We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Mechanistic quantitative structure--activity relationship model for the photoinduced toxicity of polycyclic aromatic hydrocarbons: I. Physical model based on chemical kinetics in a two-compartment system
- Authors
Dixon, D. G.; Greenberg, B. M.; Huang, X.-D.; Krylov, S. N.; Zeiler, L. F.
- Abstract
A quantitative structure-activity relationship model for the photoinduced toxicity of 16 polycyclic aromatic hydrocarbons (PAHs) to duckweed (Lemna gibba) in simulated solar radiation (SSR) was developed. Lemna gibba was chosen for this study because toxicity could be considered in two compartments: water column and leaf tissue. Modeling of photoinduced toxicity was described by photochemical reactions betweenPAHs and a hypothetical group of endogenous biomolecules (G) required for normal growth, with damage to G by PAHs and/or photomodified PAHs in SSR resulting in impaired growth. The reaction scheme includes photomodification of PAHs, uptake of PAHs into leaves, triplet-state formation of intact PAHs, photosensitization reactions that damage G,and reactions between photomodified PAHs and G. The assumptions usedwere: the PAH photomodification rate is slower than uptake of chemicals into leaves, the PAH concentration in aqueous solution is nearly constant during a toxicity test, the fluence rate of actinic radiation is lower within leaves than in the aqueous phase, and the toxicity of intact PAHs in the dark is negligible. A series of differential equations describing the reaction kinetics of intact and photomodified PAHs with G was derived. The resulting equation for PAH toxicity was a function of treatment period, initial PAH concentration, relative absorbance of SSR by each PAH, quantum yield for formation of triplet-state PAH, and rate of PAH photomodification. Data for growth in the presence of intact and photomodified PAHs were used to empirically solve for a photosensitization constant (PSC) and a photomodification constant (PMC) for each of the 16 PAHs tested. For 9 PAHs the PMC dominates and for 7 PAHs the PSC dominates.
- Subjects
TOXICITY testing; CHEMICAL kinetics; MATHEMATICAL models
- Publication
Environmental Toxicology & Chemistry, 1997, Vol 16, Issue 11, p2283
- ISSN
0730-7268
- Publication type
Article