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Sediment toxicity

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Description of key information

The 28-day NOEC for Lumbriculus variegatus was 81 mg LAS Na/kg sediment dw.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater sediment:
81 mg/kg sediment dw

Additional information

No experimental data on sediment toxicity are available for the test item. However, experimental data for source substance 2 are available and a read-across approach is applied. Please refer to read-across justification document attached in IUCLID Section 13. Furthermore, only key studies are taken into account here. For further supporting information please refer to respective REACH registration dossier of the source substance.

LAS Na (CAS 68411 -30 -3)

Toxicity to sediment dwelling organisms was investigated with linear alkylbenzene sulfonate (Comber et al., 2006). Samples of natural sediment were spiked with test substance at concentrations of 50, 75, 100, 150, 300, and 600 mg/kg/dry weight. 10 test organisms of species Lumbriculus variegatus were then added. Exposure lasted 28 days, at which time the organisms were observed for survival and biomass. The test substance half-life in aerobic sediment was approximately 20 days. The EC50 was >= 105 mg/kg sediment dw. The 28-day NOEC was 81 mg/kg sediment dw.

 

A sediment toxicity test of LAS (linear alkylbenzene sulfonate) was conducted following the OECD 218 guideline, using the midge Chironomus riparius (Pittinger, 1989).  All results are based on the measured concentration of the test substance. The LAS had an average alkyl chainlength of 11.9, and was comprised of C10 -C14 alkyl chains.

 

In an egg hatchability semi-static assay (acute test), midge eggs were exposed to a range of LAS concentrations in water and were monitored for hatching success and posthatch survival (Pittinger, 1996). No significant reduction in egg hatching was observed at the highest concentration tested (18.9 mg/L). However, significant reduction in the survival of the newly hatched larvae occurred at 4.7 mg/L. The 72h LC50 was between 1.0 and 4.7 mg/L, based on survival of newly hatched larvae.

 

In the partial life cycle bioassay in a flow-through sediment/water test system (chronic test), percentages of winged adults emerging after continuous exposure of larvae and pupae to a range of LAS concentrations were determined (van de Plassche et al., 1999). Exposure concentrations in sediment, interstitial water and overlying water were monitored by 14C liquid scintillation counting. The effect of LAS level in the water column was determined in a total of 6 chronic toxicity tests. The NOECs from these tests were 2.4 -3.0 (without sediment), and 3.0 -6.0 (with sediment). The effect of LAS on Chironomus was also evaluated in an experiment using sediment spiked with LAS. In this test, the NOEC of sediment-spiked LAS was 319 mg/kg sediment (dry weight basis). The normalized NOEC is 2.87 mg/L for C11.6 LAS (van de Plassche et al., 1999).

 

Toxicity to sediment dwelling organisms was investigated with linear alkylbenzene sulfonate (LAS). Samples of natural sediment were spiked with concentrations of 10, 50, 100, 200, 300, 400, 500, 750 and 1000 mg/kg dw mg/kg dw and controls (Comber et al. 2006). 10 test organisms of species Caenorhabditis elegans were then added. Exposure lasted 3 days, at which time the organisms were observed for survival and reproduction. The EC10 was 275 mg/kg sediment dw based on growth rate.