-positive dopaminergic neurons ameliorated, and the level of Park2 mRNA in the blood and Park2/Parkin in the midbrain and striatum were returned to the normal. Mn neurotoxicity in rats is reversible after cessation of Mn exposure. The level of Park2 mRNA in the blood could be used as a novel biomarker for Mn exposure and recovery.
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Newton A, Adams K, Serdar B, Dickinson LM, Koehler K. Personal and area exposure assessment at a stainless steel fabrication facility: an evaluation of inhalable, time-resolved PM 10, and bioavailable airborne metals. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2021; 18:90-100. [PMID: 33555996 DOI: 10.1080/15459624.2020.1854460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
This study describes a comprehensive exposure assessment in a stainless steel welding facility, measuring personal inhalable PM and metals, time-resolved PM10 area metals, and the bioavailable fraction of area inhalable metals. Eighteen participants wore personal inhalable samplers for two, nonconsecutive shifts. Area inhalable samplers and a time-resolved PM10 X-ray fluorescence spectrometer were used in different work areas each sampling day. Inhalable and bioavailable metals were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Median exposures to chromium, nickel, and manganese across all measured shifts were 66 (range: 13-300) μg/m3, 29 (5.7-132) μg/m3, and 22 (1.5-119) μg/m3, respectively. Most exposure variation was seen between workers ( 0.79 < ICC < 0.55 ) , although cobalt and inhalable PM showed most variation within workers. Manganese was the most bioavailable metal from the inhalable size fraction (16 ± 3%), and chromium and nickel were 1.2 ± 0.08% and 2.6 ± 1.2% bioavailable, respectively. This comprehensive approach to welding-fume exposure assessment can allow for targeted approaches to controlling exposures based not only on individual measurements, but also on metal-specific measures and assessments of bioavailability.
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Affiliation(s)
- Ashley Newton
- Environmental Health Sciences, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Karin Adams
- Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, USA
- Idaho National Laboratory, Idaho Falls, Idaho, USA
| | - Berrin Serdar
- Environmental Health Associates LLC, Englewood, Colorado, USA
| | - L Miriam Dickinson
- Family Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Kirsten Koehler
- Environmental Health Sciences, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA
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Balachandran RC, Mukhopadhyay S, McBride D, Veevers J, Harrison FE, Aschner M, Haynes EN, Bowman AB. Brain manganese and the balance between essential roles and neurotoxicity. J Biol Chem 2020; 295:6312-6329. [PMID: 32188696 PMCID: PMC7212623 DOI: 10.1074/jbc.rev119.009453] [Citation(s) in RCA: 162] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Manganese (Mn) is an essential micronutrient required for the normal development of many organs, including the brain. Although its roles as a cofactor in several enzymes and in maintaining optimal physiology are well-known, the overall biological functions of Mn are rather poorly understood. Alterations in body Mn status are associated with altered neuronal physiology and cognition in humans, and either overexposure or (more rarely) insufficiency can cause neurological dysfunction. The resultant balancing act can be viewed as a hormetic U-shaped relationship for biological Mn status and optimal brain health, with changes in the brain leading to physiological effects throughout the body and vice versa. This review discusses Mn homeostasis, biomarkers, molecular mechanisms of cellular transport, and neuropathological changes associated with disruptions of Mn homeostasis, especially in its excess, and identifies gaps in our understanding of the molecular and biochemical mechanisms underlying Mn homeostasis and neurotoxicity.
