The Present and the Future

Although all three population groups have seen dramatic improvements in their health, disease ecologies continue to evolve. Today virus infections remain as serious public health problems, acting differentially on the genetic variation present on the continent. Often forgotten in this context is that perplexing virus, influenza. It is perplexing because of its mutational history, with each strain - "Asian," "Hong Kong," "swine," and so forth - being distinct immunologically, and ever dangerous in light of the still readily recalled devastation caused by the 1918-20 pandemic. Recent work by Gerald Pyle, a medical geographer, epitomizes the promise of the application of geographic modeling to public health problems of tracing the diffusion of diseases such as this (Pyle 1986). The acquired immune deficiency syndrome (AIDS) has established itself as of prime concern and appears to be following much the same pattern of spread as the earlier urban-centered epi-

Table VII.8.1. Incidents of serious contamination in U.S. work sites and residential areas

Location

Chemicals Health effects

Cause of incident

Southern mirex

United States"

St. Louis Park, creosote Minn.6

Hopewell, Va.c kepone

Tyler, Tex.c

Chattanooga, Tenn.c

Times Beach, Mo.c

Times Beach, Mo.c asbestos nitrogen dioxide dioxin [TCDD] (300 ppb) and others dioxin [TCDD]

Causes cancer in mice. Toxic to crabs and shrimp. Detected mirex in fatty tissue of 25% of people living in area sprayed.

Severe skin reaction from handling creosote-bearing soil.

June 1975: A worker became ill with dizziness and trembling due to high concentration of kepone in his blood. State official investigations found 7 workers ill enough to require immediate hospitalization. Over 100 people, including wives and children, had kepone in their blood, and 30 more people were hospitalized with tremors and visual problems.

Some people may be permanently sterile, and all are threatened with possible development of liver cancer. 25-40 of 900 workers have died from breathing asbestos. The death toll is expected to reach 200 workers.

Exposed persons are more susceptible to respiratory disease, colds, bronchitis, croup, and pneumonia. Effects of dioxin exposure appeared almost immediately.

In 10 days hundreds of birds and small animals died; kittens were stillborn, and many horses died.

Miscarriages, seizure disorders, liver impairment, and kidney cancer.

Mirex was sprayed over several of the southern states in order to control fire ants.

Its use was phased out in 1978 owing to health effects.

Mirex stays in the environment longer than DDT.

Reilly Tar and Creosote Manufacturer had an 80-acre site where waste was dumped.

Nearby wells were contaminated by the site.

The Life Science Products Corporation produced the pesticide kepone and employed the people affected.

The asbestos plant closed in 1972.

TNT plant located nearby.

Levels of exposure up to 500 grains/

billion have been shown.

Man was hired to spread oil on dirt roads; oil residues plus other wastes that remained in the containers were mixed into the oil.

Dioxin in the form TCDD as high as 300 ppb (1 part per billion is the maximum dose deemed safe).

EPA purchased every piece of property in the town and ordered its evacuation.

Sources: "Gould (1986, 28-9); ^Epstein, Brown, and Pope (1987, 75); cGetis, Getis, and Feldman (1981).

demies of alien origin. Immigrants continue to introduce new potential pathogens and are the source of reintroduction of others to which the resident population may have lost herd immunity (Kliewau 1979). Urban wastes as well as technologies constantly tend to poison the environment (Greenberg 1978), and through disposal efforts and acid rain, virtually the whole population is exposed. The health effects of contamination are not always dramatic, but as Table VII.8.1 shows, the results can be very real.

Perhaps because of the shorter time lapse involved, the monitoring of birth defects and infant mortality provides an important measure of these new hazards (Puffers and Serrano 1973). Although improvements in infant survival rates encourage the belief that a new homeostasis is being reached, any marked change for the worse and any increase in congenital anomalies need to be treated very seriously.

Much remains to be learned about the natural history of health and disease in the Americas. . . . We do not know why diseases occur or do not occur at a given time and place. Even less do we know what conditions and circumstances cause them to spread within a country and between countries in the Hemisphere. Indeed, accurate knowledge of the etiology of a specific disease does not tell us about the sequence of events that produce it. Today we accept the fact that multiple causes are involved in the development of disease. (Horwitz 1973)

These causes include those of nature, inherited in infancy from the genetic stream, predisposing in all probability to a number of conditions from hypertension in black North Americans to schizophrenia and beyond. The triggers creating recognizable diseased individuals, however, often appear to remain environmental and related to poverty. The comprehensive evaluation of these links of nature and nurture remains the challenge of a historically based medical geography of the Americas.

Frank C. Innes

The support, advice, and editorial assistance of Dr. Robert Doyle, Department of Biology, was invaluable. Student assistance of Lydia Stam-Fox and Amanda James and cartography by Ron Welch together with a grant from University of Windsor Research Board made this contribution possible.

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