Quantitative Determination of Pesticides in Human Biological Fluids and Food Stuffs

The aim of present study was to assess pesticide residues in vegetables, fruits and human blood samples in the selected region of Sindh province, Pakistan. The concentrations of six pesticides were determined by gas chromatography coupled with mass selective detector (GC-MSD) in locally produced vegetables purchased from wholesale markets. A total of 200 samples of eight vegetables viz. cauliflower, green chili, eggplant, tomato, peas, bitter gourd, spinach and apple gourd were analyzed for pesticide residues. The results indicated that almost all samples were contained pesticides, only 39% contained pesticide residues at or below maximum residue limits (MRLs), and 61% contained pesticide residues above MRLs. From the six analyzed pesticides, carbofuran and chlorpyrifos were found above to MRLs with concentrations ranging from 0.01-0.39 and 0.05-0.96 mg kg -1 , respectively. A very sensitive analytical method for the determination of 26 pesticides in some fruits based on solid phase extraction (SPE) cleanup was developed using gas chromatography (GC) coupled with micro electron capture detector (μECD). The identity of the pesticides was confirmed by gas chromatography mass spectroscopy (GC-MS) using selected ion monitoring (SIM) mode. Ethyl acetate was used as a solvent for the extraction of pesticide residues with assistance of sonication. For cleanup an octadecyl, C 18 SPE column was used. A linear response of μECD was observed for all pesticides with good correlation coefficients (>0.9992). Proposed method was successfully applied for the determination of pesticide residues in the orange, apple, and grape fruits. Average recoveries achieved for all VIIof the pesticides at fortification levels of 0.05, 1.0 and 2.0 μg g -1 in analyzed fruits were above 90% with relative standard deviations (RSD) less than 6%. A market based survey was carried out to evaluate the level of 26 pesticides in some commonly used fruits in Hyderabad region, Pakistan. Gas chromatography coupled with micro electron capture detector was used to assess the levels of pesticide residues. Gas chromatography-mass spectrometry (GC-MS) was also applied for the confirmation of results. Out of total 131 analyzed samples, 53 (40%) were found contaminated with pesticide residues while only 3 (2%) samples were exceeded the MRLs of some pesticides. Chlorpyrifos and dieldrin were detected in almost all analyzed samples. Residues of chlorpyrifos (1256 μg kg -1 ) and endosulfan sulfate (1236 μg kg -1 ) were found higher in orange and apple samples, respectively. To evaluate the pesticide residues in human blood samples, two districts of Sindh Province i.e. Hyderabad and Mirpurkhas were selected. The volunteers of both districts were divided in to four groups on the basis of their exposure period to pesticides i.e. Group A- 5 to 9 years, Group B-10 to 14 years, Group C-15 to19 years and Group D-above 20 years. Out of total 188 volunteers, 145 volunteers (77.1%) were agro–professionals and 43 volunteers (32.9%) were non–agro professionals. Chlorpyrifos, endosulfan, 1, 1, 1-trichloro-2, 2-bis (p- chorophenyl) ethane (p-p–DDT) and parathion residues were detected in many samples. The predominant pesticides found in blood samples of both districts volunteers were chlorpyrifos (with highest mean concentration of 0.37 mg kg -1 in the D group of Mirpurkhas) and endosulfan (with highest mean concentration of 0.30 mg kg -1 in the D group of Hyderabad). The quantity of pesticide residues detected in some blood samples of agro-professionals were VIIIfound to be at the alarming level. The results provided important information on the current pesticide contamination status of some commonly used vegetables and pointed an urgent need to control the use of some excessively applied and potentially persistent pesticides, such as carbofuran, chlorpyrifos and endosulfan. The findings of this study provided important data about contamination of pesticide residue in some fruits sold in Hyderabad, Pakistan, and recommended that monitoring studies should be expanded to other fruits grown in different agro climatic regions, which may serve as basis for future policy about the standards and quality control of pesticides.