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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
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:
Acute daphnia LC50 for the neutral organic substance Reseda body (2-Benzyl-4,4,6-trimethyl-1,3-dioxane) is predicted to be 4.37 mg/L based on the ECOSAR SAR for neutral organics using a partition coefficient (log Kow) of 3.6, a molecular weight (MW) of 220.31 and the equation: Log 48h-LC50 (mmol/L) = -0.858 Log Kow + 1.3848. Reseda body is in the applicability domain of the ECOSAR prediction because: a) Reseda body is an acetal presenting the toxicity solely by its bioavailability (i.e. without fragments that activate this neutral organic); b) its predicted log Kow is 3.6 (measured 3.9) (=< 6.4); c) its MW is 220.31 (< 1000); and d) the toxicity predicted is below its water solubility of 396.6 mg/L.
The predicted and measured log Kow are 3.6 and 3.9, respectively showing limited uncertainty (<0.5), the fit in the applicability domain and the availability of an analogue in the training set results in limited uncertainty of the Reseda body prediction. 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 daphnia toxicity on neutral organics (see attached report). The adequate and reliable documentation, presented below, further supports this prediction.
Qualifier:
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:
no
Test organisms (species):
Daphnia sp.
Water media type:
freshwater
Total exposure duration:
48 h
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
4.37 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: ECOSAR class: Neutral organics
Validity criteria fulfilled:
yes
Remarks:
The substance is in the applicability domain of the model.
Conclusions:
The Daphnia 48-h EC50 is 4.37 mg/L
Executive summary:

Acute daphnia LC50 for the neutral organic substance Reseda body (2-Benzyl-4,4,6-trimethyl-1,3-dioxane) is predicted to be 4.37 mg/L based on the ECOSAR SAR for neutral organics using a partition coefficient (log Kow) of 3.6, a molecular weight (MW) of 220.31 and the equation: Log 48h-LC50 (mmol/L) = -0.858 Log Kow + 1.3848. Reseda body is in the applicability domain of the ECOSAR prediction because:  a) Reseda body is an acetal presenting the toxicity solely by its bioavailability (i.e. without fragments that activate this neutral organic); b) its predicted log Kow is 3.6 (measured 3.9) (=< 6.4); c) its MW is 220.31 (< 1000); and d) the toxicity predicted is below its water solubility of 396.6 mg/L.

The predicted and measured log Kow are 3.6 and 3.9, respectively showing limited uncertainty (<0.5),  the fit in the applicability domain and the availability of an analogue in the training set results in limited uncertainty of the Reseda body prediction. 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 daphnia toxicity on neutral organics (see attached report). The adequate and reliable documentation, presented below, further supports this prediction.

Description of key information

Acute daphnia LC50 for the neutral organic substanceReseda body(2-Benzyl-4,4,6-trimethyl-1,3-dioxane) is predicted to be 4.37 mg/L based on the ECOSAR SAR for neutral organics using a partition coefficient (log Kow) of 3.6, a molecular weight (MW) of 220.31 and the equation:Log 48h-LC50 (mmol/L) = -0.858LogKow + 1.3848.Reseda bodyis in the applicability domain of the ECOSAR prediction because: a)Reseda bodyis anacetalpresenting the toxicity solely by its bioavailability (i.e. without fragments that activate thisneutral organic); b) its predicted log Kow is 3.6 (measured 3.9) (=< 6.4); c) its MW is 220.31 (< 1000); and d) the toxicity predicted is belowits water solubility of 396.6 mg/L.

The predicted and measured log Kow are 3.6 and 3.9, respectively showing limited uncertainty (<0.5), the fit in the applicability domain and the availability of an analogue in the training set results in limited uncertainty of theReseda bodyprediction. 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 daphnia toxicity on neutral organics (see attached report). The adequate and reliable documentation, presented below, further supports this prediction.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
4.37 mg/L

Additional information