There are also impacts on their health arising from the overuse of chemicals for cultivation. Annual consumption of pesticides and fertilizers per hectare of cultivated land increased respectively from 7 kg and 0.3 kg in 1961 to 183 kg and 2.6 kg in 1999 (DAE, 1961; OAE, 1999). Each year, two to four thousand patients have been both fatally and non-fatally injured from chemical exposure in the agricultural sector (OEPP, 2001). The figures are likely to be under-reported, as they do not include those unattended by doctors. The practice of monoculture with high use of fertilizers have deteriorated soil quality and precipitated soil erosion. It is estimated that around two-thirds of the countries’ cultivated area is affected by soil erosion problems (Phantumvanit, et a1., 1990).