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Gonzalez-Cuyar LF, Nelson G, Nielsen SS, Dlamini WW, Keyser-Gibson A, Keene CD, Paulsen M, Criswell SR, Senini N, Sheppard L, Samy S, Simpson CD, Baker MG, Racette BA. Olfactory tract/bulb metal concentration in Manganese-exposed mineworkers. Neurotoxicology 2024; 102:96-105. [PMID: 38582332 DOI: 10.1016/j.neuro.2024.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Revised: 03/06/2024] [Accepted: 04/03/2024] [Indexed: 04/08/2024]
Abstract
BACKGROUND Manganese (Mn) is an essential micronutrient as well as a well-established neurotoxicant. Occupational and environmental exposures may bypass homeostatic regulation and lead to increased systemic Mn levels. Translocation of ultrafine ambient airborne particles via nasal neuronal pathway to olfactory bulb and tract may be an important pathway by which Mn enters the central nervous system. OBJECTIVE To measure olfactory tract/bulb tissue metal concentrations in Mn-exposed and non-exposed mineworkers. METHODS Using inductively coupled plasma-mass spectrometry (ICP-MS), we measured and compared tissue metal concentrations in unilateral olfactory tracts/bulbs of 24 Mn-exposed and 17 non-exposed South African mineworkers. We used linear regression to investigate the association between cumulative Mn exposures and olfactory tract/bulb Mn concentration. RESULTS The difference in mean olfactory tract/bulb Mn concentrations between Mn-exposed and non-Mn exposed mineworkers was 0.16 µg/g (95% CI -0.11, 0.42); but decreased to 0.09 µg/g (95% CI 0.004, 0.18) after exclusion of one influential observation. Olfactory tract/bulb metal concentration and cumulative Mn exposure suggested there may be a positive association; for each mg Mn/m3-year there was a 0.05 µg/g (95% CI 0.01, 0.08) greater olfactory tract/bulb Mn concentration overall, but -0.003 (95% CI -0.02, 0.02) when excluding the three influential observations. Recency of Mn exposure was not associated with olfactory tract/bulb Mn concentration. CONCLUSIONS Our findings suggest that Mn-exposed mineworkers might have higher olfactory tract/bulb tissue Mn concentrations than non-Mn exposed mineworkers, and that concentrations might depend more on cumulative dose than recency of exposure.
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Affiliation(s)
- Luis F Gonzalez-Cuyar
- University of Washington, School of Medicine and Department of Laboratory Medicine and Pathology, Division of Neuropathology, 325 9th Ave, Seattle, WA 98104, USA.
| | - Gill Nelson
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 27 St Andrews Rd, Parktown 2193, South Africa; Department of Neurology, Barrow Neurological Institute, 240 W Thomas Rd, Phoenix, AZ 85013, USA
| | - Susan Searles Nielsen
- Department of Neurology, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO 63110, USA
| | - Wendy W Dlamini
- Department of Neurology, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO 63110, USA; Department of Epidemiology, School of Public Health, University of Washington, 3980 15th Ave NE, Seattle, WA 98195, USA
| | - Amelia Keyser-Gibson
- University of Washington, School of Medicine and Department of Laboratory Medicine and Pathology, Division of Neuropathology, 325 9th Ave, Seattle, WA 98104, USA
| | - C Dirk Keene
- University of Washington, School of Medicine and Department of Laboratory Medicine and Pathology, Division of Neuropathology, 325 9th Ave, Seattle, WA 98104, USA
| | - Michael Paulsen
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, 1959 NE Pacific St, Seattle, WA 98195, USA
| | - Susan R Criswell
- Department of Neurology, Barrow Neurological Institute, 240 W Thomas Rd, Phoenix, AZ 85013, USA; Department of Neurology, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO 63110, USA
| | - Natalie Senini
- Department of Neurology, Barrow Neurological Institute, 240 W Thomas Rd, Phoenix, AZ 85013, USA
| | - Lianne Sheppard
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, 1959 NE Pacific St, Seattle, WA 98195, USA; Department of Biostatistics, School of Public Health, University of Washington, 3980 15th Ave NE, Seattle, WA 98195, USA
| | - Shar Samy
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, 1959 NE Pacific St, Seattle, WA 98195, USA
| | - Christopher D Simpson
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, 1959 NE Pacific St, Seattle, WA 98195, USA
