Biomedical subjects
J R Clarkson
Publications and source records attributed to J R Clarkson.
Drinking water and cancer in Louisiana. A retrospective mortality study.
Thirteen Louisiana parishes (counties) using the Mississippi river as a source of potable water have the highest mortality rates (1950-1969) in the drinking water source, a comparison of cancer deaths and noncancer deaths from 1960-1975 in selected southern Louisiana parishes was conducted. Parishes were grouped for similarities in industrialization and approximately equal exposure of the population to surface water and ground water. Cancers were studied in groups by hypothesized risk: high for bladder, colon, kidney, liver, lymphoma, rectum, and stomach; low for Hodgkin's lymphoma, leukemia, lung, malignant melanoma, multiple myeloma, and prostate; and questionable for breast, brain, esophagus, and pancreas. Noncancer deaths were randomly selected and matched 1:1 to cancer deaths on age, race, sex, and year and parish group of death. Water source at death was based on residence at death, surface or ground water, and chlorinated or nonchlorinated water. The risk associated with using surface water least likely due solely to change occurred for cancer of the rectum. Other risks which were lower but still greater than 1.0 occurred for cancer of the kidney and breast. No risk was observed for other cancers of the gastrointestinal or urinary tract. Risk for multiple myeloma was associated with use of ground water.
Aflatoxicosis in swine: a review.
Chronic effects of aflatoxins may be reducing the efficiency of swine production unit by decreasing the immune response leading to increased susceptibility to disease and increased mortality, and decreasing resistance to stress. The individual pig's response to aflatoxin is affected by many factors, but age is especially important with the younger pig much more susceptible to damage than older pigs. The greatest problem with aflatoxins in the United States appears to be in the Southeast and is associated mostly with corn and cottonseed meal. Management factors are important in the prevention and reduction of aflatoxins in feed. A simple quantative test for aflatoxins has been developed for field surveys of suspected feed and a decontamination process has also been developed.
Equivalent half-value thicknesses.
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Health effects from indoor air pollution: case studies.
In recent years there has been a growing awareness of the health effects associated with the presence of contaminants in indoor air. Numerous agents can accumulate in public buildings, homes and automobiles as a result of ongoing activities that normally occur in these closed spaces. Ventilation is a major factor in the control of indoor air pollutants since proper movement of air can prevent or minimize the build up of compounds in buildings. The recent emphasis on energy conservation has lead to measures which economize on energy for heating and air conditioning, but which also trap pollutants within a building. Three cases of indoor air pollution were investigated. A typical investigation of indoor air pollutant problems includes the following: interviews with building occupants; history of the building with regard to maintenance, pesticide treatment, etc.; a survey of the building and ventilation; and when warranted, sampling and analysis of air. Each case presented is unique in that atypical situations caused agents to accumulate in a building or section of a building. The indoor air problems in these cases were solved by identifying and removing the source of the offending agent and/or improving the ventilation in the building.