in india , more than 1 billion people are engaged in agricultural activities and a large quantity of pesticides is used to protect their crop against pests to get more yields .
india is the largest producer of pesticides in asia and the third largest consumer of pesticides in the world .
pesticide consumption has been increasing steadily in the past few years and there has been a distinct shift from organochlorine to organophosphorous ( op ) and carbamate pesticides .
these pesticides interfere with or inhibit the activity of cholinesterase ( che ) enzymes in nerves and muscle tissue , which results in accumulation of the neurotransmitter acetylcholine ( ach ) in the nervous system .
acute toxicological effects of op pesticides are a result of the inhibition of acetylcholinesterase ( ache ) in the nervous system , which can cause respiratory , myocardial , and neuromuscular transmission impairment .
chronic effects of op exposures are not well documented ; however , several recent reports indicate that certain birth outcomes ( e.g. , decreased gestational age , decreased birth length ) and abnormal reflex functions in infants may be associated with low level environmental exposures to op pesticides.[46 ] ache inhibition causes clinical features due to overstimulation of cholinergic synapses in the parasympathetic system , neuromuscular junction , and central nervous system .
decrease in che activity by 1525% , 2535% , and 3550% is caused by low , moderate , and severe intoxication with pesticides , respectively .
people are directly exposed to these pesticides through dermal contact and inhalation , and indirectly through the food chain .
annually , about 3 million people worldwide are intoxicated with organophosphates ; out of this , 300,000 either die or are severely injured . a most economical blood test for the monitoring of farm workers who are exposed to op insecticide is measurement of plasma butyrylcholinesterase ( bche ) activity .
monitoring of plasma bche has been recommended in the op - exposed population , as this could be a useful biomarker to predict and prevent health hazards of pesticides .
it is recommended that the workers che level should be assessed before they start working at a pesticide applied region . in view of this , the present study was aimed to evaluate the ache and bche activities among agriculture workers occupationally exposed to pesticide .
the study was conducted in the neighboring villages of chikkaballapur town , rural bangalore , south india , from december 2010 to march 2011 .
this study included 28 rural people who were agriculture workers , engaged in floriculture , and cultivation of cabbage , potato , and grape .
a control group consisting of 13 unexposed workers , who never had any exposure to op pesticides , was taken as the reference group .
a detailed history , including the personal and occupational details , was recorded through a questionnaire .
a written informed consent was taken from all study subjects after explaining the importance of the study in their local language .
five milliliters of venous blood was collected in dried heparinized tubes and transported in ice box to the laboratory .
blood samples of voluntarily participated agriculture workers ( n = 28 ) who have been involved mainly in pesticide spraying activities in vegetable and grape gardens were collected . a control group consisting of 13 male subjects who belonged to a similar age group and socioeconomic status and were not exposed to any kind of pesticides was selected for the study from the same localities .
blood was centrifuged at 4000 rpm for 10 min at 4c to separate the plasma .
che activity was determined by the method of ellman et al . as modified by chambers and chambers .
three milliliters of 0.25 mm of 5,5-dithiobis ( 2-nitrobenzoic acid ) ( dtnb ) prepared in 0.05 m phosphate buffer was pipetted out into a cuvette , in which 20 l of thoroughly mixed plasma sample and 100 l of 1 mm substrate ( acetylthiocholine iodide for ache assay ) were added .
the sample was placed on a uv - vis spectrophotometer set at a wavelength of 410 nm . the change in absorbance with a light path of 1 cm width
was recorded following time drive kinetic spectrophotometric method for 5 min to ensure that the linear phase of the reaction was measured at a time lag of 30 sec .
a nonenzymatic blank was included to assess the background levels of hydrolysis of the substrate .
t - test was used to compare the significance of the mean differences in che activity between exposed and control subjects .
the study was conducted in the neighboring villages of chikkaballapur town , rural bangalore , south india , from december 2010 to march 2011 .
this study included 28 rural people who were agriculture workers , engaged in floriculture , and cultivation of cabbage , potato , and grape .
a control group consisting of 13 unexposed workers , who never had any exposure to op pesticides , was taken as the reference group .
a detailed history , including the personal and occupational details , was recorded through a questionnaire .
a written informed consent was taken from all study subjects after explaining the importance of the study in their local language .
five milliliters of venous blood was collected in dried heparinized tubes and transported in ice box to the laboratory .
blood samples of voluntarily participated agriculture workers ( n = 28 ) who have been involved mainly in pesticide spraying activities in vegetable and grape gardens were collected . a control group consisting of 13 male subjects who belonged to a similar age group and socioeconomic status and were not exposed to any kind of pesticides was selected for the study from the same localities .
blood was centrifuged at 4000 rpm for 10 min at 4c to separate the plasma .
che activity was determined by the method of ellman et al . as modified by chambers and chambers .
three milliliters of 0.25 mm of 5,5-dithiobis ( 2-nitrobenzoic acid ) ( dtnb ) prepared in 0.05 m phosphate buffer was pipetted out into a cuvette , in which 20 l of thoroughly mixed plasma sample and 100 l of 1 mm substrate ( acetylthiocholine iodide for ache assay ) were added .
the sample was placed on a uv - vis spectrophotometer set at a wavelength of 410 nm . the change in absorbance with a light path of 1 cm width
was recorded following time drive kinetic spectrophotometric method for 5 min to ensure that the linear phase of the reaction was measured at a time lag of 30 sec .
