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1 DETERMINATION OF SOME ORGANOCHLORINE PESTICIDES RESIDUES IN PUMPKIN, SPINACH AND SORREL LEAVES GROWN IN AKWANGA, NASARAWA STATE NIGERIA. BY Nathaniel Yakubu 1 Ibrahim, E.G 2, and Lami Nnamonu 3 BEING A PAPER PRESENTED AT INEF, 2017 CONFERENCE BEIJING CHINA nathyaks@gmail.com

2 Pesticides is an extremely diverse group of substances with a wide potential for a variety of toxic effects. They can range in acute toxicity from being lethal at low doses, such as strychnine, to the relatively large quantities, such as sodium chloride, which is also edible in measured quantities.

3 Pesticides have helped to increase crop production by controlling the pests that destroy the crops. However, some of the pesticides have adversely affected the non-target species by inducing carcinogenic, tetraogenic, mutagenic, neuro-toxic effects as well as alterations of reproductive processes or functions in experimental animals and in man.(akan et al, 2014)

4 Akwanga is one out of the 13 Local Government Area in Nasarawa State, Nigeria, and the major occupation here is farming, with a total population of 113,430 and has a land area of 996Km 2 (Census, 2006) and it lies at latitude N and longitude E.

5 Pumpkin Leaves: Telfairia occidentalis (Local name:- Ugwu) Spinach Leaves: Amaranthus hybridus (Local name:- Alefo) Sorrel Leaves: Rumex acetosa (Local name:- Yakwa)

6 20g of the samples were chopped to pieces and then macerated to make paste with a mixer. A 15g portion of the homogenized sample was weighed into a 50ml polytetra fluoroethylene (PTFE) tube, then 15ml of acetonitrile containing 1% acetic acid (v/v) was added followed by 6g MgSO 4 and 1.5g anhydrous Sodium acetate. The sample was shaken vigorously for 3 minutes and then centrifuged at 1500rpm for 5 minutes.

7 After centrifugation, the samples were cleaned up using dspe (Dispersive Solid-Phase Extraction). 1ml of the supernatant was transferred to a 15ml PTFE tube to which 50mg each of C18 and PSA (Primary and Secondary Amine Sorbents) with 150mg MgSO4 was added and vortexed for 30s and then centrifuged for 1min at 1500rpm. The clear extract was then transferred to an auto sampler vial for GC-MS analysis.

8 Table 1: Mean concentration of organochlorine pesticide residues in three green leafy vegetables Vegetable concentration (mg/kg) Pesticides Pumpkin leaves Spinach leaves Sorrel leaves p, p 1 DDT ± ± ± 0.03 BHC ± 0.0 ND ND D BHC ± 0.0 ND ND Dieldrin ND ± ± 0.0 Aldrin ND ND ±0.03 Endosulfan II ND ND ± 0.0 ND Not Detected

9 Conc (mg/kg) Pumpkin Spinach Sorrel Figure 1: Mean concentrations of some organochlorine pesticide residues in three green leafy vegetables

10 Among DDT analogues only the p, p 1 DDT was detected in all the samples, fig. I shows that Pumpkin has the highest value with the mean value of 0.75 mg/kg followed by spinach with the value of mg/kg and the least is Sorrel with the value of mg/kg. All the concentrations of the DDT in all the vegetables were much higher than the EU set maximum residue limit (MRL) for total vegetables which is 0.05mg/kg. The high concentration of DDT and its metabolites, obtained in the result of this study indicates that high concentration of DDT pesticides could have been used in killing pests or other plants that also grow with these vegetables. This also confirms that like other developing countries organochlorine pesticides are still in use here.

11 - BHC and ɣ - BHC were detected only in Pumpkin leaves at a concentration of 0.359mg/kg and 0.647mg/kg respectively. The concentrations of this pesticide were much higher than the codex 2009 set maximum limits (MRL s) of 0.01mg/kg for -BHC and ɣ - BHC. Residues of BHC isomers in significant concentrations in the vegetable samples may be attributed to the heavy use of this pesticide in the study area. Gamma BHC is a reasonably stable compound and only under alkaline condition decomposes to yield trichlorobenzene. It is considered as one of the less persistent organochlorine pesticides. Dieldrin was detected in Spinach and Sorrel, the Sorrel has the higher concentration of 0.124mg/kg than the spinach

12 (0.053mg/kg), dieldrin was not detected in Pumpkin, this dieldrin is one of the organochlorine that is classified to be persistent in the environment even when they have not been used for a very long time. Endrin was found in Pumpkin only (0.732mg/kg) and Aldrin in Sorrel only at a concentration of 0.095mg/kg. The concentrations of these pesticide residues aldrin, endrin and dieldrin were much higher than the EU set maximum residue limits (MRL s) 0.01mg/kg. Endosulfan II was detected in Sorrel at a concentration of 0.306mg/kg far below EU MRL of 30. This endosulfan II has been considered by the peer review of persistent organic pollutant committee to be added to the list of the dirty dozens (Stuart, 2010).

13 The results from this study shows that pesticide residues were found in Pumpkin leaves, Spinach leaves and Sorrel leaves that were analyzed. The concentration of all the pesticide residues were observed to be very high in all the vegetables studied, and above the maximum residue limit set by FAO/WHO and European Union.

14 Thank you for Listening