Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Toxicity to Soil Macro Organisms

A series of studies have been conducted on soil macroorganisms and summarized in the tables below. The primary route of entry for LAS (read across) into the terrestrial environment is land application of sewage sludge intended as an amendment to agricultural lands. A large number of terrestrial ecotoxicology studies were reviewed by Jensen et al. (2007) to develop a European wide risk assessment of LAS in agricultural soils. Nine invertebrate species, three oligochaetes and six arthropods, have been evaluated in chronic toxicity to LAS in soil. Endpoints were all considered sensitive for these taxa. Only growth and reproduction endpoints were used in the PNEC derivation for soil. Effects on oligochaetes and arthropods were highly overlapping. NOECs or EC10s for oligochaetes and arthropods varied from 27-250 and 41-320 mg/kg soil, respectively. Key studies on the oligochaete Aporroectodea caliginosa and the springtail Folsomia fimeteria were conducted by Holmstrup and Krogh (1996) and Holmstrup et al. (2001) in several soil types including sand, loam and clay with varying dominant cations. A. calignosa had EC10s that ranged from 44-105 with a geometric mean of 71.7 mg/kg soil for the growth endpoint (most sensitive) and F. fimeteria had EC10s that ranged from 85-161 mg/kg soil for the reproduction endpoint (most sensitive).

Overview of Toxicity (in mg/kg soil) to Soil Macroorganisms other than Arthropods (Oligochaetes)

Method

Results
(mg/kg soil)

Class: Oligochaetes

 

OECD 207 (Earthworm, Acute Toxicity Tests)

Eisenia foetida

14 day LC50> 1000

NOEC = 250

LC10= 277

Comparable to ISO 16387 (Effects of pollutants on Enchytraeidae (Enchytraeus sp.) -- Determination of effects on reproduction and survival) Enchytraeussp.

EC10= 27  (geometric mean of 2 EC10values)

Comparable to ISO 16387 (Effects of pollutants on Enchytraeidae (Enchytraeus sp.) -- Determination of effects on reproduction and survival) Aporrectodea. caliginosa

28 day EC10= 46

 

 Overview of Toxicity (in mg/kg soil) to Soil Arthropods (Insects and Arachnids)

Method

Results
(mg/kg soil)

Class: Insects (springtails)

 

Comparable to ISO 11267 (Inhibition of reproduction of Collembola (Folsomia candida) by soil pollutants)

Hypogastrura assimilis

21day EC10= 100

Various Methods

Folsomia fimetaria

EC10= 107.6  (geometric mean of 7 data points)

ISO 11267 (Inhibition of reproduction of Collembola (Folsomia candida) by soil pollutants)

Folsomia candida

28 day EC10= 205

No Guideline Available

Isotoma viridis

EC10= 41

Class: Arachnids

 

No Guideline Available

Hypoaspis. aculeifer

21 day EC10= 82

No Guideline Available

Platynothrus peltifer

NOEC = 320

 

Toxicity to Terrestrial Plants

As part of a complete assessment of terrestrial toxicity to LAS (read across), Jensen et al. (2007) summarized available data on responses of non-crop and agricultural crop species. These are shown in the table below. Growth was universally the most sensitive endpoint and in all the experiments, LAS was added as an aqueous solution resulting in maximum bioavailability. Three blocks of studies were conducted on crop and non-crop plants. The first group of studies on crop plants by Windeat (1987) exposed sorghum, sunflower and mung bean to LAS at 0, 1, 10, 100 and 1000 mg/kg soil. EC10s ranged from 68-126 mg/kg soil and EC50s ranged from 167‑316 mg/kg soil. The second group of studies by Günther and Pestemer (1992) on oat and mustard species involved exposures from 0-10,000 mg/kg soil. The last group of studies, mostly on non crop species, by Marschner (1992) were derived from exposing plants up to 1000 mg/kg resulting in EC10 values that ranged from 55-120 mg/kg and EC50 values of 90-204 mg/kg.

Overview of Toxicity to Terrestrial Plants

Method

Results (mg/kg soil)

Crop Species

 

OECD 208 (Terrestrial Plants Test:  Seedling Emergence and Seedling Growth Test)

Sorghum (Sorghum bicolour)

21 day EC50= 167

EC10= 68

NOEC = 100

OECD 208 (Terrestrial Plants Test:  Seedling Emergence and Seedling Growth Test)

Sunflower (Helianthis annuus)

21 day EC50= 289

EC10= 116

NOEC = 100

OECD 208 (Terrestrial Plants Test:  Seedling Emergence and Seedling Growth Test)

Mung Bean (Phaseolus aureus)

21 day EC50= 316

EC10= 126

NOEC = 100

No Guideline Available (Seedling Growth)

Oats (Avena sativa)

14 day EC50= 300

EC10= 80

No Guideline Available (Seedling Growth)

White mustard (Sinapis alba)

14 day EC50= 300

EC10= 200

No Guideline Available (Seedling Growth)

Field Mustard (Brassica rapa)

14 day EC50= 164l

EC10= 86

(geometric mean of 2 values)

Non-Crop Species

 

OECD 208 (Terrestrial Plants Test:  Seedling Emergence and Seedling Growth Test)

Low Mallow  (Malva pusilla)

14 day EC50= 204

EC10= 110

OECD 208 (Terrestrial Plants Test:  Seedling Emergence and Seedling Growth Test)

Black Nightshade (Solanum nigrum)

14 day EC50= 169

EC10= 120

OECD 208 (Terrestrial Plants Test:  Seedling Emergence and Seedling Growth Test)

Pigweed (Chenopodium album)

14 day EC50= 164

EC10= 120

OECD 208 (Terrestrial Plants Test:  Seedling Emergence and Seedling Growth Test)

Redroot Amaranth (Amaranthus retroflexus)

14 day EC50= 142

EC10= 110

OECD 208 (Terrestrial Plants Test:  Seedling Emergence and Seedling Growth Test)

Wild Fennel (Nigella arvensis)

14 day EC50= 133

NOEC = 52

OECD 208 (Terrestrial Plants Test:  Seedling Emergence and Seedling Growth Test)

Quick Weed (Gallinsoga parviflora)

14 day EC50= 90

EC10= 55

 

Toxicity to Soil Micro-Organisms

LABSA is readily biodegradable in water and was not toxic to activated sludge in an OECD 301A test. The lack of toxicity of LABSA to activated sludge is relevant to its toxicity to soil micro-organisms. As LABSA is not directly applied to soil and there is no reason to assume that the toxicity of LABSA to terrestrial micro-organisms would deviate from their toxicity to aquatic micro-organisms, therefore testing of soil micro-organisms can be waived.

Additional information

LAS provides suitable read across for LAB Sulfonic Acids as both form the identical chemical species in aqueous solutions at neutral (physiological) pH. The toxicity of LAS (read across) to terrestrial organisms including soil macroorganisms, other than arthropods, and non-crop and agricultural crop species has been evaluated, and generally found to affect growth and reproduction, with growth being the most sensitive endpoint for plants. Only growth and reproduction endpoints were used in the PNEC derivation for soil. Terrestrial toxicity to soil micro-organisms and birds is not needed considering the higher rate of sensitivity, and thus protection afforded by, studies on plants and invertebrates exposed to LAS under more realistic test conditions (field trials). The primary route of entry for LAS into the terrestrial environment is land application of sewage sludge intended as an amendment to agricultural lands. The PNEC for soil is 35.3 mg/kg, based on the HC5 value (concentration that would exceed the NOEC or EC10 values for 5% of species) derived from a species sensitivity distribution of nine invertebrate species and 12 plant species.