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Pulmonary obstructive disease
in a population using paraquat
in Colombia
ME. Arroyave
Instituto Nacional de Salud, Bogota, Colombia
Paraquat, a herbicide of the bipyridil group, has been used in Colombia
with increasing frequencysince its registration in 1969. This study aimed
to discern the effects of paraquat on agricultural workers. A questionnaire
and a medical examination (including lung-function tests) were used to
determine exposure. The results indicate that there is a positive association
between the use of paraquat (at high levels of exposure), smoking habits,
and chronic obstructive pulmonary disease.
Paraquat (1,1'-dimethyl-4,4'-bipyridylium dichioride) has been used as a
broad-spectrum herbicide for nearly 30 years. Since its registration in
Colombia in 1969, paraquat has been used principally for the control of weeds
in cotton, sugarcane, potato, corn, and tomato cultivation. It is also used as a
desiccator to facilitate the harvesting of rice, sugarcane, soybeans, corn, and
sorghum crops and as a defoliant in the cultivation of bananas, cacao, oil
palms, citrus, and other fruits. In nonagricultural areas, paraquat is used as a
nonspecific contact herbicide.
Paraquat has been classified by the World Health Organization (WHO) as a
class II (moderately hazardous) compound. In experimental animals, the
systemic administration of this substance results in progressively degenerative
and potentially lethal lesions in the lungs. In addition to degenerative lung
fibrosis, observed effects in humans range from dermal toxicity and irritation
of the skin and mucous membranes (Hearn and Keir 1971) to corrosive
gastrointestinal effects, renal tubular damage, and liver dysfunction (Grant et
al. 1980). At present, there is no antidote for paraquat poisoning and treatment
is perforce symptomatic.
Paraquat is not destroyed by the biological processes of plants or mammals.
In mammals, absorbed paraquat is largely eliminated unchanged by the
kidneys because of its low molecular weight and nonvolatility. However,
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