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Group III consisted of 31 farmers whose blood was sampled just before
the beginning of the spraying season and at the end of the summer to
determine AChE levels during the off-season; and
Group IV consisted of 24 farmers whose blood was sampled after a
minimum of 3 days abstention from handling pesticides (Group IVa) or
randomly, regardless of their handling of pesticides (Group IVb).
Two farmers from the same region, with junior college or vocational training,
agreed to act as supervisors to ensure that participating farmers complied with
the experimental protocol. Methamidophos (available under the trade names
Tamaron, Prodex, and Monitor) was chosen by the farmers and was used at a
concentration of 1.2 gIL. A tractor-driven 500-L tank, fitted with a pump and
spray gun, was used for spraying. In each subgroup, farmers alternated every
20-30 mm between carrying the hose, operating the spray gun, and driving
the tractor. Thus, each farmer was exposed to about the same dose of pesticide.
Blood analyses
The level of AChE activity in 10-.tL samples of whole blood, obtained by
finger-pricking, was measured spectrophotometrically using a method developed
for field use (WHO 1984).
Dermal exposure
A standard protocol (WHO 1982), developed for field surveys, was used to
measure the extent of exposure to the pesticide during spraying operations.
Seven polyethylene-backed filter paper pads (Schleicher and Schuell, catalogue
no. 295 PE), cut to 10 x 10 cm, were attached to different parts of the
body with tape before spraying began. At the end of the work period, the pads
were removed, a 5 x 5 cm piece was cut out and placed in a plastic envelope
in a cooler for later analysis. As a control and to determine recovery, a known
concentration of the organophosphorous pesticide was placed on a pad that
was treated in a similar fashion.
Each 5 x 5 cm pad was cut into strips and placed in a beaker containing 5 mL
ethyl acetate and extracted in an ultrasonic bath for 5-7 mm. The ethyl acetate
extract was concentrated and analyzed by gas chromatography using a 30-rn
capillary column SE 54. Column temperature was 180CC, injector temperature
was 200'C, and TSD detector temperature was 300CC.
Knowledge, attitudes, and practices
The survey to determine KAP was based on a standard protocol (WHO 1982)
with certain modifications to elicit information about knowledge regarding
the toxicity of pesticides.
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