The liver is the target organ of many occupational and environmental chemicals and plays a central role in their detoxification and elimination. Bacterial and viral infections and certain chemical and physical agents encountered in the workplace also involve the liver. Tables 25–1, 25–4, and 25–5 present the main causes of occupational liver disease.
DETECTION OF OCCUPATIONAL LIVER DISEASE
With the exception of a few chemicals that cause specific lesions (Table 25–1), hepatic injury as a consequence of industrial exposure does not differ clinically or morphologically from drug-induced damage (including damage caused by ethanol). Thus, it may be difficult to differentiate occupational from nonoccupational causes on the basis of screening tests.
Table 25–1.Chemical agents associated with occupational liver disease. ||Download (.pdf) Table 25–1. Chemical agents associated with occupational liver disease.
|Compound ||Type of Injury ||Occupation or Use |
|Arsenic ||Cirrhosis, hepatocellular carcinoma, angiosarcoma ||Pesticides |
|Beryllium ||Granulomatous disease ||Ceramics workers |
|Carbon tetrachloride ||Acute hepatocellular injury, cirrhosis ||Chemical manufacturing |
|1,4-dichlorobenzene ||Acute hepatocellular injury ||Insect repellant manufacture |
|1,1,2,2-tetrachloroethane (TTCE) ||Acute hepatocellular injury ||Glues |
|Dimethylacetamide ||Acute hepatocellular injury ||Spandex production |
|Dimethylformamide ||Acute hepatocellular injury ||Solvent, chemical manufacturing |
|Dimethylnitrosamine ||Hepatocellular carcinoma ||Rocket manufacturing |
|Dioxin ||Porphyria cutanea tarda ||Pesticides |
|Halothane ||Acute hepatocellular injury ||Anesthesiology |
|Hydrazine ||Steatosis ||Rocket manufacturing |
|Methylene dianiline (MDA) ||Cholestasis || |
MDA production workers.
Polyurethane foam insulation
|2-Nitropropane ||Acute hepatocellular injury ||Painters |
|Phosphorus ||Acute hepatocellular injury ||Munitions workers |
|Polychlorinated biphenyls ||Subacute liver injury ||Production, electrical utility |
|Tetrachloroethane ||Acute or subacute hepatocellular injury ||Aircraft manufacturing |
|Trichloroethylene ||Acute hepatocellular injury ||Cleaning solvent sniffing |
|Trinitrotoluene ||Acute or subacute hepatocellular injury ||Munitions workers |
|1,1,2,2-tetrachloroethane ||Acute hepatocellular injury || |
|Vinyl chloride ||Angiosarcoma ||Rubber workers |
Occupational liver disease may be of secondary importance to damage that occurs to other organs or may occur only at high doses after accidental exposure or ingestion. While acute toxic liver injury does occur, concern is focused increasingly on chronic liver disease resulting from prolonged low-level toxic exposure. In this respect, cancer is of central concern. Because chemical studies frequently are done on animals first, the occupational health practitioner must be able to evaluate—sometimes without the assistance of adequate human studies—the results of positive carcinogenesis studies in light of actual workplace exposures (eg, methylene chloride; see Chapter 32).
In individual cases, the clinician usually is first alerted to the presence of hepatic disease by routine enzyme tests and then must make a determination about whether the cause is occupational or nonoccupational. The occupational history and result of personal or workroom air sampling are crucial to formulation of a presumptive diagnosis. It is occasionally necessary to remove the patient from exposure to the suspected workplace toxic substance to establish the workplace relationship.
Unfortunately, the detection of preclinical disease is made difficult by the lack of sufficiently sensitive and specific tests. It ...