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Affiliation(s)
| | - Somshuvra Mukhopadhyay
- Division of Pharmacology and Toxicology, College of Pharmacy, Institute for Cellular and Molecular Biology, and Institute for Neuroscience, University of Texas, Austin, Texas 78712
| | - Danielle McBride
- College of Medicine, University of Cincinnati, Cincinnati, Ohio 45267
| | - Jennifer Veevers
- College of Medicine, University of Cincinnati, Cincinnati, Ohio 45267
| | - Fiona E Harrison
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232
| | | | - Erin N Haynes
- College of Public Health, University of Kentucky, Lexington, Kentucky 40536
| | - Aaron B Bowman
- School of Health Sciences, Purdue University, West Lafayette, Indiana 47907
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Lee EY, Flynn MR, Du G, Lewis MM, Kong L, Yanosky JD, Mailman RB, Huang X. Higher Hippocampal Mean Diffusivity Values in Asymptomatic Welders. Toxicol Sci 2020; 168:486-496. [PMID: 30629252 DOI: 10.1093/toxsci/kfz011] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Chronic high-level manganese (Mn)-induced neurotoxicity has been associated with Mn accumulation in the basal ganglia and higher risk for developing parkinsonism. Recent studies in Mn-exposed animals revealed Mn accumulation in the hippocampus, the presence of Aβ diffuse plaques, and deficits in associative learning, the latter being hallmarks of Alzheimer's disease (AD) or related disorders. This and recent evidence of hippocampal Mn accumulation in welders prompted us to test the hypothesis that welders with chronic Mn exposure would display changes in the hippocampus. Subjects with (welders; n = 42) or without (controls; n = 31) welding history were studied. Mn exposure was estimated by occupational questionnaires, whole blood Mn, and R1 imaging (estimate of short-term brain Mn accumulation). Hippocampal diffusion tensor imaging (DTI; estimate of microstructural brain changes) and volume were determined. Compared with controls, welders displayed no significant difference in hippocampal volume (p = .165). Welders, however, exhibited higher DTI hippocampal mean diffusivity (MD) values compared with controls (p = .035) that was evident particularly in older welders (>50 years, p = .002). Hippocampal MD was associated significantly with age in welders (R = 0.59; p < .001) but not in controls (p = .16). Moreover, higher hippocampal MD values (age adjusted) were associated with long-term cumulative Mn exposure (R = 0.36, p = .021). Welders with chronic exposure have higher MD values in the hippocampus that become greater with increasing age, a brain change that is similar to that observed in those at risk for AD. The current results suggest that Mn exposure, coupled with aging, may make welders more vulnerable to AD or AD-like changes.
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Affiliation(s)
- Eun-Young Lee
- Department of Neurology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey, Pennsylvania 17033.,Department of Health Care and Science, Dong-A University, Busan, South Korea 49315
| | - Michael R Flynn
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Guangwei Du
- Department of Neurology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey, Pennsylvania 17033
| | - Mechelle M Lewis
- Department of Neurology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey, Pennsylvania 17033.,Department of Pharmacology
| | - Lan Kong
- Department of Public Health Sciences
| | | | - Richard B Mailman
- Department of Neurology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey, Pennsylvania 17033.,Department of Pharmacology
| | - Xuemei Huang
- Department of Neurology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey, Pennsylvania 17033.,Department of Pharmacology.,Department of Radiology.,Department of Neurosurgery.,Department of Kinesiology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey, Pennsylvania 17033
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6
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Neurobehavioral performance of patients diagnosed with manganism and idiopathic Parkinson disease. Int Arch Occup Environ Health 2019; 92:383-394. [DOI: 10.1007/s00420-019-01415-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 02/05/2019] [Indexed: 10/27/2022]
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7
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Bailey LA, Kerper LE, Goodman JE. Derivation of an occupational exposure level for manganese in welding fumes. Neurotoxicology 2018. [DOI: 10.1016/j.neuro.2017.06.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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8
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Association of exposure to manganese and iron with relaxation rates R1 and R2*- magnetic resonance imaging results from the WELDOX II study. Neurotoxicology 2017; 64:68-77. [PMID: 28847517 DOI: 10.1016/j.neuro.2017.08.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 08/17/2017] [Accepted: 08/21/2017] [Indexed: 12/28/2022]
Abstract