| | - Marissa G Baker
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, 1959 NE Pacific St, Seattle, WA 98195, USA
| | - Brad A Racette
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 27 St Andrews Rd, Parktown 2193, South Africa; Department of Neurology, Barrow Neurological Institute, 240 W Thomas Rd, Phoenix, AZ 85013, USA; Department of Neurology, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO 63110, USA
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Racette BA, Nelson G, Dlamini WW, Hershey T, Prathibha P, Turner JR, Checkoway H, Sheppard L, Searles Nielsen S. Environmental manganese exposure and cognitive control in a South African population. Neurotoxicology 2022; 89:31-40. [PMID: 34999155 DOI: 10.1016/j.neuro.2022.01.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Revised: 11/29/2021] [Accepted: 01/05/2022] [Indexed: 12/17/2022]
Abstract
OBJECTIVE To characterize the association between environmental (residential air) manganese (Mn) exposure and cognitive performance, focusing on cognitive control, in a Black African population. METHODS We administered the Go-No-Go, Digit Span, and Matrix Reasoning tests to population-based samples age ≥40 from a high Mn (smelter) exposed community, Meyerton (N = 629), and a demographically comparable low (background levels) non-exposed community, Ethembalethu, (N = 96) in Gauteng province, South Africa. We investigated the associations between community and performance on the cognitive tests, using linear regression. We adjusted a priori for age and sex, and examined the effect of adjustment for education, nonverbal IQ, smoking, and alcohol consumption. We measured airborne PM2.5-Mn to confirm community exposure differences. RESULTS Compared to Ethembalethu residents, Meyerton residents' test scores were lower (poorer) for all tests: 0.55 (95 % confidence interval [CI] 0.08, 1.03) lower scores for Matrix Reasoning, 0.34 (95 % CI -0.07, 0.75) lower for Digit Span, and 0.15 (95 % CI 0.09, 0.21) lower for Go-No-Go (high frequency discriminability index [probability]). The latter represented the most marked difference in terms of z-scores (0.50, 95 % CI 0.30, 0.71 standard deviations lower). The mean of the z-score of each of the three tests was also lower (0.34, 95 % CI 0.18, 0.50 standard deviations lower). These associations were similar in men and women, but attenuated with adjustment for education. Differences for Matrix Reasoning and Digit Span between the two communities were observed only among those who had lived in Meyerton ≥10 years, whereas for Go-No-Go, differences were also apparent among those who had lived in Meyerton <10 years. Mean PM2.5-Mn at a long-term fixed site in Meyerton was 203 ng/m3 and 10 ng/m3 in Ethembalethu. CONCLUSION Residence in a community near a high Mn emission source is associated with cognitive dysfunction, including aspects of cognitive control as assessed by the Go-No-Go test.
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Affiliation(s)
- Brad A Racette
- Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8111, St. Louis, MO 63110, USA; School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2193, South Africa.
| | - Gill Nelson
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2193, South Africa.
| | - Wendy W Dlamini
- Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8111, St. Louis, MO 63110, USA.
| | - Tamara Hershey
- Departments of Psychiatry and Radiology, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8225, St. Louis, MO, USA.
| | - Pradeep Prathibha
- Department of Energy, Environmental, and Chemical Engineering, Washington University, Campus Box 1180, One Brookings Drive, St. Louis, MO 63130, USA.
| | - Jay R Turner
- Department of Energy, Environmental, and Chemical Engineering, Washington University, Campus Box 1180, One Brookings Drive, St. Louis, MO 63130, USA.
| | - Harvey Checkoway
- Herbert Wertheim School of Public Health and Department of Neurosciences, University of California, San Diego, 9500 Gilman Drive, # 0725, La Jolla, CA 92093-0725, USA.
| | - Lianne Sheppard
- Departments of Biostatistics and Environmental and Occupational Health Sciences, University of Washington, Hans Rosling Center for Population Health, Box 351618, 3980 15th Avenue NE, Seattle, WA 98195-1618, USA.
| | - Susan Searles Nielsen
- Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8111, St. Louis, MO 63110, USA.
