rice cropping season, as well as the respective pesticides and application strategies
used to control these. We also asked about the purchase and handling of pesticides,
and for them to name the primary source of fresh water used for household
consumption.
On average, each farmer cultivated 0.15 ha of paddy rice and all farmers used
pesticides to control pest problems. The most widely used insecticides were
Conphai 15WD and Ofatox 400EC, containing the active ingredients imidacloprid
(a neonicotinoid pesticide), fenitrothion (an organophosphate) and trichlorfon (an
organophosphate), respectively. During the spring cropping season, farmers applied
pesticides, mainly insecticides, three to four times after transplanting, yielding a
total average dose of 0.9 kg ha
À1 of active ingredients. It is noteworthy that this
amount was about twice the upper dosage recommended by the distributing
companies. In total, 88 % of all farmers applied pesticides when their paddies
were ponded (i.e., under water), and of these, 58 % did not close-off the drainage
channels from their paddies during application. For those farmers who closed the
drainage channels, they opened them again 1–2 days after application.
Two-thirds of farmers washed their spraying equipment, commonly a backpack
sprayer, after use, in one of the two major irrigation channels; while others used
water from the river for cleaning. These surface water sources were also the main
locations for bathing and doing the laundry for almost all the interviewed farmers.
Groundwater wells also played a key role in Chieng Khoi, providing water for
drinking and cooking to 96 % of the households. Furthermore, we asked the farmers
to appraise the health risks they were being exposed to during pesticide application,
and in response, 42 % of the respondents thought there was no risk, while 44 % said
the risk was very small. Only 12 % felt the risk exposure to be medium, while 2 %
considered the hazard potential as significant. With regard to environmental pesticide exposure, 28 % said they had noticed a problem with water contamination
when using pesticides in some form or another in the Chieng Khoi area. In
summary, these results point to the improper use and handling of pesticides within
rice farming communities in the mountainous regions of Vietnam.
4.4 Pesticide Exposure and Eco-toxicological Risk Assessment
in the Mountainous Areas of Thailand and Vietnam
4.4.1 Measuring the Fate of Pesticides in Mountain and Remote
Areas
Surface and subsurface run-off, and leaching, largely determine the amount of
pesticides transferred from agricultural fields and orchards to surface and groundwater sources (Leu et al. 2005; Kahl et al. 2007, 2008), though spray drift can also
be a determinant (Siebers et al. 2003; Schulz et al. 2001). After their application,
pesticides are subject to various biological, chemical and physical processes, the
4 Agricultural Pesticide Use in Mountainous Areas of Thailand and Vietnam. . .
157
used to control these. We also asked about the purchase and handling of pesticides,
and for them to name the primary source of fresh water used for household
consumption.
On average, each farmer cultivated 0.15 ha of paddy rice and all farmers used
pesticides to control pest problems. The most widely used insecticides were
Conphai 15WD and Ofatox 400EC, containing the active ingredients imidacloprid
(a neonicotinoid pesticide), fenitrothion (an organophosphate) and trichlorfon (an
organophosphate), respectively. During the spring cropping season, farmers applied
pesticides, mainly insecticides, three to four times after transplanting, yielding a
total average dose of 0.9 kg ha
À1 of active ingredients. It is noteworthy that this
amount was about twice the upper dosage recommended by the distributing
companies. In total, 88 % of all farmers applied pesticides when their paddies
were ponded (i.e., under water), and of these, 58 % did not close-off the drainage
channels from their paddies during application. For those farmers who closed the
drainage channels, they opened them again 1–2 days after application.
Two-thirds of farmers washed their spraying equipment, commonly a backpack
sprayer, after use, in one of the two major irrigation channels; while others used
water from the river for cleaning. These surface water sources were also the main
locations for bathing and doing the laundry for almost all the interviewed farmers.
Groundwater wells also played a key role in Chieng Khoi, providing water for
drinking and cooking to 96 % of the households. Furthermore, we asked the farmers
to appraise the health risks they were being exposed to during pesticide application,
and in response, 42 % of the respondents thought there was no risk, while 44 % said
the risk was very small. Only 12 % felt the risk exposure to be medium, while 2 %
considered the hazard potential as significant. With regard to environmental pesticide exposure, 28 % said they had noticed a problem with water contamination
when using pesticides in some form or another in the Chieng Khoi area. In
summary, these results point to the improper use and handling of pesticides within
rice farming communities in the mountainous regions of Vietnam.
4.4 Pesticide Exposure and Eco-toxicological Risk Assessment
in the Mountainous Areas of Thailand and Vietnam
4.4.1 Measuring the Fate of Pesticides in Mountain and Remote
Areas
Surface and subsurface run-off, and leaching, largely determine the amount of
pesticides transferred from agricultural fields and orchards to surface and groundwater sources (Leu et al. 2005; Kahl et al. 2007, 2008), though spray drift can also
be a determinant (Siebers et al. 2003; Schulz et al. 2001). After their application,
pesticides are subject to various biological, chemical and physical processes, the
4 Agricultural Pesticide Use in Mountainous Areas of Thailand and Vietnam. . .
157