Can you recognize the signs and symptoms of Metal Fume Fever?

Metal Fume Fever (MFF) is an occupational hazard where the inhalation of zinc oxide smoke causes welders to feel ill. It is more dangerous in welders with heart and lung conditions or multiple exposures. Prevention starts with regular testing of the air on the job and knowing how to avoid unnecessary exposure. Luckily, fixing both MFF and excessive zinc oxide on the job is simple and relatively inexpensive; it is just as easy as treating the symptoms while the rest works itself out naturally.

Let’s dive a little deeper into what exactly MFF is, its causes, how to treat and diagnose it, and how to limit exposure!

So, What Exactly is Metal Fume Fever?

Metal Fume Fever ( MFF) is an acute, fever-based illness caused when welders inhale microscopic zinc oxide particles. These particles are found in the welding smoke (fume) created on the job. Essentially, MFF causes flu-like symptoms in welders breathing in too many particles at one time. Luckily, in most cases, symptoms normally go away after just a day or so, even without medical treatment. MFF has been reported to be caused by inhaled exposure to other metal oxides on the job site as well (namely copper, iron, and magnesium). However, it remains to be most frequently caused by zinc oxide. 

Estimates by the NCBI (National Center for Biotechnology Information) show that between 1,500 to 2,500 welders will develop MFF annually. This makes it a fairly common affliction in many, and especially longterm, welding employees.

While Metal Fume Fever is the common name for this occupational hazard, people may also know it by other “nicknames.” Some of them are brassfounder’s ague (another word for a fever based illness), the metal shakes, Spelter’s shakes, the zinc chills, and the zinc fever. The first documentation of MFF was in the mid-1800s. It remains a common diagnosis for welders.

What Are The Signs and Symptoms of Metal Fume Fever?

Most welders who come down with Metal Fume Fever say that they first noticed the signs and symptoms 3 to 10 hours after exposure. They describe them similarly to how people describe the common cold. This includes any combination of the following (however, there must be a fever for an official MFF diagnosis) : 

• Fever (of no higher than 102 degrees Fahrenheit)
• Chills (where the name “the zinc chills” comes from)
• Excessive Sweating
• Headache
• Muscle and/or joint pain
• Extreme fatigue
• Nausea
• Shortness of breath

More commonly, welders with MFF will complain of a low fever, feeling more worn down than usual, sore muscles, and headache. The doctor will start with blood work. In most cases, the white blood cell count (WBCs) will be higher than they should be (usually around 12,000 to 16,000 mm³). Normal is anywhere from 4,000 to 11,000 mm³ in a healthy welder.

There are also a few, less common but still trademark signs and symptoms to take into account as well :

• A sweet, metallic taste in the mouth
• Throat pain
• Increased thirst
• Trouble breathing, possibly painful
• Chest pain

Many doctors will also perform a chest x-ray to rule out other issues that may be causing the same symptoms. In the majority of healthy welders, the chest x-ray won’t show any significant issues. However, welders that have repeated exposure over their career or have had MFF multiple times are at higher risk. They may show signs of occupational asthma or the worsening of any pre-existing heart and lung conditions. However, keep in mind that this hasn’t been conclusively proven! While MFF does not normally need to be specifically treated, an abnormal chest x-ray may prompt additional testing and care. 

When Does MFF Become a Bigger Issue?

Symptoms of a larger, non-MFF issue include pulmonary infiltrates on the chest x-ray and a low blood oxygen level (hypoxemia). These are also common with toxicity from more dangerous metals (cadmium or nitrogen oxide), and require significantly more medical care. 

Ultimately, a final diagnosis of MFF is based on your symptoms and your job description alone. There is no actual test, and it may be missed if you don’t let your doctor know what you do for a living. 

What Are The Causes of Metal Fume Fever?

MFF can only be caused by inhaled exposure of zinc oxide. It can not happen as a result of skin or oral exposure. Zinc oxide particles are most prevalent on job sites where there is no appropriate ventilation system in place.

While there haven’t been too many studies on the mechanism of toxicity (how/why zinc oxide causes the body to react to it as a poison), the most popular current scientific theory is that it affects the cytokine in the body and specifically in the lungs.

Cytokine cells are the molecules in our bodies that talk to each other, and other cells. They then direct them to the areas that need an immune response. This means the cytokine tells the body to attack zinc in the same way it would attack a virus (like a cold), which is why MFF has similar symptoms. Inhaling zinc oxide causes the body’s immune system to turn on, switch into high gear, and take out the bad guys. This factor makes MFF different from an allergy and allows for it to be a health issue for welders as early as the first time you are exposed.

