Spectrophotometric Determination of Plasma and Red Blood Cell Cholinesterase Activity of 53 Fruit Farm Workers Pre- and Post-Exposed Chlorpyrifos for One Fruit Crop

Abstract

Chlorpyrifos (O,O-diethyl 0-(3,5,6-trichloro-2-pyridyl) phosphorothioate) belongs to the organophosphate insecticide (OPs) family, and is widely used to kill aphids in fruit farms. The demand for this insecticide is increasing. To our knowledge, there is no biological monitoring data for fruitfarm worker exposure to chlorpyrifos insecticide is available in Thailand. Biological monitoring is an essential component of any comprehensive assessment of exposure. In fact, these farm workers were at high risk of direct exposure to pesticides while mixing, loading, or spraying pesticide. [1][2][3][4] It has been reported that chlorpyrifos insecticide is rapidly absorbed by skin contact and/or oral administration, metabolized and excreted by mammals.5) The primary mechanism of action of organophosphorus (OP) insecticides like chlorpyrifos involves the inhibition of acetylcholinesterase (AChE), resulting in a wide range of neurotoxic effects in humans, such as sensory and motor neuropathy with permanent paralysis. The inhibition of cholinesterase enzyme (ChE) may cause acetylcholine accumulation at the synaptic cleft, causing the stimulation of autonomic receptors and depolarizing blocks of neuromuscular junction receptors in the human body. In addition, it was proposed that both long-term exposure to subclinical doses of OP, and after acute intoxication, could be responsible for chronic OP-induced neuropsychiatric disorders. [6][7][8][9] ChE can be used as an index of cholinergic function and changes in enzyme activity may indicate alterations in the availability of acetylcholine at the receptor level. [10][11][12][13][14] In vivo, ChE activity reflecting the functional quantities of the enzyme can be assessed using blood, plasma, and red blood cells. Inhibition of ChE leads to a down-regulation of cholinergic receptors. The levels of ChE appear to be controlled by the interaction of acetylcholine with its receptors, with enhanced interaction increasing the levels of ChE. 15)This study aims to investigate any changes in ChE activity reflecting the cholinergic function of fruit farm workers exposed to the neurotoxin, chlorpyrifos insecticide, during one fruit crop. For this purpose, the blood ChE activities of 53 farm workers on fruit farms in Rayong Province, Thailand, were collected and analyzed.In the present study, a significant decrease in plasma (PChE), but not red blood cell ChE (AChE) activity after exposure to chlorpyrifos in the spraying season, compared with the non-spraying season, was found. The results suggest an interaction between chlorpyrifos and monoaminergic-cholinergic neurotransmission that leads to a decrease in the functional enzyme available to degrade acetylcholine. We propose that PChE activity can be used as a biomarker for monitoring early toxicity induced by chlorpyrifos insecticide. Determination of baseline red blood cell and plasma cholinesterase activity among applicators in the non-spraying season is very important, before identifying the effects of these pesticide exposures. Experiment...

Comparative Study of Paraoxonase and Cholinestrase Enzymes Activities in Diagnosis of Organophosphorus Insecticide Intoxication

“…This finding is in agreement with other studies carried out by Akgur et al (2003) and Joshaghani et al (2007). However, Thetkathuek et al (2005) demonstrated significant decrease in BuChE without alteration in AChE activity in chlorpyrifos applicators. Eaton et al (2008) stated that, plasma BuChE is substantially more sensitive to inhibition by chlorpyrifos than erythrocyte AChE.…”

Cholinesterase Depression and Its Association with Pesticide Exposure across the Agricultural Season among Latino Farmworkers in North Carolina

“…Most other studies of pesticide exposure have used a study design with nonexposed controls (e.g., Cataño et al 2008; Ntow et al 2009; Rendón von Osten et al 2004) or a pre–post design (Gamlin et al 2007; Thetkathuek et al 2005) to identify cholinesterase depression. Such designs are not always practical with migrant workers in the eastern United States.…”

Factors that contribute to insecticide poisoning among immigrant agricultural workers in Thailand

“…In economically developing countries like Thailand, organophosphates (OPs) and carbamates (CMs) are widely used as pesticides among fruit farmers [6]. Serious intoxication and other poor health repercussions resulting from the inappropriate use of insecticides are frequently reported.…”

“…Serious intoxication and other poor health repercussions resulting from the inappropriate use of insecticides are frequently reported. Due to the type of work performed, immigrant agricultural workers are at an especially high risk of being exposed to insecticides [7][8][9], a problem also reported in Kenya and Nicaragua [10,11] and in other areas of Thailand where insecticides are widely used in farming [6].…”