Bioconcentration of LAS: Experimental Determination and Extrapolation to Environmental Mixtures
Received for review February 5, 1997 Revised manuscript received
July 14, 1997 Accepted August 18, 1997 Abstract: Linear alkylbenzenesulfonate (LAS) is the most widely used
synthetic surfactant. Environmental risk assessment
of
LAS requires quantitative information on the
bioconcentration
properties which, as yet, are unavailable. Here, we
present
compound- and isomer-specific bioconcentration data for
n-(p-sulfophenyl)alkanes, the constituents
of LAS, determined in flow-through experiments. BCF values ranged
between 2 and 1000 L kg-1. We derived
bioconcentration-hydrophobicity relationships and observed that bioconcentration factors as well as uptake rate constants increase
with increasing log KOW (estimated) while the
elimination rate
constants do not vary with log KOW. In an
attempt to
account for the variability of the composition of LAS
mixtures,
we found the average length of the alkyl chain of the LAS
mixture unsuitable for estimation of the bioconcentration
potential. In contrast, an estimation based on the
composition of the mixture of LAS and the bioconcentration
factors of the individual constituents overpredicts
measured
values by less than a factor of 1.5. Using the
composition
of two LAS mixtures, one typical for LAS in detergents
and one representing LAS in rivers, we calculated the
respective bioconcentration potentials to be 91 and 22
L kg-1. This indicates that
environmental processes decrease
the bioconcentration potential of LAS mixtures.
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