• The category of welding process (fusion or pressure welding, as well as the specific type). The safest arc welding type currently available is the Tungsten Inert Gas (TIG or GTAW) style. The least safe is the Flux Core Arc Welding (FCAW) style. 
• The base metal, filler metals and the composition of the welding rod
• Where the welding is happening (outside/inside, enclosed spaces)
• Appropriate ventilation controls and air movement

What Factors Affect Metal Fume Fever?

There are a variety of factors that can affect the amount of exposure that welders have to fumes. Knowing them can reduce the likelihood of developing MFF.

In addition, MFF is most likely to occur at the beginning of the workweek. This has led to some people humorously nicknaming it the Monday Morning Fever! It affects far more men than women as well. However, this is likely because there are more men than women employed in welding at this time.

What Is The Diagnosis and Treatment of Metal Fume Fever?

As stated above, the diagnosis of MFF is made based only on an evaluation of your symptoms and awareness of your job. It can be an easy diagnosis to miss, as it can mimic so many other common medical conditions. MFF relies mostly on welders knowing it is a possible option so that they can suggest it as a potential diagnosis if they end up seeking treatment.

Treatment is not needed, as the majority of symptoms go away on their own in 24 to 48 hours. If treatment is recommended, it is considered “supportive care.” This means fever reducers/NSAIDs (Tylenol or Ibuprofen), increasing water intake, and bed rest for a day or so.

While treatment for acute MFF is easy, medical support may be necessary in welders with pre-existing heart and lung conditions. Emergency treatment includes using supplemental oxygen therapy for low blood oxygen levels and bronchodilators (inhalers like Albuterol) to treat wheezing. In rare cases, hospitalization may be needed. 

There is no antidote for MFF. In addition, no personal decontamination is needed after exposure since it stops as soon as you leave the job site. There are also plenty of wives tales about drinking milk to help prevent or cure MFF. However, they have no background in actual medical research. The only true cure for MFF is time, and prevention of additional exposure.

How Can MFF Be Dangerous?

While MFF isn’t dangerous, longterm exposure to large amounts of zinc oxide during a career may contribute to occupational asthma. Again, as stated above, this link has not yet been proven. There was also a study in England where a tradesman diagnosed with MFF ended up with more significant health problems. These issues – aseptic meningitis (inflammation of the brain and spinal cord) and pericarditis (inflammation around the heart) were directly associated to their exposure. However, these cases are very few and far between and haven’t been officially correlated with MFF in any medical studies. 

There are other studies showing that longterm exposure to fumes created during welding can also lead to other health issues. This includes pneumonia (which can be severe and even fatal in those with lowered immune systems) and even cancer. These are not related to MFF.

Is There a Toxic Zinc Dose?

Resistance to zinc oxide poisoning can develop as quickly as exposure multiple days in a row (called “tachyphylaxis”). However, the ACGIH (American Conference of Governmental Industrial Hygienists) identifies a toxic dose that counts as an actual emergency situation. The IDLH (“immediately dangerous to life or health”) level is any zinc oxide amount over 500 mg/m³, which can be fatal.

It is also important to note that some welders may develop an allergic or asthmatic response to the zinc oxide fumes (in some cases, an anaphylactic reaction). This is separate from MFF as well.

How Can I Prevent Metal Fume Fever?

Preventing excessive zinc exposure while welding starts with having a supportive workplace that follows all applicable OSHA regulations. Part of that is the measurement (every 8 hours) of the ambient zinc concentrations in different areas. The PEL (permissible exposure limit) is any zinc oxide measurement below 5 mg/m³ over an eight-hour workday. Anything above that must be addressed and mediated by the business ASAP. This is a legal OSHA guideline.

In addition, all welding business owners must provide information and training to all of their employees. This must include posted guidelines, annual training, and testing to verify that every employee understands what MFF is and how to prevent it. OSHA will require proof as well.

Business owners should also consider upgrading equipment, especially any that have to do with safety engineering controls. This includes welding fume extractors (local exhaust ventilation and source-capture), which increases the safety of their employees.

Personal Prevention Tips

Here are a few personal prevention tips for welders, as well : 

• Avoid all direct contact with welding fumes.
• Make sure to use only NIOSH (National Institute for Occupational Safety and Health) approved respirator masks.
• When welding, make sure to try to stay as upwind from any fumes as possible.

Metal Fume Fever is often not serious the few times a welder may develop it. However, over time, it has the potential to lead to longer-lasting, more difficult to treat problems like asthma. It can also lead to lost wages during the time you are unable to work. In addition, MFF in otherwise unhealthy welders can make heart and lung conditions even worse. Make sure that you are watching your exposure to fumes. Also, check that your employer is following OSHA standards by monitoring the air at your job. 

Stay safe and healthy on the job!