Blood cholinesterase activities and oxidative stress status among farmworkers using pesticides in Duhok, KRG, Iraq

Abstract

Background: The use of pesticides by farmworkers poses considerable health risks. This study was undertaken to examine plasma and erythrocyte cholinesterase activities, plasma oxidative biomarkers malondialdehyde (MDA), and total antioxidant status (TAS) among farmworkers using different pesticide products in Duhok, northern of Iraq. Methods: This is a case-control study conducted between November 2021 to July 2022 on 92 male farmworkers who were exposed to pesticides in comparison with 44 non-exposed male subjects (control). The availability and uses of pesticides were obtained from 19 agrochemical shops and the farmworkers exposed to pesticides. Demographic data of pesticide-exposed farmworkers and their practice of pesticide applications were recorded. Plasma and erythrocyte cholinesterase activities and plasma MDA and TAS levels were determined in both groups. Results: The farmworkers had a significant 10.0% increase in plasma MDA level, with no significant changes in blood cholinesterase activities or the TAS level. Odds and risk ratios of reduced plasma cholinesterase activity (20.0%) suggested an association of health risks in pesticide-exposed farmworkers. Most of the pesticide products (278) in use were insecticides (47.0%), which comprised mainly 26.0% pyrethroids and 3.0-7.0% anticholinesterase insecticides, among others. The majority of the farmworkers (51%) were merely aware of the general target use of the pesticide, and 75% had an exposure history of > 5 years. Pesticide application was mostly (50.0%) manual, and 54.0% used insufficient personal protection equipment; 32.0% ate and drank at work, 48.0% practiced disposal of empty pesticide containers by burning and/or burying them, whereas 25.0% dumped the containers indiscriminately, and 25% disposed them at garbage sites openly. Conclusion: The farmworkers, with only a marginal increase in oxidative stress biomarker MDA, did not suffer from significant reductions in blood cholinesterase activities, although odds and risk ratios of reduced plasma cholinesterase activity suggested a health risk. Implementation of a national program is needed to measure pre-exposure blood cholinesterase activities in farmworkers.

Plasma Cholinesterase Activity in Patients With Rheumatoid Arthritis and Toxoplasmosis

“…We used an electrometric method to determine plasma ChE by incubating 0.2 ml of plasma aliquot with a reaction mixture containing 3 ml of distilled water, 3 ml of barbital-phosphate buffer (1.237 g sodium barbital, 0.163 g potassium dihydrogen phosphate, and 35.07 g sodium chloride/L of distilled water, pH 8.1) [ 24 , 25 ]. After measuring the pH1 of the mixture with the glass electrode of a pH meter (pH700, Eutech Instruments, Singapore), 0.1 ml of 7.1% aqueous solution of acetylcholine iodide was added, and the mixture was incubated in a water bath at 37 ºC for 20 minutes.…”

“…Aliquots of plasma samples obtained from the controls and the three RA groups (10/group) were pooled separately. We used the technique of 10-min in vitro incubation of a ChE inhibitor (in this case the organophosphate dichlorvos) with 0.2 ml of pooled plasma aliquot to induce enzyme activity inhibition as reported before [ 24 , 25 ]. An aqueous solution of dichlorvos (Dichlorvos 50% EC, Nicoz, China) was freshly prepared for in vitro inhibition usage at final concentrations of 0.25 or 0.5 μM in the plasma-ChE reaction mixture (6.3 mL).…”

“…An aqueous solution of dichlorvos (Dichlorvos 50% EC, Nicoz, China) was freshly prepared for in vitro inhibition usage at final concentrations of 0.25 or 0.5 μM in the plasma-ChE reaction mixture (6.3 mL). These concentrations of dichlorvos have been previously used for in vitro blood ChE inhibition [ 25 , 26 ]. The plasma aliquot-dichlorvos reaction mixtures were incubated in a water bath at 37 ºC for 10 minutes to initiate enzyme inhibition.…”

“…Variations (usually 20% or more are significant) in ChE activity after drug or pesticide applications have been used to assess the risk of association of changes in ChE activity by odds and risk ratios [27,28]. Observed and expected cases of 20% increment in plasma ChE activity among RA patients were used to calculate odds and risk ratios by using PAST4.13.…”

“…To achieve data categorization, an increase of 20% in plasma ChE activity (from a healthy-control value of 0.83 Δ pH/20 minutes) was taken into consideration. Accordingly, a table of odds and risk ratios of RA groups was constructed [27,28].…”