**3. Results and discussion**

#### **Acute toxicity**

270 Pesticides in the Modern World - Risks and Benefits

48 h, and results recorded. For water quality, temperature, pH, conductivity and dissolved

O,O-dimethyl

benzofuranyl

Source: Extoxnet (1996 ); Chemical Book (2007); Compendium of Pesticide common name (2008 a, 2008

Chronic toxicity of pesticides to *M. micrura* followed the procedure recommend by US.EPA document 6004-91/002 (1994). Based on acute toxicity result, *M. micrura* were exposure to control and concentration test malathion concentration of 0.05, 0.25 and 0.50 µg/L, chlorpyrifos concentration of 0.00005, 0.00025 and 0.00045 µg/L, carbofuran concentration of 0.25,1.00 and 2.50 µg/L, neem extract concentration of 15, 40 and 65 µg/L and glyphosate concentration of 50, 250 and 325 µg/L. In the chronic tests, three replication of 10 neonates (< 24 h )per treatment and control laboratory well – water were used. The neonates were exposed in a 50 ml glass beaker containing 30 ml for each test concentration and control. Test organism were fed with a concentrated suspension of the green algae, *Chlorella* sp. Test solution and food were renewed completely every day. The measurement of water quality at the beginning and end of the test on control and treatments. The number of offspring was noted each day used to evaluate the effect of pesticide on reproduction of test organism.

The values of lethal concentration 24 and 48 h LC50 and 95 % confidence limit were caculated by appropriate statistical method intervals by probit analysis.Data from chronic

1563-66-2

121-75-5

88-2

17-6

**(Chemical Abstract Service)** 

phosphorodithioate of diethyl mercapto- succinate ; CAS no.

Phosphorodithioic acid, O,Odiethyl O- (3,5,6-trichloro-2 pyridyl) ester; CAS no:2921-

3,3-dihydro-2,2-dimethyl-7-

methylcarbamate CAS no.

Azadirachin; CAS no. 1141-

glycine; CAS no. 1071-83-6

.

**Structure** 

oxygen were measured according to APHA (1992).

(organophosphate)

(organophosphate)

(carbamate)

(biopesticide)

Glyphosate Herbicide (amine) N - (Phosphonomethyl)

Table 1. Chemical formulation of pesticides tested with *M. micrura*

Malathion Insecticide

Chlorpyrifos Insecticide

Carbofuran Insecticide

Neem extract Insecticide

**2.3.2 Chronic toxicity test** 

**2.4 Statistic analysis** 

b, 2008 c)

**Pesticide Group of pesticide Chemical name and number** 

Table 2. show the estimated 48-h LC50 for pesticides, with were calculated from standard toxicity test with *M. micrura*.

**Malathion.:** Our 48-h *M. Micrura* LC50 of 10.44 µg/L was compareable to the 48-h LC50 to other Cladocera species. This results shown 48-h- LC50 *M. Micrura* were nealy repoted the 5- 10 µg/L for *M. marcocopa* by Wang et al. (1994) and the 8 and 13 µg/L that reported by Khan et al. (1993) and Siefirt (1987) for *D. Magna.* Differnce in LC50 value were observed wih *Cerodahnia dubia* have been reported between 1.14 -3.35 µg/L(Hernadez et al.,2004; Maul et al., 2006; Nelson et al.,1997,1998; Ankley et al., 1991).

**Chlorpyrifos:** Of the five pesticides tested in this study, chlorpyrifos was the most toxic to *M. Micrura*. The 48-h LC50 value for *M. micrura* was 0.08 µg/L. Other values in literature were higher between 0.13-3.7 µg/L using *D. ambigue, D. Magnaand and D. Duplex* (Caceres et al.,2007; Van Wijngaarden et al., 1993; Barata et al.,2004; Kersting et al.,1997; Van der Hoeven and Gerrisen, 1997).

