Bangladesh J. Zool. 38(2): 157-162, 2010

PESTICIDE RESIDUE LEVEL IN MADE TEA IN BANGLADESH

M. Ahmed and M.S.A. Mamun Entomology Division, Bangladesh Tea Research Institute,

Srimangal, Moulvibazar, Bangladesh

Abstract: A study was carried out to quantify the residue level of pesticides in made tea in Bangladesh from 2005 to 2009. Made tea samples were collected from the different tea estates and tea marketing companies of Bangladesh. The samples were analyzed in the pesticide residue analytical laboratory of Bangladesh Tea Research Institute (BTRI) using Gas Chromatography (GC). Results revealed that the average residue level of commonly used pesticides against major pests of tea, such as Endosulfan, Propargite and Ethion were found 0.72, 1.95 and 1.05 ppm, respectively. None of the samples exceeded the prescribed maximum residue limit (MRL) fixed by EPA, Codex/FAO, EU.

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Key words: Pesticides, residue, made tea, MRL, gas chromatography.

INTRODUCTION

Tea is a long established plantation crop of enormous economic importance to Bangladesh meeting the entire domestic demand of this cheapest health beverage. Tea is subjected to the attack of several insects, mites, fungal pathogens and weeds. About 15% of its crop could be lost by various pests particularly insects, mites, nematodes and diseases if adequate control measures are not taken (Ahmed 2005). To combat this problem, different groups of pesticides have been used in the tea gardens since early 60s. With no exception in other tea growing countries, in Bangladesh also chemical control has been a dominating feature in pest control of tea and passed through three generation of pesticides (Alam 1999). Now it is a major component of the tea pest control in Bangladesh.

The usage of pesticides on tea plantations in Bangladesh is largely governed by the Government of the Peoples’ Republic of Bangladesh under the Plant Protection Wing, Department of Agriculture Extension, Ministry of Agriculture with association with Bangladesh Tea Research Institute (BTRI). In tea estates, different group of pesticides such as Endosulfan, Propargite, Ethion, Dimethion, Cypermethrin, Deltamethrin, Sulphur and Carbofuran etc. were used in the tea

158 Ahmed and Mamun

fields for the control of insects, mites and nematodes. Once pesticides are applied they start to degrade and /or transport in four different environments like atmosphere, lithosphere (soil), hydrosphere (water) and biosphere (living organism) and survive shorter or longer periods by producing various MRL values under different natural and environmental conditions (Sattar 2007). Therefore, a pesticide should be chosen which gives a maximum effect on the pest control and a minimum side effect in terms of residues on tea (Dharmadi 2007).

As tea is a consumable commodity, the effect of residue of pesticides in made tea is harmful to human health. Tea produced in Bangladesh is exported to different countries of the world particularly Western and Eastern European as well as Middle Eastern countries. The consumers of these countries have become more conscious about the residue of the pesticides. In this perspective, EPA, Codex Commission/FAO, WHO, Japan, German Law etc. have given restrictions on producing and procuring tea having pesticide residue (Anonymous 2002). Now a days, pesticide residue (MRL) is a burning issue globally. Pesticide residue analysis in food products is gaining global interest due to the hazardous effects of the chemicals widely used for pest control in almost all crops (Singh and Kalita 2002). It is possible to control most of the major pests with synthetic chemicals but some of the effective chemicals leave residues on the end product creating hazards to the consumers.

OBJECTIVES

The specific objectives of the study were:

• To study the pesticide residue status of made tea at different tea growing areas and tea marketing companies of Bangladesh.

• To increase awareness of adverse affect of non- judicious application of pesticides.

• To find out whether the residues remain in the crop during harvest and cause any toxic hazard to consumers.

