Octadecan-1-ol

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1999-10-13 to 1999-12-22

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Remarks:

The study was conducted according to a national standard method, in compliance with GLP and analytical monitoring was carried out.

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1300 (Daphnid Chronic Toxicity Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

no

Details on sampling:

See table 1 for details.

Vehicle:

no

Details on test solutions:

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

- Method: The proportional diluter stock solutions (ca. 100 ug a.i./L) were prepared at 12 h intervals by adding 60 uL, ca. 48.2 ug a.i./L, of the test substance to 200L of silution water in a 220 L stainless steel drum and stirring continuously. After 1 h of stirring the drum wsa connected to the pump and fed to the proportional diluter system. the test solutions were flowing to the test chambers for 7 days prior to the definitive test initiation.

- Controls: dilution water only

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM

- Source: ABC laboratories in house culture

- Age of parental stock (mean and range, SD): The adults which produced the neonates used in the definitive test were approx. 19 days old and had produced at least 4 brood periods. The adults whcih produced the neonates used in the definitive test were appro. Neonates (<24 h old) collected from a subculture on October 15, 1999, were used for test initiation.

- Feeding during test

- Food type: algal suspension (S. capricornutum and A. falcatus) with each diluter cycle. Before test termination 1 ml of 5 mg/ml suspension of an artificial invertebrate diet was supplemented.

- Amount: 5.88 x 10^4 cells/ml average.

- Frequency: supplemented twice a day

ACCLIMATION

- Acclimation period: 24 h

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

- Type and amount of food: algae (S. capricornutum and/or A. falcatus) supplemented by a prepared artificial invertebrate food
- Feeding frequency:

- Health during acclimation (any mortality observed): no ephippia erre produced in the subculture, mortalities not reported.


METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES: transfer of neonates was done with a large-bore glass pipet into 24 numbered containers, the contents of the container were then added to the beakers by submierging th containers in the solution and slowly pouring the contents into the beaker.

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Hardness:

124 mg/l as CaCO3 (average)

Test temperature:

20 degrees C +/- 2

pH:

range: 8.10-8.49

Dissolved oxygen:

lowest measurement 7.87 mg/L, 5.2 mg/L represents 60% of saturation

Nominal and measured concentrations:

Nominal concentrations: 6.3, 13, 25, 50 and 100 ug a.i./L
Measured concentrations: 1.46, 5.54, 7.65, 20.6 and 47.6 ug a.i./L

Details on test conditions:

TEST SYSTEM

- Test vessel: 1 L glass beakers

- Type (delete if not applicable): covered with stainless steel mesh to prevent the daphnids from escaping

- Material, size, headspace, fill volume: glass flow splitting cells were used to thoroughly mix and divide each test concentration for delivery to the exposure chambers. each exposure chamber measured approx. 10 cm inside diameter by 15 cm in height. Solution depth was approx. 12 cm, for a volume of approx. 1000 ml.

- Aeration: before delivery to the diluter the water was aerated

- Type of flow-through (e.g. peristaltic or proportional diluter): intermittent proportional diluter

- Renewal rate of test solution (frequency/flow rate): 1 L volumen an average of 10 times in a 24 h period.

- No. of organisms per vessel: 10

- No. of vessels per concentration (replicates): 4

- No. of vessels per control (replicates): 4


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: natural surface water collected from Perche Creek near Columbia, Missouri. The natural surface water was diluted with laboratory freshwater (a blend of well water and reverse osmosis water). The diltuion water was passed through an ultraviolet irradiator before being delivered to the proportional diluter.

- Total organic carbon: 2.14 mg/l

- Alkalinity: 97 mg/L as CaCO3

- Conductivity: 230 uS/cm

- Culture medium different from test medium: not reported

- Intervals of water quality measurement: once a week pH and DO, temperature was checked daily.


OTHER TEST CONDITIONS

- Adjustment of pH: not reported

- Photoperiod: 16 h light 8 h darkness

- Light intensity: 656-773 lux


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : observation of abnormal physical appearance, neonate production, and mortality/immobility were recorded daily by visual inspection of each replicate test chamber. Dead/immobile daphnids, if present, were removed and discarded each day. After first brood release in the control on day 7, neonates were collected on a Monday, WEdnesday and Friday, by gently removing the adults from each beaker.


