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Storage of pesticides
Although the storage of pesticides is subject to international standards as in
other countries, our study shows that in Bolivia this is not adhered to. In the
lowlands, 80.9% of directly exposed workers said that they stored pesticides
in special storage areas for this purpose; however, in the mesothermal valleys,
valleys, and altiplano, 80.8%, 79.0%, and 63.6% stated that they store them at
home. Those storing pesticides at home greatly increase the risk of poisoning,
not only for the agricultural workers but also for their families and animals.
This may explain the high incidence of poisoning found in the altiplano and
valleys (INSO 1987; Malgarejo 1987).
Mixing pesticides
Pesticides must be mixed in precise quantities and applied a specified number
of times to eliminate pests. Otherwise, not only will the pest be only partially
eliminated, but strains will begin to develop that are resistant to the pesticide.
In the lowlands, the preparation work (where pongueaje, the system of exploitation
dating from the colonial times still exists) is generally carried out by
supervisors, landowners, or experts; only 29.0% of the workers said that they
mix their own pesticides. However, in the mesothermal valleys, valleys, and
altiplanos, 90.4%, 78.0%, and 60.6% of the directly exposed farmers mix their
own. It was further discovered that agricultural workers were mixing up to
five or six products in the same container and testing the concentration by
tasting it! Spraying is also often done just before harvest, so products taken to
the markets for sale to consumers are contaminated by pesticides.
Cholinesterase levels in the exposed population
The level of poisoning in a study population is usually obtained after three
tests of cholinesterase level before exposure to organophosphates establish the
normal level; an examination after exposure will give the level of absorbtion
of the toxin. This method is not always possible in countries such as ours,
where there are no established pesticide-spraying programs, and where the
health-care system does not reach the agricultural population. Great efforts
were taken in this study to obtain samples, sometimes by covering over
200 km/day over almost impassable routes and roads.
Of the DE agricultural workers in the lowlands, 10.7% showed levels of blood
cholinesterase activity below the set threshold of 75%; 0.8% were at the lower
limit of severe poisoning. Of the IE workers, only 5.3% had reduced levels of
cholinesterase activity and, in the NE group, 100% of the workers had normal
levels of activity.
In the valleys, in a sample of 24 NE workers who work in roofed nurseries in
the commercial cultivation of roses, 16.7% showed reduced cholinesterase
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