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Criswell SR, Searles Nielsen S, Dlamini WW, Warden MN, Perlmutter JS, Sheppard L, Moerlein SM, Lenox-Krug J, Checkoway H, Racette BA. Principal Component Analysis of Striatal and Extrastriatal D2 Dopamine Receptor Positron Emission Tomography in Manganese-Exposed Workers. Toxicol Sci 2021; 182:132-141. [PMID: 33881537 DOI: 10.1093/toxsci/kfab045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The relationships between the neurotoxicant manganese (Mn), dopaminergic pathology, and parkinsonism remain unclear. Therefore, we used [11C](N-methyl)benperidol (NMB) positron emission tomography to investigate the associations between Mn exposure, striatal and extrastriatal D2 dopamine receptors (D2R), and motor function in 54 workers with a range of Mn exposure. Cumulative Mn exposure was estimated from work histories, and all workers were examined by a movement specialist and completed a Grooved Pegboard test (GPT). NMB D2R nondisplaceable binding potentials (BPND) were calculated for brain regions of interest. We identified 2 principal components (PCs) in a PC analysis which explained 66.8% of the regional NMB BPND variance (PC1 = 55.4%; PC2 = 11.4%). PC1 was positively correlated with NMB binding in all regions and inversely correlated with age. PC2 was driven by NMB binding in 7 brain regions (all p < .05), positively in the substantia nigra, thalamus, amygdala, and medial orbital frontal gyrus and negatively in the nucleus accumbens, anterior putamen, and caudate. PC2 was associated with both Mn exposure status and exposure duration (years). In addition, PC2 was associated with higher Unified Parkinson's Disease Rating Scale motor subsection 3 (UPDRS3) scores and slower GPT performance. We conclude Mn exposure is associated with both striatal and extrastriatal D2R binding. Multifocal alterations in D2R expression are also associated with motor dysfunction as measured by both the GPT and UPDRS3, demonstrating a link between Mn exposure, striatal and extrastriatal D2R expression, and clinical neurotoxicity.
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Affiliation(s)
- Susan R Criswell
- Department of Neurology, Washington University School of Medicine, St Louis, Missouri 63110, USA
| | - Susan Searles Nielsen
- Department of Neurology, Washington University School of Medicine, St Louis, Missouri 63110, USA
| | - Wendy W Dlamini
- Department of Neurology, Washington University School of Medicine, St Louis, Missouri 63110, USA
| | - Mark N Warden
- Department of Neurology, Washington University School of Medicine, St Louis, Missouri 63110, USA
| | - Joel S Perlmutter
- Department of Neurology, Washington University School of Medicine, St Louis, Missouri 63110, USA.,Department of Radiology, Washington University School of Medicine, St Louis, Missouri 63110, USA.,Department of Neuroscience, Washington University School of Medicine, St Louis, Missouri 63110, USA.,Program in Physical Therapy, Washington University School of Medicine, St Louis, Missouri 63110, USA.,Program in Occupational Therapy, Washington University School of Medicine, St Louis, Missouri 63110, USA
| | - Lianne Sheppard
- Department of Environmental and Occupational Health Sciences, University of Washington, School of Public Health, Seattle, Washington 98195, USA.,Department of Biostatistics, University of Washington, School of Public Health, Seattle, Washington 98195, USA
| | - Stephen M Moerlein
- Department of Radiology, Washington University School of Medicine, St Louis, Missouri 63110, USA.,Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, Missouri 63110, USA
| | - Jason Lenox-Krug
- Department of Neurology, Washington University School of Medicine, St Louis, Missouri 63110, USA
| | - Harvey Checkoway