**Carbofuran:** The 48-h LC50 for *M. micrura* obtain in this study 6.96 µg/L is compareable to the 48-h LC50Of 2.69 µg/L obtain with *C. Dubia* (Nerberg et al.,1997) for carbofuran in *D. magna* were higher than concentration tested (6.96 µg/L). In comparison, Poirer (1990); DBR (2000) and Dopsikova (2003) found an acute 48-h LC50 were 86.1, 38.6 and 18.7 µg/L respectively.

**Neem extract:** The present study found that the 48-h LC50 for neem extract in *M. micrura* was 196.3 µg/L. The acute toxicity data for *D.magna* with 48-h LC50 were 570- 1,250 µg/L (John , 2001; Stark ,2001; Scott and Kaushik, 2001), and were <6000 – 380,000 µg/L for *D. Duplex*  (Goktepe and Plhak, 2002,2003)**.** 

**Glyphosate:** Glyphosate was the lowest toxic (LC50 was 3042 µg/L) to *M. micrura*. Other values in reports were higher between 1150 – 107,000 µg/L and 30000 µg/L for *C. Dubia and D. Magnaa,* respectively*.* The LC50 value of pesticides showed that toxicity of chlorpyrifos > carbofuran > malathion > neem extract > glyphosate. *M micrura* were susceptible to pesticides from µg/L to mg/L, with chlorpyrifos was the most toxic (LC50 = 0.08 µg/L) and glyphosate was the lowest toxic (LC50 = 3042 µg/L) to *M. micrura*.


Table 2. Acute toxicity (Medium lethal concentration [LC50 ]) of pesticides on *M. micrura* at 48 h.

Using Zooplankton*, Moina Micrura* Kurz Evaluated

Malathion *M. micrura* 10.44

Clorpyrifos *M. micrura* 0.08

Carbofuran *M. micrura* 6.96

Neem extract *M. micrura* 196.3

Glyphosate *M. micrura* 3043

species.

*M. marcocapa* 5-10 *C. dubia* 3.18 3.35 1.14 2.12 *D. magna* 0.90 8.0

*C. dubia* 0.117

*D. ambigue* 0.050

*D. magna* 0.30 - 0.80

*D. duplex* 1.0 - 3.7

*C. dubia* 2.69

*D. magna* 86.1

*D. magna* 1250 *D. duplex* 570 - 680

*C. dubia* 1150

*D. spinulata* 30000 *D. magna* 20000 - 21880 *D. duplex* 218000 7900

Ecotoxicology of Pesticides Used in Paddy Field in Thailand 273

This studies Wang et al. (1994) Hernadez et al. (2004) Maul et al. (2006) Nelson et al. (1997, 1998) Ankley et al. (1991) Ren et al. (2007) Khan et al. (1993) Siefirt. 1987)

This studies Bailey. (1997) Harmon et al. (2003) El- Merhibi et al. (2004) Harmon et al. (2003) Caceres et al. (2007)

Van Wijngaarden et al. (1993)

Van der Hoeven and Gerrisen. (1997)

Barata et al. (2004) Kersting et al. (1997)

This studies Nerberg et al. (1997) Poirer (1990) DBR (2000) Dopsikova (2003)

This studies John. (2001) Stark. (2001)

This studies Hensen et al. (1994) Tsui et al. (2004) Lutufu et al. (2001) Al –Omar et al. (2000) Henry et al. (1994)

Hooftmant et al. (1993)

Scott and Kaushik. (2001) Goktepe and Plhak. (2002) Goktepe and Plhak. (2003)

Office of pesticide program. (2000)

**Pesticide Species 48-h LC50 References** 

13

0.056

0.035

1.28

0.13 > 1.6 0.17-0.49

> > 20 > 162

> > 38.6 18.7

570 <6000 - 243000 30000 - 380000

5890 - 107000

Table 3. Comparison of 48-h LC50 ( µg/L) Value of *Moina micrura* and another clardocerans

