Occurrence And Tissue Distribution Of Typical Antibiotics In Fish Caught In Winter From Jilin Province

Antibiotics have been widely used in human and livestock medical treatment and used as growth promoters for livestock.They are frequently detected in the aquatic environment in recent years.They exhibit a pseudo-persistence property.Antibiotic residues will affect the living environment of aquatic organisms including fish and cause potential ecological risks.The ice-sealed water is covered with ice and has the propert of low temperature in winter in Jilin Province.There are winter fishing activities in some lakes and reservoirs of Jilin Province in China.After the water sealed by ice in winter,fishermen will pass through the ice and put nets to catch fish,which is referred to as winter fish.Previous studies have shown that freezing can affect the transport and transformation of antibiotics in the seasonal thaw-freeze waters.In addition,when the ambient temperature is low,the antibiotic contents and tissue distribution in fish may be different from those under normal temperature conditions.However,there is currently little information about the contents and tissue distribution of antibiotics in wild fish caught in the ice-cover waters.Therefore,the study focused on the typical antibiotics including quinolones,sulfonamides,tetracyclines,chloramphenicols,and macrolide.Hypophthalmichthys nobilis and Cyprinus carpio caught in winter fishing activities in Chagan Lake,Shitokoumen Reservoir,and Harnao Reservoir in Jilin Province were used as the representatives of winter fish.The antibiotic contents in fish’s meat,gills,kidney,liver,bile,and brain were determined.The tissue distribution and bioaccumulation of antibiotics in fish were explored.The human health risks were also assessed by the methods of dietary health risk assessment and E.coli resistance.Finally,the freezing effects were elaborated through comparing with the differences of distribution and bioaccumulation of antibiotics from the fish caught in free ice waters.The study reached the following conclusions: The target antibiotic contents in all tissue samples of fish caught in winter from Jilin Province ranged from undetected to35.0 ng/g wet weight(ww),and the highest value was the florfenicol content in the fish liver.Ofloxacin,florfenicol,and erythromycin were the three antibiotics with the highest detection rate among all the detected samples,with the detection frequencies of74%,72%,and 68%,respectively.The total antibiotic content characterized by fish meat in winter fish in Shitoukoumen Reservoir was significantly lower than that in Chagan Lake and Harnao Reservoir(p<0.05).The total antibiotic content of Cyprinus carpio was significantly lower than that of Hypophthalmichthys nobilis(p<0.05).The differences among the production areas and the fish species were mainly related to the antibiotic concentration in the waters,the synergistic effect by other pollutants and the living environment.The total antibiotic content in the liver of winter fish was significantly higher than other tissues(p<0.05).In addition,the distribution characteristics of different types of antibiotics in various tissues of winter fishing were different.Chloramphenicols in fish meat,bile,fish brain,liver and kidney accounted for the largest proportion.Tetracyclines in fish gills accounted for the largest proportion.The average bioaccumulation factor of all antibiotics in the winter fishing organizations was less than 3.7.According to the Canadian Ministry of Environmental Protection,it was not bioaccumulative in winter fishing.The health risk quotient and cumulative hazard index of eating winter fish meat are far less than 0.1,indicated that the health risk is low.In addition,the maximum concentration of residual antibiotics in the urine of adults through the consumption of winter fish products was far lower than the minimum inhibitory concentration of E.coli.Therefore,the intake of antibiotics in the human body through daily consumption of winter fish will not cause the selective enrichment of drug-resistant individuals in the E.coli population.The total antibiotic content in the fish meat of the fish caught during the non-freezing period was significantly higher than that in winter fish,which could be related to the higher total concentration of antibiotics in water during the non-freezing period(p<0.05).All the antibiotics were not bioaccumulative in fish tissues during non-freezing period.The health risk quotient and cumulative hazard index of fish meat during the non-freezing period were also far less than 0.1.The maximum concentration of antibiotics remained in the urine of adults caused by the consumption of fish caught in both period was far lower than the minimum inhibitory concentration of E.coli.Those results indicated that the freezing of water body did not make the antibiotics more bioaccumulative in fish and did not increase the risk of people’s intake of antibiotics due to eating fish.