Terpene hydrocarbon alcohols, terpene processing by-products

Endpoint summary

Description of key information

For Terpene hydrocarbon alcohols the following results were derived:

Species	Method	Result	Remarks
Fish (D. rerio)	Read-across	96-h LC50: 0.805 mg/L	Key study, Rel. 2. Value derived from read-across from Terpinolene (CAS 586 -62 -9; tested in an OECD TG 203 study).
Daphnia magna	Read-across	48-h EC50: 0.634 mg/L	Key study, Rel. 2. Value derived from read-across from Terpinolene (CAS 586 -62 -9; tested in an OECD TG 202 study).
Green algae (P.subcapitata)	Read-across	72-h ErC50: 0.692 mg/L 72-h ErC10: 0.273 mg/L	Key study, Rel. 2. Value derived from read-across from Terpinolene (CAS 586 -62 -9; tested in an OECD TG 201 study).
STP microorganisms	Read-across	NOEC: 25.7 mg/L	Key study, Rel. 2. Value derived from read-across from Terpineol multi (CAS 8000 -41 -7; tested in an OECD TG 310 study).

 

Additional information

The aquatic toxicity is assessed based on read-across from Terpinolene to the Terpene hydrocarbon alcohols. The executive summary of the source information is presented in the respective Endpoint summaries. The read-across rationale is presented below.

Aquatic toxicity of Terpene hydrocarbon alcohols based on read-across from data available for Terpinolene (CAS# 586-62-9).

Introduction and hypothesis for the analogue approach

Terpene hydrocarbon alcohols have the following constituent types of substances: Solely hydrocarbons-terpene type, Alcohol-type, Ketone-type and Ether-type all having a saturated or unsaturated cyclic hydrocarbon backbone. For this substance no aquatic toxicity information is available. In accordance with Article 13 of REACH, lacking information can be generated by other means than experimental testing, i.e. applying alternative methods such as QSARs, grouping and read-across. For assessing the aquatic toxicity the information from the constituent Terpinolene is used, which can represent the Terpene hydrocarbon alcohols.

Hypothesis: Terpene hydrocarbon alcohols have the same aquatic toxicity as Terpinolene.

Available information: The LC50 for fish, EC50s for Daphnia and algae and EC10 for algae are 0.81, 0.63, 0.69 and 0.27, respectively. The information is derived from OECD TG 203, 202 and 201, respectively.

Target chemical and source chemical(s)

Constituent types of the target substance and chemical structures of the source substances are shown in the data matrix, including physico-chemical properties and aquatic toxicity information, thought relevant for read across.

Purity / Impurities

Constituent types of the target substance are covered by the presented constituent types, there are no other constituent that impacts the aquatic toxicity potential.

Analogue approach justification

According to Annex XI section 1.5, read across can be used to replace testing when the similarity can be based on a common backbone and a common functional group. When using read across the result derived should be applicable for C&L and/or risk assessment and it should be presented with adequate and reliable documentation, which is presented below.

Analogue selection: For Terpene hydrocarbon alcohols one of its constituents Terpinolene was selected as an analogue for read-across because based on its high log Kow (relative to the other constituents) it is the most toxic constituent compared to other constituents for which information is available.

Structural similarities and differences: Terpene hydrocarbon alcohols all havesimilar backbones, mostly containing a hydrocarbon cyclohexyl/hexene group with a (branched) alkyl chain, and/or alkyl bridge over the cyclohexyl ring. Although the different constituents contain different functional groups, all belong to the toxicity class of neutral organics. Terpinolene is a branched cyclohexene which contains no specific functional group and is also a neutral organics.

Bioavailability: Terpene hydrocarbon alcohols constituents are all bioavailable based on molecular weight and log Kow.

Mode of action/reactivity: Terpene hydrocarbon alcohols constituents all belong to the neutral organics (narcotic type of action). Their reactivity will be related directly to their log Kow values. Terpinolene has the higher log Kow value and therefore presents a conservative aquatic toxicity. This is supported with information on the ECHA website on some other constituents. For alpha-Terpineol, experimental aquatic toxicity data is available for three trophic levels. The effect values are a 96-h LC50 of 70 mg/L in fish, a 48-h EC50 of 73 mg/L in daphnids, and 72-h ErC50 and NOErC values of 68 mg/L and 3.9 mg/L, respectively, in freshwater algae.

Conversion of the effect values from Terpinolene to the Terpene hydrocarbon alcohols as a whole: No log Kow correction needs to be performed as the estimated log Kow of Terpinolene is on the high-end of the spectrum for all constituents of the Terpene hydrocarbon alcohols. No correction for molecular weight needs to be performed, because the molecular weight of Terpinolene is on the low-end of the of the Terpene hydrocarbon alcohols (136 in a range of 136 - 154 g/mol). In addition, the effect values available for Terpinolene are not corrected for its percentage in the substance (ca. 15%).

Uncertainty of the prediction: There are no uncertainties other than those addressed above.

Data matrix

The relevant information on physico-chemical properties and toxicological characteristics are presented in the Data Matrix.

Conclusions on aquatic toxicity for hazard and risk assessment

For the Terpene hydrocarbon alcohols no aquatic toxicity information is available. Read-across is used to fill this data gap. When using read-across, the result derived should be applicable for C&L and/or risk assessment, and be presented with adequate and reliable documentation. This documentation is presented in the current text. For one of the constituents, Terpinolene, reliable data is available for the three trophic levels, algae, daphnids, and fish. The lowest acute effect value is 0.63 mg/L as observed in Daphnia magna. A chronic effect value of 0.27 mg/L is reported in algae. The effect values are not corrected for differences in log Kow and molecular weight, nor for the concentration in the substance, which presents a conservative result for aquatic toxicity.

Final conclusion: For the Terpene hydrocarbon alcohols, the 96-h LC50 in fish is 0.81 mg/L, the 48-h EC50 in daphnids is 0.634 mg/L, and the 72-h ErC50 and ErC10 values in aquatic algae 0.69 mg/L and 0.27 mg/L, respectively.

Data matrix presenting the information relevant for read across to the Terpene hydrocarbon alcohols from Terpinolene (CAS# 586-62-9)

	Terpene hydrocarbon alcohol	Terpinolene (mono)
Read-across	Target	Source
Structure
CAS#	--	586-62-9
	945-149-0	209-578-0
Constituent type (%)
Solely hydrocarbons
Terpinolene type	0-15	>80
Alcohol type
Tertiary alcohols	40-90
Secondary alcohols	7-40
Ketone type
Camphor-Type	0-17%
Ether type
Aromatic ether type	<4%
MW	136-154	136
Phys-chem properties
Appearance	Liquid	Liquid
Log Kow	3.5-5.5 (exp.)	4.33 (ECHA site)
Aquatic toxicity
Fish 96-h LC50	0.81 mg/L (Read across)	0.81 mg/L(OECD TG 203)
Daphnia 48-h EC50	0.63 mg/L (Read across)	0.63 mg/L (OECD TG 202)
Algae 72-h ErC50 72-h ErC10	0.69 mg/L 0.27 mg/L (Read across)	0.692 mg/L 0.273 mg/L (OECD TG 201)