Aquatic ecosystems in tropical regions differ from those in temperate regions. The biodiversity in tropical zones is higher than that in temperate zones, which means that in tropic regions there are potentially more species that can be exposed to certain pollutants. However, many countries in the tropics are developing countries, in which pollution control

In this studied were founded that toxicity of the insecticide group (chlorpyrifos, carbofuran, malathion and neem extract) were more toxic to *M. micrura* than the herbicide group (glyphosate), because insecticide had mode of action that affect on organism directly but herbicide acted in indirect way. US. EPA (1998) reported chlorpyrifos had very high toxicity to freshwater fish and aquatic invertebrates, carbofuran and neem extract had higher toxicity but glyphosate had less toxicity on zooplankton (Henry et al.,1994; ENTOXNET, 1996; PMRA, 2002; Dopsikova, 2003; Saglam and Saler, 2005). On the basis LC50 value, *M. micrura* of this study were sensitive to pesticides nearly Ceriodapnia species but were more sensitive to pesticides than Dahpnia species indicated by other studies in Table 3. Due to Daphnia species were bigger than Moina species and Ceriodapnia speciesthus its tolerant than M. Micrura and Ceriodapnia species. The result were found similar to Scott and Kaushik (1998); Liane (2002) and Grant and Schmutter (1987) reported were size, age, species, life-cycle of zooplankton and environment such as temparature, pH and harness have influent to chemical toxicity on zooplankton.

The observation of *M micrura*, after treated with pesticides especially in high concentration, the swimming activity of *M. micrura* was changed. They moved faster then normal conditions, after a time later, the movement on antenna and limbs become slowly and death after that. Concentration of pesticides had disrupt respiratory membrane of *M. micrura*, their swimming behavior changes in high concentration and *M. micrura* were loosed their original colored. The similar results were reported in Rassolzadegan (2000); Saglam and Saler (2005)John et al. (2007)

#### **Chronic toxicity**

Effect of sublethal pesticides concentration on the number of offspring per female of *M. micrura* is shown in (Table 4). Number of offspring per female of *M. micrura* was significant reduced (P<0.05) at malathion concentration 0.50 µg/L, chlorpyrifos concentation greater than 0.00025 µg/L, at carbofuran concentration at 2.50 µg/L and at glyphasate concentration 325 µg/L. For neem extract concentration had no effect on the number of offspring per female significantly (P>0.05). Sublethal effects for each pesticide, were founded similar to other reports (Wong et al, 1995; Alberdi et al,1996; US EPA 2006). An estimate of no observed effect concentration (NOEC) and lowest observed concentration (LOEC) were 0.25 and 0.50 µg/L for malathion, 0.00005 and 0.00025 µg/L for chlorpyrifos, 1.00 and 2.50 µg/L for carbofuran, 250 and 325 for glyphosate and LOEC 65 µg/L for neem extract. Cladocerans contribute an important component of aquatic ecosystem especially, for fish food source. If the number of clardocerans were down, it may affect fish and another organisms.

The number of offspring per female is one endpoint used to determine the maximum acceptable - toxicant concentration (MATC). The 16 % reproduction impairment have been used as the endpoint for many aquatic ecotoxicology (Biesinger and Chistensen, 1972).

Therefore, this studies used 16 % reproduction impairment estimate the chronic values MATCs for pesticides (Table 4). According to the obtained results the calculated values of MATCs and 48-h LC50 were for estimate application factor (AF) of pesticides on *M. micrura* (Table 5).

This value was used to predict the safe concentration (SC)applies for pollutant prevention in aquatic ecosystem. However, the application factor will vary with type of pesticide and organism (Mounth and Stephan, 1967).

