Alcohols, C12-15-branched and linear

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

Assessment factor:

5

Extrapolation method:

assessment factor

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

Assessment factor:

50

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

Extrapolation method:

equilibrium partitioning method

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

Alcohols, C12-15-branched and linear (CAS 90604-40-3) is a multi-constituent long-chain aliphatic alcohol (LCAA) liquid substance composed of 10 -30% C12, 20-40% C13, 20-40% C14 and 10 -30% C15. It has a measured water solubility of <1.3 mg/l at 20˚C. Whilst water solubility for a multi-constituent or UVCB substance is not meaningful scientifically for the purpose of assessment of exposure or risk, a limit value has been determined for a commercial sample. This is useful for reference. Exposure and risk are assessed on the basis of water solubility of the individual constituents.

The whole substance has a weighted average partition coefficient value of 5.81 at 20°C and pH 7. Similar to water solubility, partition coefficient for a multi-constituent or UVCB substance is not meaningful scientifically for the purpose of assessment of exposure or risk. Exposure and risk are assessed on the basis of log K_ow of the individual constituents. Log K_ow values in the range 0.102 to 5.5 were obtained for the constituents.

Alcohols, C12-15-branched and linear has no hydrolysable structural features and would be expected to be stable in water. All constituents are rapidly biodegradable.

Constituents of commercial multi-constituent LCAAs in the environment will distribute and degrade in accordance with their intrinsic environmental fate and toxicity properties, and so exposure assessment is conducted on the basis of the single cuts. Exposure and risk are assessed on the basis of each constituent of the substance.

Alcohols, C12-15-branched and linear is a member of a category of long chain aliphatic alcohols (LCAAs) with a carbon chain length range of C6-C24. The Category is limited to linear and essentially-linear aliphatic alcohols.

As carbon number increases, short- and long-term aquatic toxicity generally increase (i.e. decreasing E(L)C₅₀ and NOEC values observed) up to a threshold carbon number, above which there are no effects at the limit of solubility. For short term effects the threshold is between C13 and C14; for chronic effects it is between C15 and C16. The observed threshold in carbon number is associated with limitations on the degree to which predictable effects are expressed at the limit of solubility, which is low for the longer-chain alcohol structures in the category.

Evidence across the Category of C6-24 long-chain aliphatic alcohols (LCAAs) supports the conclusion that a similar level of susceptibility is exhibited for all three taxonomic groups in the short-term data set.

 

Alcohols in the Category have toxicity consistent with non-polar narcosis effects, in line with the very many organic non-polar narcotic organic substances that have been extensively studied and described in literature by various authors. Therefore the LCAAs in this category should be considered in the context of neutral organics.

Long-term toxicity testing across the category has been carried out with fish and Daphnia. However, significant biodegradation losses of substance in the test system still occurred, despite measures taken to prevent this. A full report detailing properties and trends across the LCAAs category, as well as further discussion on measures to prevent test substance losses is available: ECOTOXICITY Alcohols C6-24 Category report.

Short-term toxicity data are available for the alcohols, C12-15-branched and linear as the whole substance. Long-term tests have not been deemed necessary as long-term data are available for the individual constituents of the substance.

Where measured data is lacking or of unassignable reliability, quantitative structure-activity relationships ((Q)SAR’s) and expert judgement have been used to calculated predicted E(L)C₅₀ and NOEC values for short- and long-term toxicity to fish, invertebrates and algal endpoints. Further details are described in the ECOTOXICITY Alcohols C6-24 Category report.

Reduced assessment factors have been used to derive PNECs:

Basis for setting of assessment factor 

The purpose of assessment factors is to take a laboratory result and estimate a PNEC that applies to the environment itself. In summary, and as is well-known, the purpose of the factors is to account for uncertainty in:

1.     Intra-laboratory variability

2.     Inter-laboratory variability

3.     Duration

4.     Sensitivity of the environmental ecosystem relative to the range or organisms actually tested.  

For one substance standing alone, the factor of 10 is considered in the Guidance to apply to three long term NOECs or ECx values for the aquatic compartment. Similarly an assessment factor of 50 is specified when deriving a PNEC when two long-term NOECs or EC₁₀s for different taxonomic groups are available.  

Why is the Guidance default of 10 a reasonable number for long-term data? A reasoned discussion is set out in the table below. The same logic applies to Alcohols, C12-15-branched and linear.

Table 1 A basis of understanding assessment factors and application to long-term studies with alcohols  

	General rationale when three trophic levels have been studied	Members of the C6-24 Alcohols Category
1. Intra-laboratory variability	For well-performed studies with good chemical analysis point 1 is negligible	This applies. Use 1
2. Inter-laboratory variability	A factor of 2 to 5 would be realistic	For the long-chain alcohols, the inter-laboratory variation is much lower, because the substances are archetypal exemplars of non-polar narcotics. Use 2
3. Duration	When a full set of long-term NOECs or ECxvalues are available, the contributing factor associated with point 3 (duration) is relatively minor, and can be ignored.	This is definitely the case for the ecosystem, in which alcohols are ubiquitous, so duration is irrelevant. Use 1
4. Sensitivity of the environmental ecosystem	For point 4 (ecosystem sensitivity), a value of 2 to 5 is realistic	For non-polar narcotics, many species of organism have been studied, so the uncertainty regarding lab to field extrapolation should also be reduced. The ecosystem is adapted to alcohols. Suggest 2.5
Conclusion	The geometric mean of the range of the two contributing factors is 10. Whilst not set out in Guidance, such a breakdown is a reasonable basis of the factors and is consistent with such extrapolations in mammalian toxicology.	AF = 1*2*1*2.5 = 5 is implied

 

Although a full set of long-term results are not always available, the predictability of trends across the category, the low acute-to-chronic ratio and the potential for metabolism mean that the duration factor (point 3) does not need to be inflated. On the basis of this logic, the registrants of Alcohols, C12 -C15 branched and linear have proposed an assessment factor of 5 for extrapolation from the lowest NOEC or ECx value to PNEC.

The basis for setting the assessment factors is discussed further in the attached ECOTOXICITY Alcohols C6-24 Category report.

Conclusion on classification

Alcohols, C12-15-branched and linear (CAS 90604-40-3) has reliable short- term toxicity data for fish, Daphnia and algae. Algal inhibition data indicate that the EC₅₀ is <0.1 mg/L (75 h EC₅₀ 0.085 mg/l). In addition, the algal NOEC is <0.01 mg/l (72 h NOELR 0.003 mg/l).

The substance is readily biodegradable and very rapidly biodegraded in non-sterilised systems.  

These data are consistent with the following classification under Regulation (EC) No 1272/2008 (as amended) (CLP):

Acute toxicity: Category Acute 1. An M-Factor of 10 applies.

Chronic toxicity: Category Chronic 1. An M-Factor of 1 applies.