Impact of - IDL-BNC @ IDRC - International Development Research ...

Methods
The study was carried out in the four major ecological regions of Bolivia
(altiplano, valleys, mesothermal valleys, and eastern lowlands). In total, 731
workers were studied: 235 from the altiplano, 247 from the valleys, 57 from
the mesothermal valleys, and 197 from the lowlands.
The method used for choosing a sample of workers was identical in each
ecological region. Two towns or centres were chosen from which workers
would start out each day to work in the communities selected for the study.
On the day before a community was to be studied, the commission met with
its members and political leaders, parish priests, teachers, property owners,
etc., to explain the reasons for the work and to request their collaboration.
The evaluation was initiated with an educational talk and distribution of
pamphlets on the use and handling of pesticides and on how to prevent their
harmful effects for all interested people, including women, children, and the
elderly. This was followed by a medical evaluation and blood tests. The Ed son
method (Lovibond equipment) recommended for field studies by WHO was
used to assess the level of exposure to organophosphates. We considered
cholinesterase level in the blood to be normal when it was 75-100% of the mean
value in the general population; values of 50-62.5% indicated mild poisoning,
25-50% severe poisoning, and less than 25% extremely severe poisoning.
In all regions, numerous attempts were made to take blood samples for the
assessment of cholinesterase level before pesticide application as recommended
by the WHO protocols. However, this proved impossible in the
altiplano, the valleys, and the mesothermal valleys, because of the workers'
resistance to having biological samples taken more than once and the relative
difficulty of reaching the workers before spraying started. This paper, thus,
only reports the cholinesterase study carried out in the tropical lowlands. The
knowledge, attitudes, and practices (KAP) study, however, was carried out in
all regions.
Results
In the four ecological regions, 66.5% of the people in the samples were
agricultural workers, who handled pesticides or were directly exposed (DE);
19.3% did not handle pesticides, but were indirectly exposed (lE); and 14.2%
did not use pesticides and were not exposed to them (NE), the latter group
being the most difficult to find, because our rural workers tend to use pesticides
for domestic purposes as well.
Of all workers in the samples, 11.2% were under 18 years of age, which
explains the high known incidence of poisoning in the 12- to 18-year-old age
group. In the mesothermal valleys, altiplano, and valleys the proportion of
78