Controlling factors and toxicokinetic modeling of antibiotics bioaccumulation in aquatic organisms: A review

Antibiotics are emerging pollutants widely existing in the aquatic environment with adverse effects on both humans and organisms. Understanding bioaccumulation of antibiotics in aquatic organisms is important for their risk assessment. Observations on the bioaccumulation metrics (including bioconcentration factor, biomagnification factor, trophic magnification factor, bioaccumulation factor, and biota-sediment accumulation factor) of antibiotics in aquatic organisms are reviewed in this contribution. It is revealed that close attention should be paid to enrofloxacin, sulfamethiazole, doxycycline, sulfadimidine, clarithromycin, azithromycin, and chloramphenicol, because they have high bioaccumulation potential with the logarithm of bioaccumulation factor values beyond a threshold (3.3 L/kg) stipulated in the REACH regulation. Physicochemical properties of antibiotics (e.g., pH-dependent octanol-water partition coefficient and liposome-water distribution coefficient), biological characteristics of organisms (e.g., lipid content, biotransformation potential, growth stages, and feeding habits) as well as environmental factors (e.g., the presence of sediment, pH, salinity, exposure concentrations, as well as co-existence with dissolved organic matter, heavy metals, and microplastics) can control the bioaccumulation of antibiotics in aquatic organisms. One-compartment and multi-compartment toxicokinetic models on the bioaccumulation of antibiotics in aquatic organisms are summarized. The existing models of antibiotics mainly focused on fish, suggesting more efforts are needed to construct models on other aquatic species. Knowledge gaps and critical research directions on antibiotics bioaccumulation were highlighted.