Posted below is just a small selection of the most important studies related to occupation and risk factors in Parkinson’s Disease and exposure to manganese. According to these and other studies, there is simply no reliable evidence to support a connection between welding fumes or manganese and Parkinson’s Disease.

Occupation and Risk of Parkinsonism
A Multicenter Case-Control Study

Author:Caroline M. Tanner, MD, Ph.D.; G. Webster Ross, MD; Sarah A. Jewell, MD, MPH; Robert A. Hauser, MD; Joseph Jankovic, MD; Stewart A. Factor, DO; Susan Bressman, MD; Amanda Deligtisch, MD; Connie Marras, MD, Ph.D., FRCPC; Kelly E. Lyons, Ph.D.; Grace S. Bhudhikanok, Ph.D.; Diana F. Roucoux, MPH; Cheryl Meng, MS; Robert D. Abbott, Ph.D.; J. William Langston, MD
Publication:Archives of Neurology
Date:September 2009
Description:This case-control study was designed to evaluate whether working in certain occupations or exposure to specific toxicants was associated with the risk of being diagnosed with Parkinson’s disease or other types of parkinsonism. The study compared lifelong occupational and job task histories for participants that worked in a variety of occupations that had been reported elsewhere to be associated with parkinsonism, including agriculture, education, health care, and welding. Findings in 519 cases and 511 controls were analyzed and results showed that those who worked in farming, healthcare, education, and welding did not have increased rates of parkinsonism.  Neither overall risk of parkinsonism or PD, age at diagnosis, nor PIGD (postural instability and gait difficulty) subtype was associated with welding or machining. These results are consistent with national databases, industrial populations, and other clinic-based case-control studies, which do not associate welding with a greater risk of PD. The study also showed that occupational use of pesticides was associated with an almost 80% greater risk of parkinsonism. Click here to access the full study.

Environmental Risk Factors for Parkinson’s Disease and Parkinsonism: The Geoparkinson Study

Author:Finlay D. Dick, Anthony Seaton, Neva Haites, Sean E. Semple, Smita Dick, Gordon J. Prescott, Neil W. Scott, Jane E. Bennett, Carl E. Counsell, Antonio Mutti, Giuseppe De Palma, P. Mozzoni, Peter Söderkvist, Ahmad Ahmadi, Marina Otelea, Alex Felice and Stephanie Bezzina Wettinger
Publication:Occupational and Environmental Medicine
Date:March 2007
Description:Epidemiological study of 959 prevalent cases of parkinsonism and 1,989 controls in five European countries that investigated associations between Parkinson’s disease and other degenerative parkinsonian syndromes and environmental factors, including exposure to solvents, pesticides, iron, copper, and manganese. Using the average annual intensity of exposure analysis, this population-based, case-control study found no association between high or low exposure to manganese and parkinsonism or Parkinson’s disease. The study was conducted by a large group of European researchers and, as set forth in the acknowledgments section, was funded by the European Union.

Parkinson’s Disease and Other Basal Ganglia or Movement Disorders in a Large Nationwide Cohort of Swedish Welders

Author:C.M. Fored, J.P. Fryzek, L. Brandt, G. Nise, B. Sjögren, J.K. McLaughlin, W.J. Blot, and A. Ekbom
Publication:Occupational and Environmental Medicine
Date:February 2006
Description:An epidemiological linked-registry cohort study of almost 50,000 Swedish welders, followed for an average of 29 years, compared to an age and geographical matched control group of close to 500,000 Swedish non-welders, to evaluate increased risks of Parkinson’s disease or other basal ganglia and movement disorders for welders. This nationwide linked-registry study compares the rates of hospitalization and death for the two groups and concludes that there is no support for a relation between welding and Parkinson’s disease or any other neurodegenerative disorders.

Searching for a Relationship between Manganese and Welding and Parkinson’s Disease (PDF)

Author:Joseph Jankovic, MD
Description:In this review article published in Neurology, Dr. Joseph Jankovic, Professor of Neurology, Director of Parkinson’s Disease Center and Movement Disorders Clinic, Baylor College of Medicine, determines that there does not exist reliable or convincing evidence that welding is a risk factor for Parkinson’s disease or parkinsonism, or that manganese-induced parkinsonism shares any pathogenetic mechanisms with Parkinson’s disease.

Welding and Parkinson’s Disease: Is There a Bond? (PDF)

Author:Karl Kieburtz, MD, MPH; and Roger Kurlan, MD
Description:In this editorial published in Neurology, Dr. Karl Kieburtz, Professor of Neurology and Community and Preventive Medicine Unit Chief, Movement and Inherited Neurological Disorders, University of Rochester Medical Center, discusses the current state of the science around the issue of welding, manganese, Parkinson’s disease, and Parkinsonism. He posits that articles, such as those by Racette and Josephs, fail to demonstrate any causal relationship between welding and these neurological disorders because of numerous methodological flaws. Thus, he concludes, any associations of neurological syndromes with welding fume exposure are purely speculative.

