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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The toxicity to algae of components of Ziegler Bottoms has been documented within this dossier.  Adequate reliable predicted data exists for toxicity to algae to the primary constituents of Ziegler Bottoms (namely, icosan-1-ol and docosan-1-ol).  In a conservative approach the most sensitive study result from across the two constituents has been identified and used to address the hazard endpoint in question. Both constituents are considered non-toxic at the limit of solubility.  Therefore, the value used as key in the assessment is the EC50 of >0.001 mg/L which is at the limit of solubility for both docosan-1-ol and icosan-1-ol.

Key value for chemical safety assessment

EC50 for freshwater algae:
0.001 mg/L

Additional information

Ziegler Bottoms are characterized as comprising of two primary constituents; icosan-1-ol and docosan-1-ol. Together these constituents represent a structural class of components (alcohols) that constitute approximately 82% of the composition of Ziegler Bottoms. Study data, where available, for each of these primary constituents has been evaluated and considered together. In a conservative approach the most sensitive study result from across the two primary constituents has been identified and used to adequately address the Ziegler Bottoms endpoint in question. 

Several reliable (Klimisch 1 or 2) toxicity studies in algae have been conducted for constituents of Ziegler Bottoms and are included in this dossier. The reliable studies included for each constituents briefly described below. In a conservative approach the most sensitive study result from across the two constituents will be identified and used to address the hazard endpoint in question.

Icosan-1-ol

There were no reliable measured data for short-term toxicity of icosan-1-ol to algae. However, Fisk et al (2009) provided estimated short-term toxicity values for toxicity of icosan-1-ol to algae based on expert judgement on read-across from other taxonomic groups and the alcohols category to fill gaps in the database for single carbon chain length alcohols and commercial products (multi-constituent substances). However, rather than just reading-across a single value from a different substance, this has also involved taking measured and predicted data for different trophic levels into account so as to factor in any consistent patterns in their relative susceptibilities. This method for gap filling has been reported in Fisk et al. (2009) and used in the Long Chain Alcohols OECD SIDS report (2006). The basis of the judgment is that examination of the available measured data suggests that algal EC50values are of the same order, or possibly slightly lower, than theDaphnia magnaEC50values. However, there must always be uncertainty in such read across ranges have been stated in the dossier. Furthermore, conducting a study which assesses the toxicity of fatty alcohols to algae is considered technically impractical because the substance is expected to adsorb to algae and be degraded. Therefore, the 72 hr EC50 value is >0.001 mg/L non-toxic at the limit of solubility.

 

Docosan-1-ol

There were no reliable measured data for short-term toxicity of docosan-1-ol to algae. However, Fisk et al (2009) provided estimated short-term toxicity values for toxicity of docosan-1-ol to algae based on expert judgement on read-across from other taxonomic groups and the alcohols category to fill gaps in the database for single carbon chain length alcohols and commercial products (multi-constituent substances). However, rather than just reading-across a single value from a different substance, this has also involved taking measured and predicted data for different trophic levels into account so as to factor in any consistent patterns in their relative susceptibilities. This method for gap filling has been reported in Fisk et al. (2009) and used in the alcohols category SIAR (2005). The basis of the judgment is that examination of the available measured data suggests that algal EC50values are of the same order, or possibly slightly lower, than theDaphnia magnaEC50 values. However, there must always be uncertainty in such read across ranges have been stated in the dossier. Furthermore, conducting a study which assesses the toxicity of fatty alcohols to algae is considered technically impractical because the substance is expected to adsorb to algae and be degraded. Therefore, the 72 hr EC50 value is >0.001 mg/L non-toxic at the limit of solubility.

The toxicity to algae of components of Ziegler Bottoms has been documented within this dossier. Adequate reliable predicted data exists for toxicity to algae to components of Ziegler Bottoms (namely, icosan-1-ol and docosan-1-ol). In a conservative approach the most sensitive study result from across the two constituents has been identified and used to address the hazard endpoint in question. Both constituents are considered non-toxic at the limit of solubility. Therefore, the value used as key in the assessment is the EC50 of >0.001 mg/L which is at the limit of solubility for both docosan-1-ol and icosan-1-ol.