Welder’s Anthrax

Posted on by Marie A. de Perio, Katherine A. Hendricks, Chad H. Dowell, William A. Bower, Nancy C. Burton, Patrick Dawson, Caroline A. Schrodt, Johanna S. Salzer, Chung K. Marston, Karl Feldmann, Alex R. Hoffmaster, and James M. Antonini


A new journal article from researchers at the Centers for Disease Control and Prevention’s (CDC) National Institute for Occupational Safety and Health (NIOSH) and the Bacterial Special Pathogens Branch describes cases of welder’s anthrax, a newly identified, deadly occupational disease.

Welder’s anthrax is defined as pneumonia in a metalworker caused by bacteria within the B. cereus group that produces anthrax toxin. Seven patients diagnosed with what is now termed welders anthrax were reported to the CDC from 1994–2020. The job title of six patients was welder, and the job title of the seventh was metalworker. All were confirmed to be infected with B. cereus group bacteria containing anthrax toxin genes. Six of the workers were men. The median age was 39 years. Four of the patients worked in Texas and three in Louisiana.

Information on the type of welding, job activities, and type of workplace, including indoor or outdoor activities, was limited for most of the patients except for the two patients diagnosed in 2020. One patient worked on the roof of an oil tank outdoors. He welded on new A36 mild carbon steel using a shielded metal arc welding (or stick) process. The other patient worked in a wood fabrication shop. He welded on low-carbon mild steel using Metal Inert Gas (MIG) with solid or flux core wire and 75% argon/25% carbon dioxide shield gas. Both patients performed additional tasks such as scrubbing debris with a wire metal brush and grinding. Both reportedly wore respiratory protection during welding activities.

Of the six patients with available data on signs and symptoms, over half presented with each of the following: fever or chills, cough, shortness of breath (dyspnea), and coughing up blood (hemoptysis). All had abnormal chest radiographs and were diagnosed with pneumonia. All were hospitalized and were admitted to the intensive care unit if they survived past the emergency department. Five of the seven patients died. All patients received broad-spectrum antibiotic treatment. One of the surviving patients received raxibacumab, a monoclonal anthrax antitoxin.

Welders at Increased Risk

Several studies have shown an increased risk of pneumonia and death among welders and other workers exposed to metal fumes and mineral dusts [1-6]. Research suggests it is possible that exposure to metal fumes might increase susceptibility to lung infection, even with common, relatively harmless infectious agents [7]. Furthermore, iron oxide deposited in the lungs after inhaling welding fume has been found in the lungs for years, even after removal from exposure [8].

How metal fumes cause disease is mostly unknown. Theories include that metal fumes (or iron) act as a growth nutrient for bacteria, enhance the binding of bacteria to lung tissues, or impair immune responses in the lung through oxidative stress [1,5,6,9]. Like all pathogens, B. anthracis and B. cereus anthrax toxins need iron to survive and thrive.

While iron overload might partially explain the increased susceptibility of welders for B. cereus infections, exposure is still important. Several researchers have noted that soil iron is much higher around welding sites than elsewhere [10,11]. Future research measuring soil iron levels may provide useful information.


The hierarchy of controls can be used to prevent workplace exposure to welding fumes and gases, and soils that may be contaminated with B. cereus group bacteria producing anthrax toxins.

  • Employers should conduct a hazard assessment on all welders, other metalworkers, and supervisors at worksites.
  • Elimination and substitution controls to help reduce exposure to fume and gases from welding and soils that may be contaminated with cereus group include:
    • Using a less toxic welding type or consumable.
    • Ensuring that welding surfaces are free of any coatings, dirt, and dust that may lead to potentially toxic exposures.
  • Engineering controls can include the use of general and local exhaust ventilation. Do not assume that welding outdoors or in open areas provides adequate general ventilation, even when the welder uses proper positioning and natural drafts. Local exhaust systems should be positioned to draw fume and gases away from the welder and other workers in the area.
  • Administrative controls include maintaining a clean and dirt-free worksite.
    • Workplaces should be routinely cleaned with a vacuum equipped with a high-efficiency particulate air (HEPA) filter or wet cleaning methods.
    • Compressed air and dry sweeping or brushing should not be used.
    • Dust control programs in outdoor workplaces and near workplaces open to the outdoors can minimize dirt and dust exposure, and activities in the immediate vicinity should be limited to help minimize disturbing dry dust.
    • In surrounding areas, adding water, hydroscopic compounds, or surfactants to roadways and surfaces that are heavily traveled can help control dirt and dust exposures. However, these substances should not be applied in the immediate area where welding occurs as this may cause an electrocution hazard.
  • Welders and other metalworkers must understand their potential occupational health risks and how to protect themselves. The Occupational Safety and Health Administration’s (OSHA’s) Hazard Communication Standard requires employers to inform and train workers on potential work hazards and associated safe practices, procedures, and protective measures.
  • Personal protective equipment (PPE) may include coveralls and work boots in the workplace to prevent their skin and clothing from being contaminated and taking contaminants home. NIOSH-approved respirators, as part of a written respiratory protection program, may be needed when other controls do not reduce exposures to safe levels.

