LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
2) Sulfophenylcarboxylic acids (SPC5 and SPC11) (formed from successive
oxidation of terminal methyl groups on the alkyl chain)
Reference: Navas, J.M., Gonzalez-Mazo, E., Wenzel, A., Gomez-Parra, A., and Segner,
H. 1999. Linear alkylbenzene sulfonates and intermediate products from
their degradation are not estrogenic. Marine Pollution Bulletin 38:880-884.
Reliability: 2 Valid with restrictions
(d)
Results: The final predicted no-effect concentration (PNEC) for C11.6 LAS was 250
µg/L based on a single species PNEC of 320 µg/L and the range of field
NOECs of 250-500 µg/L. All data values are expressed as dissolved
concentrations.
Method: Predicted no-effect concentrations (PNECs) were derived for LAS and three
other surfactants using three stages in an aquatic effects assessment. In the
Initial stage, assessment factors are applied to available short-term toxicity
data. In the Refined stage, statistical extrapolation based on long-term (i.e.,
chronic) toxicity data are employed. In the Comprehensive stage of effects
assessment, a wide variety of laboratory and field model ecosystem studies
are incorporated into the analysis. To determine the PNEC for LAS, all data
types were compiled and evaluated. Since toxicity is related to carbon chain
length, all data were normalized to LAS with a mean carbon chain length of
11.6, the structure typically present in the environment based on the
monitoring study described by Matthijs et al. 1999.
Remarks: For LAS, the predicted environmental concentrations (PECs) in the
environment are about 50 to 100 times lower than the PNECs. This PNEC
determination is part of an extensive monitoring program executed jointly by
the Dutch Soap Association (NVZ) and the Dutch Ministry of Housing,
Spatial Planning and the Environment (VROM).
Reference: van de Plassche, E.J., de Bruijn, J.H.M., Stephenson, R.R., Marshall, S.J.,
Feijtel, T.C.J., and Belanger, S.E. 1999. Predicted no-effect concentrations
and risk characterization of four surfactants: Linear alkylbenzene sulfonate,
alcohol ethoxylates, alcohol ethoxylated sulfates, and soap. Environmental
Toxicology and Chemistry 18:2653-2663.
Reliability: 2 Valid with restrictions
(e)
Results: A realistic worst-case estimation of the LAS concentration in sludgeamended
soil is predicted to be 7 mg/kg dry weight, which is compared to the
PNEC of 4.6 mg/kg. The LAS concentration will drop to a level below the
PNEC within 6 to 24 days after sludge application, depending on the
degradation rate of LAS.
Methods: LAS can be found in high concentrations in sewage sludge and may enter the
soil compartment as a result of sludge application. To evaluate the effects
and risk to soil organisms, a probabilistic (log-normal) distribution model
was used to predict a no effect concentration (PNEC) for soil fauna, flora,
and a combination of these. By extrapolation, the method determines a lower
statistical tolerance limit. The preferred inputs to the current model are EC10
data from laboratory studies. By use of the log-normal distribution, a
concentration (Kp) is found, for which the EC10 or NOEC values for 95% of
all species in the community are greater. The value of Kp is used as the
estimate of the PNEC. The soil concentration after sludge application was
predicted by a number of scenarios and used as the predicted environmental
concentration (PEC) in the risk characterization and calculation of risk
quotients (RQ = PEC/PNEC). A LAS concentration of 4.6 mg/kg was used
as the current best estimate of PNEC in all RQ calculations. The exposure
scenarios included three levels of LAS contamination (530, 2,600 and 16,100
UNEP PUBLICATIONS 250