TY - JOUR
T1 - A physiologically based toxicokinetic model for dermal absorption of organic chemicals by fish
AU - Nichols, John W.
AU - McKim, James M.
AU - Lien, Gregory J.
AU - Hoffman, Alex D.
AU - Bertelsen, Sharon L.
AU - Elonen, Colleen M.
PY - 1996/6
Y1 - 1996/6
N2 - A physiologically based toxicokinetic model was developed to describe dermal absorption of waterborne organic chemicals by fish. The skin was modeled as a discrete compartment into which compounds diffuse as a function of chemical permeability and the concentration gradient. The model includes a countercurrent description of chemical flux at fish gills and was used to simulate dermal-only exposures, during which the gills act as a route of elimination. The model was evaluated by exposing adult rainbow trout and channel catfish to hexachloroethane (HCE), pentachloroethane (PCE), and 1,1,2,2-tetrachloroethane (TCE). Skin permeability coefficients were obtained by fitting model simulations to measured arterial blood data. Permeability coefficients increased with the number of chlorine substituent groups, but not in the manner expected from a directly proportional relationship between dermal permeability and skin:water chemical partitioning. An evaluation of rate limitations on dermal flux in both trout and catfish suggested that chemical absorption was limited more by diffusion across the skin than by blood flow to the skin. Modeling results from a hypothetical combined dermal and branchial exposure indicate that dermal uptake could contribute from 1.6% (TCE) to 3.5% (HCE) of initial uptake in trout. Dermal uptake rates in catfish are even higher than those in trout and could contribute from 7.1% (TCE) to 8.3% (PCE) of initial uptake in a combined exposure.
AB - A physiologically based toxicokinetic model was developed to describe dermal absorption of waterborne organic chemicals by fish. The skin was modeled as a discrete compartment into which compounds diffuse as a function of chemical permeability and the concentration gradient. The model includes a countercurrent description of chemical flux at fish gills and was used to simulate dermal-only exposures, during which the gills act as a route of elimination. The model was evaluated by exposing adult rainbow trout and channel catfish to hexachloroethane (HCE), pentachloroethane (PCE), and 1,1,2,2-tetrachloroethane (TCE). Skin permeability coefficients were obtained by fitting model simulations to measured arterial blood data. Permeability coefficients increased with the number of chlorine substituent groups, but not in the manner expected from a directly proportional relationship between dermal permeability and skin:water chemical partitioning. An evaluation of rate limitations on dermal flux in both trout and catfish suggested that chemical absorption was limited more by diffusion across the skin than by blood flow to the skin. Modeling results from a hypothetical combined dermal and branchial exposure indicate that dermal uptake could contribute from 1.6% (TCE) to 3.5% (HCE) of initial uptake in trout. Dermal uptake rates in catfish are even higher than those in trout and could contribute from 7.1% (TCE) to 8.3% (PCE) of initial uptake in a combined exposure.
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U2 - 10.1006/faat.1996.0095
DO - 10.1006/faat.1996.0095
M3 - Article
AN - SCOPUS:26844464460
SN - 0272-0590
VL - 31
SP - 229
EP - 242
JO - Fundamental and Applied Toxicology
JF - Fundamental and Applied Toxicology
IS - 2
ER -