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Pesticides cover a range of compounds that include insecticides, fungicides, herbicides, rodenticides, molluscides, nematicides, plant growth regulators among others (Aktar et al., 2009). Indicators focus on the risk and environmental impact of pesticides on water quality, human health, and death of species (Padovani et al., 2004; Damalas and Eleftherohorinos, 2011). Pesticides have benefits that include improving productivity through protection from crop losses, vector control that reduces diseases, and indirect impacts like increased food security and nutrition. On the cost side, pesticides are dangerous to the targeted and nontargeted species and when used in excess amounts may kill nontargeted plants, insects, and animal species, which can affect biodiversity and other ecosystems services (Padovani et al., 2004). In addition, pesticides may contaminate agricultural foods and exposure at application may also have effects on human health (Dagupta et al., 2007; London and Bailie, 2001; Aktar et al., 2009; Damalas and Eleftherohorinos, 2011).
The first mass cases of pesticide poisoning were reported in India in 1958 where 100 people died after consuming contaminated wheat flour (Karunakaran, 1958). This raised awareness for the need to test and examine the levels of pesticide contaminations in food in the years that followed in India. In Europe, programs began examining the levels of pesticides in food products as early as 1999, when the European Union commissioned “Monitoring of Pesticide Residues in Products of Plant Origin in the European Union, Norway, and Iceland 1999 Report” (SANCO, 2001). Such reports have continued.
The data on risk of exposure to pesticide by farm workers is scanty yet high levels of exposure have been reported above the allowable limits in some studies (Dasgupta et al, 2007). For example, a study in Vietnam that took blood samples from rice farmworkers who had been exposed to insecticides (e.g., compounds containing carbamates and organophosphates) associated with health risks such as DNA damage, birth defects, hormonal changes and fetal death (Zahm et al, 1997; Dasgupta et al, 2007). Thirty-five percent of the farmers (n=190) were reported to have acute pesticide poisoning. However, it should be noted that blood tests are not always performed to assess the levels of poisoning in farmworkers. Instead subjective surveys are performed to assess symptoms and these may not provide conclusive results (Dasgupta et al., 2007). Subjective surveys and blood and health tests should be performed in tandem. Increased surveillance of pesticide poisoning and contamination in agricultural foods is also needed to understand the potential effect and how these levels are associated with some demographic and socio-economic factors (Aktar et al., 2009). In this section we cover both aspects of measurement such as the chemical tests and health center data.
How to operationalize the metric
Method of data collection and data needed to compute the method:
Pesticide contamination indicators and metrics need to be integrated in projects where pesticide use is an intervention. But measurement of the effects of these indicators and data collection may require expert knowledge of the following: 1) the composition of the pesticide being used and 2) the effects of those components on human health (symptoms of exposure). Having this information may allow those gathering health data to examine whether some symptoms that are reported in those areas may be linked to pesticide use. Additionally, researchers can determine more direct measurement is required for the exposed population.
The most direct method is collection of data from the exposed population. This should be done with the help of a health worker. A selected sample should be tested for exposure to the given chemical contaminants from the pesticides. Studies such as Dasgutpa et al. (2011) have used blood samples from the populations that were subsequently analyzed in the lab for the presence of contaminant in blood.
Unit of analysis:
The tests by health workers determine if the level of contaminant is above the maximum allowable level in humans. The units for assessment are obtained from the health specialist when needed.
Limitations regarding estimating and interpreting:
The main limitations to pesticide assessment are the costs of assessments and sometimes a low level of response from policy makers.. Due to nonspecific information on the long-term effects of exposure to pesticides and the low levels of reported poisoning (compared to added benefits of pesticides), some areas have not invested in this research. Additionally, a thorough examination of the pesticide contaminations may be costly and require a high level of expertise.