MATERIAL AND METHODS

The study was carried out during the years from 2005 to 2009 to quantify the residues of pesticides in made tea in Bangladesh. Tea samples were collected from different tea estates of North Sylhet, Juri circle, Lungla, Monu Doloi, Balisera, Luskerpore, Chittagong and Panchagarh areas in Bangladesh. Some blended tea samples were also collected from some renowned tea marketing companies of Bangladesh. The samples included CTC (Crushing, Tearing and

Pesticide residue level in made tea in Bangladesh 159

Curling) types of teas. The samples were analyzed at the Pesticide Residue Analytical Laboratory of BTRI at Srimangal, Moulvibazar, Bangladesh following the methods developed by Ahmed and Sarker (2002). It may be mentioned that the laboratory is accredited by Intergovernmental Group (IGG) of FAO for ring tests to fix MRL in black tea globally (Anonymous 2009). The analysis was done using Gas Chromatography (GC) following Good Laboratory Practices.

Collected and processed black tea samples were ground in a coffee grinder and hydrated. Subsequent extraction and clean up were carried out. The determination of pesticides in the samples was done by Electron Captured Detector (ECD) for Organochlorine, Pyrethroid and Unclassified groups, and Flame Thermoionic Detector (FTD) for Organophosphate and Carbamate groups using Gas Chromatography (Model-Shimadzu 14B) with DB-5 capillary column (30m x 0.25mm i.d.). Nitrogen (99.997% purity) was used as carrier gas for both ECD and FTD. Hexane and Acetone were used as extracting reagents and Florisil was used as clean-up reagent.

RESULTS AND DISCUSSION

Results revealed that the residues of pesticides of collected made tea samples from the different tea gardens as well as tea companies in Bangladesh for last five years are much below their MRL fixed by EPA, Codex Commission/FAO and EEC/EU (Table 1). Table 1. Samples on pesticide residues in made tea in Bangladesh from the years 2005 to

2009.

MRL in ppm Residues (ppm) in the number of samples Pesticides EU EPA FAO ND* <0.01 0.01-0.1 0.1-0.5 >1

Bifenthrin 5.0 - - - - - - - Chorpyrifos 0.1* - 2.0 1 - - - - Cypermethrin 0.5 20 20 5 - - - - DDT 0.2* - - - - - - - Deltamethrin 5.0 - 5 1 - - - - Dicofol 20 45 50 2 - - - - Dimethoate 0.05* - - 1 - - - - Endosulfan 30 24 30 2 2 3 3 2 Ethion 3.0 10 - 7 - 1 2 1 Fenvalerate 0.05* - - 2 - - - - Malathion 0.5 - - 1 - - - - Propargite 5.0 10 5.0 4 - - 1 3 Sulphur Exempted - - 10 - - - -

*Indicates lower limit of analytical determination; ND- Not Detectable; EU-European Union, the original EU list contains more than 200 chemicals; N.B. Lower the MRL value higher the toxicity level

160 Ahmed and Mamun

All the regulatory agencies have fixed the maximum residue levels of pesticides in black/green tea since these are the commodities being traded. However, the residues of the samples collected from the different tea estates and tea companies which obtained from the peaks of the GC are presented in Table 2. So far, none of the samples exceeded the MRL fixed by the EPA, Codex Commission/FAO and EEC/EU. Table 2. Residue level of pesticides of the samples collected from different tea estates in

Bangladesh.

Name of Tea Estate Name of chemical Residue Level (ppm) Remarks Rajkie T.E. Endosulfan 0.18 Below MRL Level Allynugger T.E. Endosulfan 0.10 Below MRL Level Karimpore T.E. Endosulfan 0.48 Below MRL Level Amo T.E. Endosulfan 0.54 Below MRL Level Abul Khair Group Endosulfan 1.00 Below MRL Level Seylon Tea Endosulfan 2.04 Below MRL Level Lungla T.E. Propargite 1.59 Below MRL Level Karimpore T.E. Propargite 0.00 Not detected from peaks Chatlapore T.E. Propargite 0.00 Not detected from peaks Etah T.E. Propargite 2.44 Below MRL Level Shumshernugger T.E. Propargite 0.00 Not detected from peaks Ootterbagh T.E. Propargite 0.00 Not detected from peaks Duncan Brothers Propargite 1.82 Below MRL Level Siloah T.E. Ethion 1.98 Below MRL Level Chaklapunji T.E. Ethion 0.20 Below MRL Level Karimpore T.E. Ethion 0.96 Below MRL Level

