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NIOSH Program Portfolio

 

Manufacturing

NORA Manufacturing Sector Strategic Goals

927ZBEF - Lung Effects of Resistance Spot Welding Using Adhesives

Start Date: 10/1/2007
End Date: 9/30/2010

Principal Investigator (PI)
Name: James Antonini
Phone: 304-285-6244
E-mail: jga6@cdc.gov
Organization: NIOSH
Sub-Unit: HELD
Funded By: NIOSH

Primary Goal Addressed
5.0

Secondary Goal Addressed
9.0


Attributed to Manufacturing
75%

Project Description

Short Summary

Aerosols formed during resistance spot welding may cause respiratory irritation in exposed workers. Information about the composition of substances generated during resistance spot welding is lacking. A robotic welding arm in the NIOSH welding lab will be configured and programmed to perform resistance spot welding to expose laboratory animals using process parameters common in the automotive industry. By using an animal model to mimic workplace exposures, our goal is to determine which component of the aerosols generated during resistance spot welding may be potentially toxic to exposed workers. With the information collected from the proposed NORA-funded study, it may be possible to eliminate or substitute with more inert chemicals the component of the process that is most hazardous to a significant number of workers in the Construction and Manufacturing sectors concerning respiratory disease and exposure to nanoparticles.



Description

In a Health Hazard Evaluation (#2006-0059-3009) performed by NIOSH at an automotive assembly plant, it was observed that numerous resistance spot welders had evidence of respiratory illness. Some chemicals that are associated with adhesives used in resistance welding were detected in the air of the plant. Several of these substances (e.g., methyl methacrylate, acetic acid, phthalic anhydride, formaldehyde, and styrene) have the potential to cause respiratory illness, including asthma and bronchitis. Little information exists about the composition and characterization of aerosols generated during resistance spot welding of metals treated with different adhesives and anti-slag agents. The objectives of the proposed NORA study are to identify the substances and to determine the potential mechanisms that may be involved with the development of lung injury and inflammation and alterations of basal lung function and airway reactivity after exposure to aerosols generated during resistance spot welding. A robotic welding arm in the NIOSH welding lab will be configured and programmed to perform resistance spot welding on sheet metal using process parameters common in the automotive industry. Spot welding will be performed on untreated sheet metal as well as on sheet metal that has been coated with commonly used anti-slag material and adhesives of different chemical compositions. Chemical and physical characterization of the resulting aerosols generated from the different spot welding procedures will be performed. Metal analysis of the welding particles will be determined by inductively coupled plasma-atomic emission spectroscopy. To assess the generation of volatile organic compounds, additional air samples will be collected onto thermal desorption tubes and analyzed by gas chromatography with a mass selective detector. Particle size distribution of the generated particulate will be determined by using a Moudi and Nano-Moudi impactor system. Male Sprague-Dawley rats will be exposed by acute and repeated dosing regimens to aerosols generated from the different spot welding procedures. Control animals will be exposed to filtered air. Animals will be divided into different treatment groups. To develop dose-response information, groups of animals will be exposed to varying periods of time to known aerosol concentrations that have been measured in the breathing zone of the exposed animals. Before and after the daily exposures, lung function tests will be performed to monitor the exposed animals for changes in respiration and symptoms of hyper-reactivity (asthma). At different time points after exposure, the animals will be humanely sacrificed, and standard histopathological and biochemical methods will be used to quantify pulmonary injury and inflammation. With the information collected from this proposed 3-year study, it may be possible to eliminate or substitute with more inert chemicals the component of the process that is most hazardous to workers. Information from the study will be disseminated directly to NIOSH stakeholders to be implemented to modify work practices to minimize exposure. In addition, it will be possible to generate dose-response data that could be used for risk assessment and the establishment of safe workplace exposure information for spot welding. This information will be invaluable to federal agencies (e.g., EPA, OSHA, and NIOSH) as well as to trade unions (e.g., United Auto Workers) and societies (e.g., American Welding Society) in an effort to educate and protect a significant number of exposed workers in the Construction and Manufacturing sectors.



