Gastrointestinal magnification: the mechanism of biomagnification and food chain accumulation of organic chemicals

Abstract

Dietary bioaccumulation experiments with chlorobenzenes, PCBs, and mirex in guppies and goldfish are presented. The results demonstrate that, in the gastrointestinal tract of fish, the fugacity of very hydrophobic, nonmetabolizable chemicals (log Kow > 6) is elevated above the fugacity in the consumed food as a result of food digestion and absorption. Observed fugacities in fecal matter were up to 4.6-fold greater than the fugacity in the administered food. Fecal to food fugacity ratio ranged between 0.07 and 4.6 in guppies and between 0.014 and 4.5 in goldfish and increased with increasing Kow-Food digestion in the gastrointestinal tract was found to increase the chemical fugacity in the food 5-fold by altering the fugacity capacity of the food. An additional 2-3-fold increase in the chemical concentration and fugacity in the gastrointestinal tract is due to food absorption from the gastrointestinal tract. The findings support the "digestion" hypothesis as being the driving force of the biomagnification and food chain accumulation of hydrophobic organic chemicals. The study further illustrates the application of static head-space analysis to measure chemical fugacities in food and fecal samples.

Gastrointestinal absorption, metabolic debromination, and hydroxylation of three commercial polybrominated diphenyl ether mixtures by common carp

“…If PBDEs are absorbed at a lower rate than that of the food, then food absorption will result in an increase of PBDE concentration in the feces and vice versa. Gobas et al [27] had demonstrated that the administration of the food to water did not affect the chemical fugacity in the food. Additionally, the chemical losses from feces to water are probably insignificant during 10-h feces collection because of the high lipophilic character of the PBDEs (K OW > 10 6 ).…”

Assessing Biomagnification and Trophic Transport of Persistent Organic Pollutants in the Food Chain of the Galapagos Sea Lion (Zalophus wollebaeki): Conservation and Management Implications

“…It is well recognized that the increase in organic chemical concentrations in lipids of organisms with increasing trophic level in food-webs originates from the magnification of the chemical concentration in the gastro-intestinal tract caused by food digestion and absorption [5,14]. In this study, the biomagnification capacity of organochlorine contaminants in the tropical food chain of the Galapagos sea lion is established (i.e.…”

“…Biomagnification is a special case of bioaccumulation and is defined as the process by which concentrations of contaminants or chemical substances (i.e. thermodynamic activities of chemical substances often measured by the lipid normalized concentration) in consumer and higher trophic level organisms exceed those concentrations in the diet or organism's prey [5][6][7]. This process can occur at each step in a food chain, potentially producing very high and toxic concentrations in upper-trophic-level species [7].…”

Data Gap Analysis and Database Expansion of Parameters for Munitions Constituents

“…The model also uses rate constants for diffusive uptake and elimination, which can be estimated according to Sijm and Linde (1995). Thomann (1989) and Gobas (1993) have developed physiologically based kinetic models, including rate constants for chemical uptake and elimination based on physiological parameters (i.e. gill ventilation, feeding, and chemical assimilation).…”

“…The steady-state food web bioaccumulation model of Gobas (1993) was developed to estimate bioconcentration factors, biomagnification factors, and bioaccumulation factors as well as concentrations and fugacities in phytoplankton, zooplankton, benthic invertebrates, and fish species in water and sediments. The model uses rate constants to describe the considered processes for organisms of a defined food web.…”