In this studied were founded that toxicity of the insecticide group (chlorpyrifos, carbofuran, malathion and neem extract) were more toxic to *M. micrura* than the herbicide group (glyphosate), because insecticide had mode of action that affect on organism directly but herbicide acted in indirect way. US. EPA (1998) reported chlorpyrifos had very high toxicity to freshwater fish and aquatic invertebrates, carbofuran and neem extract had higher toxicity but glyphosate had less toxicity on zooplankton (Henry et al.,1994; ENTOXNET, 1996; PMRA, 2002; Dopsikova, 2003; Saglam and Saler, 2005). On the basis LC50 value, *M. micrura* of this study were sensitive to pesticides nearly Ceriodapnia species but were more sensitive to pesticides than Dahpnia species indicated by other studies in Table 3. Due to Daphnia species were bigger than Moina species and Ceriodapnia speciesthus its tolerant than M. Micrura and Ceriodapnia species. The result were found similar to Scott and Kaushik (1998); Liane (2002) and Grant and Schmutter (1987) reported were size, age, species, life-cycle of zooplankton and environment such as temparature, pH and harness

The observation of *M micrura*, after treated with pesticides especially in high concentration, the swimming activity of *M. micrura* was changed. They moved faster then normal conditions, after a time later, the movement on antenna and limbs become slowly and death after that. Concentration of pesticides had disrupt respiratory membrane of *M. micrura*, their swimming behavior changes in high concentration and *M. micrura* were loosed their original colored. The similar results were reported in Rassolzadegan (2000); Saglam and Saler

Effect of sublethal pesticides concentration on the number of offspring per female of *M. micrura* is shown in (Table 4). Number of offspring per female of *M. micrura* was significant reduced (P<0.05) at malathion concentration 0.50 µg/L, chlorpyrifos concentation greater than 0.00025 µg/L, at carbofuran concentration at 2.50 µg/L and at glyphasate concentration 325 µg/L. For neem extract concentration had no effect on the number of offspring per female significantly (P>0.05). Sublethal effects for each pesticide, were founded similar to other reports (Wong et al, 1995; Alberdi et al,1996; US EPA 2006). An estimate of no observed effect concentration (NOEC) and lowest observed concentration (LOEC) were 0.25 and 0.50 µg/L for malathion, 0.00005 and 0.00025 µg/L for chlorpyrifos, 1.00 and 2.50 µg/L for carbofuran, 250 and 325 for glyphosate and LOEC 65 µg/L for neem extract. Cladocerans contribute an important component of aquatic ecosystem especially, for fish food source. If the number of clardocerans were down, it may affect fish and another

The number of offspring per female is one endpoint used to determine the maximum acceptable - toxicant concentration (MATC). The 16 % reproduction impairment have been used as the endpoint for many aquatic ecotoxicology (Biesinger and Chistensen, 1972). Therefore, this studies used 16 % reproduction impairment estimate the chronic values MATCs for pesticides (Table 4). According to the obtained results the calculated values of MATCs and 48-h LC50 were for estimate application factor (AF) of pesticides on *M. micrura*

This value was used to predict the safe concentration (SC)applies for pollutant prevention in aquatic ecosystem. However, the application factor will vary with type of pesticide and

have influent to chemical toxicity on zooplankton.

(2005)John et al. (2007)

**Chronic toxicity** 

organisms.

(Table 5).

organism (Mounth and Stephan, 1967).


Table 3. Comparison of 48-h LC50 ( µg/L) Value of *Moina micrura* and another clardocerans species.

Aquatic ecosystems in tropical regions differ from those in temperate regions. The biodiversity in tropical zones is higher than that in temperate zones, which means that in tropic regions there are potentially more species that can be exposed to certain pollutants. However, many countries in the tropics are developing countries, in which pollution control

Using Zooplankton*, Moina Micrura* Kurz Evaluated

**Pesticide Concentration** 

0.00 0.05 0.25 0.50 0.00 0.00005 0.00025 0.00045 0.00 0.00005 0.00025 0.00045 0.00 15.00 40.00 65.00 0.00 50.00 250.00 325.00

Malathion

Chlorpyrifos

Carbofuran

Neem extrat

Glyphosate

significantly different (P>0.05).

