BIOCONCENTRATION KINETICS OF CHLOROBENZENES AND THE ORGANOPHOSPHORUS PESTICIDE CHLORTHION IN THE POND SNAIL LYMNAEA-STAGNALIS - A COMPARISON WITH THE GUPPY POECILIA-RETICULATA
Kchm. Legierse et al., BIOCONCENTRATION KINETICS OF CHLOROBENZENES AND THE ORGANOPHOSPHORUS PESTICIDE CHLORTHION IN THE POND SNAIL LYMNAEA-STAGNALIS - A COMPARISON WITH THE GUPPY POECILIA-RETICULATA, Aquatic toxicology, 41(4), 1998, pp. 301-323
Bioconcentration factors and uptake and elimination rate constants are
determined for seven chlorobenzenes and for the organophosphorus pest
icide chlorthion in the pond snail Lymnaea stagnalis. The toxicokineti
c parameters are related to octanol-water partition coefficients (K-ow
) and compared with literature data for the guppy (Poecilia reticulata
). In contrast to the guppy, uptake rate constants for chlorobenzenes
in the pond snail increase proportionately with K-ow in the pond snail
. Elimination rate constants decrease with increasing K-ow values, sim
ilarly to the guppy. Absolute elimination rate constants, however, are
higher than in the guppy. For the pond snail, the relationship betwee
n bioconcentration factors of chlorobenzenes and hydrophobicity is des
cribed as: log BCF = 1.97 log K-ow -7.45 (r(2) = 0.93). The slope of t
his relationship is remarkably steeper than for the guppy and aquatic
organisms in general. Bioconcentration kinetics of clorthion in the po
nd snail do not suggest a significant impact of biotransformation. By
means of the application of the fish kinetic bioconcentration model, d
ifferences in the kinetic behaviour of chlorobenzenes in the guppy and
the pond snail are examined with respect to differences in their weig
ht, surface area and lipid content. The observed higher elimination ra
tes in the pond snail are reasonably well predicted by the model and c
an as such be explained by its lower lipid content in combination with
its slightly lower surface to mass ratio. Uptake rate constants of th
e lower chlorinated benzenes in the pond snail are substantially overe
stimated by the model. Furthermore, the model seems incompetent to des
cribe their dependency on hydro phobicity. The insufficiencies of the
model are discussed with respect to possibly inaccurate assumptions in
parametrization of the model and to the model itself, being founded o
n first-order one-compartment kinetics and diffusive mass transfer. Pr
otein binding is suggested to be most likely responsible for the obser
ved discrepancies. (C) 1998 Elsevier Science B.V. All rights reserved.