Welding fume exposure in the workplace is a serious occupational hazard. Employee exposure to welding fumes, specifically to those that contain manganese, has garnered national media attention within the last few years. Thousands of welders have filed lawsuits against welding rod manufacturers, distributors and suppliers alleging that the manganese present in welding fumes causes a host of illnesses, including Parkinson's disease. While manganese exposure does lead to symptoms that are similar to Parkinson's disease, further research must be conducted to confirm a connection between manganese and Parkinson's.
This article is adapted from recent print and online resources to provide an overview of:
Welding is the method of joining two metal parts together by applying intense heat between them, which causes the parts to melt and intermix. This process can be done directly between the two parts or through the use of an intermediate molten filler metal. The filler, base metal and base metal coating used during welding operations and the subsequent gases that are formed during the welding process release small, solid particles into the air creating a plume. This plume is called "welding fume."
All welding processes produce these fumes, but most fumes are produced during arc welding. In this type of welding process, high heat from an electric arc (formed between the work and an electrode) is used to melt and fuse the metal at the joint between the two parts. When a welder strikes an arc, the arc's heat vaporizes a small quantity of metal and releases welding fumes into the air, which can adversely affect the health of the welder as well as the health of those in the immediate area.
The contents of the welding fumes depend on the components of the base metal, coatings and/or filler materials and the temperatures used in the welding process. Types of metals commonly found in welding fumes include aluminum, beryllium, cadmium oxides, chromium, copper, fluorides, iron oxide, lead, manganese, molybdenum, nickel, vanadium and zinc oxides. Welding fumes also produce gases, which can contain carbon monoxide, fluorine, hydrogen fluoride, nitrogen oxide and ozone.
Exposure to welding fumes can cause numerous health problems. When inhaled, welding fumes can enter the lungs, bloodstream, brain nerve cells, spinal cord and other organs and can cause both short- and long-term health effects (see sidebar above).
Of the many welders who work in factories or in the construction, ironworks, manufacturing, mining, metallurgy, petrochemical, railroad, shipbuilding or steel industries, most suffer from some sort of respiratory illness or pulmonary infection. In recent years, however, the effects of manganese welding fume exposure on welders' health have warranted closer study.
Manganese is a naturally occurring metal and the twelfth most abundant element on earth. It is a highly reactive gray-white metal that resembles iron, and it is often added to carbon steel and stainless steel to increase hardness, stiffness and strength. In addition to steel, manganese is found in many different types of welding rods and wire, and it is considered the most harmful metal present in welding fumes. Even when used properly, manganese welding rods can still emit manganese fumes.
An essential trace nutrient, manganese is necessary for healthy skin, bones and cartilage in humans, but high concentrations of manganese in the body, often referred to as "manganese poisoning" or "manganism," can irreversibly damage the brain and central nervous system. Studies have shown that exposure to high levels of manganese welding fumes for only a few months can cause sickness, and since many welders are exposed to these fumes on a regular basis, they are at an increased risk of developing manganism or "Welder's Disease."
According to National Safety Council, exposure to manganese dust or fumes can cause:
Documented cases of manganese poisoning date back to the early 19th century. During this time, J. Couper, an English physician, published a report in which he described how workers in a manganese ore grinding plant in France developed symptoms of manganese poisoning such as loss of muscle control, slowed movements and lowered speech. Throughout the 20th century, other occurrences of manganese poisoning had been found in Chilean miners, Taiwanese ferromanganese smelters and in those involved in the manufacture of dry batteries. As these and other cases mounted, few could deny the link between routine manganese exposure and ill health.
Further studies have addressed the effects of manganese on welders. In 1932, a published article advised welders to avoid working with manganese electrodes. In 1963, Dr. Irving Sax, a toxicologist, published a book in which he detailed the negative effects of manganese on the nervous system and the risks of manganese exposure during electric arc welding. In 1981, World Health Organization (WHO) recognized chronic manganese poisoning as a serious occupational health hazard among welders.
Today, studies show that a substantial percentage of welders have developed symptoms similar to Parkinson's disease (see sidebar below). This condition is referred to as "manganese-induced parkinsonism, which is different from Parkinson's disease. Still, many contend that manganese welding fumes are a direct cause of Parkinson's disease and of the increased risk of the disease among welders.
