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Ecotoxicological information

Short-term toxicity to fish

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short-term toxicity to fish
Type of information:
Adequacy of study:
key study
Study period:
July 2017
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
The acute fish toxicity for Tetrahydromyrcenol is predicted using ECOSAR Neutral organics. The full justification is presented in the accompanying files. Executive summary: The 96h acute fish LC50 for the neutral organic substance Tetrahydromyrcenol (2,6-dimethyloctan-2-ol) is predicted to be 4.73 mg/L based on the ECOSAR SAR for neutral organics using a partition coefficient (Log Kow) of 3.603 (estimated), a molecular weight (MW) of 158.29 and the equation: 96h LC50(mg/L) = MW x 10^ (-0.8981 Log Kow + 1.7108).
Tetrahydromyrcenol is in the applicability domain of the ECOSAR prediction because: a) the substance is an alcohol presenting the toxicity solely by its bioavailability (i.e. without fragments that activate this neutral organic); b) its predicted log Kow is 3.603 (measured 3.2) (=< 6.4); c) its MW is 158.29 (< 1000); and d) the toxicity predicted is below its predicted water solubility of 188.9 mg/l (measured = 281.9 mg/l).
The fit in the applicability domain and the availability of an analogue in the training set results in limited uncertainty of the Tetrahydromyrcenol prediction. Tetrahydromyrcenol is categorised as a neutral organic and is expected to have a similar uncertainty as the data in the training set. The measured log Kow of the substance is slightly lower than the predicted one and as the predicted value is used, the predicted value is somewhat conservative. The acute fish toxicity data from the analogues in the ECOSAR training set confirm the fact that variability is less than the factor of three. This shows that the prediction is reliable and a Klimisch 2 can be assigned. In accordance with REACH Annex XI, the validity of the (Q)SAR is documented in a QMR for acute fish toxicity on neutral organics (see attached report). The adequate and reliable documentation presented, further supports this prediction.
according to guideline
other: REACH Guidance R.6: QSARs and grouping of chemicals. Version May 2008
Version / remarks:
In the QMR attached the model specifications are presented. In this QMR is referenced to the Methodology document for the ecological Structure-Activity Relationship model (ECOSAR) Class Programm MS Windows v1.1'. United States Environmental Protection Agency, Office of Pollution Prevention and Toxics, Washington DC (2011).
GLP compliance:
Test organisms (species):
other: fish
Water media type:
Total exposure duration:
96 h
Key result
96 h
Dose descriptor:
Effect conc.:
4.73 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Remarks on result:
other: ECOSAR class: Neutral organics
Validity criteria fulfilled:
The substance is within the applicability domain of the model and reliable and adequate documentation is present.
The 96-h LC50 for fish is 4.73 mg/L

Description of key information

The LC50 fish is 4.73 mg/l using ECOSAR Neutral Organic prediction.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Effect concentration:
4.73 mg/L

Additional information