RANGE-FINDING STUDY

- Test concentrations: not conducted

- Results used to determine the conditions for the definitive study: test concentrations were selected on the basis of the estimated water solubility and preliminary analytical work.

Reference substance (positive control):

no

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

20.6 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

47.6 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

> 47.6 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

other: reproduction and survival

Details on results:

See table 2 for further details.

- Mortality of parent animals: 5% in control, 2.5% in treatments, no statistical difference between treatment and controls

- No. of offspring produced per day per female: control: 12.65, 13.27 at 1.46 ug/L, 6.78 at 47.6 ug/L

- Time to first brood release or time to hatch: day 7 for control and concentrations =<20.6 ug/L, 8 days at 47.6 ug/L

- Brood size: the total number of young produced by first generation daphnids exposed ranged from 7960 at 1.46 ug/L to 3702 at 476. ug/L, 7513 in controls.

Reported statistics and error estimates:

statistical analysis was carrid out using SAS for Windows (6.12). Fisher's exact test, Dunnett's test were conducted. EC50s could not be determined.

Table 2. Summary of reproductive and survival parameters (averages of replicates).

 

Mean measured concentration (µg a.i./L)	Cumulative % immobilisation	Day of first brood	Number of adult reproduction days	Number of young produced	Number of young per reproductive day
Control	5	7	594	7513	12.65
1.46	0	7	600	7960	13.27
5.54	2.5	7	587	7430	12.68
7.65	2.5	7	592	7718	13.05
20.6	2.5	7	597	6909	11.57
47.6	2.5	8	546	3702	6.78*

 

* Significantly lower than the control

 

Table 3. Measured concentrations of PMN P98-963 during a 21 day exposure to D. magna.

 

Nominal test concentrations (µg a.i./L)	Measured concentration (µg a.i./L)
	Day ¿N*	Day 0	Day 3	Day 7	Day 10	Day 14	Day 17	Day 21	Mean
Control	2/38	1.17	1.17	2.2	2.4	2.48	1.93	2.39	1.96
6.3	0.78	1.9	0.36**	2	0.98***	0.56	2.3**	2.09	1.46
13	5.8	5.09	3.42**	7.55	NS	4.51	NS	7.14	5.54
25	9.22	7.26	NS	12.0	6.52**	5.78	NS	6.69	7.65
50	20.7	18.2	NS	27.6	NS	16.5	23.3**	17.3	20.6
100	43.1	37.7	35.4**	59.5	46.6**	41.3	63.9**	48.5	47.6
100 stock	60.6	56.6	NS	94.2	NS	74.8	NS	65.1	72.7

 

** value not included in calculation of means

*** mean of four replicate values

NS not sampled

Validity criteria fulfilled:

yes

Conclusions:

A reliable 21 d NOEC(reproduction) value of 20.6 ug a.i./L has been determined for the effects of octadecanol branched on the number of reproductive young produced per day of the freshwater cladoceran Daphnia magna.

Reference 2

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

other: experimental result for constituent C15 of multiconstituent substance

Adequacy of study:

key study

Study period:

2005-04-20 to 2005-05-13

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to the appropriate OECD test guideline, and in compliance with GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Deviations:

yes

Remarks:

to allow aeration of the vessels, test media eas prepared daily, water changes occured daily, daphnia were carefully rinsed at each water change

Principles of method if other than guideline:

Deviations from the guideline was as follows: due to the unavoidable biodegradation process caused by the presence of algae (daphnia feed), severe oxygen depletion occurred, cautious aeration with sterile filtered air was implemented in order to overcome this.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: All the test concentrations were sampled for chemical analysis three times a week at renewal of the test media.

- Sampling method: A 500 mL aliquot of the fresh solutions was used for analysis. After 24 h, at the next renewal, the aged test liquids were pooled (vessels 1- 5 and  6-10) and analysed. 