The MRLs of Endosulfan imposed by the EPA, Codex Commission, EEC/EU and German law were 24, 30, 30 & 30 ppm, respectively (Muraleedharan and Radhakrishnan 2006). In this study, the residue of Endosulfan was detected in the made tea of Rajkie T.E., Allynugger T.E, Amo T.E., Abul Khair Group, Seylon Tea & Karimpore T.E. which were 0.18, 0.10, 0.54, 1.00, 2.04 & 0.48 ppm, respectively indicating none of the samples exceeded the MRL fixed by the International organizations.

The residue level of propargite was higher in made tea of Etah T.E. (2.44 ppm) followed by Duncan Brothers (1.82 ppm) and Lungla T.E. (1.59 ppm). It might be caused due to variation of environmental factors specially temperature, light and rainfall and the manufacturing process of the Factory. But none of the samples exceeded the MRL value provided by EPA (10 ppm) and EEC/EU (5 ppm). The residue level of propargite in made tea of Karimpore, Chatlapore, Shumshernugger, Ootterbagh and Indanugger tea estates could not be detected from the peak of the Chromatogram.

Pesticide residue level in made tea in Bangladesh 161

The MRLs of Ethion prescribed by the EPA, Codex Commission, EEC/EU were 10, 5 and 3 ppm, respectively. In this study the residue of Ethion was determined in the made tea of Siloah, Chaklapunji and Karimpore tea estates, which were 1.20, 0.20 and 0.96 ppm, respectively indicating that none of the samples exceeded the MRL. No such residue of Sulphur was detected from the gas chromatographic peaks in the tea samples of Chaklapunji, Naloa, Luskerpore, Mazdehee, Shumshernugger, Amo and Chandpore tea estates.

Kazi & Kazi T.E. at Panchagarh district is successfully producing and marketing organic tea home and abroad. Moreover, for confirmation tea samples were collected from the Kazi & Kazi T.E. at Panchagarh district for the determination of any residues of commonly used pesticides in tea, such as Endosulfan, Dicofol, Malathion, Dimethion, Ethion, Fenvalerate, Cypermethrin and Propargite. No such residues of the above chemicals were detected from the gas chromatographic peak. The average residue level of commonly used pesticides such as Endosulfan, Propargite and Ethion was found 0.72, 1.95 and 1.05 ppm, respectively in Bangladesh tea.

Environmental factors especially temperature, light and rain are mainly responsible for gradual decline of the residue level (Ahmed 2005). Biochemical reaction is also a factor in degrading the absorbed pesticide inside the plant cell (Mukharjee and Gopal 1994). On the other hand, thermal degradation during manufacturing of tea is the main reason in declining the residue level of black tea compared to green leaves of the same day. During tea manufacture better part of the chemicals present as residues are degraded at high temperatures (2100F to 2400 F) (Choudhuri 1999).

CONCLUSION

Tea being an export-oriented food commodity all the required measures must be taken to keep the residues well below the Maximum Residue Level (MRL). According to the Good Agricultural Practice (GAP), Pre Harvest Index (PHI) of tea crop, i.e. interval between the application of pesticide and harvesting of crop is seven days. Maximum level of residues (MRL) in made tea is accounted following the approved PHI. It is concluded that tea samples collected from different tea estates and tea marketing companies of Bangladesh are rather free from residues of pesticides. Moreover, the residue level of commonly used pesticides in tea should be assessed periodically.

Acknowledgement: The authors gratefully acknowledge to Mr. Mihir Lal Sarker, former Scientific Instrumentation Specialist, BTRI for his endless technical support for the study.

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(Manuscript received on March 15, 2010; revised on November 22, 2010)