Bioaccumulation Behavior of Pharmaceuticals and Personal Care Products in Adult Zebrafish (Danio rerio): Influence of Physical-Chemical Properties and Biotransformation

The factors influencing bioaccumulation of pharmaceuticals and personal care products (PPCPs) in aquatic organisms are not well understood. The present study involved a comprehensive laboratory investigation to assess the bioaccumulation behavior of several PPCPs in adult zebrafish ( Danio rerio ). The studied PPCPs included several ionogenic organic compounds (IOCs) such as weak acids and weak bases. Experiments involved two exposure groups (high and low) and a control group, with a 6 day aqueous exposure, followed by a 7 day depuration phase under flow-through conditions. Uptake rate constants ( k u ) ranged between 0.19 and 8610 L·kg –1 ·d –1, while depuration rate constants ( k d ) ranged between 0.14 and 5.14 d –1 in different fish tissues. Steady-state bioconcentration factor (BCF ss ) values varied widely among the studied PPCPs, ranging from 0.09 to 6,460. In many cases, BCF ss values of individual PPCPs differed substantially among different fish tissues. Positive linear relationships were observed between log BCF ss values and physical-chemical properties such as octanol–water distribution coefficients (log D ow ), membrane–water distribution coefficients (log D mw ), albumin–water distribution coefficients (log D BSAw ), and muscle protein–water distribution coefficients (log D mpw ), indicating the importance of lipid–, phospholipid–, and protein–water partitioning. The results also showed that for many PPCPs, the estimated whole-body metabolism rate constant ( k m ) values were comparable to the observed depuration rate ( k d ), indicating that metabolism plays a major role in the overall elimination of these compounds in zebrafish. An exception was sertraline, which exhibited a k d value (0.4–0.5 d –1 ) that was much higher than the estimated whole-body k m (0.03 d –1 ). Overall, the results help to better understand the influence of physical-chemical properties and biotransformation on bioaccumulation behavior of these contaminants of concern in aquatic organisms.