a nonenzymatic blank was included to assess the background levels of hydrolysis of the substrate .
students t - test was used to compare the significance of the mean differences in che activity between exposed and control subjects . the values of p < 0.05 were considered significant .
the demographic data of lifestyle habits , type of crop cultivation , pesticides used , and frequency of application collected on both exposed and control subjects are summarized in table 1 . the average age of exposed subjects and controls were 34.6  8.22 and 28.1  9.33 years , respectively . about 53.6% of study subjects were using pesticides weekly once and 21.4% were using weekly thrice for their crop protection .
the majority of the workers did not use any protective equipment and a normal cloth was used to cover their face as a mask while spraying .
about 6871% had complained having the symptoms of headache and eye irritation [ table 1 ] .
characteristics of agricultural workers ( n=28 ) table 2 shows the list of commonly used pesticides in the study locations and world health organization ( who ) classification .
majority of the pesticides used were in the categories of moderately hazardous to highly hazardous .
pesticides used were in the chemical group of op , organochlorine , carbamates , and synthetic pyrethroids .
list of commonly used pesticides in the study area ache and bche activities measured in the blood plasma of exposed and control subjects are given in table 3 .
ache activity among exposed subjects ranged between 1.65 and 3.54 moles / min / ml , with a mean concentration of 2.51 moles / min / ml , whereas in the control group it ranged between 2.22 and 3.51 moles / min / ml .
the bche activity in agricultural workers ranged between 0.16 and 5.2 moles / min / ml , with a mean concentration of 1.66 moles / min / ml , whereas in the control group it was 2.195.06 moles / min / ml , with a mean concentration of 3.87 moles / min / ml ( p < 0.05 ) .
the measured levels of ache and bche activities in exposed subjects were comparatively less than in the control subjects [ figure 1 ] .
cholinesterase activity ( moles / min / ml ) among exposed and control group subjects variation in cholinesterase activity between exposed and control groups ( p<0.05 , t - test )
the finding suggests that the ache activity in agriculture workers was decreased ( 14% ) when compared to that of controls due to the inhibition of ache activity by pesticides .
the inhibition of ache might have resulted in the accumulation of ach at the synaptic junctions , which may lead to cytotoxicity .
occupational exposures to che inhibiting pesticides used in india for agricultural pest control can impair the respiratory health of agricultural workers who work in the field . in agreement with the present study ,
california agricultural pesticide applicators showed considerable changes in ache inhibition and low ache activities due to exposure to pesticides during the high exposure period .
their study also demonstrated that relations exist between change in che inhibition and symptoms , especially respiratory symptoms , symptoms of the cns ( analysis including controls ) , and eye symptoms ( internal analysis ) .
studies by hillman and clarke et al . indicated that there was a significant decrease in activity of ache and bche found among the op pesticide sprayers as compared to the controls .
reduction in plasma bche activity ( 56% ) in the present study supports similar findings observed by various researchers .
the use of che inhibiting pesticides in the agricultural activity caused the depletion of ache and bche activities among workers . from earlier reports and the present results ,
it can be speculated that decreased plasma che activity is due to prolonged exposures to op pesticides among the study subjects as compared to controls [ figure 1 ] .
this study was carried out as part of the academic dissertation and a large number of people could not be included
. however , the data generated highlights the effects of pesticide exposures and it would help conduct further studies .
this study was carried out as part of the academic dissertation and a large number of people could not be included
. however , the data generated highlights the effects of pesticide exposures and it would help conduct further studies .
the ache and bche activities measured were significantly lesser due to multiple exposures to different groups of pesticides used for agricultural activity .
unscientific way of pesticide mixing , improper way of handling pesticides , and entering agriculture field immediately after pesticide application play significant roles in reducing plasma che activity .
preventive measures coupled with biomonitoring of pesticide exposure using che inhibition as a marker are very much important
. this will create awareness among the agriculturists , pesticide manufacturers , agriculture department , etc .
 background : cholinesterase determination indicates whether the person has been under pesticide exposure is not . 
 it is recommended that the workers cholinesterase level should be assessed for workers at a pesticide applied region . 
 hence , cholinesterase activities in blood samples of agricultural workers exposed to vegetables and grape cultivation with age matched , unexposed workers , who never had any exposure to pesticides , were estimated.methods:the detailed occupational history and lifestyle characters were obtained by questionnaire . 
 cholinesterase activity was determined by the method of ellman as modified by chambers and chambers.results:ache was ranging from 1.65 to 3.54moles / min / ml in exposed subjects where as it was ranged from 2.22 to 3.51moles / min / ml in control subjects . 
 bche activity was ranging from 0.16 to 5.2moles / min / ml among exposed subjects , where as it was ranged from 2.19 to 5.06moles / min / ml in control subjects . 
 the results showed statistically significant reduction in enzyme activities ( ache 14% ; bche 56% ) among exposed subjects.conclusion:it was concluded that the reduction in cholinesterase activity may lead to varieties of effects . 
 hence it is compulsory to use protective gadgets during pesticide spray . 
 further a continuous biomonitoring study is recommended to assess pesticide exposure . 
INTRODUCTION
MATERIALS AND METHODS
Study area and subjects
Blood sample collection
Sample processing and enzyme assay
Statistical analysis
RESULTS
DISCUSSION
Limitations of the study
CONCLUSION