PRINCIPLES OF TOXICOLOGY - Biology East Borneo

500 OCCUPATIONAL AND ENVIRONMENTAL HEALTHIllnesses associated with hazardous exposures both in the workplace and in the general environmenthave been recognized for thousands of years. For example, the toxic effects of lead, includingabdominal pain, pallor (anemia), and paralysis, appear to have been described by several observersamong the ancient Greeks and Romans. In the first known textbook of occupational medicine, DeMorbis Artificum Diatriba, the Italian physician Bernardino Ramizzini (1633–1717), often called thefather of occupational medicine, described diseases of the occupations and instructed physicians ofthe time: “and to the questions recommended by Hippocrates, the physician should add one more—what is your occupation?” In the United States, Dr. Alice Hamilton (1869–1970) had a major role inestablishing occupational medicine as a legitimate clinical discipline. Dr. Hamilton, the first womanappointed to the faculty of the Harvard Medical School, wrote in her autobiography: “American medicalauthorities had never taken industrial diseases seriously . . . employers could, if they wished, shut their eyesto the dangers their workmen faced, for nobody held them responsible, while the workers accepted the riskswith fatalistic submissiveness.” Among her many legacies, Dr. Hamilton fought, without success, theintroduction of tetraethyl lead into gasoline, correctly predicting that it would result in widespread leadcontamination of the environment and adverse health effects in the exposed population.How big a problem is occupational diseases? Two kinds of numbers are informative: counts andrates. Suppose there are two industries, one employing 1,000 workers nationally, the other employing50,000 workers nationally. Suppose that the incidence of work-related asthma is 12 per 100 workersper year in the first industry, and only 4 per 100 workers per year in the second industry. By thismeasure, the first industry is more hazardous. But 120 workers in the first industry develop asthmaeach year, compared to 2,000 workers in the second industry. From a public health point of view, thelarger burden of illness in the second industry might merit more attention. Counts and rates both provideuseful information, but they can yield different conclusions.There are two principal sources of data that help answer this question: employer reports, andinsurance records. Employers are required by OSHA to record all work-related injuries and illnesses,and each year, a sample of employers provide information to the Bureau of Labor Statistics. This servesas the national data source on occupational illnesses. As for insurance, the Workers Compensationsystem acts as the health insurer for workers with occupational illnesses, and the records of claimsmade or claims paid also serves as a potential data source. In both cases, there is considerableunder-reporting. Employers and workers may not recognize that an illness is work-related, oremployers may deny a worker’s claim of work-relatedness. Employers may in some cases fail to reportrecognized cases. Sometimes, occupational illnesses arise long after the exposure, perhaps afteremployment has ended, making data recording difficult.Other sources of information on occupational illnesses exist. Examples include clinical laboratories,which can yield data on cases of elevated blood lead, and physician reporting of specific diseases.While such sources are important in specific settings, none has gained widespread use.TABLE 20.1 Leading Categories of Work-Related DiseasesOccupational lung diseases: asbestosis, byssinosis, silicosis, coal worker’s pneumoconiosis, lung cancer, occupationalasthmaMusculoskeletal injuries: disorders of the back, trunk, upper extremity, neck, lower extremity, trauma-inducedRaynaud’s phenomenonOccupational cancers (other than lung cancer): leukemia, mesothelioma, cancers of the bladder, nose, and liverOccupational cardiovascular diseases: hypertension, coronary artery disease, acute myocardial infractionDisorders of reproduction: infertility, spontaneous abortion, teratogenesisNeurotoxic disorders: peripheral neuropathy, toxic encephalitis, psychoses, extreme personality change (exposure-related)Noise-induced hearing lossDermatologic conditions: dermatoses, burns (scaldings), chemical burns, contusions (abrasions)Psychological disorders: neuroses, personality disorders, alcoholism, drug dependency