Morbidity Profile and Cholinesterase Levels among Sprayers in Selected Tea Plantations in South India.

Background: The tea plantation industry is composed of a complex chain of workers whose functions often overlap. There has been an extensive use of pesticides in this sector, and in the long term, these can have detrimental effects on the chemical sprayers working in the tea plantations. Aims: To assess the morbidities related to pesticide toxicity and document the most recent plasma cholinesterase levels among the pesticide sprayers working in selected tea plantations in South India.
Methods: A cross-sectional study was conducted among 290 chemical sprayers in selected tea plantations in South India after approval from the Institutional Ethics Committee and permission from the plantations. A structured interview schedule was administered by face-to-face interview with the selected sample. The blood cholinesterase detection done at the Estate Hospital was documented by the interviewer.
Results: The mean age of the participants was 45.6 ± 8.5 years and all of them were males. About 35.2% of the participants had reported at least one symptom of organophosphorus toxicity. The most common symptom was headache (21.7%) followed by itching of the eyes (20%) and watering of the eyes (16.2%). The blood cholinesterase values were normal in most of the sprayers in the study and only four (1.4%) sprayers had values less than the reference range. There was a significant association between the duration of work, method of spraying, and the blood cholinesterase levels indicating that greater duration of exposure and more direct contact with the chemical raise the cholinesterase levels significantly.
Conclusion: The symptoms of pesticide toxicity were reported among the sprayers. The blood cholinesterase levels were normal for most of them. Copyright:

INTRODUCTION

Tea is one of the most popular beverages all over the world. India is the second-largest producer of tea in the world next to China, with a production of 1,267 million kilograms of tea annually. South India contributes to almost one-third of the total production.[1]

The plantation industry is composed of a complex chain of workers whose functions often overlap. The main workforce in the plantation industry includes people involved in various activities like spraying pesticides, weeding, tree cutting, pruning, and plucking.

In the recent era of an agricultural boom, there has been extensive use of pesticides and insecticides which can have detrimental effects on humans, flora, and fauna, and our environment.[23]

The use of pesticides has been increasing steadily in the past few years and there has been a distinct shift from organochlorine to organophosphorus (OP) and carbamate pesticides in the plantations.[45] These pesticides in humans interfere with the activity of cholinesterase enzymes in the nerves and muscle tissue, which result in acute toxic effects.[6789]

While there are a few studies conducted among the plantation workers, very few have been conducted to date on the sprayers of tea plantations; hence, there is scope to explore this area of work further. The objectives of the study were to assess the morbidities related to pesticide toxicity and to document the most recent plasma cholinesterase levels among the sprayers working in tea plantations.

METHODOLOGY

A cross-sectional study was conducted among 290 male sprayers in selected tea plantations in South India in two months (September–October 2018). The approval was obtained from the Institutional Ethics Committee and all the tea estates with whom the Division of Work Environment, Department of Community Health, St John's Medical College have worked in the past were approached for permission to conduct the study among their sprayers. Letters of approval were obtained from six plantations in South India. All the chemical sprayers working in these six plantations were included in the sampling frame.

A mutually agreed date was fixed for the health appraisals of the sprayers and the investigators visited the estates on these agreed dates to conduct the interviews with the sprayers. With the help of the Medical Officer, Estate Hospital, and the managers of the consenting estates, a list of all the sprayers working in their estates was made. From the total list, simple random sampling was done to select the sprayers for the study. A structured interview schedule was administered by face-to-face interview with the sprayers.

The sample size was calculated using the formula n = {z2(pq)/d2}. The finite population correction was done for the sample size calculation as the exact number of the sprayers was known.

Finite population correction = (√N-n/N-1) * Calculated sample size

N = Known sample population (here, the total number of sprayers was 750)

n = calculated sample size

Finite population correction = 0.721

Corrected sample size = 0.721 * 354 = 255

However, in this study, we were able to interview all the sprayers who attended the annual health appraisals on the days of data collection. In total, 290 sprayers were included in our study.

A pilot study was conducted among the pesticide sprayers in the vegetable farms in Mugalur, Anekal Taluk, and Bengaluru in December 2017. A total of 10 sprayers were interviewed in the field. The purpose of this pilot study was to assess the utility and feasibility of the research instruments and the methods used. The language and cognitive validation were also done. Suitable changes were then incorporated into the final study tools and methodology. The data about the pilot study have not been included in this study.