- Department of Family Medicine and Public Health, University of California, San Diego, School of Medicine, La Jolla, California 92093, USA.,Department of Neurosciences, University of California, San Diego, School of Medicine, La Jolla, California 92093, USA
| | - Brad A Racette
- Department of Neurology, Washington University School of Medicine, St Louis, Missouri 63110, USA.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Parktown 2193, South Africa
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Racette BA, Nelson G, Dlamini WW, Hershey T, Prathibha P, Turner JR, Checkoway H, Sheppard L, Searles Nielsen S. Depression and anxiety in a manganese-exposed community. Neurotoxicology 2021; 85:222-233. [PMID: 34087333 DOI: 10.1016/j.neuro.2021.05.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 05/24/2021] [Accepted: 05/31/2021] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To characterize the association between residential environmental manganese (Mn) exposure and depression and anxiety, given prior associations among occupationally-exposed workers. METHODS We administered the Beck Depression Inventory (BDI) and the State-Trait Anxiety Inventory (STAI) to 697 study participants in their preferred languages. These participants represented a population-based sample of residents aged ≥40 from two predominantly Black African communities in Gauteng province, South Africa: 605 in Meyerton, adjacent to a large Mn smelter, and 92 in Ethembalethu, a comparable non-exposed community. We investigated the associations between community (Meyerton vs. Ethembalethu) and severity of depression and anxiety, using linear regression, adjusting for age and sex. To document community-level differences in Mn exposure, we measured airborne PM2.5-Mn. RESULTS Meyerton residents had BDI scores 5.63 points (95 % CI 3.07, 8.20) higher than Ethembalethu residents, with all questions contributing to this significant difference. STAI-state scores were marginally higher in Meyerton than Ethembalethu residents [2.12 (95 % CI -0.17, 4.41)], whereas STAI-trait scores were more similar between the communities [1.26 (95 % CI -0.82, 3.35)]. Mean PM2.5-Mn concentration was 203 ng/m3 at a long-term fixed site in Meyerton and 10 ng/m3 in Ethembalethu. CONCLUSION Residence near Mn emission sources may be associated with greater depression symptomatology, and possibly current, but not lifetime, anxiety.
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Affiliation(s)
- Brad A Racette
- Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8111, St. Louis, MO, 63110, USA; School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2193, South Africa.
| | - Gill Nelson
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2193, South Africa.
| | - Wendy W Dlamini
- Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8111, St. Louis, MO, 63110, USA.
| | - Tamara Hershey
- Departments of Psychiatry and Radiology, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8225, St. Louis, MO, 63110, USA.
| | - Pradeep Prathibha
- Department of Energy, Environmental, and Chemical Engineering, Washington University, Campus Box 1180, One Brookings Drive, St. Louis, MO, 63130, USA.
| | - Jay R Turner
- Department of Energy, Environmental, and Chemical Engineering, Washington University, Campus Box 1180, One Brookings Drive, St. Louis, MO, 63130, USA.
| | - Harvey Checkoway
- Herbert Wertheim School of Public Health, University of California, San Diego, 9500 Gilman Drive, #0725, La Jolla, CA, 92093, USA.
| | - Lianne Sheppard
- Departments of Biostatistics and Environmental and Occupational Health Sciences, Box 357232, University of Washington, Seattle, WA, 98195, USA.
| | - Susan Searles Nielsen
- Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8111, St. Louis, MO, 63110, USA.
