Sulfadiazine is an antibiotic used in animals and humans, this molecule is being released increasingly into the aquatic environment, which is why the depletion of this molecule in rainbow trout (Oncorhynchus mykkis) was studied using radiometric techniques with 14C, for which a specific activity of 3.5171 MBq mg−1 was used, during 14 days in semi-static conditions. The study found accumulation in trout on day four 5.10 × 10−4 mg g−1 after the exposure phase, and 1.0 × 10−4 mg g−1 after the purification phase, indicates that the concentration used puts human health at risk because exceed the maximum residual limits.