Iron
Classification:
Iron is a common chemical element.
Cas:
7439-89-6
Synonyms/Trade Names:
Ancor EN 80/150, Armco Iron, Carbonyl Iron; Arc Welder’s Lung, Haematite Foundry Worker’s Lung, Iron Oxide Lung, Siderosilicosis, Siderosis, Siderosis Pulmonum.
Chemistry/Composition:
Fe.
Structure:
Cubic body centered.
Crystallographic Constants:
2.86 2.86 2.86 90.000 90.000 90.000.
Crystal Group:
Cubic.
Color:
Metallic gray.
Optical Properties:
Opaque.
Pleochroism:
None.
Powder Diagram:
2.03 1.17 1.43 0.91 (6-669).
Natural Sources:
World-wide, but only in oxidic forms. The important crystal ores are magnetite, haematite, goethitete, limonite (Fe2O .H2O+aq), siderite, chamosite (3FeO×Al2O3×2SiO2×3H2O) and rarely in other ores; compare to goethitete, haematite, magnetite, siderite.
Medical Importance:
Key Hazards:
Possibly fibrogenic, possibly mutagenic.
Involved Organs:
Lung.
Exposure/Epidemiology:
Iron is used in many technical products. The main producing countries are Australia, Brazil, Canada, Liberia, Sweden, the USA, and Russia. World production was 878×106 tons in 1976. Exposure may occur during mining, in foundry work, welding, and steel production.
Thresholds:
In Germany, MAK 6 mg/m3.
Etiology/Pathophysiology:
Iron oxide is inert to the human lung. Large amounts of iron dust can be ingested by macrophages and deposited in the lung parenchyma without severe fibrosis; however, additional presence of silica can result in benign interstitial lung fibrosis. A correlation between the severity of the lung fibrosis and the quartz concentration in the inhaled dust has not been found. A few studies mentioned a higher risk for carcinoma of the lung in men working in underground haematite mines, which may be related to the Radon concentration in the mines. Pure iron-oxide is not carcinogenic; however, it may be cocarcinogenic with benzo(a)pyren. Haematite mines normally contain quartz. An increased risk of lung, stomach and gastrointestinal cancer, and cancer of the genitourinary system was found in iron and steel foundry workers. The increased risk was not noted in men working in sulfuric acid production, where Fe2O3 is created. Haematite can induce a fibrosis of the lung, if it is contaminated with silica. Some studies assumed that iron-oxide dust can protect the lung against fibrosis. Many siderite miners from the Siegerland (Germany) suffered from silicosis, but only a few in the Salzgitter area (Germany). In addition, acute intoxication is known.
Lung Diseases:
Benign pneumoconiosis, also called siderosis.
Clinical Presentation:
Pure dust of iron-oxide induces no symptoms. Reddish-brown sputum and a cor pulmonale may occur after long periods of exposure. In acute intoxications, paralysis, vomiting, diarrhoea, hypotonia, and metabolic acidosis (possibly) are seen.
Lung Function:
Pure iron-oxide is inert.
Bronchoalveolar Lavage:
Usually normal findings.
Radiology:
Chest radiographs show nodular opaque shadows, in early cases only siderotic changes without progression. The radiological signs may develop years after termination of the exposure.
Pathology:
Gross:
The lung parenchyma is of brick -red color and displays three different categories of fibrosis: a) massive with central necrosis, usually seen in the upper lobes; b) diffuse interstitial fibrosis related to the lobular septae, and usually seen in both the upper and lower lobes; c) nodular and uniformly distributed fibrosis.
Histology:
The findings include whorled interstitial fibrosis which can be massive with central necrosis or nodular and diffuse with scattered mononuclear inflammatory infiltrates. Black, Prussian-blue-negative dust particles are usually present as well as birefringent crystals, which correspond to silica. The normal texture of the lung parenchyma is destroyed. The pulmonary artery branches show collections of acellular collagen intermingled with haematite dust and dustladen macrophages. Small foci of mononuclear inflammatory infiltrates are present.
Prognosis:
The prognosis is good, and the severity of the disease may decrease after termination of the exposure.
Additional Diseases:
Welders Lung:
A specific presentation of siderosis.
Tuberculosis:
The higher incidence of tuberculosis seen in haematite miners may be related to the contamination of minerals like quartz. It has not been mentioned in pure iron-oxyde-dust exposed persons.
Silver Polishers’ Lung:
The final stage in the manufacture of silverware is the polishing with iron-oxide containing powder. The exposure may induce a non-fibrosing benign pneumoconiosis, and seldom a massive fibrosis.