OBJECTIVE Magnetic resonance imaging is a non-invasive method that allows the indirect quantification of manganese (Mn) and iron (Fe) accumulation in the brain due to their paramagnetic features. The WELDOX II study aimed to explore the influence of airborne and systemic exposure to Mn and Fe on the brain deposition using the relaxation rates R1 and R2* as biomarkers of metal accumulation in regions of interest in 161 men, including active and former welders. MATERIAL AND METHODS We obtained data on the relaxation rates R1 and R2* in regions that included structures within the globus pallidus (GP), substantia nigra (SN), and white matter of the frontal lobe (FL) of both hemispheres, as well as Mn in whole blood (MnB), and serum ferritin (SF). The study subjects, all male, included 48 active and 20 former welders, 41 patients with Parkinson's disease (PD), 13 patients with hemochromatosis (HC), and 39 controls. Respirable Mn and Fe were measured during a working shift for welders. Mixed regression models were applied to estimate the effects of MnB and SF on R1 and R2*. Furthermore, we estimated the influence of airborne Mn and Fe on the relaxation rates in active welders. RESULTS MnB and SF were significant predictors of R1 but not of R2* in the GP, and were marginally associated with R1 in the SN (SF) and FL (MnB). Being a welder or suffering from PD or HC elicited no additional group effect on R1 or R2* beyond the effects of MnB and SF. In active welders, shift concentrations of respirable Mn>100μg/m3 were associated with stronger R1 signals in the GP. In addition to the effects of MnB and SF, the welding technique had no further influence on R1. CONCLUSIONS MnB and SF were significant predictors of R1 but not of R2*, indicative of metal accumulation, especially in the GP. Also, high airborne Mn concentration was associated with higher R1 signals in this brain region. The negative results obtained for being a welder or for the techniques with higher exposure to ultrafine particles when the blood-borne concentration was included into the models indicate that airborne exposure to Mn may act mainly through MnB.
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9
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Abstract
Although an essential nutrient, manganese (Mn) can be toxic at high doses. There is, however, uncertainty regarding the effects of chronic low-level Mn-exposure. This review provides an overview of Mn-related brain and functional changes based on studies of a cohort of asymptomatic welders who had lower Mn-exposure than in most previous work. In welders with low-level Mn-exposure, we found: 1) Mn may accumulate in the brain in a non-linear fashion: MRI R1 (1/T1) signals significantly increased only after a critical level of exposure was reached (e.g., ≥300 welding hours in the past 90days prior to MRI). Moreover, R1 may be a more sensitive marker to capture short-term dynamic changes in Mn accumulation than the pallidal index [T1-weighted intensity ratio of the globus pallidus vs. frontal white matter], a traditional marker for Mn accumulation; 2) Chronic Mn-exposure may lead to microstructural changes as indicated by lower diffusion tensor fractional anisotropy values in the basal ganglia (BG), especially when welding years exceeded more than 30 years; 3) Mn-related subtle motor dysfunctions can be captured sensitively by synergy metrics (indices for movement stability), whereas traditional fine motor tasks failed to detect any significant differences; and 4) Iron (Fe) also may play a role in welding-related neurotoxicity, especially at low-level Mn-exposure, evidenced by higher R2* values (an estimate for brain Fe accumulation) in the BG. Moreover, higher R2* values were associated with lower phonemic fluency performance. These findings may guide future studies and the development of occupation- and public health-related polices involving Mn-exposure.
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Lewis MM, Lee EY, Jo HJ, Du G, Park J, Flynn MR, Kong L, Latash ML, Huang X. Synergy as a new and sensitive marker of basal ganglia dysfunction: A study of asymptomatic welders. Neurotoxicology 2016; 56:76-85. [PMID: 27373673 PMCID: PMC5729892 DOI: 10.1016/j.neuro.2016.06.016] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 06/20/2016] [Accepted: 06/29/2016] [Indexed: 12/29/2022]
Abstract
BACKGROUND Multi-digit synergies, a recently developed, theory-based method to quantify stability of motor action, are shown to reflect basal ganglia dysfunction associated with parkinsonian syndromes. In this study, we tested the hypothesis that multi-digit synergies may capture early and subclinical basal ganglia dysfunction. We chose asymptomatic welders to test the hypothesis because the basal ganglia are known to be most susceptible to neurotoxicity caused by welding-related metal accumulation (such as manganese and iron). METHODS Twenty right-handed welders and 13 matched controls were invited to perform single- and multi-finger pressing tasks using the fingers of the right or left hand. Unified Parkinson's Disease Rating Scale and Grooved Pegboard scores were used to gauge gross and fine motor dysfunction, respectively. High-resolution (3T) T1-weighted, T2-weighted, T1 mapping, susceptibility, and diffusion tensor MRIs were obtained to reflect manganese, iron accumulation, and microstructural changes in basal ganglia. The synergy index stabilizing total force and anticipatory synergy adjustments were computed, compared between groups, and correlated with estimates of basal ganglia manganese [the pallidal index, R1 (1/T1)], iron [R2* (1/T2*)], and microstructural changes [fractional anisotropy and mean diffusivity]. RESULTS There were no significant differences in Unified Parkinson's Disease Rating Scale (total or motor subscale) or Grooved Pegboard test scores between welders and controls. The synergy index during steady-state accurate force production was decreased significantly in the left hand of welders compared to controls (p=0.004) but did not reach statistical significance in the right hand (p=0.16). Anticipatory synergy adjustments, however, were not significantly different between groups. Among welders, higher synergy indices in the left hand were associated significantly with higher fractional anisotropy values in the left globus pallidus (R=0.731, p<0.001) but not with the pallidal index, R1, or R2* values in the basal ganglia. CONCLUSIONS These data suggest that multi-digit synergy metrics may serve as preclinical markers for basal ganglia dysfunction in welders and other populations at risk for neurodegenerative diseases involving parkinsonian symptoms. This finding may have important clinical, scientific, and public/occupational health implications.
