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LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

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OECD SIDS <strong>LINEAR</strong> <strong>ALKYLBENZENE</strong> <strong>SULFONATE</strong> (<strong>LAS</strong>)<br />

(i)<br />

Reference: 1) Grieve, A.M. and Pitman, M.G. 1978. Salinity damage to Norfolk Island<br />

pines caused by surfactants. III. Evidence for stomatal penetration as the<br />

pathway of salt entry to leaves. Aust. J. Plant. Physiol. 5:397-413.<br />

2) Hamwijk, C. 2002. Literature study: Exposure and possible indirect<br />

effects of aerosol borne surfactants on coastal vegetation. TNO Chemistry<br />

report, Study number 02-4077/01. Prepared for CEFIC ERASM.<br />

Reliability: 4 Not assignable. Original studies were not directly reviewed.<br />

Species: Pinus halepensis (pine tree)<br />

Endpoint: Accumulation of <strong>LAS</strong> in plant tissues<br />

Exposure period: 2 minutes<br />

Method: The concentration of <strong>LAS</strong> tested was 1.7 x 10 -4 mol/kg, which is equivalent<br />

to 58 mg/L based on a C11.6 <strong>LAS</strong> with a molecular weight of 342. Three<br />

batches of ten 2-year old pine trees were immersed for 2 minutes in distilled<br />

water alone (batch 1), in <strong>LAS</strong>-distilled water (batch 2), or <strong>LAS</strong>-synthetic sea<br />

water (batch 3). The objective was to simulate the exposure to severe storms<br />

on the seashore. Only the aerial parts of the plants were immersed in a large<br />

volume container (50 x 50 x 8 cm) containing 1 L of the respective solutions.<br />

The root system was isolated with a plastic bag enclosure and not exposed<br />

directly to the solutions. Controls were run on ten plants. Trees were<br />

removed from the solutions and gently shaken to eliminate liquid droplets.<br />

Radiolabeled and control trees were kept in a greenhouse for 48 hours under<br />

a 16:8 day:night photoperiod, temperatures of 22° C (day):16° C (night), and<br />

a constant relative humidity. Before analysis, the trees were washed twice in<br />

distilled water for 1 minute while shaking to simulate rainfall. Trees were cut<br />

back at the soil surface and the aerial part divided into several parts for<br />

analysis (epicuticular wax from needles, dewaxed needles, and remaining<br />

plant material consisting of branches without needles and tree stem).<br />

Respective samples were extracted, prepared, and the radioactivity measured<br />

in each fraction using a liquid scintillation cocktail and spectrometer. For<br />

scanning electron microscopy, 48 hours after the exposure period ten needles<br />

from each of the five replicates of treated and control plants were cut into<br />

small segments and air dried, fixed on aluminium stubs with conductive glue<br />

and carbon coated. Axial surfaces were examined with a Stereoscan 90B<br />

electron microscope with 15 kV acceleration voltage.<br />

GLP: Yes [ ] No [X] ? [ ]<br />

Test substance: Stated by authors as <strong>LAS</strong> with an alkyl chain length of 12 carbons, with no<br />

further information. For our review, we have assumed this to be the typical<br />

European C11.6 <strong>LAS</strong> (average MW = 342). <strong>LAS</strong> was radiolabeled with 35 S in<br />

the sulphonate group attached to the phenyl ring and had a specific<br />

radioactivity of 8712 µCi/mol.<br />

Results: The amount of <strong>LAS</strong> (as a percent of total in solution; mean ± SD) found in<br />

each analyzed fraction of the trees and the wash water is shown below:<br />

Fraction<br />

Distilled water only<br />

(Batch 1 )<br />

<strong>LAS</strong>-distilled water<br />

(Batch 2 )<br />

<strong>LAS</strong>-seawater<br />

(Batch 3 )<br />

Epicuticular waxes ~ 0 0.18 ± 10 1.48 ± 1.03<br />

Dewaxed needles ~ 0 ~ 0 0.09 ± 0.16<br />

Remaining plant<br />

material<br />

~ 0 ~ 0 ~ 0<br />

Distilled water wash ~ 0 0.17 ± 0.06 1.41 ± 0.57<br />

The amount of uptake and percent of the total radioactivity incorporated in<br />

each fraction for the <strong>LAS</strong>-seawater and <strong>LAS</strong>-distilled water treatments are<br />

shown below:<br />

<strong>UNEP</strong> PUBLICATIONS 233

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