Bioaccumulation ratio

The bioaccumulation ratio of fenitrothion (concentration in fish on test day/average concentration in water during test day) in rainbow trout and minnows was calculated. This revealed that bioaccumulation ratio did not increase on longer exposure and that the ratio was more or less independent of the fenitrothion concentration in water. The ratio was not so different between the two fish species, being approximately 250, 230 and 200 (at its maximum) in underyearling trout, yearling trout and minnow, respectively. 

In contrast, 0.01 ppm DDT in water was rapidly absorbed and accumulated by yearling rainbow trout, the bioaccumulation ratio of total DDT as sum of DDT, DDE and TDE being 2700 after 14 days. The highest content was encountered in intestine (76.8 ppm), followed by stomach (46.0 ppm) and pyloric caeca (29.8 ppm). 

Bioaccumulation ratios of total radiocarbon and fenitrothion relative to the water concentrations are shown in Table VIII. 

They reveal that the ratio is not so high, at the maximum 180, and in fish it tends to decrease with longer incubation of the system, whereas in daphnids and algae the bioaccumulation ratio of fenitrothion was increasing under the present static conditions, due to quite rapid disappearance of fenitrothion in water. In any event, the bioaccumulation ratio was obviously far less than that of DDT and its degradation products. 

Table VIII. Bioaccumulation ratio of total C and fenitrothion in aquatic model ecosystem.

In a static model ecosystem, several amino derivatives of fenitrothion, probably derived from the soil metabolism, were demonstrated in carp tissues, together with the nitro-containing compounds. The concentration of fenitrothion in carp, snails, daphnids and algae decreased with time, although its bioaccumulation ratio relative to the concentration in water tended to increase gradually in snails, daphnids and algae, presumably due to lower metabolic activity and/or slow excretion. 

Organism Biomass Time for maximum absorption hr Bioaccumulation Ratio ... 

Broman D, Naf C, Rolfif C, Zebuhr Y, Fry B, Hobbie J. 1992. Using ratios of stable nitrogen isotopes to estimate bioaccumulation and flux of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in two food chains from the northern Baltic. Environ Toxicol Chem 11 331-345. 

Another entry point for accumulation of organic in animal tissue and animal food products is direct ingestion of contaminated soil by grazing animals [44]. The compounds of main concern are the halogenated aromatics, including PCBs, organochlorine pesticides, PCDDs and PCDFs, which are resistant to metabolization and tend to accumulate in animal fat. The bioaccumulation factor (the ratio of the concentration of animal tissue or produce to the concentration in the diet) can be as high as 5-6 [43]. Compounds such as PAHs and phthalate esters are readily metabolised and excreted by the animals and thus do not accumulate in animal tissue or products. 

The Swedish Classification Scheme initiated in 2005 by the Swedish Association of Pharmacy Industries (LIF), the Swedish Medical Products Agency, Apoteket (National Corporation of Swedish Pharmacies), the Swedish Association of Local Authorities and Regions and the Stockholm County Council, take in account Persistence, Bioaccumulation and Toxicity (PBT) characteristics of pharmaceutical products. This voluntary scheme looks at the environmental hazard and the associated risk of pharmaceutical products. The environmental risk is calculated based on the ratio PEC/PNEC according to the EMEA guideline [17,124, 127]. The obtained information is only available on the website www.fss.se, since due to European restrictions it is not possible to include warning labels on the packaging of medications [17]. 

Octanol/Water Partition Coefficient (Kow) — the equilibrium ratio of the concentrations of material partitioned between octanol and water. This coefficient is considered to be an index of the potential of a chemical to be bioaccumulated. Higher values of K, are associated with greater bioaccumulative potential. 

This is defined as the ratio between the concentration of the unionized substance in the water-immiscible organic solvent and the concentration of both ionized and unionized substance in the aqueous phase, and this also is usually quoted as its logio value. This value is not a constant but varies with pH. Its advantage is that it can be measured for any pH value (normally around pH 7), which provides an environmentally relevant measure of lipophilicity and thus a clear indication of whether the substance in question is likely to bioaccumulate via partitioning. 

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