Bioaccumulation and Depletion of the Antibiotic Sulfadiazine 14 C in Lambari (Astyanax bimaculatus).

Simple Summary: Antibiotics are present in the environment and can be bioaccumulated by organisms and transferred through the food chain, which poses a problem when considering fish meat consumption. The study focused on lambari, a fish with potential in aquaculture because of its ease of rearing in small-scale operations. The objective of the study was to measure the bioaccumulation and clearance of the antibiotic sulfadiazine (SDZ) in lambaris. The tests were divided into two phases: exposure and depletion. During exposure, the fish were fed medicated feed for seven days, and during depletion they were transferred to clean tanks and fed uncontaminated feed for another seven days. SDZ concentrations increased in the fish over the days, with the greatest accumulation occurring on day seven. After the depletion phase, SDZ concentrations decreased. The results showed that there was little bioaccumulation of SDZ in the fish, but that the compound was more present in the water. The results also indicated that the concentrations of SDZ were below the established maximum limit. This study contributes to the understanding of the dynamics of SDZ in an aquatic species native to Brazil. Antibiotics are present in the environment, primarily due to their release through wastewater treatment plants, agricultural practices, and improper disposal of unused medications. In the environment, these drugs can be bioaccumulated by organisms and transferred along the food chain. This is a problem when considering the consumption of fish meat. In the United States, legislation stipulates that the maximum residue limit for sulfadiazine (SDZ) should not exceed 100 μg kg−1. Lambari fishes have potential economic importance in aquaculture, as they are relatively easy to breed and can be raised in small-scale operations. Finally, studying the biology and ecology of lambari could provide valuable information about freshwater ecosystems and their inhabitants. The current work aimed to measure the bioaccumulation and depletion of the antibiotic SDZ 14C in lambari (Astyanax bimaculatus). For this purpose, the tests were divided into two stages; seven days of exposure and seven days of depletion, where one fish was randomly selected and sampled every day. In the exposure phase, the fish were fed the medicated feed three times a day at a concentration of 2.5 mg·g−1. The control fish were fed uncontaminated feed. For the depletion phase, the remaining lambari were transferred to clean tanks and fed uncontaminated feed three times a day. The fish samples were burned in the Oxidizer and the reading of radioactivity was performed in a liquid scintillation spectrometer. It is worth noting that on day 7 and day 14, the water in the aquariums was filtered through filter paper to collect the metabolic excrement. SDZ concentrations increased over the days and accumulation occurred in the fish, with day seven presenting the maximum accumulation value of 91.7 ng·g−1 due to feeding uptake. After the depletion phase on day 13, the value found was 0.83 ng·g−1. The bioconcentration factor calculated was 20 L·kg−1. After the bioaccumulation period, the concentrations of SDZ in the water and excreta were 4.5 µg·L−1 and 363.5 ng·g−1, respectively. In the depletion period, the concentrations in the water and excreta were 0.01 µg·L−1 and 5.96 ng·g−1, respectively. These results imply that there was little SDZ bioaccumulation in the fish, but that it was distributed in larger amounts in the water. This is due to the physicochemical properties of the molecule with the low Log P value. Regarding the maximum residue limit, the value was below the established value. This study contributes to understanding SDZ dynamics in an aquatic species native to Brazil. [ABSTRACT FROM AUTHOR]