Thailand is an agricultural country that produces one of the largest quantities of rice in the world. In 2009, the total area of rice farming in Thailand covered approximately 26 million acres across the country [1]. Organophosphate (OP) pesticides contain chemicals which are primarily used in agriculture [2]. Besides being rapidly decomposed, these components are somewhat non persistent in the environment. However, they are described as being highly and acutely toxic [3]. As a result, farmers, as well as the general public, may run the risk of exposure to such substances which can be exposed to in several ways such as breath, oral cavity, and skin [4].
OP pesticides include a high toxicity on humans due to the fact that they act as acetyl cholinesterase inhibitor, resulting in the blockage of the nervous system [5]. The activity of cholinesterase enzymes in the blood can be measured used as a biomarker for the effect of organophosphates. AChE is characteristically used as an indicator for chronic exposure. On the contrary, PChE turnover is much more rapid. PChE is a more efficient short-term indicator [6]. A lot of methods can be used to test cholinesterase level. However, normal method used was a screening test, which should be confirmed by Ellman methods [7]. Therefore, this research aims to find the association between health effects and organophosphate pesticides exposure among rice farmers and non-farmers by using blood cholinesterase levels; both blood enzymes erythrocyte cholinesterase (AChE) and plasma cholinesterase (PChE). Cholinesterase level was tested by Ellman method; Test-mate ChE (Model 400).