LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
(a)
Type of test: static [ ]; semi-static [ ]; flow-through [ ]; other [X] outdoor experimental
streams
open-system [X]; closed-system [ ]
Analytical monitoring: Yes [X] No [ ] ? [ ]
Method and Results: An integrated model stream ecosystem fate and effects study of a C12LAS
homologue, with a high content (35.7%) of its most hydrophobic and toxic
2-phenyl isomer, was performed in the summer and fall of 1996 in Procter
and Gamble’s Experimental Stream facility. The study addressed responses
of periphytic microbes, immature benthic fauna including abundance and
drift, and emergence of adult insects in a 56-day exposure. Exposures
ranged from 126 to 2978 µg/L and were continuously presented in a singlepass,
flow through test system. Microbial heterotrophs acclimated to
C12LAS exposure quickly (14 days) and biodegraded C12LAS at all
concentrations. Blue-green algae responded by increasing in abundance
with increasing C12LAS concentration. Invertebrates responded by
increased drift and reduced benthic abundances at concentrations exceeding
293 µg/L. Emergence at 927 µg/L also declined relative to the control.
Adverse responses for mayflies and chironomids were indicated using
univariant statistical techniques. Multivariant techniques indicated these
taxa plus molluscs, aquatic worms, caddisflies, and stoneflies were
impaired at some concentrations. Bioavailability of C12LAS was
investigated in streams as a function of the total suspended solids load in
the water column driven by local weather and watershed patterns. A
continuous bioavailability model indicated exposure was reduced by an
average of 8.5 ± 8.9%. A model ecosystem NOEC (no-observed-effectconcentration)
was concluded to be 293 µg/L based on measured water
column exposure and adjusted to 268 µg/L by the bioavailability model. A
summary of selected population and community responses at 8 weeks from
the current study is shown in the following table:
Community/Measure
Heterotrophic microbial
Biomass (total lipid phosphate/mm 2 )
Amino acid uptake ( 3 H dpm/mm 2 /min)
Phospholipid fatty acid (PLFA) distr.
Surfactant mineralization (% CO2)
Autotrophic microbial
Bicarbonate uptake ( 14 C dpm/mm 2 /min)
Algal density (cells/mm 2 )
Algal biovolume (µm 3 /mm 2 )
Blue-green algal density (cells/mm 2 )
Green algal density (cells/mm 2 )
Diatom algal density (cells/mm 2 )
Algal richness
Dominant taxa (cells/mm 2 )
Cocconeis placentula
Melosira varians
Chrococcus sp.
Nitzschia dissipata
Navicula salinarum v. intermedia
Pleurosira (= Biddulphia) laevis
Nitzschia inconspicua
Nitzschia palea
Diatoma vulgare
Dose
Response
NS
NS
+
NS
NS
++
NS
NS
-
-
NS
+
NS
NS
NS
++
+
--
Temporal
Shift at >293 µg/L
Acclimation at all conc.
NOEC
(µg/L)
UNEP PUBLICATIONS 235
+
++
-
-
+
++
+
--
927
927
927