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Affiliation(s)
- Mechelle M Lewis
- Department of Neurology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, United States; Department of Pharmacology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, United States
| | - Eun-Young Lee
- Department of Neurology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, United States
| | - Hang Jin Jo
- Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, United States
| | - Guangwei Du
- Department of Neurology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, United States
| | - Jaebum Park
- Institute of Sport Science, Seoul National University, Seoul, South Korea
| | - Michael R Flynn
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, United States
| | - Lan Kong
- Department of Biostatistics, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, United States
| | - Mark L Latash
- Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, United States.
| | - Xuemei Huang
- Department of Neurology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, United States; Department of Pharmacology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, United States; Department of Radiology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, United States; Department of Neurosurgery, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, United States; Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, United States.
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Lee EY, Flynn MR, Du G, Lewis MM, Herring AH, Van Buren E, Van Buren S, Kong L, Mailman RB, Huang X. Editor's Highlight: Lower Fractional Anisotropy in the Globus Pallidus of Asymptomatic Welders, a Marker for Long-Term Welding Exposure. Toxicol Sci 2016; 153:165-73. [PMID: 27466214 DOI: 10.1093/toxsci/kfw116] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
INTRODUCTION Welding fumes contain several metals including manganese (Mn), iron (Fe), and copper (Cu) that at high exposure may co-influence welding-related neurotoxicity. The relationship between brain accumulation of these metals and neuropathology, especially in welders with subclinical exposure levels, is unclear. This study examined the microstructural integrity of basal ganglia (BG) regions in asymptomatic welders using diffusion tensor imaging (DTI). METHODS Subjects with (n = 43) and without (age- and gender-matched controls; n = 31) history of welding were studied. Occupational questionnaires estimated short-term (HrsW; welding hours and E90; cumulative exposure, past 90 days) and long-term (YrsW; total years welding and ELT; cumulative exposure, lifetime) exposure. Whole blood metal levels (Mn, Fe, and Cu) were obtained. Brain MRI pallidal index (PI), R1 (1/T1), and R2* (1/T2*) were measured to estimate Mn and Fe accumulation in BG [caudate, putamen, and globus pallidus (GP)]. DTI was used to assess BG microstructural differences, and related with exposure measurements. RESULTS When compared with controls, welders had significantly lower fractional anisotropy (FA) in the GP. In welders, GP FA values showed non-linear relationships to YrsW, blood Mn, and PI. GP FA decreased after a critical level of YrsW or Mn was reached, whereas it decreased with increasing PI values until plateauing at the highest PI values. GP FA, however, did not show any relationship with short-term exposure measurements (HrsW, E90), blood Cu and Fe, or R(2)* values. CONCLUSION GP FA captured microstructural changes associated with chronic low-level Mn exposure, and may serve as a biomarker for neurotoxicity in asymptomatic welders.
