Bioconcentration, Bioaccumulation, and Metabolism of Pesticides in Aquatic Organisms

Abstract

The ecotoxicological assessment of pesticide effects in the aquatic environment should normally be based on a deep knowledge of not only the concentration of pesticides and metabolites found but also on the influence of key abiotic and biotic processes that effect rates of dissipation. Although the bioconcentration and bioaccumulation potentials of pesticides in aquatic organisms are conveniently estimated from their hydrophobicity (represented by log K(ow), it is still indispensable to factor in the effects of key abiotic and biotic processes on such pesticides to gain a more precise understanding of how they may have in the natural environment. Relying only on pesticide hydrophobicity may produce an erroneous environmental impact assessment. Several factors affect rates of pesticide dissipation and accumulation in the aquatic environment. Such factors include the amount and type of sediment present in the water and type of diet available to water-dwelling organisms. The particular physiological behavior profiles of aquatic organisms in water, such as capacity for uptake, metabolism, and elimination, are also compelling factors, as is the chemistry of the water. When evaluating pesticide uptake and bioconcentration processes, it is important to know the amount and nature of bottom sediments present and the propensity that the stuffed aquatic organisms have to absorb and process xenobiotics. Extremely hydrophobic pesticides such as the organochlorines and pyrethroids are susceptible to adsorb strongly to dissolved organic matter associated with bottom sediment. Such absorption reduces the bioavailable fraction of pesticide dissolved in the water column and reduces the probable ecotoxicological impact on aquatic organisms living the water. In contrast, sediment dweller may suffer from higher levels of direct exposure to a pesticide, unless it is rapidly degraded in sediment. Metabolism is important to bioconcentration and bioaccumulation processes, as is detoxification and bioactivation. Hydrophobic pesticides that are expected to be highly stored in tissues would not be bioconcentrated if susceptible to biotic transformation by aquatic organisms to more rapidly metabolized to hydrophilic entities are generally less toxic. By analogy, pesticides that are metabolized to similar entities by aquatic species surely are les ecotoxicologically significant. One feature of fish and other aquatic species that makes them more relevant as targets of environmental studies and of regulation is that they may not only become contaminated by pesticides or other chemicals, but that they constitute and important part of the human diet. In this chapter, we provide an overview of the enzymes that are capable of metabolizing or otherwise assisting in the removal of xenobiotics from aquatic species. Many studies have been performed on the enzymes that are responsible for metabolizing xenobiotics. In addition to the use of conventional biochemical methods, such studies on enzymes are increasingly being conducted using immunochemical met...

Pharmaceutical bioaccumulation by periphyton and snails in an effluent-dependent stream during an extreme drought

“…For example, (Smith et al (2010) demonstrated that hepatic metabolism of fluoxetine in trout was limited unless induced by pre-exposure to carbamazepine. In fact, limited information exists on invertebrate metabolism of organic chemicals (Katagi, 2010); however, biotransformation by the invertebrate G. pulex has been to shown to alter internal concentrations of xenobiotics . Clearly, an advanced understanding of biotransformation of pharmaceuticals in fish, invertebrate, plant and periphytic communities is needed to improve bioaccumulation assessments .…”

Occurrence and seasonal loads of pesticides in surface water and suspended particulate matter from a wetland of worldwide interest—the Ria Formosa Lagoon, Portugal

“…Among the most toxic pesticides are the organochlorine pesticides, recognized to have potential to induce hormonal disruption and cancer (Ehrlich et al 2011;Mearns et al 2012;Vallack et al 1998), mainly due to their extreme persistency, bioaccumulating and/or rippling through the food chain (Chopra et al 2011;Katagi 2010). So, the abusive use of pesticides and inefficient treatment of residues increase their probability of reaching estuarine and marine environments affecting fish nurseries as well as the benthic and pelagic communities (Liu et al 2008;McMillin and Means 1996).…”

A Pharm-Ecological Perspective of Terrestrial and Aquatic Plant-Herbivore Interactions

“…The gap in knowledge related to mechanisms required to process nutrients in marine herbivorous fishes, for example, has only recently begun to close (Choat and Clements, 1998;Clements et al, 2009). Moreover, despite a long history of investigating how aquatic animals process chemical contaminants (Chambers and Yarbrough, 1976;Katagi, 2010;Rewitz et al, 2006;Smital et al, 2004), studies investigating how they process dietary secondary metabolites have only recently been initiated (Gross and Bakker, 2012;Liang et al, 2007;Richardson et al, 2009). An understanding of pharmacology can fill these gaps in both terrestrial and aquatic systems.…”