Ecotoxicology of Pesticides Used in Paddy Field in Thailand 275

carbamate insecticides. From 1999 to 2001, a survey of three major rivers along paddy field areas (Thachin river in Suphanburi and Nakornpathom, the Chao Phraya river in Pathumthani and Nonthaburi, and the Bangpakong river in Chachengsao), found the highest residues of the insecticide endosulfan in the Thachin River, followed by the Chao Phraya and Bangpakong Rivers. In all cases, the levels of pesticide residues were above the

In 2001, groundwater in the lower Central and the lower Northeastern region of Thailand was contaminated with pesticides residues, in many cases in concentration above the safety limit set by the EU (0.1 μg/l). In the lower Central region during the rainy season in 2001, 68% of 15 GRL-TN-03-2008 the total groundwater samples were contaminated with endosulfan and other insecticides, in concentration ranging from 0.02 to 3.2 μg/l, and paraquat, 2,4-D, butachlor, atrazine and metribuzin herbicide residues ranging from 0.02 to 18.9 μg/l. In lower Northeastern region during the dry season in 2001, 71.2% of the total groundwater samples were contaminated with endosulfan and other insecticides, in concentrations from 0.01 to 0.33 μg/l, and atrazine and paraquat herbicide residues at the level of 0.5-4.0 μg/l (Sakultiangtrong, et.al., 2002). In 1993, the Department of Agriculture investigated shallow groundwater wells from Rayong Province. From 160 samples collected from wells, 67% were contaminated with organochlorine and organophosphate pesticides,

safety limit set by the European Union (0.1 μg/L) (Chatsantiprapha, et. al., 2002).

but in concentration below the safety limits (Pollution Control Department, 2004).

\*Note:Value are maen + standard deviation. Mean with the same letter in the column are not

Table 4. Chronic toxicity of malathion, chlorpyrifos, carbofuran, neem extract and gyphosate on the number of offspring per female and % reproductive impairment of M. micrura.

**(µg/L) Number of offspring per female % Reproductive** 

55.13+0.45a 53.13+0.50a 49.03+0.70a 36.50+0.46b 53.37+0.35a 53.37+0.35a 49.77+0.41b 43.00+0.52c 53.37+0.35a 53.37+0.35a 49.77+0.41b 43.00+0.52c 56.33+3.15a 55.10+2.12a 53.76+1.72a 52.33+1.99a 56.06+1.62a 55.17+0.95a 47.66+2.12a 42.43+3.74b **impairment**

0.00 3.68 11.06 33.79 0.00 6.741 9.43 28.23 0.00 6.74 19.43 28.23 0.00 2.18 4.56 7.10 0.00 1.59 14.19 24.31

is not carried out due to a lack of funds and other resources. Furthermore environmental quality criteria for some pollutants are often obtained by extrapolating toxicity data derived for a reduced number of species mainly distributed in temperate regions (e.g. Europe or the US) (Kim *et al.*, 2001 in Kwok *et al.,* 2007). Kwok *et al.* (2007) investigated to which extent the sensitivity distributions of temperate species to toxic substances were similar to those of tropical species. They found that the temperate species seemed to be more sensitive to metals than the tropical species (Kwok *et al.,* 2007). However, it should be noted that these differences might be due to the different species composition included in the species sensitivity distributions (SSD). Kwok *et* al (2007) used mainly fish species, which could be less sensitive to pollutants than the invertebrate species that are predominantly used in the temperate species sensitivity distributions. A better comparison can be made when using similar taxonomic groups for the distribution.

In Thailand ecotoxicological research is quite new and has many limitations. Although ecotoxicological issues arise in this country and there is a need for water quality management and ecological risk assessment tools, there is a lack of ecotoxicological data on aquatic organisms from Thailand. Until now, like other developing countries, they have relied on over sea data to develop ecotoxicological test guidelines. However, these guidelines may be unsuitable for Thailand. The Thai indigenous aquatic organisms might be more or less sensitive to contaminants than their temperate surrogate species (Iwai, 2004; Iwai and Noller, 2010; Somparn et al., 2010). Moreover, there are differences in physicochemical and biological characteristics of aquatic habitats between tropical and temperate regions (Kwok et al., 2007). The characteristic of the sediment and water in Thai rivers may differ from those in other countries (Iwai and Noller, 2010; Somparn et al., 2010), influencing the concentration, availability and accumulation of pollutants and therefore their toxicity. An example of this is given by Jeon et al. (2010). They found that clay and food content in the water influence the toxicity of pollutants on aquatic biota.

