Metal fume fever

Metal fume fever, also known as brass founders' ague, brass shakes,^[1] zinc shakes, galvie flu, metal dust fever, or Monday morning fever,^[2] is an illness primarily caused by exposure to certain fumes. Workers breathe in fumes from chemicals such as zinc oxide (ZnO) or magnesium oxide (MgO), which are themselves created by heating or welding certain metals, particularly galvanized steel. Other common sources are fuming silver, gold, platinum,^[3] chromium^[4] (from stainless steel), nickel, arsenic, manganese, beryllium, cadmium, cobalt, copper, lead, selenium. and zinc.^[5]

Welders are commonly exposed to the substances that cause metal fume fever from the base metal, plating, or filler. Brazing and soldering (a type of metal work in which only the filler is melted) can also cause metal poisoning from lead, zinc, copper, or cadmium in the filler metal.^[5] In extreme cases, cadmium^[6] (present in some older silver solder alloys) can cause loss of consciousness within a matter of minutes.

Signs and symptoms

The signs and symptoms are nonspecific but are generally flu-like and include fever, chills, nausea, headache, fatigue, muscle aches, joint pains, lack of appetite, shortness of breath, pneumonia, chest pain, blood pressure change, and cough. A sweet or metallic taste in the mouth may also be reported along with a dry or irritated throat which may lead to hoarseness.^[7] Symptoms of a more severe metal toxicity may also include a burning sensation in the body, shock, no urine output, collapse, convulsions, shortness of breath, yellow eyes or yellow skin, rash, vomiting, watery or bloody diarrhea or low or high blood pressure, which require prompt medical attention.^[8] Flu-like symptoms will normally disappear within 24 to 48 hours. Full recovery often requires one to three weeks.

Cause

Metal fume fever is due to the inhalation of certain metals, either as fine dust or most commonly as fumes. Simple compounds of the metals, such as the oxides, are equally capable of causing it. The effects of particularly toxic compounds, such as nickel carbonyl, are not considered merely metal fume fever.

Exposure usually arises through hot metalworking processes, such as smelting and casting of zinc alloys, welding of galvanized metals, brazing, or soldering. If the metal concerned is particularly high-risk, the residue from cold sanding processes may also cause fume fever, though the dose is lower. It may also be caused by electroplated surfaces or metal-rich anti-corrosion paint, such as cadmium passivated steel or zinc chromate primer on aluminium aircraft parts. Exposure has also been reported in use of lead-free ammunition, by the harder steel core stripping excess metal from the jacket of the bullet and barrel of the rifle.^[9]

The most plausible metabolic source of the symptoms is a dose-dependent release of certain cytokines, an event which occurs by inhaling metal oxide fumes that injure the lung cells. This is not an allergic reaction, though allergic reactions to metal fumes can occur.^[10]

Diagnosis

Diagnosis is primarily anecdotal, that is, it depends upon a good occupational history. Diagnosis of metal fume fever can be easily missed because the complaints are non-specific, resemble a number of other common illnesses, and presentation occurs typically 1–4 days after the exposure. When respiratory symptoms are prominent, metal fume fever may be confused with acute bronchitis or pneumonia. The diagnosis is based primarily upon a history of exposure to metal oxide fumes. Cain and Fletcher (2010) report a case of metal fume fever that was diagnosed only by taking a full occupational history and by close collaboration between primary and secondary health care personnel.^[11]

Physical symptoms vary among persons exposed, depending largely upon the stage in the course of the syndrome during which examination occurs. Patients may present with wheezing or crackles in the lungs. They typically have an increased white blood cell count, and urine, blood plasma and skin zinc levels may (unsurprisingly) be elevated. Chest X-ray abnormalities may also be present.^[10]

An interesting feature of metal fume fever involves rapid adaptation to the development of the syndrome following repeated metal oxide exposure. Workers with a history of recurrent metal fume fever often develop a tolerance to the fumes. This tolerance, however, is transient, and only persists through the work week. After a weekend hiatus, the tolerance has usually disappeared. This phenomenon of tolerance is what led to the name "Monday Fever".

In 2006, approximately 700 metal fume exposures were reported to the United States Poison control center. The American Welding Society estimated that 2500 employees in the steel industry develop metal fume fever in the US each year and that the majority of the cases are not reported.

Treatment

Treatment of mild metal fume fever consists of bedrest, keeping the patient well hydrated, and symptomatic therapy (e.g. aspirin for headaches) as indicated. In the case of non-allergic acute lung injury, a standard or even recommended approach to treatment has not been studied.^[10]

A traditional remedy is to consume large quantities of cow's milk, either before or immediately after exposure.^[1] However, this advice is challenged by the United Kingdom Health and Safety Executive (the national independent watchdog for work-related health, safety and illness), which warns, "Don’t believe the stories about drinking milk before welding. It does not prevent you getting metal fume fever."^[12]

Prevention

Prevention of metal fume fever in workers who are at potential risk (such as welders) involves avoidance of direct contact with potentially toxic fumes, improved engineering controls (exhaust ventilation systems), personal protective equipment (respirators), and education of workers regarding the features of the syndrome itself and proactive measures to prevent its development.

Particularly for cadmium, the design of the product may be changed so as to eliminate it. NiCd rechargeable batteries are being replaced by NiMH. These contain other toxic metals, such as chromium, vanadium and cerium. Cadmium plating is replaced with zinc or nickel. Silver solder alloys now rarely contain it.

See also

• Occupational asthma

References

External links

• Inhalation fever
• http://files.aws.org/technical/facts/FACT-25.pdf
• Inorganic Dust Pneumonias

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