Parkinson's disease is a neurological disorder that damages brain cells in the midbrain or substantia nigra. This area produces dopamine, a chemical that helps to transmit signals in the brain. Dopamine loss can cause slow and unsteady body movements, stiff limbs, poor balance and tremors. Other classic symptoms include:
Although the cause of Parkinson's disease remains unknown, many believe that environmental factors are to blame, especially since welders tend to develop Parkinson's at a higher rate than others. A recent study of 20,000 welders determined that 10 percent had developed Parkinson's disease as compared to only one percent of the general population. Also, the onset of the disease in welders tends to occur around age 46, about 17 years earlier than in other Parkinson's patients. Many assert that exposure to manganese welding fumes is directly responsible for the elevated rate of Parkinson's disease among welders. However, no conclusive studies confirm this theory.
It is important to note that manganese-induced parkinsonism differs from Parkinson's disease because it appears to affect the basal ganglia region of the brain and not the substantia nigra. Those with manganese-induced parkinsonism also do not respond well to dopamine therapy, which is normally used to treat Parkinson's patients.
While exposure to manganese can disrupt normal neurological processes, welding fumes contain other metals such as aluminum, copper and lead, which may also be risk factors in the development of Parkinson's disease. Other issues, such as how much manganese must be present in welding fumes to incur toxic effects and the duration of exposure to these fumes, are still under debate. Some suggest that Parkinson's disease may actually encompass a combination of symptoms that have overlapping characteristics.
Before a concrete association between manganese welding fume exposure and Parkinson's disease can be determined, further research must be conducted that takes into account the neurological differences behind manganese-induced parkinsonism and Parkinson's disease.
Approximately 10,000 welders nationwide have filed lawsuits against current and former welding rod manufacturers, distributors and suppliers on the grounds that welding fume exposure caused them to develop manganese-induced parkinsonism as well as Parkinson's disease. The plaintiffs include welders who already have manganese-induced parkinsonism, early onset Parkinson's disease or no symptoms but a history of manganese exposure. The plaintiffs also claim breach of express and implied warranties, civil conspiracy, fraud, intentional and negligent misrepresentation, loss of consortium, negligence, strict liability, survival actions and wrongful death.
Within the last 15 years, seven cases were ruled in favor of the welding rod industry when it could not be proven that the industry had failed to protect workers from manganese in welding fumes. That changed on Oct. 28, 2003, when Larry Elam, a former welder, received $1 million from a Madison County, IL, jury against Lincoln Electric, Hobart Brothers and BOC. Elam claimed that he developed manganese-induced parkinsonism as a result of breathing welding rod fumes at work. The jury decided that welding rod manufacturers neglected to warn Elam about the potential health risks associated with breathing welding rod fumes.
In July 2005, a federal panel ruled that a large number of welding fume lawsuits in the U.S. would be consolidated before U.S. District Judge Kathleen McDonald O'Malley in Cleveland. The lawsuits allege that the defendants knew of the health hazards associated with welding fumes and failed to warn welders about them. O'Malley has allowed the plaintiffs in these cases to testify that welding fume exposure indeed causes Parkinson's disease, which will allow thousands of other welding fume cases to proceed in state courts.
Plaintiffs' attorneys believe that welding fumes cause Parkinson's disease, and they have requested welding fume warnings and improved ventilation for those working in the welding industry. If juries rule in favor of the plaintiffs, the plaintiffs could then sue those in the welding industry for damages. At this stage, it is difficult to predict how these lawsuits will affect the welding industry when a definitive link between welding fumes and Parkinson's disease has yet to be determined, but organizations such as the Gases and Welding Distributors Assn. (GAWDA) have taken precautionary measures. GAWDA's board of directors has created a Joint Defense Fund for Welding Fume Litigation that will assist GAWDA members defend against welding fume claims.
In the meantime, more and more welders have begun to file workers' compensation claims citing welding fume exposure, and a class-action lawsuit involving 3,700 plaintiffs was recently filed in West Virginia. Many legal experts predict that welding fume litigation could rival that of asbestos given the considerable number of claimants.
Until the potential health hazards of welding fume exposure can be confirmed, employers should make every effort to safeguard employees against welding fumes. Ventilation systems, respirators, training, industrial hygiene monitoring and alternative welding methods can help to improve fume conditions in work areas.