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Affiliation(s)
- Eun-Young Lee
- *Department of Neurology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033
| | - Michael R Flynn
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Guangwei Du
- *Department of Neurology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033
| | - Mechelle M Lewis
- *Department of Neurology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033; Department of Pharmacology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033
| | - Amy H Herring
- Department of Biostatistics, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Eric Van Buren
- Department of Biostatistics, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Scott Van Buren
- Department of Biostatistics, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Lan Kong
- Department of Public Health Sciences
| | - Richard B Mailman
- *Department of Neurology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033; Department of Pharmacology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033
| | - Xuemei Huang
- *Department of Neurology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033; Department of Pharmacology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033; Department of Radiology; Department of Neurosurgery; Department of Kinesiology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033
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Malheiros JM, Paiva FF, Longo BM, Hamani C, Covolan L. Manganese-Enhanced MRI: Biological Applications in Neuroscience. Front Neurol 2015. [PMID: 26217304 PMCID: PMC4498388 DOI: 10.3389/fneur.2015.00161] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Magnetic resonance imaging (MRI) is an excellent non-invasive tool to investigate biological systems. The administration of the paramagnetic divalent ion manganese (Mn2+) enhances MRI contrast in vivo. Due to similarities between Mn2+ and calcium (Ca2+), the premise of manganese-enhanced MRI (MEMRI) is that the former may enter neurons and other excitable cells through voltage-gated Ca2+ channels. As such, MEMRI has been used to trace neuronal pathways, define morphological boundaries, and study connectivity in morphological and functional imaging studies. In this article, we provide a brief overview of MEMRI and discuss recently published data to illustrate the usefulness of this method, particularly in animal models.
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Affiliation(s)
- Jackeline Moraes Malheiros
- Department of Physiology, Universidade Federal de São Paulo - UNIFESP , São Paulo , Brazil ; Centro de Imagens e Espectroscopia In vivo por Ressonância Magnética, Institute of Physics of São Carlos, Universidade de São Paulo , São Carlos , Brazil
| | - Fernando Fernandes Paiva
- Centro de Imagens e Espectroscopia In vivo por Ressonância Magnética, Institute of Physics of São Carlos, Universidade de São Paulo , São Carlos , Brazil
| | - Beatriz Monteiro Longo
- Department of Physiology, Universidade Federal de São Paulo - UNIFESP , São Paulo , Brazil
| | - Clement Hamani
- Department of Physiology, Universidade Federal de São Paulo - UNIFESP , São Paulo , Brazil ; Research Imaging Centre, Centre for Addiction and Mental Health , Toronto, ON , Canada ; Centre for Addiction and Mental Health, Campbell Family Mental Health Research Institute , Toronto, ON , Canada
| | - Luciene Covolan
- Department of Physiology, Universidade Federal de São Paulo - UNIFESP , São Paulo , Brazil
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13
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Ex vivo magnetic resonance imaging in South African manganese mine workers. Neurotoxicology 2015; 49:8-14. [PMID: 25912463 DOI: 10.1016/j.neuro.2015.04.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 03/14/2015] [Accepted: 04/13/2015] [Indexed: 11/22/2022]
Abstract
BACKGROUND Manganese (Mn) exposure is associated with increased T1-weighted magnetic resonance imaging (MRI) signal in the basal ganglia. T1 signal intensity has been correlated with occupational Mn exposure but not with clinical symptomatology or neuropathology. OBJECTIVES This study investigated predictors of ex vivo T1 MRI basal ganglia signal intensity in neuropathologic tissue obtained from deceased South African mine workers. METHODS A 3.0 T MRI was performed on ex vivo brain tissue obtained from 19 Mn mine workers and 10 race- and sex-matched mine workers of other commodities. Basal ganglia regions of interest were identified for each subject with T1-weighted intensity indices generated for each region. In a pathology subset, regional T1 indices were compared to neuronal and glial cell density and tissue metal concentrations. RESULTS Intensity indices were higher in Mn mine workers than non-Mn mine workers for the globus pallidus, caudate, anterior putamen, and posterior putamen with the highest values in subjects with the longest cumulative Mn exposure. Intensity indices were inversely correlated with the neuronal cell density in the caudate (p=0.040) and putamen (p=0.050). Tissue Mn concentrations were similar in Mn and non-Mn mine workers. Tissue iron (Fe) concentration trended lower across all regions in Mn mine workers. CONCLUSIONS Mn mine workers demonstrated elevated basal ganglia T1 indices when compared to non-Mn mine workers. Predictors of ex vivo T1 MRI signal intensity in Mn mine workers include duration of Mn exposure and neuronal density.