Tirado et al. (2008) report that the main rivers in Thailand were monitored from 1993 to 1999 for the presence of pesticide residues; most water samples contained insecticide and herbicide residues in levels above advisable limits, whereas less contamination was observed in sediment samples. In river water, organochlorine pesticides were detected in 40.62% of the samples (in concentration ranging from 0.01 to 1.21 μg/L), organophosphate pesticides were detected in 20.62% of samples (in concentration ranging from 0.01 to 5.74 μg/L). The safety limit established by the European Union is 0.1 μg/L for any single pesticide and 0.5 μg/l for the sum of all pesticides detected. Both organochlorine and organophosphate pesticide residues were found above those safety limits. Additional compounds, like carbamate pesticides were detected in 12.39% of samples (in concentration ranging from 0.01 to 13.67 μg/l), triazines were detected in 20.0% of samples (in concentration ranging from 0.01 to 6.63 μg/L), and paraquat was detected in 21.36% of samples (in concentration ranging from 0.14 to 87.0 μg/L) (Chulintorn et al., 2002). An earlier study has also found residues of the pesticides DDT and dieldrin in five Thai rivers (Upper Ping, Lower Ping, Wang, Yom, Nan, Chee), in concentrations above acceptable standard levels (Sombatsiri, 1997). The Division of Agricultural Toxic Substances in the Department of Agriculture (Ministry of Agriculture and Cooperatives) has also monitored the presence of pesticide residues in rivers and canals around agricultural areas in the country. The contamination of pesticides in water and sediments was generally low in water resources used for domestic consumption like ponds and reservoirs that have no connection to agricultural plantations. However, the water resources in certain agricultural areas, like orchid and ornamental plantations, were contaminated with organophosphate and

is not carried out due to a lack of funds and other resources. Furthermore environmental quality criteria for some pollutants are often obtained by extrapolating toxicity data derived for a reduced number of species mainly distributed in temperate regions (e.g. Europe or the US) (Kim *et al.*, 2001 in Kwok *et al.,* 2007). Kwok *et al.* (2007) investigated to which extent the sensitivity distributions of temperate species to toxic substances were similar to those of tropical species. They found that the temperate species seemed to be more sensitive to metals than the tropical species (Kwok *et al.,* 2007). However, it should be noted that these differences might be due to the different species composition included in the species sensitivity distributions (SSD). Kwok *et* al (2007) used mainly fish species, which could be less sensitive to pollutants than the invertebrate species that are predominantly used in the temperate species sensitivity distributions. A better comparison can be made when using

In Thailand ecotoxicological research is quite new and has many limitations. Although ecotoxicological issues arise in this country and there is a need for water quality management and ecological risk assessment tools, there is a lack of ecotoxicological data on aquatic organisms from Thailand. Until now, like other developing countries, they have relied on over sea data to develop ecotoxicological test guidelines. However, these guidelines may be unsuitable for Thailand. The Thai indigenous aquatic organisms might be more or less sensitive to contaminants than their temperate surrogate species (Iwai, 2004; Iwai and Noller, 2010; Somparn et al., 2010). Moreover, there are differences in physicochemical and biological characteristics of aquatic habitats between tropical and temperate regions (Kwok et al., 2007). The characteristic of the sediment and water in Thai rivers may differ from those in other countries (Iwai and Noller, 2010; Somparn et al., 2010), influencing the concentration, availability and accumulation of pollutants and therefore their toxicity. An example of this is given by Jeon et al. (2010). They found that clay and food

