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The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

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Toxicity to microorganisms

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toxicity to microorganisms, other
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
The study was conducted according to an appropriate OECD test guideline, and in compliance with GLP. The study is considered reliable without restriction.
Principles of method if other than guideline:
Method: other: OECD Oxygen Consumption Test
GLP compliance:
Analytical monitoring:
not specified
Test organisms (species):
Pseudomonas putida
Key result
30 min
Dose descriptor:
Effect conc.:
> 10 000 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
activated sludge respiration inhibition testing
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
The hypothesis is that the category members have similar structures and properties (lack of inhibitory effects in aquatic microorganisms up to the limit of solubility), which are consistent across the category (Scenario 6 in the RAAF). The consistency of this property across the category is discussed in the endpoint summary.

Please refer to the test material identity information within each endpoint study record.

The long chain linear aliphatic alcohol Category has at its centre an homologous series of increasing carbon chain length alcohols. The category members are structurally very similar. They are all primary aliphatic alcohols with no other functional groups. The category members are linear or contain a single short-chain side-branch at the 2-position in the alkyl chain, which does not significantly affect the properties (‘essentially linear’). The category members have saturated alkyl chains or contain a small proportion of naturally-occurring unsaturation(s) which does not significantly affect the properties. The branched and unsaturated structures are considered to have such similar properties that their inclusion in the category is well justified.
Impurities: Linear and/or ‘essentially linear’ long chain aliphatic alcohols of other chain lengths may be present. These are not expected to contribute significantly to the properties in respect of this endpoint due to consistent properties (see point 3).
There are no impurities present at or above 1% which are not category members or which would affect the properties of the substance.

The category members are structurally very similar (see point 2) and are biochemically very similar. The metabolic synthesis and degradation pathways are well established. This Category is associated with a consistency and predictability in the physicochemical, environmental, and toxicological property data across its members.

The consistency of observations in this property across the range of chain lengths covered by this Category is described in the Endpoint Summary and in the Category Report attached in Section 13.

In this registration, the information requirement is fulfilled by read-across from octadecan-1-ol, a neighbouring member of the category with shorter chain length and very similar chemical properties, for which the comparability is strongest (in view of the similar physico-chemical properties of the source and target substances).

A data matrix for the C6-24 alcohols Category is attached in Section 13.
Reason / purpose for cross-reference:
read-across source
30 min
Dose descriptor:
Effect conc.:
> 10 000 mg/L

Description of key information

Inhibition of WWTP microorganisms (Docosan-1-ol): no significant inhibitory effects on respiration of activated sludges or specific microbial strains relevant to WWTP, at or above the limit of solubility (based on inhibition tests and lack of toxicity in ready biodegradability tests).

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
10 000 mg/L

Additional information

In accordance with Column 2 of REACH Annex VIII, the activated sludge respiration inhibition study (required in Section 9.1.4 of REACH) does not need to be conducted as the substance is readily biodegradable and the applied test concentrations are in the range that can be expected in the influent to a sewage treatment plant. Reliable studies are available within the C6-24 alcohols category, for the species Pseudomonas putida. Octadecan-1-ol has EC0 of 10000 mg/l in the single-strain study; i.e. the EC50 is greater than the limit of solubility (Kirch, 1994).

This is supported by results of non-assignable reliability studies with shorter chain-lengths within the C6 -24 Alcohols Category, indicating EC50in the hundreds of mg/l (in some cases, up to and exceeding the limit of solubility) for respiration of a mixed microbial culture.


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


A number of studies of the toxicity of LCAAs to single species of micro-organisms have been identified. A range of results are shown in Table 7.21 of the Category CSR, for test species relevant to WWTP (studies on various other organisms are also available).


The ready biodegradation studies (Federle, 2009 and Flach, 2012, discussed in Section 5.2.1) gives evidence that rapid biodegradation by aquatic activated sludge microorganisms is seen, even in the presence of an excess of test substance (for the longer chain length category members tested). It is notable that the biodegradation in the ready test was very high compared to ThCO2, indicating that over the course of the test the exposure of organisms to test substance must have been complete.


At or above the limit of solubility, the data set shows that the alcohols in the chain length range C6-24 category have no significant inhibitory effects on respiration of activated sludges or specific microbial strains relevant to WWTP. There is limited evidence of inhibition of growth in some specific microbial strains but ready biodegradation evidence suggests this is not significant for mixed populations.

The reliability of some of these data individually is not high, but it presents a consistent weight of evidence.


In general it can be said that the micro-organisms examined in these tests were less susceptible to the LCAAs than fish, invertebrates and algae and that in general, IC50values for respiration effects are at or significantly above the limit of water solubility.


WWTP microorganisms have been demonstrated to be capable of synthesising significant concentrations of aliphatic alcohols (e.g. Mudge et al., 2008).


Mudge, S. M., Belanger, S. E., Nielsen, A. M., (2008). Fatty Alcohols — Anthropogenic and Natural Occurrence in the Environment. Royal Society of Chemistry, London, UK. ISBN 978-0-85404-152-7.