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Abstract
The central nervous system's extrapyramidal system provides involuntary motor control to the muscles of the head, neck, and limbs. Toxicants that affect the extrapyramidal system are generally clinically characterized by impaired motor control, which is usually the result of basal ganglionic dysfunction. A variety of extrapyramidal syndromes are recognized in humans and include Parkinson's disease, secondary parkinsonism, other degenerative diseases of the basal ganglia, and clinical syndromes that result in dystonia, dyskinesia, essential tremor, and other forms of tremor and chorea. This chapter briefly reviews the anatomy of the extrapyramidal system and discusses several naturally occurring and experimental models that target the mammalian (nonhuman) extrapyramidal system. Topics discussed include extrapyramidal syndromes associated with antipsychotic drugs, carbon monoxide, reserpine, cyanide, rotenone, paraquat, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), and manganese. In most cases, animals are used as experimental models to improve our understanding of the toxicity and pathogenesis of these agents. Another agent discussed in this chapter, yellowstar thistle poisoning in horses, however, represents an important spontaneous cause of parkinsonism that naturally occurs in animals. The central focus of the chapter is on animal models, especially the concordance between clinical signs, neurochemical changes, and neuropathology between animals and people.
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Affiliation(s)
- David Dorman
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA.
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15
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Antonini JM, Badding MA, Meighan TG, Keane M, Leonard SS, Roberts JR. Evaluation of the Pulmonary Toxicity of a Fume Generated from a Nickel-, Copper-Based Electrode to be Used as a Substitute in Stainless Steel Welding. ENVIRONMENTAL HEALTH INSIGHTS 2014; 8:11-20. [PMID: 25392698 PMCID: PMC4216652 DOI: 10.4137/ehi.s15260] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 06/03/2014] [Accepted: 06/04/2014] [Indexed: 06/04/2023]
Abstract
Epidemiology has indicated a possible increase in lung cancer among stainless steel welders. Chromium (Cr) is a primary component of stainless steel welding fume. There is an initiative to develop alternative welding consumables [nickel (Ni)- and copper (Cu)-based alloys] that do not contain Cr. No study has been performed to evaluate the toxicity of fumes generated from Ni- and Cu-based consumables. Dose-response and time-course effects on lung toxicity of a Ni- and Cu-based welding fume (Ni-Cu WF) were examined using an in vivo and in vitro bioassay, and compared with two other well-characterized welding fumes. Even though only trace amounts of Cr were present, a persistent increase in lung injury and inflammation was observed for the Ni-Cu WF compared to the other fumes. The difference in response appears to be due to a direct cytotoxic effect by the Ni-Cu WF sample on lung macrophages as opposed to an elevated production of reactive oxygen species (ROS).
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Affiliation(s)
- James M Antonini
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - Melissa A Badding
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - Terence G Meighan
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - Michael Keane
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - Stephen S Leonard
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - Jenny R Roberts
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, USA
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16
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Li SJ, Jiang L, Fu X, Huang S, Huang YN, Li XR, Chen JW, Li Y, Luo HL, Wang F, Ou SY, Jiang YM. Pallidal index as biomarker of manganese brain accumulation and associated with manganese levels in blood: a meta-analysis. PLoS One 2014; 9:e93900. [PMID: 24718592 PMCID: PMC3981755 DOI: 10.1371/journal.pone.0093900] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 03/09/2014] [Indexed: 12/18/2022] Open
Abstract
OBJECTIVE The current study was designed to evaluate the sensitivity, feasibility, and effectiveness of the pallidal index (PI) serving as a biomarker of brain manganese (Mn) accumulation, which would be used as an early diagnosis criteria for Mn neurotoxicity. METHODS The weighted mean difference (WMD) of the PI between control and Mn-exposed groups was estimated by using a random-effects or fixed-effects meta-analysis with 95% confidence interval (CI) performed by STATA software version 12.1. Moreover, the R package "metacor" was used to estimate correlation coefficients between PI and blood Mn (MnB). RESULTS A total of eight studies with 281 occupationally Mn-exposed workers met the inclusion criteria. Results were pooled and performed with the Meta-analysis. Our data indicated that the PI of the exposed group was significantly higher than that of the control (WMD: 7.76; 95% CI: 4.86, 10.65; I2 = 85.7%, p<0.0001). A random effects model was used to perform meta-analysis. These findings were remarkably robust in the sensitivity analysis, and publication bias was shown in the included studies. Seven out of the eight studies reported the Pearson correlation (r) values. Significantly positive correlation between PI and MnB was observed (r = 0.42; 95% CI, 0.31, 0.52). CONCLUSIONS PI can be considered as a sensitive, feasible, effective and semi-quantitative index in evaluating brain Mn accumulation. MnB can also augment the evaluation of brain Mn accumulation levels in the near future. However, the results should be interpreted with caution.
