1,6-Octadien-3-ol, 3,7-dimethyl-, acid-isomerized

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

The read-across is based on the hypothesis that the source substance (Sinpine P) and target substance (Lime oxide) have similar ecotoxicological properties as a result of their similar composition, the same expected aquatic toxicity mode of action for the components and similar concentrations of the component blocks (monoterpene hydrocarbons and monoterpene ethers). The component blocks present in both substances also have similar physical chemical properties relevant for exposure to and uptake by aquatic organisms. The expected similar strength in aquatic toxicity is confirmed by experimental data for acute toxicity to daphnia. Full details for the analogue approach justification are provided in the attached document " Acute fish Read-Across Justification for Lime Oxide".

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

96 h

Dose descriptor:

LL50

Effect conc.:

6.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: Estimate based on read-across

Conclusions:

In a guideline study, conducted according to GLP, the source substance was found to have a 96h LL50 of 6.8mg/L. The detailed information provided in the read-across justification document indicates that the aquatic
ecotoxicity of Sinpine P (source substance) and Lime oxide (target substance) are expected to be similar as a result of similar compositions, the same expected aquatic toxicity mode of action for the components and similar concentrations of each component block (group of structurally similar substances). The component blocks present in both substances also have similar physical chemical properties relevant for exposure to and uptake by aquatic organisms. The read-across is justified and considered adequate for the purposes of classification and labelling.
A reliable estimate of the short-term toxicity to fish for Lime Oxide is a 96h LL50 of 6.8 mg/L.

Description of key information

The 96h LL50 for Lime Oxide was estimated to be 6.8mg/L based on read-across. This value can be used directly for classification but is unsuitable for derivation of PNEC since partitioning in the environment of the two groups of components present in Lime oxide will make comparison with PEC meaningless. In order to derive appropriate PNECs, acute daphnia information for the two assessment entities has been used since the daphnia endpoint was identified as the most sensitive species for both groups (see aquatic toxicity endpoint summary for details).

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

6.8 mg/L

Additional information

To assess the acute fish toxicity of the registered substance, read-across to Sinpine P has been employed. The read-across works within the spirit of REACH and the stated aim of the legislation to reduce animal testing where possible. This is an analogue approach for which the read-across hypothesis is based on different substances which have similar properties. The source substance (Sinpine P) and target substance (Lime oxide) are expected to have similar ecotoxicological properties as a result of their similar composition. Many components are common to both substances and others are structurally related. In summary, both substances are mixtures of unsaturated monoterpene hydrocarbons and oxygen-containing monoterpenes. All components are expected to act via narcosis.This mechanism is non-structure dependent and is driven by hydrophobicity (as modelled by log Kow). Thus the components are not expected to influence each other's toxicity and the aquatic toxicity of both multi-constituent substances will be driven by the relative ratio of the unsaturated monoterpene hydrocarbons (estimated log Kow 4.35-4.88) and oxygen-containing monoterpenes (estimated log Kow 2.85-3.53) and the resulting composition of the water-accommodated fractions tested. The relative concentration of the two component blocks is similar in Sinpine P and Lime Oxide (approx 69-74% unsaturated monoterpene hydrocarbons and 23-25% oxygen-containing monoterpenes). The expected similarity in the strength of aquatic toxicity is supported by experimental data for acute toxicity to daphnia (5.3mg/L for the target substance, 2.8 mg/L for the source substance). Therefore, read-across from Sinpine P is considered to give a reliable estimate of the fish 96h LL50 for Lime Oxide, which is 6.8 mg/L based on loading rates. The value is considered adequate for the regulatory purpose of acute enviromental classification. A detailed scientific justification for the read-across is provided as an attachment in the IUCLID endpoint record. The data matrix supporting the read-across is provided below:

Data Matrix – Physicochemical and ecotoxicological data on the source and target substance

Substance Name	Sinpine P  (source substance)	Lime Oxide (target substance)
Component Data
Monoterpene unsaturated hydrocarbons -         Typical total, % w/w -         Log Kow (estimated values) -         Water solubility, mg/L	74 4.27 - 4.88 2.22 -7.56	69 4.75 – 4.88 2.01 - 9.02
Oxygen-containing monoterpenes -         Typical total % w/w -         Log Kow (estimated values) -         Water solubility (estimated values)	23 2.85 – 3.33 32.28 – 584.1	25 3.13-3.54 68.88-584.1
Ecotoxicological information
Short-term Daphnia toxicity, 48h EL50(mg/L)	2.8^i	5.3^ii
Growth inhibition study aquatic plant (algae), 72h ErL50(mg/L)	No data available	15^iii
Growth inhibition study aquatic plant (algae), 72h ErL10(mg/L)	No data available	11^iii
Short-term toxicity to fish, 96h LL50(mg/L)	6.8^iv	Read-across from source substance
i) WIL Research, Project 506046, 2015 – presented in the respective REACH dossier of Sinpine P ii) Envigo Research Limited, Study No 41400820, 2015 – included in this REACH dossier iii) Envigo Research Limited, Study No 41400821, 2015- included in this REACH dossier iv) WIL Research, Project 506047, 2015 – included in this REACH dossier