A Cohort Study of Parkinson’s Disease and Other Neurodegenerative Disorders in Danish Welders (PDF)

Authors:Jon Fryzek, PhD, Johnni Hansen, PhD, Sarah Cohen, MS, Jens Peter Bonde, M.D., DMSc, Maria Therese Llambias, MS, Henrik Kolstad, M.D., PhD, Axel Skytthe, PhD, Loren Lipworth, ScD, William Blot, PhD, Jorgen Olsen, M.D., DMsc.
Publication:Journal of Occupational and Environmental Medicine
Date:May 2005
Description:Epidemiological cohort study used data collected over a 25-year period to evaluate the prevalence of Parkinson’s Disease, as well as other neurodegenerative disorders including manganism, in a group of 9,817 male workers who were either welders or exposed to welding fumes while working in departments where mild or stainless steel welding occurred. This large study with long-term follow-up concluded that men who engaged in mild and stainless steel welding did not have increased hospitalizations for Parkinson’s Disease or other neurodegenerative disorders and that welders were no more likely to develop Parkinson’s Disease or other neurodegenerative diseases than the general public of Denmark.

Report of David Garabrant, M.D., M.P.H. (PDF)
Certain portions of this document have been temporarily edited out in order to comply with a court-imposed confidentiality order.

Description:In this report filed by the defense in the multi-district litigation, Dr. David Garabrant, Professor of Occupational Medicine and Epidemiology at the University of Michigan School of Public Health, reviews the relevant medical and scientific literature and determines that there does not exist reliable scientific evidence to support an opinion that there exists a link between exposure to welding fume and the development of Parkinson’s disease or parkinsonism.

Occupations and Parkinson’s Disease:
A Multi-Center Case-Control Study in South Korea

Authors:Jungsun Park, Cheol-In Yoo, Chang Sun Sim, Hyo Kyung Kim, Jae Woo Kim, Beom S. Jeon, Ki-Rak Kim, Oh-Young Bang, Won-Yong Lee, Yunjeong Yi, Kap-Yeol Jung, Soo-Eun Chung, Yangho Kim
Date:January 2005
Description:A hospital-based case-control study to evaluate the role of occupational exposure to manganese as a cause of Parkinson’s disease and discover whether an association exists between occupation and Parkinson’s disease. A study found that manganese exposure is not a risk factor for Parkinson’s disease and that occupations with potential exposure to manganese such as welder, smelter, welding rod manufacturer, manganese miner, workers in the iron and steel industries, and dry cell battery manufacturers showed consistently negative associations with PD after adjusting the confounders such as age, sex and smoking, and education level.

Reprinted from Neurotoxicology, Volume 26, Pages 99-105, Copyright 2005, with permission from Elsevier

Occupational Risk Factors in Parkinson’s Disease (PDF)

Authors:Joseph K.C. Tsui, M.D., FRCPC, Donald B. Calne, M.D., FRCPC, Yue Wang, M.D., Michael Schulzer, M.D., Ph.D., Stephen A. Marion, M.D., FRCPC
Publication:Canadian Journal of Public Health
Date:September-October 1999
Description:A case-control study evaluated whether occupations, including welding, were associated with an increased risk of PD among the general population of Vancouver, British Columbia, Canada. Although Dr. Tsui reported associations between PD and numerous occupations, welding was not among those found to be associated with PD. This very large study does not support a conclusion that welders are at increased risk of PD.

Reprinted with permission of the Canadian Public Health Association. Published in the Canadian Journal of Public Health, September/October 1999., Vol. 90, No. 5, pages 334-37.

Occupation and Risk of Parkinson’s Disease (PD): A Preliminary Investigation of Standard Occupational Codes (SOC) in Twins Discordant for Disease (PDF)

Authors:Caroline M. Tanner, Samuel M. Goldman, Sunnyvale, CA, Patricia Quinlan, San Francisco, CA, Robert Field, Sunnyvale, CA, Diana A. Aston, Sunnyvale, CA, Kathleen Comyns, Amanda Smith, Cheryl Meng, Zhi Hui Wang, Connie Marras, Monica Korell, J. William Langston, Sunnyvale, CA, G. Webster Ross, Honolulu, HI
Publication:Neurology, the official journal of the American Academy of Neurology
Date:March 2003
Description:A case-control study evaluated whether welding was associated with an increased risk of PD. Dr. Tanner’s study consisted of World War II veteran twin pairs, where one twin had PD and the other did not. The study found that while teachers and healthcare workers were shown to have an increased risk, perhaps because of their exposure to infectious diseases, individuals who performed welding did not show any increased risk of PD.