Tirado et al. (2008) report that the main rivers in Thailand were monitored from 1993 to 1999 for the presence of pesticide residues; most water samples contained insecticide and herbicide residues in levels above advisable limits, whereas less contamination was observed in sediment samples. In river water, organochlorine pesticides were detected in 40.62% of the samples (in concentration ranging from 0.01 to 1.21 μg/L), organophosphate pesticides were detected in 20.62% of samples (in concentration ranging from 0.01 to 5.74 μg/L). The safety limit established by the European Union is 0.1 μg/L for any single pesticide and 0.5 μg/l for the sum of all pesticides detected. Both organochlorine and organophosphate pesticide residues were found above those safety limits. Additional compounds, like carbamate pesticides were detected in 12.39% of samples (in concentration ranging from 0.01 to 13.67 μg/l), triazines were detected in 20.0% of samples (in concentration ranging from 0.01 to 6.63 μg/L), and paraquat was detected in 21.36% of samples (in concentration ranging from 0.14 to 87.0 μg/L) (Chulintorn et al., 2002). An earlier study has also found residues of the pesticides DDT and dieldrin in five Thai rivers (Upper Ping, Lower Ping, Wang, Yom, Nan, Chee), in concentrations above acceptable standard levels (Sombatsiri, 1997). The Division of Agricultural Toxic Substances in the Department of Agriculture (Ministry of Agriculture and Cooperatives) has also monitored the presence of pesticide residues in rivers and canals around agricultural areas in the country. The contamination of pesticides in water and sediments was generally low in water resources used for domestic consumption like ponds and reservoirs that have no connection to agricultural plantations. However, the water resources in certain agricultural areas, like orchid and ornamental plantations, were contaminated with organophosphate and

content in the water influence the toxicity of pollutants on aquatic biota.

similar taxonomic groups for the distribution.

carbamate insecticides. From 1999 to 2001, a survey of three major rivers along paddy field areas (Thachin river in Suphanburi and Nakornpathom, the Chao Phraya river in Pathumthani and Nonthaburi, and the Bangpakong river in Chachengsao), found the highest residues of the insecticide endosulfan in the Thachin River, followed by the Chao Phraya and Bangpakong Rivers. In all cases, the levels of pesticide residues were above the safety limit set by the European Union (0.1 μg/L) (Chatsantiprapha, et. al., 2002).

In 2001, groundwater in the lower Central and the lower Northeastern region of Thailand was contaminated with pesticides residues, in many cases in concentration above the safety limit set by the EU (0.1 μg/l). In the lower Central region during the rainy season in 2001, 68% of 15 GRL-TN-03-2008 the total groundwater samples were contaminated with endosulfan and other insecticides, in concentration ranging from 0.02 to 3.2 μg/l, and paraquat, 2,4-D, butachlor, atrazine and metribuzin herbicide residues ranging from 0.02 to 18.9 μg/l. In lower Northeastern region during the dry season in 2001, 71.2% of the total groundwater samples were contaminated with endosulfan and other insecticides, in concentrations from 0.01 to 0.33 μg/l, and atrazine and paraquat herbicide residues at the level of 0.5-4.0 μg/l (Sakultiangtrong, et.al., 2002). In 1993, the Department of Agriculture investigated shallow groundwater wells from Rayong Province. From 160 samples collected from wells, 67% were contaminated with organochlorine and organophosphate pesticides, but in concentration below the safety limits (Pollution Control Department, 2004).


\*Note:Value are maen + standard deviation. Mean with the same letter in the column are not significantly different (P>0.05).

Table 4. Chronic toxicity of malathion, chlorpyrifos, carbofuran, neem extract and gyphosate on the number of offspring per female and % reproductive impairment of M. micrura.

Using Zooplankton*, Moina Micrura* Kurz Evaluated

875-53217-9,Washington, D.C.