For indoor welding operations, all employers should ensure that proper ventilation systems are incorporated into welding work areas. These systems, which may include hoods, roof vents and high-speed intake and exhaust fans, should capture toxic fumes and gases at their source and remove them so that they never enter the welder's breathing space. Most source-capture mechanisms are ducts that can be easily attached to exhaust or filter systems, but welding guns can also help to extract fumes from the air.
To capture welding fumes in large work areas, the use of downdraft worktables is recommended so that the fumes are directed down and away from the welder's breathing space. Ceilings more than 16 feet high and routine air monitoring to determine any changes in exposure levels will also help to reduce welding fumes and gases in work areas.
For outdoor welding operations, all employers should instruct welders to avoid standing directly in or near the fume plume and to work upwind to reduce their exposure. This is especially critical for welders who work in small outdoor welding boxes where ventilation may be overlooked, thus allowing fumes to collect. Fans may also be used to blow fumes away from welders.
Employers may choose to supplement ventilation systems in welding work areas with respiratory protection. All respirators used in the workplace must be certified by NIOSH, and employers should select those that afford welders the best possible protection. Employers must also adhere to OSHA's Respiratory Protection Standard, which requires employers to implement a written respirator program with procedures that are specific to the work area, develop a medical surveillance program to evaluate employee's medical capability to wear a respirator and deliver training on the proper use and storage of respiratory protection. This program should be evaluated regularly. Employers are responsible for selecting the right respirators for their individual employee jobs while providing welders with guidelines for appropriate respirator storage, cleaning and filter replacement.
In addition to training welders in the correct use of respirators and other PPE, all employers should advise welders to avoid standing directly in the welding fume plume (no matter whether they are working indoors or outdoors) and to position themselves so that the fumes and dust particles do not accumulate inside their face shields. Employers should also train nonwelders not to stand in or near the welding fume plume. Employers should enforce the use of engineering controls, safety practices and emergency procedures that mitigate welders' exposure to fumes, and they should also teach welders to heed all signs, labels and other markings in the work area which warn welders of fume exposure hazards. These warnings must be clearly presented throughout the area. All employers and welders should be familiar with ANSI Z49.1, Safety in Welding, Cutting and Allied Processes, copies of which should be readily available throughout the workplace.
Employers should also make a conscious effort to promote healthy habits among welders. A company-sponsored smoking cessation program and annual physical exams are just a few ways in which employers can positively impact the well-being of their welders.
All employers should have an industrial hygiene monitoring plan in place for all welding work areas, and industrial hygienists should be present in all work areas to monitor welders for exposures and potential exposures. Industrial hygiene monitoring in the form of both personal and area monitoring should be performed to assess exposure levels. This information can also be used to determine the appropriate respiratory protection, where required. Typical analysis of samples collected by filter cassette may include a broad metal scan to detect metals such as iron, lead and manganese to comprehensively analyze welding fumes. Industrial hygienists should also work one-on-one with welders to educate them about the dangers of welding fumes.
To further reduce welding fumes in work areas, employers may want to consider using less-hazardous materials such as low-fume welding rods and alternative welding methods such as stick welding, which creates less fumes than flux core welding. OSHA also recommends that all paint, solvents and other residues be removed from materials before any welding or torch-cutting processes are performed to curb hazardous fume release.
Since galvanized steel tends to produce more hazardous fumes during welding and creates poor-quality welds, most welders do not weld on it. Galvanized metals in general tend to produce more fumes because they are covered with a zinc coating. However, if galvanized steel is used, most welders will grind back the zinc coating on the steel at least four inches from either side of the weld area to get a higher-quality weld. This practice helps to reduce the release of harmful fumes as well.
Employers may also decide to galvanize steel after fabrication. Although this practice is costly, takes more time and must be performed carefully to ensure an even coating and to inhibit rust formation, post-fabrication galvanized steel has been shown to release less-harmful fumes during welding.
As welding fume lawsuits escalate in number and severity, employers must play an active role in preventing welding fume exposure in the workplace. The health risks associated with routine manganese exposure are many, but more must be done to verify the existence of a relationship between manganese and Parkinson's disease.
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SIDEBAR No. 1:
Short-Term Health Effects of Welding Fume Exposure
Long-Term Health Effects of Welding Fume Exposure
Sidebar No 2:
Symptoms of Manganese-Induced Parkinsonism