Abstract
This study was carried out to survey the residual characteristic of chlorpyrifos and estimate their residues in squash before harvest. The pesticide was sprayed onto the crop at the recommended and its double rates 10 days before the prearranged harvest and sampling was done at 0, 2, 3, 5, 6, 7 and 10 days after spraying. The amounts of the chlorpyrifos residue in the crop was analyzed by chromatographic method. Limit of detection (LOD) of chlorpyrifos was 0.005 mg/kg and its recovery ranged from 95.21 to 102.69%. The initial concentration of chlorpyrifos sprayed with recommended dose exceeded its MRL of 0.1 mg/kg but its concentration was less than its MRL 10 days after application. However its concentration in case of the double dose was over its MRL both immediately and 10 days after application. Biological half-lives of chlorpyrifos sprayed onto squash was 2.5 and 2.9 days at the recommended and double doses, respectively. Ten days later, the residual concentration of chlorpyrifos in squash was decreased substantially. The concentration of chlorpyrifos was estimated in squash at the given day using its regression equations. The estimated concentration of chlorpyrifos in case of application with recommended dose was below its MRL at 10 days after application but its concentration in case of application with double dose was over its MRL at 10 days of the prearranged harvest. The rate of the estimated daily intake (EDI) of chlorpyrifos to its acceptable daily intake (ADI) was 282% right after application but it decreased to less than 18% at 10 days of the prearranged harvest.
본 연구는 애호박 중 chlorpyrifos의 수확 전 최종 농약 살포일로부터 수확 일까지 농약의 잔류량 감소 추이를 파악하여 생산단계 농산물 중 농약의 잔류 특성 조사, 수확전 수확 예정일의 잔류량 예측 및 생산단계 농산물의 안전성을 평가하기 위하여 수행하였다. Chlorpyrifos의 검출한계는 0.005 mg/kg이었고, 검출한계의 10배와 50배 수준으로 농약을 처리하여 수행한 회수율은 95.2-102.7%로 양호하였다. 최종 약제 살포 당일 기준량 및 배량 처리구의 잔류량은 MRL인 0.1 mg/kg을 초과하였으나 수확 예정일인 10일차의 기준량 처리구는 MRL 이하였으며, 배량 처리구의 경우 MRL을 초과하였다. 애호박 중 chlorpyrifos의 생물학적 반감기는 기준량과 배량 처리구 각각 2.5일과 2.9일이었다. 최종 약제 살포 후 애호박 중 chlorpyrifos의 잔류량은 시간이 경과되면서 감소하는 경향이었는데, 이는 농약의 분해와 더불어 애호박이 증체함에 따라 잔류농약의 농도가 희석된 결과라고 판단되었다. 잔류시험 후 시험농약의 잔류량을 바탕으로 작성한 회귀곡선을 이용하여 수확전 잔류량을 예측한 결과 수확 당일 기준량 처리구에서 MRL 이하였으나 배량 처리구에서는 수확 예정일에 MRL을 초과하였다. 또한 애호박 중 chlorpyrifos의 잔류량으로 산출한 일일섭취허용량(ADI) 대비 일일섭취추정량(EDI)은 배량 처리구에서 282%로 높았으나 수확 예정일에는 18%로 감소하였다.