Written informed consent was obtained and a structured interview schedule was administered by face-to-face interview. Blood samples of the sprayers were collected by the laboratory technician, Estate Hospital, for assessment of the blood cholinesterase levels. All the tests were done using standardized procedures and calibrated equipment at the Estate Hospital. These values were collected by the interviewer for the study.

RESULTS

Socio-Demography of the study population

Among the 290 sprayers in the study, the mean age of the participants was 45.6 ± 8.5 years and all of them were males. In this study, 45.5% had completed high school and 29.7% had middle school education. A majority of them were married (97.2%) and 18% of them were migrants coming mostly from the northeastern parts of India. Half the study population belonged to class 3 of BG Prasad socioeconomic classification. In this study, modified BG Prasad's scale for socioeconomic status classification was used taking the Consumer Price Index = 307.[10]

Work profile of the study population

More than half of the study population had worked for over 20 years as sprayers on the plantation. The most common devices used for spraying were high-volume sprayer—Lu Shyong (39%) and the knapsack sprayer (36.6%). Apart from spraying, the other activities done by the study population were plucking, weeding, and pruning [Table 1].

Table 1

Work profile of the study population (n=290)

Duration of work as a sprayer (Years)	Frequency (%)
0-10	46 (15.9%)
11-20	69 (23.8%)
21-30	129 (44.5%)
≥31	46 (15.9%)
Total	290
Methods of spraying	Frequency (%)
High-volume sprayer	113 (39%)
Knapsack (manually operated) sprayers	106 (36.6%)
Power machine (operated by petrol)	71 (24.5%)
Other activities done by sprayers	Frequency (%)
Pruning	104 (35.9%)
Weeding	151 (52.1%)
Plucking	214 (73.8%)
Shade lopping (tree cutting)	35 (12.1%)

Morbidity profile of the study population

In this study, it was seen that 35.2% of the participants had reported at least one symptom of organophosphorus toxicity during their work. The most common symptom was headache (21.7%) followed by ocular symptoms like irritation (20%) and watering of the eyes (16.2%). A majority (71, 24.5%) of the symptomatic workers reported that these symptoms developed on the day of spraying and would subside by the end of the day. Other symptoms reported by the sprayers were nasal irritation cough, redness of the eyes, tiredness, and body pain. Only 15.1% of the morbidities associated with pesticide exposure needed any medical intervention [Table 2].

Table 2

Self-reported symptoms organophosphorus of toxicity (n=290)

Any health symptoms on the days of spraying	102 (35.2%)
General
Tiredness	53 (18.3%)
Body aches	21 (7.2%)
Sleep disturbances	2 (0.7%)
Dermatological
Redness	3 (1%)
Rash	3 (1%)
Itching	2 (0.7)
Gastrointestinal
Nausea	6 (2.1%)
Vomiting	3 (1%)
Neurological
Headache	63 (21.7%)
Fainting	8 (2.8%)
Giddiness	7 (2.4%)
Muscle twitching	1 (0.3%)
Tremors	1 (0.3%)
Respiratory
Nasal irritation	43 (14.8%)
Cough	35 (12.1%)
Throat irritation	27 (9.3%)
Dyspnea	4 (1.4%)
Wheeze	1 (0.3%)
Ocular
Watering	58 (20%)
Irritation/itching	47 (16.2)
Redness	35 (12.1%)
Eye pain	11 (3.8%)

The blood cholinesterase values were normal in most of the sprayers in the study and only four (1.4%) sprayers had values less than the reference range [Table 3].

Table 3

Cholinesterase distribution in the study population (n=290)

Cholinesterase levels (U/L)	Frequency (%)
<4090	4 (1.4%)
4091-9770	271 (93.4%)
>9771	15 (5.2%)

The association between the duration of work in years and mean blood cholinesterase levels of the sprayers showed a significant association (P < 0.05) between the variables according to the Kruskal–Wallis test. The association between the methods of spraying, type of machine used for spraying, and blood cholinesterase levels also showed a significant association (P < 0.05) by Kruskal–Wallis test indicating that the study population using a high-volume sprayer had higher blood cholinesterase levels and the values seemed to fall in those using knapsack sprayer and power machine [Table 4].

