IJERD – International Journal of Environmental and Rural Development (2011) 2–1

Research article
erd

Risk Assessment of Pesticide Residues in Organic Waste inNortheast Thailand
JARUPONG PRASOPSUK
Faculty of Agriculture, Khon Kaen University,Khon Kaen, Thailand.
Email: ja.prasopsuk@gmail.com; chulee_b@kku.ac.th

CHULEEMAS BOONTHAI IWAI
Faculty of Agriculture Khon Kaen University,Khon Kaen, Thailand.
Received 10 December 2010

Accepted 25 January 2011

Abstract The objective of this study aims to monitor pesticide residues in organic waste inNortheast Thailand. Pesticides are widely used in agriculture and trade of agricultural
products to increase agricultural yield and to protect plants from diseases, weeds andinsect damage. The increasing use of pesticides has significantly increased crop
contamination and human health hazard. On the Thai markets, fruit and vegetables havehigh risk for pesticide contamination. Uneatable and unusable parts of these goods
transform to a fraction of organic waste. The quantity of waste in terms of solid wastefrom Northeast Thailand was 11,820 tons/day and over 50% was organic waste.
Composting (such as compost, biological fermentation fertilizer) and animal feed areconventional methods to manage waste from vegetables and fruit in Northeast Thailand.
However, the risk assessment of pesticide residue in organic waste should be studied andtaken into consideration for environmental safety and human health. A total of 22
pesticides from different chemical groups (organochlorine, organophosphate andpyrethroid) in the different organic wastes collected from the markets in Khon Kaen
provinces, in the Northeast of Thailand, were monitored in the rainy and winter season in
the year 2010 by gas chromatography with electron capture detector (ECD) and flamephotometric detector (FPD). Pesticide residues were found in organic waste. The mostfrequently found pesticides were cypermethrin followed by chlorpyrifos deltametrhrin andlambda-cyhalothrin, respectively ranging from 0.044 to 2.608 mg kg-1. Pesticide residue inorganic waste was found to be higher in the winter season than in the rainy season.
Pesticide residue was found higher in cabbages followed by kale, lettuce and corn peel,respectively. Therefore, a monitoring program for pesticide residues and a risk assessment
study  in  organic  waste  are  needed  for  protection  of  human’s  health  and  the  environment.
Keywords organic waste, biological waste, pesticide, pesticide residues, Northeast
Thailand

INTRODUCTION
Thailand is an agricultural country where agriculture is a very important part of the economy.
Thailand expanded exports of agricultural products and also imports fertilizers and pesticides
intensively. Pesticides are used widely in agriculture and trade of agricultural products to increase
agricultural yield and to protect plant from diseases, weeds and insect damage (Department ofAgricultural, 2010). The result from increasing pesticides uses has resulted in significant increased
crop contamination and human health hazard (Office of Epidemiological, 2009). The risk ofpesticide contamination in fruits and vegetables in Thai market often occurs. Pesticide residues inagricultural products such as vegetables and fruit were studied   in Northeast Thailand (Table 1)  (Office of Agricultural Research and Development Region 3, 2010; Office of Agricultural
Research and Development Region 4, 2010). Uneatable and unusable parts of agricultural products
transform to a fraction of organic waste. The quantity of waste in term of solid waste from© ISERD49IJERD – International Journal of Environmental and Rural Development (2011) 2–1

Northeast Thailand was 11,820 tons/day and over 50% was organic waste. Solid waste in Khon
Kaen province occurred about 800 tons/day (Pollution Control Department, 2010).
As agricultural production is vast worldwide, the increasing of waste and its adverse effects on
the environment are of great concern. Waste management takes an important role for maintaining asustainable environment. The organic waste management has been done in three main ways: 1)
organic waste can be used for soil improvement, 2) animal feeding, and 3) alternative source ofenergy (biogas) (Lardinois and Klundert, 1993; Pollution Control Department, 2009). Composting(such as compost, biological fermentation fertilizer) and animal feed are the conventional methods
to manage waste from organic waste in Northeast Thailand.
Composting is an important waste management strategy in Europe. The end product, compost,
can be used as soil conditioner and fertilizer, thereby recycling nutrients back to agriculture andhorticulture. However, compost may contain a wide range of organic pollutants (Kupper et al.,2008).
Therefore, using compost may be a case a hidden input of pesticides into the environment.
Once incorporated into the soil the fate of pesticides is not fully clear (Taube, et al., 2002; Hart andPluimers, 1996). The concern about the pollutants in the organic waste in Thailand has been
increasing.   However, most studies have dealt with the heavy metals contamination in the waste but
less research has been done on pesticides. Therefore, the risk assessment of pesticide residues inorganic waste were studied by monitoring pesticide residues in organic waste from the markets inKhon Kaen province in two seasons (rainy and winter season).
Table 1 Pesticide residues in vegetables and fruit in Northeast Thailand in 2009
Regionsamples

