bioaccumulates

Bioaccumulates is the verb form used to describe the process by which a substance builds up in an organism over time, as a result of continual uptake from the environment and from diet, coupled with slower loss through metabolism or excretion. This process is most pronounced for persistent, lipophilic compounds that resist rapid elimination. When an organism continually absorbs a contaminant faster than it can be removed, the chemical concentration in the organism increases, potentially to levels higher than those in the surrounding environment.

Uptake can occur through multiple routes: waterborne uptake through gills or skin, ingestion of contaminated food, and, in some species, inhalation or dermal exposure. Once inside the body, chemicals may be stored in tissues such as fat, liver, or other organs. Metabolism may transform substances, but many persistent pollutants resist degradation. Excretion may be slow, leading to accumulation over time. The extent of bioaccumulation is often expressed by factors such as the bioconcentration factor (BCF) or the bioaccumulation factor (BAF); BCF typically refers to uptake from water, while BAF accounts for all exposure routes.

When multiple trophic levels are involved, concentrations can increase up the food chain, a process known as biomagnification, which poses greater risks to predators, including humans who consume contaminated organisms.

Common examples include mercury, certain chlorinated pesticides, and polychlorinated biphenyls (PCBs). Bioaccumulation is a central consideration in environmental risk assessment and regulatory policies aimed at controlling persistent contaminants.