Diagnosis and Treatment

Physicians should consider welder’s anthrax in welders who present with pneumonia, particularly those working in U.S. Gulf Coast states. Welders and other metalworkers who present with welder’s anthrax should be treated the same as a patient with inhalation anthrax.

If infection with anthrax toxin-expressing B. cereus group is suspected, it is important to notify the state health department; a consultation with CDC is recommended. Anthrax antitoxins should be considered as adjunctive therapy if the patient’s clinical condition suggests systemic illness. However, the role of anthrax vaccine pre- or post-exposure for welders is not currently recognized or understood.

Next Steps

It is possible that cases of welder’s anthrax were missed due to limited detection and understanding of anthrax toxins, underdiagnosis, and under-reporting of the patient’s occupation. To improve data collection in surveillance systems, the NIOSH Surveillance Program recommends that occupational questions should be standardized, and information on both industry and occupation should be collected and analyzed. Other helpful information for the investigation of welder’s anthrax includes the employer’s name, work location, job duties, and questions about specific types of welding, metals, and other exposures and protective measures taken.

Communication and cooperation between clinicians, employers, and public health practitioners is important to identify cases of welder’s anthrax and occupational and personal risk factors. More research is needed to better understand the mechanisms of infection and disease among welders. Additional research is needed to better understand how exposure to metal fumes and other welding hazards may increase susceptibility to and severity of lung infection in welders. The effectiveness of interventions to minimize workers’ exposure to metal fumes, including engineering controls and respiratory protection, should also be explored.

Welder’s anthrax is a new and rare disease. We would like to raise awareness of this infection among welders and clinicians. If you have ideas for how to do so, please contact us through the comment section below.


Marie A. de Perio, Chad H. Dowell, Nancy C. Burton, Karl Feldmann, and James M. Antonini are with the CDC’s National Institute for Occupational Safety and Health.

Katherine A. Hendricks, William A. Bower, Caroline A. Schrodt, Johanna S. Salzer, Chung K. Marston, and Alex R. Hoffmaster are with the CDC’s National Center for Emerging and Zoonotic Infectious Diseases.

Patrick Dawson is with the CDC’s Office of Science.



  1. Torén, K.; Blanc, P.D.; Naidoo, R.N.; Murgia, N.; Qvarfordt, I.; Aspevall, O.; Dahlman-Hoglund, A.; Schioler, L. Occupational Exposure to Dust and to Fumes, Work as a Welder and Invasive Pneumococcal Disease Risk. Environ. Med. 2019, 77, 57–63.
  2. Koh, D.H.; Moon, K.T.; Kim, J.Y.; Choe, S.W. The Risk of Hospitalisation for Infectious Pneumonia in Mineral Dust Exposed Industries. Environ. Med. 2011, 68, 116–119.
  3. Torén, K.; Qvarfordt, I.; Bergdahl, I.A.; Järvholm, B. Increased Mortality from Infectious Pneumonia after Occupational Exposure to Inorganic Dust, Metal Fumes and Chemicals. Thorax 2011, 66, 992–996.
  4. Wong, A.; Marrie, T.J.; Garg, S.; Kellner, J.D.; Tyrrell, G.J.; SPAT Group. Welders Are at Increased Risk for Invasive Pneumococcal Disease. J. Infect. Dis. 2010, 14, e796–e799.
  5. Palmer, K.T.; Cullinan, P.; Rice, S.; Brown, T.; Coggon, D. Mortality from Infectious Pneumonia in Metal Workers: A Comparison with Deaths from Asthma in Occupations Exposed to Respiratory Sensitisers. Thorax 2009, 64, 983–986.
  6. Marongiu, A.; Hasan, O.; Ali, A.; Bakhsh, S.; George, B.; Irfan, N.; Minelli, C.; Canova, C.; Schofield, S.; De Matteis, S.; et al.. Are Welders More at Risk of Respiratory Infections? Findings from a Cross-sectional Survey and Analysis of Medical Records in Shipyard Workers: The WELSHIP Project. Thorax 2016, 71, 601–606.
  7. Lockey, J.E.; Schenker, M.B.; Howden, D.G.; Desmeules, M.J.; Saracci, R.; Sprince, N.L.; Harber, P.I. Current Issues in Occupational Lung Disease. Rev. Respir. Dis. 1988, 138, 1047–1050.
  8. Kalliomaki, P.-L.; Kalliomaki, K.; Rahkonen, E.; Aittoniemi, K. Lung Retention of Welding Fumes and Ventilatory Lung Functions. A Follow-Up Study among Shipyard Welders. Occup. Hyg. 1983, 27, 449–452.
  9. Coggon, D.; Inskip, H.; Winter, P.; Pannett, B. Lobar Pneumonia: An Occupational disease in Welders. Lancet 1994, 344, 41–43.
  10. Dheeba, B.; Sampathkumar, P. Evaluation of Heavy Metal Contamination in Surface Soil around Industrial Area, Tamil Nadu, India. J. Chem. Tech. Res. 2012, 4, 1229–1240.
  11. Adekeye, E.A.; Ojo, M.A.; Ajayi, O.O. Contributions of Metal Welding Workshops to Environmental Pollution in Akure Metropolis, Ondo State, Nigeria. Environ. Iss. Agric. Dev. Ctry. 2011, 3, 1–7.


