Sodium dodecyl sulphate

Toxicity to aquatic algae and cyanobacteria

Description of key information

72h-EC50 > 120 mg/L (nominal concentration) for growth rate of Desmodesmus subspicatus (DIN 38412, part 9)

72h-EC10 = 30 mg/L (nominal concentration) for yield of Desmodesmus subspicatus (DIN 38412, part 9)

Key value for chemical safety assessment

EC50 for freshwater algae:

120 mg/L

EC10 or NOEC for freshwater algae:

30 mg/L

Additional information

Several studies are available investigating the toxicity of sodium dodecyl sulfate (SDS) algae (see table 1), since SDS is an economically important surfactant and was frequently used as reference substance in toxicity tests. The data set is comprised of several publications with acceptable quality and validity focusing on standard and non-standard freshwater and marine species as well as one study report investigating the toxicity to the standard species Desmodesmus subspicatus (BASF 1994). The GLP study was performed according to OECD guideline 201 testing concentrations between 15 and 120 mg/L. The test substance concentrations were measured and showed to be stable throughout the test. The 72h-EC50 value is determined to be above the highest tested concentration of 120 mg/L based on growth rate and nominal concentrations. A 72h-NOEC value of 30 mg/L was recorded based on yield and nominal concentrations. Although this effect value is not the lowest observed in the data set it was used for hazard assessment since (i) this study is rated as the most comprehensive and reliable one and (ii) the remaining data set is biased because several effect values are existing in the literature for some of the additional (standard) species tested but always the lowest obtained value per species is listed and no averaging was performed. This was done because the data set is primarily presented to statistically assess the general susceptibility ofalgaeto SDS in comparison to fish and aquatic invertebrates using a conservative approach. To use the effect value from BASF (1994) is considered to be acceptable for hazard assessment since classification and labeling as well as PNEC derivation is not based on algal toxicity and since this value adequately represents the toxicity (= harmful) of SDS to algae (see table 1).

In general algae show to be less susceptible to SDS than fish and aquatic invertebrates. The data set is not robust enough to conclude on differences in susceptibility between freshwater and marine species.

Table 1: Acute toxicity of SDS to different freshwater and marine algae. Publications showing the lowest obtained effect values for a single species are listed.

Species	Exposure time	EC/LC50 [mg/L]	marine/freshwater	Reference
Tetraselmis chuii	96h	30.2	m	Nunes et al. 2005
Chlamydomonas reinhardtii	72h	18.8	fw	Brack & Rottler 1994
Lemna minor	7d	18	fw	Bishop 1979
Desmodesmus subspicatus	72h	> 100	fw	BPCN, unpublished data
Pseudokirchneriella subcapitata	96h	117	fw	Nyholm & Damgaard