PRINCIPLES OF TOXICOLOGY

500 OCCUPATIONAL AND ENVIRONMENTAL HEALTH
Illnesses associated with hazardous exposures both in the workplace and in the general environment
have been recognized for thousands of years. For example, the toxic effects of lead, including
abdominal pain, pallor (anemia), and paralysis, appear to have been described by several observers
among the ancient Greeks and Romans. In the first known textbook of occupational medicine, De
Morbis Artificum Diatriba, the Italian physician Bernardino Ramizzini (1633–1717), often called the
father of occupational medicine, described diseases of the occupations and instructed physicians of
the 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 in
establishing occupational medicine as a legitimate clinical discipline. Dr. Hamilton, the first woman
appointed to the faculty of the Harvard Medical School, wrote in her autobiography: “American medical
authorities had never taken industrial diseases seriously . . . employers could, if they wished, shut their eyes
to the dangers their workmen faced, for nobody held them responsible, while the workers accepted the risks
with fatalistic submissiveness.” Among her many legacies, Dr. Hamilton fought, without success, the
introduction of tetraethyl lead into gasoline, correctly predicting that it would result in widespread lead
contamination 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 and
rates. Suppose there are two industries, one employing 1,000 workers nationally, the other employing
50,000 workers nationally. Suppose that the incidence of work-related asthma is 12 per 100 workers
per year in the first industry, and only 4 per 100 workers per year in the second industry. By this
measure, the first industry is more hazardous. But 120 workers in the first industry develop asthma
each year, compared to 2,000 workers in the second industry. From a public health point of view, the
larger burden of illness in the second industry might merit more attention. Counts and rates both provide
useful information, but they can yield different conclusions.
There are two principal sources of data that help answer this question: employer reports, and
insurance 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 serves
as the national data source on occupational illnesses. As for insurance, the Workers Compensation
system acts as the health insurer for workers with occupational illnesses, and the records of claims
made or claims paid also serves as a potential data source. In both cases, there is considerable
under-reporting. Employers and workers may not recognize that an illness is work-related, or
employers may deny a worker’s claim of work-relatedness. Employers may in some cases fail to report
recognized cases. Sometimes, occupational illnesses arise long after the exposure, perhaps after
employment 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 Diseases
Occupational lung diseases: asbestosis, byssinosis, silicosis, coal worker’s pneumoconiosis, lung cancer, occupational
asthma
Musculoskeletal injuries: disorders of the back, trunk, upper extremity, neck, lower extremity, trauma-induced
Raynaud’s phenomenon
Occupational cancers (other than lung cancer): leukemia, mesothelioma, cancers of the bladder, nose, and liver
Occupational cardiovascular diseases: hypertension, coronary artery disease, acute myocardial infraction
Disorders of reproduction: infertility, spontaneous abortion, teratogenesis
Neurotoxic disorders: peripheral neuropathy, toxic encephalitis, psychoses, extreme personality change (exposure-related)
Noise-induced hearing loss
Dermatologic conditions: dermatoses, burns (scaldings), chemical burns, contusions (abrasions)
Psychological disorders: neuroses, personality disorders, alcoholism, drug dependency