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

Leak-prone spraying components - Leaky sprayer components are a major
cause of pesticide contamination among small-scale farmers. Pump cylinders,
air chambers, and cut-off valves may leak because of worn-out parts, such as
the piston head, ball bearings, and washers, or because they are not greased
properly. Leaks at hose connection points are mainly due to the use of crimp
ferrule; continual use and flexing of the hose causes cracking.
Positioning of components If the pump body and the air chamber are not
firmly secured to the tank or are awkwardly positioned at the side of the tank
body, misalignment of the piston head in the cylinder and leakage at weld
points in the air chamber can easily result from knocks and falls during
spraying operations. Misalignment was found in 64% of the knapsack sprayers
owned and used by farmers in the rice-bowl area of Malaysia (Anas et at.
1987).
Large mesh and absence of strainers and filters - A common cause of
contamination during spraying operations is blockage of the nozzle opening
by solid foreign matter when strainers and filter mesh are too large, i.e., larger
than 1 mm for strainers and 0.5 mm for filters, or completely absent. In
Southeast Asian countries, water used to dilute the pesticides comes from
irrigation canals, small streams, or rain-water storage tanks, which contain
much foreign debris. As a result, nozzle blockage is common. Farmers often
attempt to free blockages with sharp hard objects, such as pins or steel wire
(possibly damaging the nozzle opening) or by blowing into the nozzle, contaminating
both their hands and mouths. In a survey in Malaysia's rice-bowl
area, 89% of 193 knapsack sprayers had strainers with a mesh size larger than
1-mm and none had filters at the cut-off valve and the nozzle (Anas et al. 1987).
Absence of an agitator Not all lever-operated knapsack sprayers produced
locally are fitted with an agitator. When wettable powder (WP) formulations
are used, agitators keep the powder suspended in the solution, thus preventing
it from settling or becoming aggregated and blocking the nozzle opening
during spraying.
Length and design of the spray lance - All locally produced knapsack
sprayers currently available are equipped with a 50-cm spray lance. This is too
short to prevent drifting spray droplets from contaminating the operator. A
1-rn lance, curved slightly at the front end, could make directing the spray
much easier and decrease contamination due to dirt (Jusoh Mamat and Anas
1988).
Poor quality brass used for tank body - According to Anas et al. (1987),
50-58% of sampled sprayers had body indentations and evidence of corrosion.
These were caused by knocks and falls, testifying to poor user habits as well
as the poor quality brass sheets used by manufacturers. In Malaysia, local
manufacturers produce sprayers with a price range from 60 to 120 MYR
(2.6875 Malaysian ringitts (MYR) = 1 US dollar (USD) in 1991) according to
brass content or thickness of the brass sheet used for the tank body. Sprayers
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