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Affiliation(s)
- Shao-Jun Li
- Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China
| | - Li Jiang
- Department of Radiotherapy, the First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
| | - Xue Fu
- School of Health Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - Shuang Huang
- Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China
| | - Yan-Ni Huang
- Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China
| | - Xiang-Rong Li
- Department of Radiology, the First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
| | - Jing-Wen Chen
- Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China
| | - Yong Li
- Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China
| | - Hai-Lan Luo
- Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China
| | - Fang Wang
- Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China
| | - Shi-Yan Ou
- Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China
| | - Yue-Ming Jiang
- Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China
- * E-mail:
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17
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Kim CY, Sung JH, Chung YH, Park JD, Han JH, Lee JS, Heo JD, Yu IJ. Home cage locomotor changes in non-human primates after prolonged welding-fume exposure. Inhal Toxicol 2013; 25:794-801. [DOI: 10.3109/08958378.2013.849316] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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18
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Lee JH, Kim YS, Song KS, Ryu HR, Sung JH, Park JD, Park HM, Song NW, Shin BS, Marshak D, Ahn K, Lee JE, Yu IJ. Biopersistence of silver nanoparticles in tissues from Sprague-Dawley rats. Part Fibre Toxicol 2013; 10:36. [PMID: 24059869 PMCID: PMC3734196 DOI: 10.1186/1743-8977-10-36] [Citation(s) in RCA: 163] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Accepted: 07/31/2013] [Indexed: 11/13/2022] Open
Abstract
Silver nanoparticles are known to be distributed in many tissues after oral or inhalation exposure. Thus, understanding the tissue clearance of such distributed nanoparticles is very important to understand the behavior of silver nanoparticles in vivo. For risk assessment purposes, easy clearance indicates a lower overall cumulative toxicity. Accordingly, to investigate the clearance of tissue silver concentrations following oral silver nanoparticle exposure, Sprague–Dawley rats were assigned to 3 groups: control, low dose (100 mg/kg body weight), and high dose (500 mg/kg body weight), and exposed to two different sizes of silver nanoparticles (average diameter 10 and 25 nm) over 28 days. Thereafter, the rats were allowed to recover for 4 months. Regardless of the silver nanoparticle size, the silver content in most tissues gradually decreased during the 4-month recovery period, indicating tissue clearance of the accumulated silver. The exceptions were the silver concentrations in the brain and testes, which did not clear well, even after the 4-month recovery period, indicating an obstruction in transporting the accumulated silver out of these tissues. Therefore, the results showed that the size of the silver nanoparticles did not affect their tissue distribution. Furthermore, biological barriers, such as the blood–brain barrier and blood-testis barrier, seemed to play an important role in the silver clearance from these tissues.
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Affiliation(s)
- Ji Hyun Lee
- Institute of Nanoproduct Safety Research, Hoseo University, 165 Sechul-ri, Baebang-myun, Asan 336-795 South Korea.
