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To investigate the presence and measure the concentration of paraquat
in the blood and urine of the population;
To assess the possible and actual levels of exposure in the population by
measuring the concentration of paraquat in the air during spraying; and
To establish an association between different exposure levels and the
physiopathological manifestations observed in the population.
Materials and methods
The study population consisted of 21 932 inhabitants of the rural township of
Carmen de Viboral. Due to geographical and socioeconomic differences, 2725
inhabitants of this area were not included in the sampling.
Census and other information were obtained from the Ministry of Health,
together with maps and plans from the Department of National Statistics
Administration. All data were verified by the investigators. One in every four
houses was chosen for the survey. The sample of 941 homes consisted of 5483
people, all of whom were interviewed. For medical examination, 896 people
(a random subsample of about 20% of the original population) aged 7 years
and older (except women more than 3 months pregnant) were selected. For
the pulmonary function study, this sample was further reduced to 485 by
including only men between the ages of 15 and 70 years.
Between April and July 1986, a questionnaire was administered to obtain
information on sociodemographic status, occupational or other exposure to
paraquat, and general health (particularly regarding the respiratory system).
Variables likely to influence the effect of paraquat, such as smoking habits and
previous exposure to other lung risk factors, were also determined. In consultation
with medical personnel at the San Juan de Dios University Hospital in
Bogota and on the basis of current knowledge of the effects of paraquat on
humans, the American Thoracic Society's 1978 revision of the Medical
Research Council's questionnaire for respiratory function was adopted for this
study. The questionnaire was pretested in a pilot study and refined accordingly.
All 896 subjects in the subsample underwent a general medical examination
during this same period. Lung function was evaluated by spirometry. Thoracic
x-ray examination was not performed for ethical reasons. According to the
values for the components of the test, lung function was classified as follows:
Restrictive = forced vital capacity (FVC) 80% of the predicted value;
forced expiratory volume per second (FEy1.0) divided by FVC 75%;
and residual volume (RV) or total lung capacity (TLC) or both 120%
of the predicted value;
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