Occupation and Parkinson’s Disease (PD) Onset Age in a Movement Disorders Clinic (PDF)

Authors:Samuel M. Goldman, Robert D. Field, Warren Olanow, New York, NY, J. William Langston, Caroline M. Tanner, Sunnyvale, CA
Date:April 27, 2004
Description:A recent survey of the medical records of approximately 1,000 consecutive PD patients seen between 2000 and 2002 at the Parkinson’s Institute in Sunnyvale, CA, in order to determine if welding was associated with an earlier age of PD onset; the authors specifically concluded that welding was not associated with an earlier onset of PD in the clinical population they studied.

The health of Arc Welders in Steel Ship Construction (PDF)

Authors:Waldemar C. Dreessen, Hugh P. Brinton, Robert G. Keenan, Thalbert R. Thomas, Edwin H. Place, James E. Fuller
Publication:Federal Security Agency – Public Health Bulletin
Description:Dr. Waldemar C. Dreessen extensively examined the health of thousands of World War II welders and presented the results of an investigation by the U.S. Maritime Commission into the health hazards of a group of shipyard arc welders who engaged in mild steel and galvanized steel welding. Although the report primarily addressed respiratory and cardiovascular health issues, significantly, no neurological problems were noted among such a large group of welders who engaged in a significant amount of welding. Dr. Dreessen credited safety in ventilating procedures in the shipyards as a material reason for the welders’ lack of diseases of industrial origin.

Mortality Patterns Among U.S. Veterans by Occupation and Smoking Status (PDF)

Authors:Judy Walrath, Ph.D., Eugene Rogot, M.A., James Murray, D.V.M., Aaron Blair, PhD
Publication:National Institute of Health Publication
Date:October 21, 1985
Description:Cohort study examining mortality patterns among U.S. Veterans classified by occupation. Despite the high level of welding that took place during World War II, PD was not the cause of death in any of the 771 veterans classified as welder or flame cutter.

Occupational Mortality in Washington State (PDF)

Author:Samuel Milham, Jr., M.D., M.P.H.
Publication:U.S. Department of Health and Human Services; Public Health Service; Centers for Disease Control and Prevention; National Institute for Occupational Safety and Health
Date:March 1997
Description:A cohort study of manganese and PD in which Dr. Milham analyzed the death certificates of nearly 600,000 men and 90,000 women who died in Washington State between 1950 and 1989. Dr. Milham found only 4 cases of PD among welders and flame cutters — roughly 8 were expected — and found no statistically significant association between welding and PD.

Parkinson’s Disease: A Test of the Multifactorial, Etiologic Hypothesis (PDF)

Authors:Karen M. Semchuk, Ph.D., Edgar J. Love, Ph.D., Robert G. Lee, MD, FRCPC
Publication:Neurology, the official journal of the American Academy of Neurology
Date:June 1993
Description:Population-based, case-control study of PD in the city of Calgary, Alberta, Canada to test for an association between the development of PD and family histories and various occupational exposures, including manganese. Dr. Semchuck did not find any association between occupational exposure to manganese and PD.

Multiple Risk Factors for Parkinson’s Disease (PDF)

Authors:Jay M. Gorell, Edward L. Peterson, Benjamin A. Rybicki, Christine Cole Johnson
Publication:Journal of the Neurological Sciences
Description:Follow-up article further examining the data from their 1999 study. The report found that after adjusting for age, sex and race, there was no exposure to manganese to be statistically significantly associated with PD.

Long Term Exposure to Manganese in Rural Well Water Has No Neurological Effects (PDF)

Authors:P. Vieregge, B. Heinzow, G. Korf, H.-M. Teichert, P. Schleifenbaum, H.-U. Mösinger
Publication:Canadian Journal of Neurological Sciences
Date:November 1995
Description:Cohort study testing the neurological impact of chronic exposure to manganese through well water. The authors concluded that exposure to manganese in drinking water is not a risk factor for PD.

Possible Environmental Occupational and Other Etiologic Factors for Parkinson’s Disease: A Case-Control Study in Germany (PDF)

Authors:A. Seidler, MD, W. Hellenbrand, MD, MPH, B.-P. Robra, MD, MPH, P. Vieregge, MD, P. Nischan, PhD, J. Joerg, MD, W.H. Oertel, MD, G. Ulm MD, E. Schneider, MD
Publication:Neurology, the official journal of the American Academy of Neurology
Date:May 1996
Description:Case-control study of PD enrolling various patients from German neurologic clinics, neighborhood controls, and regional controls. The authors could not report an association between manganese exposure and PD.