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Dlamini WW, Nielsen S, Ushe M, Nelson G, Racette BA. A Rapid Motor Task-Based Screening Tool for Parkinsonism in Community-Based Studies. Front Neurol 2021; 12:653066. [PMID: 34054697 PMCID: PMC8155367 DOI: 10.3389/fneur.2021.653066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 04/12/2021] [Indexed: 11/28/2022] Open
Abstract
Background: The prevalence of parkinsonism in developing countries is largely unknown due to difficulty in ascertainment because access to neurologists is often limited. Objective: Develop and validate a parkinsonism screening tool using objective motor task-based tests that can be administered by non-clinicians. Methods: In a cross-sectional population-based sample from South Africa, we evaluated 315 adults, age >40, from an Mn-exposed (smelter) community, using the Unified Parkinson Disease Rating Scale motor subsection 3 (UPDRS3), Purdue grooved pegboard, and kinematic-UPDRS3-based motor tasks. In 275 participants (training dataset), we constructed a linear regression model to predict UPDRS3. We selected motor task summary measures independently associated with UPDRS3 (p < 0.05). We validated the model internally in the remaining 40 participants from the manganese-exposed community (test dataset) using the area under the receiver operating characteristic curve (AUC), and externally in another population-based sample of 90 participants from another South African community with only background levels of environmental Mn exposure. Results: The mean UPDRS3 score in participants from the Mn-exposed community was 9.1 in both the training and test datasets (standard deviation = 6.4 and 6.1, respectively). Together, 57 (18.1%) participants in this community had a UPDRS3 ≥ 15, including three with Parkinson's disease. In the non-exposed community, the mean UPDRS3 was 3.9 (standard deviation = 4.3). Three (3.3%) had a UPDRS3 ≥ 15. Grooved pegboard time and mean velocity for hand rotation and finger tapping tasks were strongly associated with UPDRS3. Using these motor task summary measures and age, the UPDRS3 predictive model performed very well. In the test dataset, AUCs were 0.81 (95% CI 0.68, 0.94) and 0.91 (95% CI 0.81, 1.00) for cut points for neurologist-assessed UPDRS3 ≥ 10 and UPDRS3 ≥ 15, respectively. In the external validation dataset, the AUC was 0.85 (95% CI 0.73, 0.97) for UPDRS3 ≥ 10. AUCs were 0.76–0.82 when excluding age. Conclusion: A predictive model based on a series of objective motor tasks performs very well in assessing severity of parkinsonism in both Mn-exposed and non-exposed population-based cohorts.
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Affiliation(s)
- Wendy W Dlamini
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, United States
| | - Searles Nielsen
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, United States
| | - Mwiza Ushe
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, United States
| | - Gill Nelson
- Faculty of Health Sciences, School of Public Health, University of the Witwatersrand, Parktown, Johannesburg, South Africa.,Institute for Global Health, University College London, London, United Kingdom
| | - Brad A Racette
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, United States.,Faculty of Health Sciences, School of Public Health, University of the Witwatersrand, Parktown, Johannesburg, South Africa
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Racette BA, Nelson G, Dlamini WW, Prathibha P, Turner JR, Ushe M, Checkoway H, Sheppard L, Nielsen SS. Severity of parkinsonism associated with environmental manganese exposure. Environ Health 2021; 20:27. [PMID: 33722243 PMCID: PMC7962371 DOI: 10.1186/s12940-021-00712-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 03/03/2021] [Indexed: 05/03/2023]
Abstract
BACKGROUND Exposure to occupational manganese (Mn) is associated with neurotoxic brain injury, manifesting primarily as parkinsonism. The association between environmental Mn exposure and parkinsonism is unclear. To characterize the association between environmental Mn exposure and parkinsonism, we performed population-based sampling of residents older than 40 in Meyerton, South Africa (N = 621) in residential settlements adjacent to a large Mn smelter and in a comparable non-exposed settlement in Ethembalethu, South Africa (N = 95) in 2016-2020. METHODS A movement disorders specialist examined all participants using the Unified Parkinson Disease Rating Scale motor subsection part 3 (UPDRS3). Participants also completed an accelerometry-based kinematic test and a grooved pegboard test. We compared performance on the UPDRS3, grooved pegboard, and the accelerometry-based kinematic test between the settlements using linear regression, adjusting for covariates. We also measured airborne PM2.5-Mn in the study settlements. RESULTS Mean PM2.5-Mn concentration at a long-term fixed site in Meyerton was 203 ng/m3 in 2016-2017 - approximately double that measured at two other neighborhoods in Meyerton. The mean Mn concentration in Ethembalethu was ~ 20 times lower than that of the long-term Meyerton site. UPDRS3 scores were 6.6 (CI 5.2, 7.9) points higher in Meyerton than Ethembalethu residents. Mean angular velocity for finger-tapping on the accelerometry-based kinematic test was slower in Meyerton than Ethembalethu residents [dominant hand 74.9 (CI 48.7, 101.2) and non-dominant hand 82.6 (CI 55.2, 110.1) degrees/second slower]. Similarly, Meyerton residents took longer to complete the grooved pegboard, especially for the non-dominant hand (6.9, CI -2.6, 16.3 s longer). CONCLUSIONS Environmental airborne Mn exposures at levels substantially lower than current occupational exposure thresholds in the United States may be associated with clinical parkinsonism.