Table 4

Association between the method used for spraying and blood cholinesterase levels

Method used for spraying	Blood cholinesterase levels (Median and IQR)	P
Lu Shyong	7061 (5880-7889)	0.021#
Knapsack machine	6479 (5348-8038)
Power sprayer	6434 (5221-7557)

# Kruskal–Wallis test, P<0.05 is significant

DISCUSSION

Among the 290 sprayers in the study, the finding that all the sprayers in this study were males was obviously due to the selection of only males for the activity of spraying, considering it strenuous and exhaustive. The other reasons could be social issues, tradition, and that the use of heavy machinery which might be difficult for the females. Similarities were seen in other studies conducted in Lucknow among pesticide sprayers which reported that only male sprayers were included in the study which could be obviously due to the employment of predominantly males for this activity in those areas also.[81011121314] But the employment in tea plantations as such does not have any gender preferences and females are usually employed more and involved in activities like plucking, weeding, transportation, pruning, and nursing young plants.[15]

The age group of many of the sprayers was found in the 41–50 years category as it was seen that the majority of the workers had been employed at the tea estate at a very young age and continued to work there for more than 20 years whereas their children have been educated and moved out of the estates to find other employment.

It was seen that 18% of the workers in the study were migrants from the northeastern parts of India. This pattern of internal migration is now very common in our country and the most common reason for migration as per the National Sample Survey (NSS) report is for employment.[1316]

The duration of work in the tea plantations was not available in any of the studies conducted in the plantations, but the studies on exposure to pesticides among the farmers in South India showed that only 11.4% of them had engaged in the spraying profession for over 20 years.[1718] A similar study was done among the chemical sprayers in the mango orchards in Lucknow. The mean years of exposure to the chemical were 16.2 years.[19] This difference could be because farming as an occupation is seasonal and the participants would have been employed in other activities during the off-season months and tea plantation needs perennial care, and hence, the workers are employed throughout the year.

In this study, it was seen that 35.2% of the participants had reported at least one symptom of organophosphorus toxicity during their work. The most common symptom was headache (21.7%) followed by ocular symptoms like irritation (20%) and watering of the eyes (16.2%). The studies on the prevalence of toxicity among farmers in Kenya showed similar results with the most common symptoms being headache (84.4%), giddiness (76.2%), and burning sensation of the skin (64.9%).[20] Morbidities among pesticide sprayers in North India showed that headache was the most common symptom and ocular problems were present in 17% of the study participants.[21] The studies done in the Philippines, Tanzania, and Australia to identify the toxicities related to pesticide exposure also showed that the most common symptoms were headache, muscle pain, and eye redness.[202122]

The blood cholinesterase values were normal in most of the sprayers in the study and only four (1.4%) sprayers had values less than the reference range and 15 (5.2%) had values greater than the reference range. It was also seen that there was a significant association between the method used for spraying and the blood cholinesterase levels.

The vital reason for only a small percentage of the participants getting lower than the expected values in this study is due to the strict enforcement of the personal protective equipment among the sprayers and the training and continuous supervision for the same.

In a study conducted to identify chronic pesticide exposure in South India, 4.2% of the sprayers and 1.5% of the non-sprayers had cholinesterase levels less than the standard lower range and the difference was not statistically significant.[18] Among these pesticide sprayers, the mean cholinesterase level was 7,358 U/L and the median was 7,640 U/L, which was similar to the findings in this study.

The method of spraying was found to have a significant association with the mean cholinesterase levels. The sprayers working with a power sprayer and knapsack machine were found to have lower cholinesterase levels than those working with the high-volume sprayer (trade name: LU SHYONG). This might be due to the greater chances of spill from the smaller machines and the fact that these machines are carried by the sprayers themselves, whereas, in the high-volume sprayer, only the pipes from the machines are used by the participants for spraying. Hence, the chances of leak of the chemical and exposure may be less.

CONCLUSION

Exposure to harmful chemicals used in agriculture including tea plantations results in multiple morbidities. Continuous monitoring of the plantation employees involved in chemical mixing and spraying like the sprayers is vital to understand their health problems and to do the needful rectification to prevent further worsening of their health condition.

Cholinesterase levels were normal in 98.6% of the study population. It was seen that 35.2% of the participants had reported at least one symptom of organophosphorus toxicity during their work.

Recommendations

Mechanization can further help substitute the sprayers, and thus, reduce the contact between the chemicals and people. The sprayers were advised to spray the chemicals in the direction of the wind to reduce their exposure to chemicals.

The employers ensured that those sprayers with low-plasma cholinesterase levels were removed from activities involving exposure to pesticides such as mixing and spraying. These sprayers were placed for other activities in the estate like plucking, pruning, and manuring. It is vital to recheck the plasma cholinesterase levels after 6 months to ensure that safe levels have been reached, and after this, if required, they can be involved in spraying.

Financial support and sponsorship

ICMR funding for postgraduate thesis in 2018.

Conflicts of interest

There are no conflicts of interest.