Docosan-1-ol

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2000-05-08 to 2000-05-12

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

The study was conducted according to the appropriate OECD guideline and was compliant with GLP. No analytical monitoring was carried out.

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

yes

Remarks:

to allow for testing with filtered WAFs; the test substance was not quantified in the test medium

Qualifier:

according to guideline

Guideline:

EU Method C.1 (Acute Toxicity for Fish)

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)

- Method: 20 g of test substance was added directly to 2 litres of dechlorinated tap water with the aid of high shear mixing at approximately 7500 rpm or 10 minutes. This mixture was then added to a final volume of 20 litres of dechlorinated tap water and stirred by magnetic stirrer (vortex depth set at 25% of the water column height) for 23 hours. The mixture was then allowed to stand for 1 hour and then filtered through 0.2 pm filters to give the 1000 mg/L loading rate filtered WAF.

- Controls: dilution water

- Evidence of undissolved material (e.g. precipitate, surface film, etc): As the test medium was observed to be a cloudy white dispersion during mixing, at the end of mixing and after the 1 hour settling period, it was considered appropriate to filter the mixture to remove any undissolved test material, thus preventing any physical effects on the test fish and ensuring exposure to the bioavailable fraction only. lt was considered that careful siphoning
would not have removed the undissolved test material from the aqueous phase.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM

- Common name: rainbow trout

- Source: Brow Well Fisheries, Hebden, Nr. Skipton, Yorkshire, UK

- Length at study initiation (mean, SD): 4.5 cm (s.d=0.3), end of test value

- Weight at study initiation (mean, SD): 0.89 g (s.d=0.2), end of test value

- Feeding during test: no


ACCLIMATION

- Acclimation period: 2 weeks

- Acclimation conditions (same as test or not): same as test

- Type and amount of food: commercial trout pellets

- Health during acclimation (any mortality observed): 1% during 7 days prior to the test initiation

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Hardness:

ca. 100 mg/L as CaCO3

Test temperature:

14 degC

pH:

range: 7.9-8.1

Dissolved oxygen:

range: 9.4 - 9.9 mg O2/L

Salinity:

Not Applicable

Nominal and measured concentrations:

Nominal Loading rate: 1000 mg/L

Details on test conditions:

TEST SYSTEM

- Test vessel:

- Material, size, headspace, fill volume: 20 L glass fibre tank

- Aeration: yes, via narrow bone glass tubes

- Renewal rate of test solution (frequency): daily

- No. of organisms per vessel: 7

- No. of vessels per concentration (replicates): 2

- No. of vessels per control (replicates): 2

- Biomass loading rate: 0.31 g bodyweight/L based on weight at the end of the test


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: dechlorinated tap laboratory water

- Metals: maximum value 40 ug/L (zinc)

- Chlorine: max 0.32 mg/L total chlorine

- Alkalinity: 92 mg/L

- Ca/mg ratio: 7:1

- Conductivity: 416 uS/cm

- Intervals of water quality measurement: daily


OTHER TEST CONDITIONS

- Photoperiod: 16 h light and 8 h dark with a 20 min dawn and dusk transition period.



EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Mortalities and adverse reactions were recorded at 3, 6, 24, 48, 72 and 96 hours


TEST CONCENTRATIONS

- Spacing factor for test concentrations: limit test

- Range finding study

- Test concentrations: 0, 10, 100 and 1000 mg/L

- Results used to determine the conditions for the definitive study: 0% mortality at 1000 mg/L

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

LL50

Effect conc.:

> 1 000 other: mg/L as WAFs (water accommodated fractions)

Nominal / measured:

nominal

Conc. based on:

other: loading rate

Basis for effect:

mortality (fish)

Details on results:

- Behavioural abnormalities: none observed

- Mortality of control: 0%

- Effect concentrations exceeding solubility of substance in test medium: the test was conducted at concentrations above the limit of solubility of the test substance. The exposures were conducted via a loading rate of WAFs.

Reported statistics and error estimates:

No statistical analysis was carried out as no mortalities was observed.

