Predicting the bioconcentration factor of highly hydrophobic organic chemicals.
Bioconcentration refers to the process of uptake and buildup of chemicals in living organisms. Experimental measurement of bioconcentration factor (BCF) is time-consuming and expensive, and is not feasible for a large number of chemicals of regulatory concern. Quantitative structure-activity relationship (QSAR) models are used for estimating BCF values to help in risk assessment of a chemical. This paper presents the results of a QSAR study conducted to address an important problem encountered in the prediction of the BCF of highly hydrophobic chemicals. A new QSAR model is derived using a dataset of diverse organic chemicals previously tested in a United States Environmental Protection Agency laboratory. It is noted that the linear relationship between the BCF and hydrophobic parameter, i.e., calculated octanol-water partition coefficient (ClogP), breaks down for highly hydrophobic chemicals. The parabolic QSAR equation, log BCF=3.036 ClogP-0.197 ClogP(2)-0.808 MgVol (n=28, r(2)=0.817, q(2)=0.761, s=0.558) (experimental log BCF range=0.44-5.29, ClogP range=3.16-11.27), suggests that a non-linear relationship between BCF and the hydrophobic parameter, along with inclusion of additional molecular size, weight and/or volume parameters, should be considered while developing a QSAR model for more reliable prediction of the BCF of highly hydrophobic chemicals.
Computational Science Research Center, San Diego State University, San Diego, CA 92182-7720, USA. Electronic address: rg004747@yahoo.com.
Rajni
R
Garg
Health, Safety & Environment, Albemarle Corporation, Baton Rouge, LA 70801-1765, USA.
Carr J
CJ
Smith
D000818:Animals; D003530:Cyprinidae; D057927:Hydrophobic and Hydrophilic Interactions; D009930:Organic Chemicals / Q000737:chemistry* / Q000493:pharmacokinetics*; D021281:Quantitative Structure-Activity Relationship; D011897:Random Allocation; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods; D014481:United States; D014484:United States Environmental Protection Agency
D009930:Organic Chemicals
Bioconcentration factor; Hydrophobicity; Octanol–water partition coefficient; Organic chemicals; QSAR; Risk assessment