Bioconcentration Kinetics

The bioconcentration process of non-degradable chemicals can generally be interpreted as a passive partitioning process between the lipids of the organisms 

The bioconcentration factor can be estimated by exposing fish or other aquatic organisms, for an appropriate time period, to a constant chemical concentration in water by using a flow-through system until a steady-state concentration in the organism is reached. However, for many chemicals - especially very hydrophobic chemicals - a steady-state cannot be reached in an appropriate time. Therefore, the kinetic approach is the only method which can be used for the determination of a real BCF value. 

If during the experiment, the fish are growing and the chemical is metabolized, the specific growth rate constant (kg) and the metabolism rate constant (kup) must be included in Eq. (3)  

It should be noted that the BCF can also be determined solely from the uptake curve of the chemical in the organisms. The method and equations for calculating the BCF values in this way were recently published by Wang et al. [23]. An important paper on different compartment models and the mathematical descriptions of uptake, elimination and bioconcentration of xenobiotics in fish and other aquatic gill-breathing organisms was given by Butte [24]. 

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Smith, A.D., Bharath, A., Mullard, C., Orr, D., McCarthy, L.S., Ozbum, G.W. (1990) Bioconcentration kinetics of some chlorinated benzenes and chlorinated phenols in American flagfish, Jordanella floridae (Goode and Bean). Chemosphere 20, 379-386. 

Hawker, D.W., Connell, D.W. (1988) Influence of partition coefficient of lipophilic compounds on bioconcentration kinetics with fish. Water Res. 22, 701-707. 

Welling, W. and J.W. de Vries. 1992. Bioconcentration kinetics of the organophosphorus insecticide chlorpyrifos in guppies (Poecilia reticulata). Ecotoxicol. Environ. Safety 23 64-75. 

Branson, D.R., I.T. Takahashi, W.M. Parker, and G.E. Blau. 1985. Bioconcentration kinetics of 2,3,7,8-tetrachIorodibenz.o-p-dioxi n in rainbow trout. Environ. Toxicol. Chem. 4 779-788. 

Sijm, D.T.H.M., K.W. Broersen, D.F. De Roode, and P. Mayer. 1998. Bioconcentration kinetics of hydrophobic chemicals in different densities of Chlorella pyrenoidosa. Environ. Toxicol. Chem. 17 1695-1704. 

Kociba, R.J., Schwetz, B.A., Keyes, D.G., Jersey, G.C., Ballard, J.J., Dittenber, D.A., Quasi, J.F., Wade, C.E., and Humiston, C.G. Chronic toxicity and reproduction studies of hexachlroobutadieneinrats. Environ. Health Perspect., 21 49-53, 1977. Koelmans, A.A., van der Woude, H., Hattink, J., and Niesten, DJ.M. Long-term bioconcentration kinetics of hydrophobic chemicah in Selenastrum capricornutum and Microcystis aeruginosa. Environ. Toxicol. Chem., 18(6) 1164-1172, 1999. 

Legierse, K.C.H.M., Sijm, D.T.H.M., van Leeuwen, C.J., Seinen, W., and Mermens, J.L.M. Bioconcentration kinetics of chlorobenzenes and the organophosphorus pesticide chlorthion in the pond snail Lymnaea stagnalis n comparison with the guppy Poecilia reticulata, Aquat. Toxicol., 41(3) 301-323, 1998. 

Sijm DTHM, Van der Linde A. 1995. Size-dependent bioconcentration kinetics of hydrophobic organic chemicals in fish based on diffusive mass transfer and allometric relationships. Environ Sci Technol 29 2769-2777. 

Water solubility is one of the major parameters which affect the fate and distribution in the environment. Hydrophobic compounds with high octanol-water partition coefficients tend to bio accumulate. Opperhuizen and Voors [63] have shown that hydrophobicity of PCDEs determines the bio concentration factor of PCDEs and that bioconcentration kinetics of PCDEs resemble those of PCBs. 

As well, the link between aqueous toxicity and bioconcentration appears to be relatively simple the kinetics are similar but the internal concentration endpoints - constant for toxicity and variable for biocentration - are different. Thus apparent differences between toxicity and bioconcentration kinetics may well be simply related to the fact that rate constants are typically expressed as a fraction per unit of time of the internal toxicant concentration which, as noted, is different for toxicity and bioconcentration. 

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