Validity criteria fulfilled:

yes

Conclusions:

A 96 h LL50 value of >1000 mg/L loading rate (filtered WAFs) was determined for the effects of the test substance on mortality of the freshwater fish O. mykiss. This value is much higher than the limit of solubility of the test substance, therefore the result should be treated with caution and the LL50 is >LoS (limit of solubility).

Description of key information

Short-term toxicity to fish: LC50 96h >1000 mg/L (WAF) (non-toxic at the limit of solubility) for the effects of docosan-1-ol on mortality of Oncorhynchus mykiss, in accordance with guideline OECD 203.

Additional information

A 96 h LC₅₀ value of >1000 mg/L tested with Water Accommodated Fractions (WAFs) has been calculated for the effects of docosan-1-ol on Oncorhynchus mykiss (Safepharm, 2000). This result signifies that the test substance is not expected to be toxic at the limit of solubility. Due to the very low water solubility of the substance, the test was conducted with WAFs. The WAFs used in this study were filtered.

This is the only experimental value available for this endpoint and therefore has been selected as key.

Additionally, a 96 h LC₅₀ value of >100 mg/L has been calculated for the effects of docosan-1-ol on fish (Fisk et al. 2009). This result signifies that the test substance is not expected to be toxic at the limit of solubility, i.e. the LC₅₀ is >0.001 mg/L. 

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

Single constituent LCAAs

The toxicity of the single carbon number chain length LCAAs increases from an LC₅₀ of 97 mg/L for C6 to 1.0 mg/L for C12. At higher carbon number chain lengths there is an absence of short-term toxicity (LC₅₀ values are reported as being greater than the highest test concentration or higher than the water solubility of the test substance) and this is explained by the water solubility of an LCAA limiting its bioavailability, such that a toxic concentration for short-term exposure is not achieved.

The results of a 7-day, semi-static toxicity test with 1-octanol using Pimephales promelas larvae aged 1, 4 and 7 days at the start of the study have also been reported by Pickering et al., 1996. NOECs based on nominal concentrations were 1.5-11.9 mg/L for survival. Measured concentrations in the test were reduced to non-detectable levels in most test vessels in the old media. The poor maintenance of exposure concentrations means that the reported NOEC values are almost certainly underestimates of the true toxicity of the substance. The results of this test are also discussed later with respect to long-term toxicity.

Multi-constituent LCAAs

The data for multi-constituent substances of different carbon chain length LCAAs (commercial products) show that substances containing LCAAs with carbon numbers in the ranges of C8-10 and C6-12 exert short-term toxic effects at concentrations of between 0.7 and 10 mg/L. At these concentrations, all the constituents are likely to have been fully dissolved.

In contrast, multi-constituent substances - Alcohols, C12-13; Alcohols, C12-13-branched and linear and Alcohols, C12-15-branched and linear - exhibited effects at loading rates where not all constituents were fully dissolved. Under such circumstances the presence of retained undissolved test material, such as occurred in the Shell Toxicology Laboratory (1978a) test, opens up the possibility for physical fouling of the test organism and this needs to be kept in mind when interpreting the result. The multi-constituent substances containing LCAAs with carbon chain length C12 and above did not exhibit short-term toxicity effects at loading rates where the solubility of the constituent LCAAs was exceeded.

The data for nonanol, branched and linear, decanol branched and linear, decanol branched and undecanol branched alcohols, have been read-across from their linear alcohols counterparts (C9, C10 and C11) since they are essentially linear alcohols.

Alcohols, C14-15 ecotoxicity assessment is based on weight of evidence from two studies; Shell Internationale Chemie (1973) and Shell Toxicology Lab (1978a). Both studies report the LC₅₀ to be above the limit of solubility. The Shell Internationale Chemie (1973) study tested the toxicity of the substance via the WAF preparation method (the preferred method of testing with poorly soluble mixtures) however it does not report complete information on the study methods and conditions. The Shell Toxicology Lab (1978a) did not utilise WAF methods but it is reported more comprehensively.

The results for both single carbon number LCAAs and the multi-constituent substances indicate that, for fish, there is a short-term toxicity cut-off for LCAAs with carbon numbers >C14.