229-235, ISSN 0007-4861

139, ISSN 0166-445x

*Canada,* Vol. 29, pp. 1691-1700

4497-4503, ISSN 0043-1354

No.3, pp103-108, ISSN 1212-2580

**5. Acknowledgment** 

University.

**6. References** 

Ecotoxicology of Pesticides Used in Paddy Field in Thailand 277

This work was supported by the Higher Education Research Promotion and National Research University Project of Thailand, Office of the Higher Education Commission. The authors wish to express their sincere thanks to Khon Kaen University for the research funding, Groundwater research centre (GWRC) and Graduate School Khon Kaen

Abdullah, A.R., Bajet, C.M, Matin, M.A., Nhan, D.D. & Sulaiman, A.H. (2007). Ecotoxicology

Ankly, G.T., Call, D.J., Cox, J.S., M.D., Kahl, M.D., Hoke, R.A. & Kosian, P.A. (1994) Organic

Alberdi J.L., Sáenz M.E., Di Marzio W. D. and Tortorelli M. C. (1996). Comparative Acute

Al-Omar, M.A & Hassan, N.A. (2000). Simple and Rapid Method for the Detection of Early

Bailey, H.C., DiGiorgio, C., Kroll, K., J., Miller, L., Hinton, D.E.& Starrett. G. (1996) .

Barata, C., Solayan A.& Porte,C. (2004). Role of B-Esterases in Assessing Toxicity of

Bailey, H.C., Miller, J.L., Miller, M.J., Wiborg, L.C., Deanovic, L. & Shed. T. (1997). Joint

Caceres, T., He, W. Naidu, R. & Megharaj, M. (2007). Toxicity of Chlorpyrifos and TCP

Dobsikova, R. (2003). Acute toxicology of carbofuran to selected species of aquatic and

*Toxicology and Chemistry*, Vol.11, No.6, pp. 2304-2308, ISSN 0730-7268 Biesinger. K.E. & G.M. Chistensen. (1972). Effects of Various Metals on Survival, Growth,

*Chemistry*, Vol.26, No. 1, pp.59-70, ISSN 0730-7268

*Chemistry*, Vol.65, No.5, pp.553- 559, ISSN 0007-4861

1996 ), Vol.15, No.6, pp. 837-845, ISSN 0730-7268

of pesticides in the tropical paddy field system. *Environmental Toxicology and* 

carbon patitioning as a basis for predicting the toxicity of chlorpyrifos in sediment. *Environmental Toxicology and Chemistry*, Vol.13, No.4, pp.621- 626, ISSN 0730-7268 American Public Health Association. (1992). American Water Works Association and

Federal Water Pollution Control Administration. *Standard method for the Examinationof Water and Wastewater*. American Public Health Association, ISBN 0-

Toxicity of Two Herbicides, Paraquat and Glyphosate to *Daphnia magna* and *D. spinulata*. *Journal of Earth and Environmental Science*, (March 1996),Vol.57, No.2, pp.

Signs of Toxicity in *Daphnia magna* Straus. *Bulletin of Environmental Toxicology and* 

Development of Procedures for Identifying Pesticide Toxicity in Ambient Waters: Carbofuran, Diazinon, Chlorpyrifos*. Environmental Toxicology and Chemistry*, ( June

Organophosphorus (Chlorpyrifos, Malathion) and Carbamate (Carbofuran) Pesticides to *Daphnia magna*. Aquatic Toxicology, ( July 2003),Vol.66, No.2, pp. 125-

Acute Toxicity of Diazinon and Chlorpyrifos to Ceriodaphnia dubia. *Environmental* 

Reproduction, Metabolism of *D. magna*. *Journal of the Fisheries Research Board of* 

Alone and in Combination to Daphnia carinata: The Influence of Microbial Degradation in Natural Water. *Water Resevation*, (June 2007), Vol.41, No.19, pp.

terrestrial organisms. *Journal of Plant Protection Science*, (September 2003), Vol 39,


Table 5. The maximum acceptable - toxicant concentration (MATC) and Application factor (AF) for each pesticide.