Objectives

Millions of workers worldwide are exposed to welding aerosols daily. Nearly 350,000 workers are classified as full-time welders in the United States. Because of its extensive use in the Construction and Manufacturing sectors in the United States, thousands of workers are exposed on a daily basis to aerosols generated during resistance spot welding. In a Health Hazard Evaluation (#2006-0059-3009) performed by NIOSH at an automotive assembly plant, it was observed that numerous resistance spot welders had evidence of respiratory illness. Little information exists about the composition and characterization of aerosols generated during resistance spot welding of metals treated with different adhesives and anti-slag agents. A robotic welding arm in the NIOSH welding lab will be configured and programmed to perform resistance spot welding to expose laboratory animals using process parameters common in the automotive industry.

By using an animal model to mimic workplace exposures, our goal is to determine which component of the aerosols generated during resistance spot welding may be potentially toxic to exposed workers. With the information collected from this proposed 3-year study, it may be possible to eliminate or substitute with more inert chemicals the component of the process that is most hazardous to workers. Information from the study will be disseminated directly to NIOSH stakeholders to be implemented to modify work practices to minimize exposure. Detailed descriptions of the methodologies and results from the study will be published in peer-reviewed journals and presented at international scientific conferences in the fields of toxicology, occupational and environmental health, aerosol science and technology, and respiratory health. Results will be shared with welding trade associations, unions, and automotive plant employees. The objectives of the project are: (1) to develop a resistance spot welding generation and inhalation system to characterize the aerosols formed during this type of process; (2) to expose laboratory animals and determine the potential mechanisms that may be involved with the development of lung injury and inflammation and alterations on basal lung function and airway reactivity.



Mission Relevance

Because of its extensive use in the Construction and Manufacturing sectors, thousands of workers are exposed on a daily basis to aerosols generated during resistance spot welding. In a Health Hazard Evaluation (HETA #2006-0059) performed by NIOSH at an automotive assembly plant, it was observed that numerous workers in a body shop complained of respiratory ailments, including evidence of new-onset asthma and worsening of pre-existing asthma. Little is known about the composition of aerosols generated during resistance spot welding. The long-term goals of the proposed NORA-funded study that will be performed under the Respiratory Disease Cross-Sector Program are: 1) to develop a resistance spot welding generation and inhalation system to characterize the aerosols formed during this type of process; 2) to expose laboratory animals and determine the potential mechanisms that may be involved with the development of lung injury and inflammation and alterations on basal lung function and airway reactivity. The overall objective of the proposed project is to identify the hazardous substances generated during resistance spot welding and reduce or eliminate their use from the workplace to protect large numbers of exposed workers. Information from the study will be disseminated directly to NIOSH stakeholders to be implemented to modify work practices and minimize exposures. This information will be invaluable to federal health and regulatory agencies as well as to trade unions and professional welding societies in an effort to educate and protect exposed workers.

Research results will address the following goals: 1) Construction Sector (25%): 09PPCONSG6- Reduce welding fume exposures and future related health risks among construction workers by increasing the availability and use of welding fume controls and practices for welding tasks. Intermediate Goal 6.5 (09PPCONIG6.5) – Evaluate hazard and exposure assessment research gaps associated with welding fumes in construction. Research Goal 6.5.1 (09PPCONAOG6.5.1) – Health hazard testing component. 2) Manufacturing Sector (75%): 09PPMNFSG5- Reduce the number of respiratory conditions and diseases due to exposures in the manufacturing sector; 09PPMNFSG9- Enhance the state of knowledge related to emerging risks to occupational safety and health in manufacturing. 3) Respiratory Disease Cross-Sector Health Outcome (100%): 09PPRDRSG1- Prevent and reduce work-related airways diseases; Intermediate Goal 1.2 (09PPRDRIG1.2) – Prevent and reduce COPD; Strategic Goal 3 (09PPRDRSG3): Prevent and reduce work-related respiratory infectious diseases.; Activity/Output Goal (09PPRDRAOG3.2.1): evaluate the impact of occupational exposures on susceptibility to respiratory infection, including underlying mechanisms. Occupational exposures of current concern include welding fume and its constituents; diesel exhaust; residual oil fly ash (ROFA); silica; and potentially others, if evidence suggests that exposure increases risk of respiratory infection. 4) Other Cross-Sector Programs, Nanotechnology (50%): 09PPNANSG1- Determine if nanoparticles and nanomaterials pose risks of work-related injuries and illnesses. Intermediate Goal 2 (09PPNANIG2) – Toxicity and internal dose.



Page last updated: June 3, 2011
Page last reviewed: May 23, 2011
Content Source: National Institute for Occupational Safety and Health (NIOSH) Office of the Director

 

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