Benzyl alcohol

Toxicity to aquatic algae and cyanobacteria

Description of key information

The 72h-EC50 of benzyl alcohol in Pseudokirchnerella subcapitata was determined to be 770 mg/L.
The 72h-NOEC of benzyl alcohol in Pseudokirchnerella subcapitata  was determined to be 310 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

770 mg/L

EC10 or NOEC for freshwater algae:

310 mg/L

Additional information

The toxicity of benzyl alcohol to algae is described in four publications. In accordance with the OECD SIDS on Benzoates (2001) two of these publications are considered as relevant for the environmental hazard assessment:

• The toxicity of benzyl alcohol to algae was assessed by Knie (1983) using Warburg apparatus according to Tümpling (1972). The test duration was 4 hours and the effect was measured as percent inhibition of oxygen production of algae Haematococcus pluvialis. The EC50 was determined to be 2600 mg/L. This publication has been assessed in the US EPA Document (1989) and the OECD SIDS Report (2001) and was used as critical study for the derivation of the SIDS endpoint.
• The toxicity of benzyl alcohol to algae was assessed in a cell multiplication inhibition test (Bringmann & Kühn 1959a). The test duration was 96 hours and test species green algae of the genus Scenedesmus. The lowest effect concentration was found to be 360 mg/L. This publication has been assessed in the US EPA Document (1989) and the OECD SIDS Report (2001) and was used as critical study for the derivation of the SIDS endpoint.

In addition to the above mentioned publications, the Japanese Ministry of Environment has conducted a GLP-compliant acute toxicity test with Pseudokirchnella subcapitata according to the OECD Guideline 201 (NITE 2009). The 72h-EC50 and NOEC for growth were determined to be 770 and 310 mg/L, respectively. The EC50 and NOEC for the area under the growth curve were determined to be 500 and 310 mg/L, respectively.

In accordance with the Endpoint Specific Guidance (Chapter R.7B, Section 7.8.4.1), the 72h-EC50 and NOEC for growth, derived from the study by the Japanese Ministry of Environment (NITE 2009), are considered to be the most adequate values describing the toxicity of benzyl alcohol to algae. Thus, this study was determined as key study for the present dossier and the studies by Knie at al. (1983) and Bringmann & Kühn (1959a) are defined as supporting studies.

Studies which are regarded as not relevant for the hazard assessment:

• The first publication by Stratton & Corke has been assessed in the US EPA Document (1989) and the OECD SIDS report (2001). According to the US EPA Document (1989), five algae species were tested in the publication by Stratton & Corke (1982). EPA concludes that the EC50 values are related to effects on photosynthesis and nitrogenase activity and exceeded 100 mg/L in all five species tested. In the OECD SIDS (2001), only the results onChlorella pyrenoidosa(3h-EC50 = 95 mg/L) are regarded as relevant for the hazard assessment, while the results on the other species were not used because the endpoints were either about inhibition of photosynthesis and not growth (rate), which should be used according to the Endpoint Specific Guidance RIP 3.2 (Chapter R.7B, Section 7.8.4.1). Since the EC50 for Chlorella is based on photosynthesis and since the duration of the test was only 3 hours, the EC50 for Chlorella should neither be used for the hazard assessment.
• In the second publication by Trenel & Kühn (1982), the effect of benzyl alcohol on the growth of algaeScendesmus subspicatuswas determined in a 7-day cell multiplication inhibition test. According to the Endpoint Specific Guidance RIP 3.2 (Chapter R.7B, Section 7.8.4.1), the results from tests with a duration > 96 hours cannot be used, unless the available raw data show monotone exponential growth of the controls. Since no raw data from this publication are available and thus the criterion cannot be validated and since the study was not conducted according to a guideline, the publication is regarded as not assignable and the resulting toxicological limit concentration (TGK) of 16 mg/L will not be used for the hazard assessment.