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Affiliation(s)
- Brad A. Racette
- Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8111, 63110 St. Louis, Missouri, USA
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, 2193 Parktown, South Africa
| | - Gill Nelson
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, 2193 Parktown, South Africa
- Research Department of Infection & Population Health, UCL Institute for Global Health, University College London, London, UK
| | - Wendy W. Dlamini
- Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8111, 63110 St. Louis, Missouri, USA
| | - Pradeep Prathibha
- Department of Energy, Environmental, and Chemical Engineering, Washington University, Campus Box 1180, One Brookings Drive, 63130 St. Louis, Missouri, USA
| | - Jay R. Turner
- Department of Energy, Environmental, and Chemical Engineering, Washington University, Campus Box 1180, One Brookings Drive, 63130 St. Louis, Missouri, USA
| | - Mwiza Ushe
- Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8111, 63110 St. Louis, Missouri, USA
| | - Harvey Checkoway
- Department of Family Medicine & Public Health, University of California, 9500 Gilman Drive, # 0725, La Jolla, 92093-0725 San Diego, California USA
| | - Lianne Sheppard
- Departments of Biostatistics and Environmental and Occupational Health Sciences, University of Washington, Box 357232, Washington, 98195 Seattle, USA
| | - Susan Searles Nielsen
- Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8111, 63110 St. Louis, Missouri, USA
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Dlamini WW, Nelson G, Nielsen SS, Racette BA. Manganese exposure, parkinsonian signs, and quality of life in South African mine workers. Am J Ind Med 2020; 63:36-43. [PMID: 31647574 DOI: 10.1002/ajim.23060] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 09/10/2019] [Indexed: 11/07/2022]
Abstract
BACKGROUND Manganese (Mn) neurotoxicity is associated with parkinsonism; the associated motor deficits can affect individuals' quality of life (QoL). We investigated associations between Mn exposure, parkinsonian signs, and QoL in Mn mine workers. METHODS We assessed parkinsonian signs and QoL in 187 black South African Mn mine workers, using the Unified Parkinson Disease Rating Scale motor subsection 3 (UPDRS3) and the Parkinson Disease Questionnaire (PDQ-39), respectively. We estimated cumulative Mn exposure in mg Mn/m3 -years using complete occupational histories and a job-exposure matrix. We investigated the cross-sectional association between cumulative Mn exposure and UPDRS3 score, and the UPDRS3 score and PDQ-39, adjusting for age, using linear regression. RESULTS Participants' mean age was 41.8 years (range, 21-67 years); 97.3% were male. Estimated mean cumulative Mn exposure at the time of examination was 5.4 mg Mn/m3 -years, with a mean of 14.0 years working in a Mn mine. The mean UPDRS3 score was 10.1 and 25.7% of the workers had a UPDRS3 score greater than or equal to 15. There was a U-shaped dose-response relation between cumulative Mn exposure and UPDRS3 score, with a positive association up to 15 mg Mn/m3 -years of exposure and an inverse association thereafter. Greater UPDRS3 scores were associated with poorer self-reported QoL. CONCLUSION In this cohort of employed Mn mine workers, parkinsonian signs were common and were associated with both estimated cumulative Mn exposure and poorer QoL.
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Affiliation(s)
- Wendy W Dlamini
- Occupational Health Division, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
- Department of Neurology, Washington University School of Medicine, St Louis, Missouri
| | - Gill Nelson
- Occupational Health Division, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
- Department of Infection & Population Health, Institute for Global Health, University College London, London, UK
| | - Susan Searles Nielsen
- Department of Neurology, Washington University School of Medicine, St Louis, Missouri
| | - Brad A Racette
- Occupational Health Division, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
- Department of Neurology, Washington University School of Medicine, St Louis, Missouri
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