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19
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Grünecker B, Kaltwasser SF, Zappe AC, Bedenk BT, Bicker Y, Spoormaker VI, Wotjak CT, Czisch M. Regional specificity of manganese accumulation and clearance in the mouse brain: implications for manganese-enhanced MRI. NMR IN BIOMEDICINE 2013; 26:542-556. [PMID: 23168745 DOI: 10.1002/nbm.2891] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 10/17/2012] [Accepted: 10/21/2012] [Indexed: 06/01/2023]
Abstract
Manganese-enhanced MRI has recently become a valuable tool for the assessment of in vivo functional cerebral activity in animal models. As a result of the toxicity of manganese at higher dosages, fractionated application schemes have been proposed to reduce the toxic side effects by using lower concentrations per injection. Here, we present data on regional-specific manganese accumulation during a fractionated application scheme over 8 days of 30 mg/kg MnCl2 , as well as on the clearance of manganese chloride over the course of several weeks after the termination of the whole application protocol supplying an accumulative dose of 240 mg/kg MnCl2 . Our data show most rapid accumulation in the superior and inferior colliculi, amygdala, bed nucleus of the stria terminalis, cornu ammonis of the hippocampus and globus pallidus. The data suggest that no ceiling effects occur in any region using the proposed application protocol. Therefore, a comparison of basal neuronal activity differences in different animal groups based on locally specific manganese accumulation is possible using fractionated application. Half-life times of manganese clearance varied between 5 and 7 days, and were longest in the periaqueductal gray, amygdala and entorhinal cortex. As the hippocampal formation shows one of the highest T1 -weighted signal intensities after manganese application, and manganese-induced memory impairment has been suggested, we assessed hippocampus-dependent learning as well as possible manganese-induced atrophy of the hippocampal volume. No interference of manganese application on learning was detected after 4 days of Mn(2+) application or 2 weeks after the application protocol. In addition, no volumetric changes induced by manganese application were found for the hippocampus at any of the measured time points. For longitudinal measurements (i.e. repeated manganese applications), a minimum of at least 8 weeks should be considered using the proposed protocol to allow for sufficient clearance of the paramagnetic ion from cerebral tissue.
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Affiliation(s)
- B Grünecker
- Max Planck Institute of Psychiatry, Munich, Germany
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20
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Sriram K, Lin GX, Jefferson AM, Roberts JR, Andrews RN, Kashon ML, Antonini JM. Manganese accumulation in nail clippings as a biomarker of welding fume exposure and neurotoxicity. Toxicology 2012; 291:73-82. [DOI: 10.1016/j.tox.2011.10.021] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 10/20/2011] [Accepted: 10/31/2011] [Indexed: 11/15/2022]
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21
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Persistence of deposited metals in the lungs after stainless steel and mild steel welding fume inhalation in rats. Arch Toxicol 2010; 85:487-98. [PMID: 20924559 DOI: 10.1007/s00204-010-0601-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Accepted: 09/22/2010] [Indexed: 10/19/2022]
Abstract
Welding generates complex metal fumes that vary in composition. The objectives of this study were to compare the persistence of deposited metals and the inflammatory potential of stainless and mild steel welding fumes, the two most common fumes used in US industry. Sprague-Dawley rats were exposed to 40 mg/m(3) of stainless or mild steel welding fumes for 3 h/day for 3 days. Controls were exposed to filtered air. Generated fume was collected, and particle size and elemental composition were determined. Bronchoalveolar lavage was done on days 0, 8, 21, and 42 after the last exposure to assess lung injury/inflammation and to recover lung phagocytes. Non-lavaged lung samples were analyzed for total and specific metal content as a measure of metal persistence. Both welding fumes were similar in particle morphology and size. Following was the chemical composition of the fumes-stainless steel: 57% Fe, 20% Cr, 14% Mn, and 9% Ni; mild steel: 83% Fe and 15% Mn. There was no effect of the mild steel fume on lung injury/inflammation at any time point compared to air control. Lung injury and inflammation were significantly elevated at 8 and 21 days after exposure to the stainless steel fume compared to control. Stainless steel fume exposure was associated with greater recovery of welding fume-laden macrophages from the lungs at all time points compared with the mild steel fume. A higher concentration of total metal was observed in the lungs of the stainless steel welding fume at all time points compared with the mild steel fume. The specific metals present in the two fumes were cleared from the lungs at different rates. The potentially more toxic metals (e.g., Mn, Cr) present in the stainless steel fume were cleared from the lungs more quickly than Fe, likely increasing their translocation from the respiratory system to other organs.
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