Metal Fumes and Lung Diseases

 

Metal Fumes and Lung Diseases

PKGhatak,MD

People do not encounter metal fumes every day and many may be completely unaware of them. It is a different story for factory workers, foundry workers, ironworkers and workers in many other workplaces where exposure to metal fume inhalation is a daily occurrence.

Lungs are exposed to the environment directly; whatever is in the air it finds its way eventually into the lungs. The gastrointestinal tract is very well protected by a layer of very strong acid secreted by the stomach, the skin is impervious to most agents to a certain degree and the eyes are partially protected by tear secretion.

Reactions of lung to metal fumes.

Metals used in industries and household products come in several forms. The metals may be in the pure metallic form, combined with other elements like oxide, sulfide, nitrite, halide, carbide and also combined with organic compounds. For these discussions, all are simplified as metals. Also, important to point out the toxicities not only vary from compound to compound but also in the frequency of exposure and concentration in the air. The solubility of metal compound influence pulmonary reactions; poorly soluble compounds are caught and eliminated by the mucociliary escalator, and soluble compounds react with tissues directly and produce more intense reactions.

Certain metal fumes produce only minimal fibrosis in the lung, the metal merely fills up the lung. An example is iron.

The inhalation of nickel and beryllium produces intense inflammation leading to extensive fibrosis of the lungs.

Many other metals produce in between these two reactions.

In some cases, the metals combine with the protein of the body become antigenic and produce immune reactions. These metals act as Heptane, for example- platinum, chromium, cobalt, etc.

Some metals produce only one type of pulmonary disease, others like chromium produce a number of different clinical diseases.

Clinical conditions produced by metal fumes.

Acute bronchitis, chronic bronchitis and sinusitis are common occurrences. Example-cadmium, lead, zinc, and chromium.

Occupational asthma is a frequent occurrence, example-nickel, chromium, and cobalt.

Hypersensitive pneumonitis is seen in platinum exposure.

Pneumonitis without fibrosis; for example- iron, tin, and barium.

Pneumonitis with fibrosis, example-barium, antimony.

Pulmonary emphysema, for example - cadmium.

Granulomatous lung disease is similar to sarcoidosis, for example – beryllium. Rarely tin, and aluminum.

Desquamative giant cell interstitial pneumonitis, for example -cobalt.

Lung cancer, for example - radium, Iron.

Pulmonary edema, for example - lithium, zinc, lead.

Chronic obstructive pulmonary disease, for example - Zinc, lead.

Alveolar Proteinosis example - aluminum.

In addition to lung diseases metals also produce liver, kidney and other organ damage. Those are not discussed here.

Professions outside metal manufacturing are susceptible to pulmonary diseases.

Diamond polisher – exposure to cobalt.

Aerospace industries – exposure to beryllium.

Electronic, computer and ceramic – exposure to beryllium.

Dental technicians – exposure to align, beryllium.

Housewife/spouse (workers bringing home) - beryllium dust in their clothing.

Painters – pigments containing various metal compounds.

Boilermakers and Oil tanker cleaners - exposure to vanadium.

Firework and explosive makers - exposure to aluminum.

Hard metal toolmakers and users - exposure to tungsten

Chrome plating – exposure to chrome.

Glass polishers and lens makers - exposure to cerium (rare earth).

How metals act in tissues.

1. Metals like iron, copper, magnesium, cobalt, and zinc are coenzymes in many enzyme systems.  2. Many transport proteins are compounds of metals. 3. Some metals readily combine with proteins and sensitize immune cells. 4. Metals combined with macromolecules hinder DNA repair.

The incidence of inhaled metal compounds and pure metal fumes is increasing due to the expansion of manufacturing facilities near residential districts and the relaxation of air quality standards in recent years.

The lung diseases caused by metal fumes have no easily distinguished features from usual chronic lung conditions like chronic bronchitis or pneumonitis and pneumonia. People are well aware that lung cancer and COPD are related to cigarette smoking. However, many nonsmokers develop COPD and lung cancer, and they are baffled and ask their doctors what caused their illness.

It is only by a careful and detailed history of occupation, home environment, recreation and hobby habits a cause can be identified.

Tests for identification of metals.

High Performance Liquid chromatography. And Gas Chromatography.

The final identification depends on the demonstration of that metal in the respiratory tissues or secretions or bronchial washing fluid by one of the two tests mentioned above.

Immunoassays.

The specific antibodies against the suspected metal tests are available but are not as sensitive and specific as chromatography.

 

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