Alcohols, C9-11-branched and linear

Endpoint summary

Additional information

Short-term toxicity

Short-term toxicity whole substance tests results are available with Alcohols C9-11 branched and linear (CAS 85711-26-8) and Alcohols C9-11 linear only (CAS 66455-17-2) for freshwater fish (Onconrhynchus mykiss), marine fish (Scophthalmus maximus), freshwater invertebrates (Daphnia magna), marine invertebrates (Crangon crangon) and algae (Pseudokirchneriella subcapitata).

 

The relevant short-term values are:

Fish:

96-hour LC₅₀: Freshwater: 6.3 – 10 mg/l (nominal) [Shell, 1979].

96-hour LC₅₀: Marine water: 5.8 mg/l (nominal) [Shell Chemicals, 1991].

Invertebrates:

48-hour EC₅₀: Freshwater: 7.0 mg/l (nominal) [Garforth, 1983];

48-hour LC₅₀: Marine water:  5.6 mg/l; 96-hour EC₅₀: 4.6 mg/l (nominal) [HLS, 1991].

Algae:

EC₅₀(96 h): 2.7 mg/l; NOEC: 1.0 mg/l (based on growth rate) [Stephenson, 1982].

 

Long-term toxicity

There are no measured long-term toxicity data available for alcohols C9-11 branched and linear. The needs associated with a sound understanding of long-term aquatic toxicity to fish and invertebrates are adequately met by the available data on the linear isomer of each constituent. For the purpose of risk assessment aquatic PNECs for individual constituents have been derived using chronic data for aquatic invertebrates.

 

The relevant long-term data for the individual constituents:

Long-term toxicity to aquatic invertebrates:

C9 linear only: Predicted 21-d EC₁₀ value has been calculated (QSAR) to lie in the range of 0.4 - 0.9 mg/l based on mortality and reproduction of Daphnia magna [Schafers, 2009].

C10 linear only: Measured 21-d EC₁₀ value of 0.21 mg/l based on mortality and reproduction of Daphnia magna (measured concentrations) [Schafers, 2005].

C11 linear only: Predicted 21-d EC₁₀ value has been calculated (QSAR) to lie in the range of 0.075 - 0.46 mg/l based on mortality and reproduction of Daphnia magna [Schafers, 2009].

 

The presence of branched structures does not appear to confer aliphatic alcohols any different environmental properties compared to the linears only substances, therefore the data is freely read-across between Alcohols C9-11 branched and linear and Alcohols C9-11 linear only substances.

 

Toxicity to microorganisms

At or above the limit of water solubility, the registered substance has no significant inhibitory effects on respiration of activated sludges or specific microbial strains relevant to WWTP, based on consistent category evidence for C6-24 aliphatic alcohols. There is no hazard for WWTP microorganisms.

 

Long-term sediment toxicity

In accordance with Column 2 of REACH Annex X, long-term toxicity testing with sediment organisms (required in Section 9.5.1) is not needed as the chemical safety assessment according to Annex I indicates that this is not necessary.

Discussion of trends in the Category of C6-24 linear and essentially-linear aliphatic alcohols:

Many short-term aquatic toxicity tests have been carried out on this family of long chain aliphatic (LCAAs), addressing toxicity to organisms from three trophic levels; fish, invertebrates and algae. For studies in which the test substance had a single carbon chain length, a key study has been identified for each taxonomic level. Where there were two or more reliable studies of the same quality but on different species within the same taxonomic group, the lower toxicity value (highest level of toxicity) was chosen. For studies in which the test substance was a multi-constituent LCAAs (commercial products) and where there was more than one type of the substance a key study was identified for each type.

The results of short-term tests performed on single carbon chain length LCAAs are generally reported in terms of the nominal or measured dissolved concentration of the alcohol in the test medium and are identified as EC50 or LC50 values. However there are also instances where the reported effect concentration exceeded the solubility of the LCAA. These instances are distinguished in the results tables either by the result being reported as an LL50 or EL50, implying that the test medium was a water accommodated fraction (WAF), or by a note indicating that the test substance loading exceeded the solubility of the LCAA. In the latter case it has had to be assumed (because it is not apparent from the test report) that undissolved LCAA may have been present in the test medium and that there was the potential for physical (rather than toxicity) effects to occur.

For studies using multi-constituent substances it is possible to interpret the results on the basis of measured dissolved concentrations of the LCAA constituents but they cannot be directly related to the concentration of the multi-constituent substance itself. This is because the test medium does not contain dissolved concentrations of the constituents in the same ratio as present in the substance itself. The toxicity data for mixed carbon chain length LCAAs are therefore also expressed using different conventions. Where the effect concentrations occurred at concentrations below the solubility limit of a multi-constituent substance they are reported as nominal or measured concentrations and are again identified as EC50 or LC50 values. In cases where the test media were WAFs, or where the loading of a multi-constituent substance exceeded the solubility of one or more of its constituents, the result is reported either as an LL50 or EL50, denoting that the test medium was a Water Accommodated Fraction (WAF), or by a note indicating that the test substance loading exceeded the solubility limit of the multi-constituent substance. Once again in the latter case it has had to be assumed (because it is not apparent from the test report) that undissolved LCAA may have been present in the test medium and that there was the potential for physical (rather than toxicity) effects to occur.

In Section 4 it was highlighted that biodegradation is likely to be a significant loss mechanism from aquatic media for the LCAAs under review. If loss of test substance from aquatic test media is significant it will undermine the results of tests where analysis of exposure was not performed. For example, exposure concentrations of octan-1-ol (No. 111-87-5) in a 7-day test with the fathead minnow (Pimephales promelas) declined by >90% in the unspecified period between media renewals (Pickeringet al., 1996). However the NOEC has been expressed relative to nominal concentrations and must represent a significant overestimate of the true value and therefore an underestimate of the true toxicity. Similarly, the exposure concentration of the same substance that corresponded to the NOEC determined in a 21-day semi-static long-term test withDaphnia magna, declined by >35% over the 3-4 day period between media renewals (Kuhnet al., 1989). This suggests that exposure concentrations, expressed as nominal values, would have significantly overestimated the actual concentrations. The above examples highlight that test results expressed only in terms of nominal concentrations must be treated with considerable caution and may underestimate the toxicity of the substance.

Where there were no available data for a linear LCAA the data has been read-across (see CSR section 1.4) from reliable data for the closest linear alcohols with a smaller carbon chain length.

For multi-constituent substances lacking measured short-term toxicity data, the data has been read-across from the major constituent linear LCAAs in cases where these formed >90% of the multi-constituent substance. This approach is deemed valid because it is considered very unlikely that the minor constituents present at <10% will contribute significantly to short-term effects. This approach has not been adopted for long-term toxicity data because here the potential for the minor constituents to contribute to effects is much greater.

In the absence of suitable read-across data for linear and multi-constituent LCAAs, validated QSAR methods have also been developed to fill data gaps for short-term toxicity to fish and invertebrates. QSARs for linear alcohols have also been developed to fill data gaps for long-term toxicity to invertebrates.

References:

Kuhn, R., Pattard, M., Pernak, K., and Winter, A. (1989). Results of the harmful effects of water pollutants to Daphnia magna in the 21 day reproduction test. Wat. Res. 23(4): 501-510.

Pickering, Q.H., Lazorchak, J.M., and Winks, K.L. (1996). Subchronic sensitivity of one-, four-, and seven-day-old fathead minnow (Pimephales promelas) larvae to five toxicants. Environ. Toxicol. Chem. 15(3): 353-359.