Biological monitoring of occupational pesticides exposure

Abstract

Two kinds of measurement: (1) enzyme activities in blood, and (2) unchanged pesticides and their metabolites in urine or blood have been used in biological monitoring for assessing exposure to pesticides. The assays of acetylcholinesterase (AChE) activity in whole blood and erythrocytes are mainly applied to estimate inhibition by organophosphates (OPs) and carbamates. A level at 70% of an individual's baseline or of a mean population AChE activity has been recommended as a reference value for exposure control. The measurement of lymphocyte "neuropathy target esterase (NTE)" activity in subjects handling axonopathic OPs is mainly for research application. Analytical methods are available for detecting alkylphosphates, carbamates, pyrethroids, chlorinated hydrocarbons, some herbicides and fungicides, chlordimeform, chlorobenzilate, dichloropropene, dinitrocresol and pentochlorophenol or their metabolites in urine or blood. However, due to lack of significant dose-response or dose-effect relationship, the majority of these determinants can only be used as biological exposure indicators to confirm exposure or to estimate internal dose. Further research in developing adequate indicators and methods for biological monitoring of occupational pesticides exposure is needed. Pre-exposure value and/or reference value of relevant indicators are necessary for assessing the degree of exposure and absorption.

Assessment of Exposure for Pesticide Handlers in Agricultural, Residential and Institutional Environments

“…Biomarkers of exposure will be the subject of this section, including monitoring of pesticide metabolites in urine and of parent compounds in saliva. Several reviews have been published on the general topic of biological monitoring of pesticides (Wang et al, 1989;He, 1993;Woollen, 1993;ICPS, 1996). Details for the conduction of a study that includes biological monitoring are contained in the 1987 USEPA Guideline for applicator exposure monitoring (USEPA, 1987).…”

Occupational Exposure to Pesticides: Blood Cholinesterase Activity in a Farming Community in Ghana

“…The assays of cholinesterase (ChE) activity in whole blood and erythrocytes are mainly applied to estimate inhibition by organophosphates (OPs) and carbamates (He 1993;WHO Task Group 1986a, 1986b. However, under many field conditions, procedures using whole blood are more practical than those using separated erythrocytes (He 1993).…”

“…The assays of cholinesterase (ChE) activity in whole blood and erythrocytes are mainly applied to estimate inhibition by organophosphates (OPs) and carbamates (He 1993;WHO Task Group 1986a, 1986b. However, under many field conditions, procedures using whole blood are more practical than those using separated erythrocytes (He 1993). Additionally, because the serum and erythrocyte enzymes of whole human blood differ importantly, studies on either enzyme alone are inadequate to value the role played by the ChE activity of whole blood (Alles and Hawes 1939, downloaded from www.jbc.org on December 19, 2006).…”

Measurement of organophosphate metabolites in postpartum meconium as a potential biomarker of prenatal exposure: a validation study.

“…Thus use of available biomarkers as dosimeters can lead to exposure misclassification if sample collection is not timed to pesticide application. Although erythrocyte acetylcholinesterase is a good biomarker for acute organophosphate exposure, large intraindividual (13%-25%) and interindividual (10%-40%) variability makes it unreliable as a dosimeter in lowlevel exposure settings unless preexposure values have been determined on each subject (21)(22)(23).…”