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Category information on the aquatic hazard and risk assessment of alcohol ethoxylate

The toxicity mechanism for alcohol ethoxylates is accepted to be non-polar narcosis (Boeije et al. 2006), in which the AE homologues with longer hydrocarbon chains and higher logKow are more efficient at penetration of the cell membrane, and thus more toxic. However, the alcohol ethoxylates homologues must be sufficiently soluble in water to allow a toxic concentration to reach the target organism. For the long chain alcohols (hydrocarbon chain lengths of 15 and above) the toxicity is restricted by solubility considerations. The available toxicity data follows this generally accepted pattern, and also indicates that the linear, essentially linear and branches AE are of similar toxicity (HERA, 2009).

Since long-term data are not available for all category members, precise long-term effect values were calculated with alcohol ethoxylate specific QSARs (Wind & Belanger, 2006; Boeije et al., 2006; Belanger et al., 2006). The used QSARs allow describing the toxicity for each registered mixture based on their individual composition. The effects are described as EC20 values, since the QSARs are more robust for the EC20 values than for NOEC or EC10 values (Boeije et al., 2006). As usual the lowest long-term value is used as key value for classification and labelling.

For the risk assessment (PNEC-derivation) a species sensitivity distribution (SSD) method was used, which based on the assumption of a larger dataset of endpoints for aquatic organisms. These values were summarized by Belanger et al. (2006) and the HERA-report (2009). Belanger et al. (2006) listed the chronic ecotoxicity of alcohol ethoxylates for 17 aquatic species conducted in 60 tests. By using these data the authors first determined EC10-values from the initial test data (i. e. NOEC-values) per endpoint and species. In a second step specific QSAR-models were used to predict toxicity of tested distributions and then toxicity of all pure homologues of alcohol ethoxylates. After construction of a matrix of normalized EC10-values per species, HC5-values were calculated by using the method of Aldenberg and Jaworska (2000). These HC5-values were used for the refined calculation of PNEC-values for the alcohol ethoxylate mixtures to be registered. Mixture toxicity is then calculated according to the formula of Finney (1942). Therefore, respectively, minimal and maximal content of a certain pure alcohol ethoxylate available in the mixture is used. In a second step an arithmetic mean of all values is prepared which is used as HC5-value for the mixture. More information on PNEC-derivation are given in the discussion field of IUCLID chapter 6 (Ecotoxicological Information).

More details on the category approach are given in a separate document (see attached IUCLID chapter 13).

Key information for the assessment of alcohol ethoxylate (Z)-9-Octadecen-1-ol ethoxylated, < 2.5 EO, CAS 9004-98-2)

 

Acute toxicity based on study data

Fish: LC50 (96h) = 108 mg/L for Danio rerio

Crustacea: EL50 (48h) = 51 mg/L for Daphnia magna

Algae: EL50 (72h) > 10 mg/L for Pseudokirchneriella subcapitata

 

Chronic toxicity based on alcohol ethoxylate specific QSARs

Fish: EC20 (30d) = 0.249 mg/L for Pimephales promelas

Crustacea: EC20 (21d) = 0.048 mg/L for Daphnia magna

Algae: ErC20 = 0.145 mg/L for Desmodesmus subspicatus

 

HC5 value estimated on the basis of the chain length distribution

HC5 = 0.0019 mg/L