At CIH Enterprises, Inc. we have spent decades gathering ISO 17025 quantitative data from across the world with millions of data points that allow for our team to conduct occupational studies assessing retrospective exposures, it is ideal to have historical quantified measurements on all study participants. As part of an ongoing epidemiological study of parkinsonism in welders, the objective and mission of our company is to help companies develop and validate a multivariate model to estimate quantitative levels of welding fume exposures based on welding particulate mass and manganese (Mn) concentrations specific to their industry and occupational applications.
Fume generated during welding processes is a complex mixture of gases, metal oxides, silicates, and fluorides. The generation and composition of welding fume are dependent on a number of factors that include current and voltage applied, welding process performed, shielding gas used (if any), type and composition of the fluxes and/or electrodes used, and the type of base metal being welded. Exposure to welding fume is also dependent on work practices (number of welders, posture or position during welding, work speed and technique, and use of respirator), the degree of enclosure of the work environment, and the type and effectiveness of mechanical ventilation provided.
Both acute and chronic health effects due to inhalation of welding fume have been well described. For instance, welders have increased frequency, severity, and duration of respiratory tract infections compared to the general population. Other respiratory complications associated with welding include pulmonary function abnormalities, bronchitis, siderosis, and asthma. Welding fume has been classified as a possible human carcinogen by the International Agency for Research on Cancer (IARC, 1990). Exposure to specific metals in welding fume is also of concern. Iron exposures can lead to siderosis; zinc, copper, and magnesium exposures can cause metal fume fever; and chromium VI can cause severe irritation to the upper respiratory tract and has also been classified as carcinogenic to humans by the IARC (IARC, 1990).
Concerns about exposure to manganese (Mn) have also increased over recent years. Manganese (Mn), recognized as a neurotoxin since the mid 1800s, is commonly found in welding fume. Many welders are regularly overexposed to the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 0.2 mg/m3. Two studies in industrial and construction settings estimated that 62% of welders and 72% of boilermakers, respectively, were overexposed to the manganese (Mn) TLV manganese Fume generated during welding processes is a complex mixture of gases, metal oxides, silicates, and fluorides. The generation and composition of welding fume are dependent on a number of factors that include current and voltage applied), welding process performed, shielding gas used (if any), type and composition of the fluxes and/or electrodes used, and the type of base metal being welded. Exposure to welding fume is also dependent on work practices (number of welders, posture or position during welding, work speed and technique, and use of respirator), the degree of enclosure of the work environment, and the type and effectiveness of mechanical ventilation provided.
Both acute and chronic health effects due to inhalation of welding fume have been well described. For instance, welders have increased frequency, severity, and duration of respiratory tract infections compared to the general population. Other respiratory complications associated with welding include pulmonary function abnormalities, bronchitis, siderosis, and asthma. Welding fume has been classified as a possible human carcinogen by the International Agency for Research on Cancer (IARC, 1990). Exposure to specific metals in welding fume is also of concern. Iron exposures can lead to siderosis; zinc, copper, and magnesium exposures can cause metal fume fever; and chromium VI can cause severe irritation to the upper respiratory tract and has also been classified as carcinogenic to humans by the IARC (IARC, 1990).
Concerns about exposure to manganese (Mn) have also increased over recent years. Manganese (Mn), recognized as a neurotoxin since the mid 1800s, is commonly found in welding fume. Many welders are regularly overexposed to the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 0.2 mg/m3. Two studies in industrial and construction settings estimated that 62% of welders and 72% of boilermakers, respectively, were overexposed to the manganese (Mn) TLV. Furthermore, a study that analyzed three distinct welding data sets from the United States Occupational Safety and Health Administration (OSHA), The Welding Institute, and the Center for Construction Research and Training reported mean manganese (Mn) levels as 0.21, 0.26, and 0.27mg/m3, respectively. The ACGIH TLV of 0.2 mg/m3 was primarily set in regard to neurological effects (ACGIH, 1992), and there is a reason to believe that these common overexposures may play a role in the development of parkinsonism.
A limitation of these studies is that occupational exposure assessment has typically been minimal, whereby only current exposures were measured in cross-sectional studies, or job title or ‘ever employed’ in the industry has been used as the exposure index in the case reports and case–control studies. This type of classification is considered the weakest indicator or approximation of exposure and can introduce a significant amount of exposure misclassification. True exposure–response associations may then be missed. It is recognized that additional scientific evidence is needed to determine the role of welder’s exposure to manganese (Mn) or other welding fume constituents might play in the development of welding-related parkinsonism or PD. More sophisticated exposure assessment is needed to aid continued epidemiological work.
In studies assessing retrospective exposures, it is ideal to have historical quantified measurements on all study participants. However, in some studies, such detailed information on past exposures may not be available or accessible from workplace records. Estimates of individual exposure must then be made from other available data sources, including self-reported exposure information and exposure values found in the published literature. As part of an ongoing epidemiological study of parkinsonism in welders, the objective of this study was to develop and validate a multivariate model to estimate quantitative levels of welding fume exposures based on welding particulate mass and manganese (Mn) concentrations reported in the published literature.
Furthermore, a study that analyzed three distinct welding data sets from the United States Occupational Safety and Health Administration (OSHA), The Welding Institute, and the Center for Construction Research and Training reported mean manganese (Mn) levels as 0.21, 0.26, and 0.27mg/m3, respectively (Flynn and Susi, 2010). The ACGIH TLV of 0.2 mg/m3 was primarily set in regard to neurological effects (ACGIH, 1992), and there is a reason to believe that these common overexposures may play a role in the development of parkinsonism.
A limitation of historical studies is that occupational exposure assessment has typically been minimal, whereby only current exposures were measured in cross-sectional studies, or job title or ‘ever employed’ in the industry has been used as the exposure index in the case reports and case–control studies. This type of classification is considered the weakest indicator or approximation of exposure and can introduce a significant amount of exposure misclassification. True exposure–response associations may then be missed. It is recognized that additional scientific evidence is needed to determine the role of welder’s exposure to manganese (Mn) or other welding fume constituents might play in the development of welding-related parkinsonism or Parkinson’s disease (PD). At CIH Enterprises, Inc . we execute exposure assessments that are needed to aid in continued epidemiological work and allow companies to understand potential toxic tort liabilities.