Upper
NortheastThailand

1,422

Lower
NortheastThailand

1,689

Pesticide residues foundNumber of Samples
Over MRL
394(27.7%)31(2.18%)605(35.8%)111(6.6%)

Pesticides foundchlorpyrifos,cypermethrin,ethoprophos,deltamethrin,diazinon,cyfluthrin,
lambda-cyhalothrin, methidathion
cypermethrin, chlorpyrifos,
profenofos, lambda-cyhalothrin,
fenvalerate

MRL = Maximum residue limit
Source: Office of Agricultural Research and Development Region 3, (2010)
Office of Agricultural Research and Development Region 4, (2010)

MATERIALS AND METHODS
Chemicals
Hexane, ethyl acetate and acetonitrile (PR grade), sodium chloride (analytical grade), magnesium
sulfate anhydrous, primary secondary amine (PSA) and 1% acetic acid in acetonitrile were used forthe pesticide extraction process.
Sample collection
The selection of the samples was based on the typical composition of organic waste. The samples
chosen for analysis should match the fractions presenting a high percentage of the total organic
waste. The samples were collected from three main markets in Khon Kaen province, Northeast
Thailand in the rainy and winter season in 2010. Altogether, 3 samples of organic waste from eachmarket and 4 samples of organic waste based on the typical composition of organic waste(cabbages, lettuce, kale and peel corn) were analyzed in three replicates by using the QuEChERS
method (Anastassiades, et al., 2003).

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IJERD – International Journal of Environmental and Rural Development (2011) 2–1

Extraction and clean up
To prepare the samples, 15 g of a previously homogenized food material sample was transferred
into a suitable vessel and filled with fifteen milliliters of acetonitrile. The vessels were capped
before mixing on a Vortex mixer for 1 min at optimum speed. Once the initial sample mixing wascompleted, 1 g NaCl and 4 g anhydrous MgSO4 were added and immediately mixed on a Vortex
mixer for 1 min. To separate the phases, the samples were centrifuged for 5 min at 4000 rpm.
Using an adjustable repeating pipette, 6.0 ml aliquot of upper acetonitrile layer was transferred into
a 15 ml centrifuge tube containing 900 mg anhydrous MgSO4 and 150 mg PSA sorbent. Thecentrifuge tube was tightly capped and shaken on a Vortex mixer for 1 min before the extracts (orthe batch of extracts) were centrifuged for 5 min at 4000 rpm to separate the solids from thesolution. The solution was then transferred into a vial for Gas Chromatograph (GC) analysis.
Pesticide residues analysis
The samples were analyzed for 22 pesticides from different chemical groups (organochlorine,organophosphate and pyrethroid) using GC multi-methods with ECD and FPD detection.
Organophosphorus group were chlorpyrifos, diazinon, dicrotophos, dimethoate, ethoprophos,
fenitrothion, malathion, methamidophos, methidathion, mevinphos, monocrotophos, parathionmethyl, pirimiphos-methyl, prothiophos, triazophos. For organochlorine group were -endosulfan,
-endosulfan, endosulfan sulfate and pyrethroid group are lambda-cyhalothrin, cypermethrin,deltamethrin, fenvalerate, permethrin, cyfluthrin. GC-ECD used capillary column HP-5 5% Phenyl
Methyl   Siloxane  (30m   x   0.25mm   ID,   0.25   μm   flim   thickness)   with   helium   (2.0   ml   min-1) carriergas, splitless injection and used electron capture detector (ECD) for organochlorine group andPyrethroid group. GC-FPD   used   capillary   column   DB1701   (30m   x   0.32mm   ID,   0.25   μm   flim  thickness) helium (1.9 ml min-1) carrier gas, splitless injection and used flame photometric detector(FPD) for organophosphorus group.
RESULTS
The analyses revealed that most of the samples contained pesticide. Residues were found in 100%of the samples from mixed organic waste (Table 2) in three markets. Pesticide residues (mg kg-1)
were found in the different kinds of organic waste collected in Khon Kaen province (Table 3).
Pesticide residue in organic waste was found to be higher in the winter season than in the rainyseason. The most frequently found pesticides were cypermethrin followed by chlorpyrifos,
deltametrhrin and lambda-cyhalothrin, respectively ranging from 0.044 to 2.608 mg kg-1. Most
pesticides were recovered in the range of 70% – 110% with relative standard deviation (RSD)
usually less than 10%.
Table 2 Pesticide residues (mg kg-1) found in organic waste collected in Khon Kaen province
Rainy

