LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
Sorbent refers to the standard or natural soil or sediment used, as the affinity
for sorption depends on both the chemical substance and the characteristics
of the sorbent. All data were drawn from the original sources referenced in
the table.
Remarks: The nonlinearity parameter implies that sorption affinity decreases with
increasing LAS concentrations, which suggests that concentration
dependency should be taken into account when assessing sorption of
surfactants such as LAS.
Reference: Tolls, J. and Sijm, D.T.H.M. 2000. Estimating the properties of surfaceactive
chemicals. In: Boethling, R.S. and Mackay, D. Handbook of Property
Estimation Methods for Chemicals. Lewis Publishers.
Reliability: 4 Not assignable because the original articles were not directly reviewed.
3.3.2 THEORETICAL DISTRIBUTION (FUGACITY CALCULATION)
(a)
Media: Air-biota [ ]; Air-biota-sediment-soil-water [X]; Soil-biota [ ];
Water-air [ ]; Water-biota [ ]; Water-soil [ ]
Method: Fugacity level I [ ]; Fugacity level II [ ]; Fugacity level III [X]; Fugacity
level IV [ ]; Other (calculation) [ ]; Other (measurement)[ ]
Five stage Mackay-type modelling including evaluative, regional and localscale
models. The first two stages involve classifying the chemical and
quantifying the emissions into each environmental compartment. In the third
stage, the characteristics of the chemical are determined using a quantitative
equilibrium criterion model (EQC), which is conducted in three steps using
levels I, II, and III versions of the model that introduce increasing
complexity and more realistic representations of the environment. The EQC
uses a generic, evaluative environment, which is 100,000 km 2 in area. In the
fourth stage, ChemCAN, which is a level III model for specific regions of
Canada, was used to predict the chemical’s fate in southern Ontario. The
final stage was to apply local environmental models to predict environmental
exposure concentrations. For LAS, the WW-TREAT, GRiDS, and ROUT
models were used to predict the fate of LAS in a sewage treatment plant and
riverine receiving waters. Estimated properties used as input parameters to
the models are shown below for LAS (from various sources; average values;
based on the best default environmental and physicochemical values
available at the time of modeling):
Molecular mass 348
Air-water partition coefficient 0
Aerosol-water partition coefficient 100
Soil-water partitition coefficient (L/kg) 20
Sediment-water partitition coefficient (L/kg) 570
Fish-water partitition coefficient (L/kg) 250
Half-life in air (h) --
Half-life in water (h) 24
Half-life in soil (h) 480
Half-life in sediment (h) 96
The level I calculation assumes a steady-state equilibrium partitioning of a
fixed quantity of LAS (100,000 kg) with no reaction or advection processes.
The level II calculation assumes a fixed input of 1000 kg/h, which is
balanced by reaction and advection losses. Relative partitioning is identical
to level I. For level III, the ChemCAN model assumes the following
estimated input quantities for LAS:
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