Remarks:
A higher incidence of lung carcinoma has been noted in iron miners (especially in haematite miners). This is probably associated with simultaneous radon exposure.
References:
search Pubmed for Iron
Battista G, Belli S, Carboncini F, Comba P, Levante G, Sartorelli P, Strambi F, Valentini F, Axelson O: Mortality among pyrite miners with low-level exposure to radon daughters. Scand J Work Environ Health 14 (1988) 280-285
Brakhnova IT: Studies of soviet science: Environmental hazards of metals. Consultants Bureau, New York (1975)
Chen SY, Hayes RB, Wang JM, Liang SR, Blair A: Nonmalignant respiratory disease among haematite mine workers in China. Scand J Work Environ Health
5 (1989) 319-322
Dail DH, Hammar SP: Pulmonary Pathology. Springer, New York (1988)
Dunhill MS : Pulmonary pathology. Churchill Livingstone, Edinburgh (1982)
Elinder CG: Iron. In: L Friberg, GF Nordberg, VB Vouk (Eds): Handbook of the toxicology of metals. Elsevier, Amsterdam, New York (1990)
Finkelstein MM: Use of “time windows” to investigate lung cancer latency intervals at an Ontario steel plant. Am J Ind Med 19 (1991) 229-235
Finkelstein MM, Boulard M, Wilk N: Increased risk of lung cancer in the melting department of a second Ontario steel manufacturer. Am J Ind Med 19 (1991) 183-194
Fraser RG, Paré JAP: Diagnosis of diseases of the chest. WB Saunders Comp, London, Toronto (1979)
Godden DJ, Kerr KM, Watt SJ, Legge JS: Iron Lung: bronchoscopic and pathological consequences of aspiration of ferrous sulphate. Thorax 46 (1991) 142-143
IARC: Overall evaluations of carcinogenicity: an updating of IARC monographs volumes 1 to 42. IARC Mono Eval Carcinog Risk Human Suppl 7 (1987)
IARC: Cancer: causes, occurrence and control. IARC Sci Publ 100 (1990)
Kayser K: Analytical Lung Pathology. Springer, Heidelberg, New York (1992)
Lawler AB, Mandel JS, Schumann LM, Wibin JH: A retrospective cohort mortality study of iron oxide (haematite) miners in Minnesota. J Occup Med 27 (1985) 507-517
Lewis RJ: Carcinogenically active chemicals. Van Nostrand Reinhold, New York (1991)
Mur JM, Meyer-Bisch C, Pham QT, Massim N, Moulin JL, Lavallier C, Sadoni P: Risk of lung cancer among iron ore miners: a proportional mortality study of
1075 deceased miners in Lorraine, France. J Occup Med 29 (1987) 762-765
Nakamura M, Chiyotani K, Takishima T. Pulmonary dysfunction in pneumoconiosis. Maruzen, Tokyo (1991)
Pham QT, Gaertner M, Mur JM, Braun P, Gabiano M, Sadoul P: Incidence of lung cancer among iron workers. In: JBL Gee, WKC Morgan, SM Brooks (Eds): Occupational lung disease. Raven Press, New York (1984) 247
Reichel G: Auf anorganische Stäube mit gerimgem oder fehlendem Quarzgehalt zurückgehende Lungenveränderungen. In: WT Ulmer (Ed): Handbuch der inneren Medizin, Bd IV: Pneumokoniosen. Springer, Heidelberg (1978) 468-508
Robalo-Cordeiro AJA, Bagaha MF, Bernarda RA, Oliveira M, Gaspar E, Lima MAM: Occupational respiratory patterns in ferroalloy (Ferrisilicon) workers. In: JBL Gee, WKC Morgan, SM Brooks (Eds): Occupational lung disease. Raven Press, New York (1984) 247
Sadoul P, Horsky P: Modified underground working conditions change the picture of iron miner pneumoconiosis. Chest 91 (1987) 307
Valentin H, Lehnert G, Petry H, Weber G, Wittgens H, Woitowitz HJ: Arbeitsmedizin Vol 2. Thieme, Stuttgart (1985)
Wilson JD, Braunwald E, Isselbach KJ, Petersdorf RG, Martin JB, Fauci AS, Root RK: Harrison’s principles of internal medicine. McGraw Hill, New York (1991)
Wirth W, Gloxhuber C: Toxikologie. Thieme, Stuttgart (1985)