Markets

Pesticide(mg kg-1)

Banglumphu

WinterxSD%RSD

Pesticide(mg kg-1)

cypermethrin
lambda cyhalothrin

0.044

0.003

7.329

cypermethrin

0.086

0.003

3.076

0.054

0.004

7.955

chlorpyrifos

0.077

0.003

4.193

O-Jiracypermethrin

0.050

0.004

8.075

deltamethrin
cypermethrin
chlorpyrifosdeltamethrin

0.281
2.608
1.066
0.736

0.020
0.018
0.069
0.028

7.183
0.678
6.507
3.832

Srimuangthongcypermethrin

0.072

0.007

9.130

cypermethrin
chlorpyrifosdeltamethrin

1.667
0.742
0.761

0.045
0.042
0.060

2.716
5.629
7.898

x = Average, SD = Standard deviation, %RSD = Repeatability© ISERD

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SD%RSD

IJERD – International Journal of Environmental and Rural Development (2011) 2–1

Table 3 Pesticide residues (mg kg-1) found in the different kinds of organic waste collected inKhon Kaen province
Rainy

Organicwaste

WinterPesticide(mg kg-1)

xSD

%RSD

cabbages

cypermethrin

0.059

0.005

7.685

kale

cypermethrin
lambda cyhalothrin

0.050

0.002

0.079

0.006

lettuce

NDpeel corn

NDPesticide(mg kg-1)

xSD%RSD

4.323

cypermethrin
chlorpyrifosdeltamethrin
cypermethrin

0.586
1.926
0.460
1.415

0.022
0.036
0.020
0.035

3.762
1.872
4.367
2.498

7.804

chlorpyrifos

0.129

0.002

1.187

deltamethrin
cypermethrindeltamethrin
cypermethrin
chlorpyrifosdeltamethrin

1.297
0.096
0.269
0.075
0.102
0.148

0.082
0.008
0.019
0.004
0.004
0.006

6.329
7.791
6.895
4.807
3.922
3.833

ND = Less than limit of detection, x = Average, SD = Standard deviation, %RSD = Repeatability

Table 4 The maximum residue limits (MRL) of pyrethroids and organophosphorous
pesticides in vegetables
Pesticides
cypermethrin

lambda -cyhalothrindeltamethrin

chlorpyrifos

Vegetables
cabbagescorn
leafy vegetables
cabbagescabbagescorn
lettuce, kaleleafy vegetables
cabbages
sweet Corn

MRL (mg kg-1)
1.00*
0.05*
0.70*
0.30**
0.10*
1.00*
0.50*
2.00**
1.00**
0.01***ACFS, Ministry of Agriculture and Cooperatives (2008)** FAO/WHO (2010)

CONCLUSION
The results from this study give information about the pesticide residues of the organic waste.
Biological waste contains a variety of pesticides and some of them were higher than the MRL. In
the composting process of organic waste, pesticides might be degraded or mineralized. However,they might also be persistent to biological degradation and still occur in the process. Althoughpesticide residues analyses in organic wastes are not legally required, a hidden and uncontrolled
input of pesticides to the soil environment might take place. Generally, organic waste products areconsidered environmental friendly as they are one of the waste management solutions. However,
persistent pesticides introduced into this agricultural system might appear in the product and affecthuman health. Therefore, a monitoring program for pesticide residues and a risk assessment studyin  organic  waste  are  needed  for  protection  of  human’s  health  and  the  environment.
ACKNOWLEDGEMENTS
The author would like to thank Khon Kaen University for the support, Department of Plant Sciencesand Agricultural Resources, Land Resources and Environment Section, Faculty of Agriculture, Khon
Kaen University, the Research Centre for Environmental and Hazardous Substance Management, Khon
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Kaen University, Thailand and Office of Agricultural Research and Development Region3, Departmentof Agriculture, Ministry of Agriculture and Cooperative, Thailand.

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