Residue And Risk Assessment Of7Kinds Of Pyrethroids In Water Environment In The Pearl River Delta

Synthetic pyrethroid insecticides are the new third-generation pesticides. In the lastdecades, synthetic pyrethroid insecticides have increasingly replaced organochlorinepesticides due to their relatively lower mammalian toxicity, selective insecticide activityand lower environmental persistence, thus them become one of the most widely usedpesticides. Compared with organochlorine pesticides, pyrethroids insecticides are lessharm to the environment, but the pyrethroids insecticides which enter the body throughthe food chain could have side effects on mammalian reproductive, immune andcardiovascular, and have highly toxic aquatic organisms, causing damage to aquaticsystem.This study was intended to investigate levels content, composition of thedistribution, and toxicity assessment of7kinds of pyrethroid pesticides in the21sampling station of the Pearl River Delta, including the13station in the Pearl RiverDelta and8sampling station in the the Pearl River Estrary, and the median lethalconcentration and safe concentration of fenpropathrin on Megalobrama hoffmanni bythe acute toxicity test.In May, The mass fraction of7kinds of pyrethroids at21stations in the surfacewater ranged from0.01to0.73μg·L-1, with an average of0.12μg·L-1.7kinds ofpyrethroids were detected in water, in which permethrin was the next most abundantpyrethroids, with concentration equating to57.6%of total pyrethroid concentrations andthe detection rate of61.9%, followed by fenpropathrin, which accounted for15.7%ofthe total pyrethroids mass fraction, and the detection rate was33.3%. The high detectionconcentration and rate, may be related with the widespread use of permethrin ineveryday life.The total pyrethroids contents in the surface sediments ranged from ND to6.59μg·kg-1, and averaged0.75μg·kg-1. The highest content of pyrethroids was in the Pearl River Bridge. The proportions of permethrin were higher in the Pearl River Estuarywhich was57.63%of total pyrethroids.The content of pyrethroid pesticides in fish muscle, shrimp, and shellfish rangedfrom ND to3.05μg·kg-1(mean0.90μg·kg-1), from0.05to1.13μg·kg-1(mean0.41μg·kg-1), and from0.69to1.20μg·kg-1(mean0.99μg·kg-1), respectively. Detection ofseven kinds of pyrethroid pesticides were100%, but bifenthrin in shrimp and shellfishwas75%, and the detection of permethrin was100%in fish muscle. The pesticidedetected at the highest concentration was permethrin at52.2%and55.4%of totalpyrethroid pesticides in fish muscle and shellfish, respectively. The proportions ofdeltamethrin were highest in shrimp (33.0%of total pyrethroids). Japanese eel (Anguillajaponica Temminck et Schlegel) and giant tiger prawn (Penaeus monodon Fabricius)can be used as a pollution indicator species of permethrin and deltamethrin, respectively.The enrichment capability of pyrethroid pesticides in aquatic organisms may be relatedwith inherent metabolism in the body and the KOW.The hydrostatic test method was to explore the acute toxicity test of fenpropathrinon Megalobrama hoffmanni at room temperature. Results show that LC50(96h) offenpropathrin on triangular bream was1.866μg·L-1, and the safe concentration was0.187μg·L-1. Fenpropathrin has high toxic to Megalobrama hoffmanni.The clustering analysis with pyrethroids of water and sediment in the Pearl RiverDelta, respectively, the results show that some big cities such as Guangzhou, Jiangmenand Panyu, near sampling position, have high concentration of pyrethroids, and this maybe related to a large population of big cities, including lots of pyrethroid productswidely used in the daily life of the residents. The sources of pyrethroids includelandscaping maintence, mosquito control, urban stormwater runoff and road runoff,resulting in pyrethroids concentration increased in the Pearl River.The chemical carcinogen of human body health hazard risk degree calculationmodel was used to evaluate exposure risk to pyrethroid via water and food consumptionin the pearl river, and the results show that overall human health hazard risk evaluationvalues ranged from2.61×10-13to6.00×10-13a-1in the Pearl River Delta. Which is farbelow the level of risk to human health hazard maximum acceptable level of risk (10-6a-1), namely the Pearl river water pyrethroid pesticide health risk levels within anacceptable range. overall human health hazard risk evaluation values were between3.96×10-13a-1and1.21×10-10a-1, and the safety consumption of aquatic products is5.54x 104kg·d-1, the health risks of pyrethroids in aquatic product is negligible, therefore, Thehealth risks of pesticides in aquatic products in the pearl river delta for seven kinds ofpyrethroids were in the acceptable range.Toxic units based on the LC50of Hyallela Azteca were calculated to estimate thetoxicity risk, the∑TU in the Pearl River Estuary range0from0.09, suggesting therewas no obvious toxic effects of pyrethroids on Hyallela Azteca, and there was litterecological risk of pyrethriods in the Pearl River Estuary.