Posted on by Marie A. de Perio, Katherine A. Hendricks, Chad H. Dowell, William A. Bower, Nancy C. Burton, Patrick Dawson, Caroline A. Schrodt, Johanna S. Salzer, Chung K. Marston, Karl Feldmann, Alex R. Hoffmaster, and James M. Antonini

8 comments on “Welder’s Anthrax”

Comments listed below are posted by individuals not associated with CDC, unless otherwise stated. These comments do not represent the official views of CDC, and CDC does not guarantee that any information posted by individuals on this site is correct, and disclaims any liability for any loss or damage resulting from reliance on any such information. Read more about our comment policy ».

    Very interesting – especially since I am an industrial hygienist in the Gulf Coast region. I know that many welders are gig workers that perform work during turnarounds at chemical plants and refineries in this area. A potential opportunity to provide awareness could be through the Area Safety Councils where contractors go to get the required site-specific training prior to starting work at a chemical plant or refinery.

    Thank you for this great suggestion! Welders can work in so many different industries. We will follow up on this.

    My industrial hygiene work has never been around welding, and this is mostly above my cognitive ceiling, but any chance that all the welders were also “metalworkers” and exposed to metalworking fluid with B. cereus in it? Even scrubbing and grinding might have an exposure to the fluids, and if they were also cutting as part of their jobs, then perhaps more exposure to highly aerosolized fluids.

    Not a journal reference, but, https://www.walleniuswater.com/process-fluids/blog/the-most-common-bacteria-in-metalworking-fluid.

    I’ve also never sampled metalworking fluids, but many have.

    Thank you for your comments! While B. cereus can contaminate metalworking fluids, metalworking fluids were not present at either of the workplaces of the 2020 cases, and information on the workplaces of the earlier cases is limited. We did conduct environmental sampling at the two workplaces in 2020, and we found PCR positives in the soil, gravel, and some surfaces in one workplace. The results are summarized in our paper, which can be found here: https://www.mdpi.com/2076-0817/11/4/402. We will continue to learn more about this newly identified disease as more research is conducted and more cases are identified.

    From my time as a welder, experiencing an episode of “metal fume fever” this article caught my attention. With my education as an IH, I learned that anthrax was predominately a soil or animal based disease.
    In a news article in https://www.texasstandard.org/stories/inside-texas-anthrax-triangle/?msclkid=4c18ef75c5bb11ecb80f341a8c05fc28 there is a region in SW Texas where anthrax is endemic in the soil and animal populations. This is confirmed in an article from Texas A&M https://today.tamu.edu/2019/07/24/tracking-the-anthrax-spike-in-texas/?msclkid=f77c0bd5c5bd11ecab40ca4b009aeac5
    Was there an outside chance these welders have been in this area of Texas, perhaps hunting in this area?

    Perhaps a non-occupational exposure was the source of the anthrax and that future questions asked by the clinicians should also include side gigs and hobbies such as hunting, ranching, taxidermy.

    Was there a chance that these workers picked it up from soils that were transferred onto the metals, which were cleaned during welding prep work as written above, “as scrubbing debris with a wire metal brush and grinding.” and not the metal nor fluxes actually involved in the welding processes?

    It will be interesting to follow the developments of this unique disease.

    Thank you for sharing these insights! The organism that has caused these welder’s anthrax cases is not Bacillus anthracis, but it can produce anthrax toxins. We have limited information on the prior cases, but we did explore non-occupational outdoor activities of the 2020 case patients. We describe some possible mechanisms of infection and disease in our journal paper, which can be found here: https://www.mdpi.com/2076-0817/11/4/402. We are interested in exploring the geographic aspects and occupational aspects of this infection further.

    NIOSH is in regular communication with OSHA about emerging occupational hazards. They have read the NIOSH publication on welder’s anthrax with interest and concern, and NIOSH will keep them informed of any additional cases that may arise.

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Page last reviewed: April 21, 2022
Page last updated: April 21, 2022