Vehicle:

yes

Details on test solutions:

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

- Method: Test solutions were prepared daily by stirring the test substance in test media under slow stir conditions (21 h) in sterilized mixing vessels. The mixing vessels were cylindrical brown glass bottles with teflon covered screw caps, fitted with a drain port near the bottom for drawing off the test solution. The volume of the mixing vessels was 2 L. After stirring, the contents of the vessels were left to settle for 2 h. The saturated aqueous phase was then taken out of the drain port. The first fraction 0-100 mL was withdrawn. The fraction between 100 and 1800 mL was used for rinsing (200 mL) and filling (1000 mL) the test flasks for toxicity testing and for analytical measurements (500 mL), if done. Rinsing of the test vessels was carried out to saturate the surfaces of the test vessels. After filling, the vessels were closed immediately by using autoclaved silicone stoppers and only opened to introduce the test organisms and again at the renewals of the test media. The test media were not stored for more than 1 - 2 hours prior to testing.

- Controls: controls were prepared as an ethanolic stock solution using dilution water.

- Chemical name of vehicle (organic solvent, emulsifier or dispersant): ethanol

- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): 1ml in 2 L


- Evidence of undissolved material (e.g. precipitate, surface film, etc): presence of very fine undissolved particles or droplets at the higher test concentrations.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM

- Common name: water flea

- Strain/clone: Daphnia magna STRAUS

- Source: Umweltbundesamt (German Federal Environment Agency). Test organisms bred in the laboratory of the Fh-IME (testing facility).

- Age of parental stock (mean and range, SD):  4 - 24  hours old

- Feeding during test

- Food type: The Daphnia magna were fed with suspensions of unicellular green algae. The suspensions of Desmodesmus subspicatus (daily prepared from axenic cultures) were controlled analyzed for microbial contamination one and two weeks after test start by using "Cult-Dip combi® Dip Slides (Merck)". No bacterial contamination was detected. The content of food in the test suspensions, measured as turbidity at 758 nm, increased during the test from 7 mg C/L equivalents to 15 mg C/L equivalents.

- Frequency: at each water renewal.


ACCLIMATION

- Acclimation period: bred at the testing facilities

- Acclimation conditions (same as test or not): water is changed once per week instead of daily (breeding in testing facilities).

- Type and amount of food: fed with an algal suspension (Desmodesmus subspicatus) and LiquizellR (HOBBY). Algae growing in the log phase are centrifuged and the pellet is re-suspended in a few ml of medium. 30ml of this suspension is given to 1L Daphnia medium.

- Feeding frequency: daily


METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES: Newborn daphnia were separated by sieving in the breeding stage before testing.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Post exposure observation period:

none

Hardness:

total hardness of dilution water: 0.9 mmol/L

Test temperature:

The test temperature during the test was in the range 20.7 to 21.8°C

pH:

Mean: 9.2 to 9.4 at all treatment levels

Dissolved oxygen:

Range: 66 to 103% (the lowest concentration was equivalent to 5.4 mg/L)

Salinity:

Not Applicable

Nominal and measured concentrations:

Nominal test concentrations were 0, 30, 65, 139 and  300 µg test item/L. The concentrations were targeted at achieving a top concentration of 200 µg test item/L by taking into account 30% adsorption to glassware.
Mean measured concentrations of the freshly prepared test solutions were 

Details on test conditions:

TEST SYSTEM

- Test vessel:

- Type (delete if not applicable): closed with silicone stoppers

- Material, size, headspace, fill volume: Each Daphnia magna was exposed separately in a numbered vessel flask) containing 100 mL of test medium. 

- Aeration: yes

- Renewal rate of test solution: daily:

- No. of organisms per vessel: 1

- No. of vessels per concentration (replicates): 10

- No. of vessels per vehicle control (replicates): 10 (vehicle control was the only control tested)



TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: purified drinking water (filtrated with activated charcoal, passage through limestone column, aeration until oxygen saturation and autoclaved before use).

- Total organic carbon: DOC 0.0 mg/L

- Metals: Cu 0.0019 mg/L, Fe 0.0024 mg/L, Mg 0.0002 mg/L, Zn 0.0000 mg/L

- Alkalinity: 1.4-1.6 mmol/L

- Conductivity: 178-183 uS/cm

- Culture medium different from test medium: no

- Intervals of water quality measurement: every day, before and after renewal of test solution


OTHER TEST CONDITIONS

- Photoperiod: The vessels were subjected to a light/dark cycle of 16/8 hours

- Light intensity: The light intensity was in the range 568 to 659 lux.


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : The parent Daphnia magna were assessed visually daily for immobility and any other abnormalities in appearance and behaviour. At study termination, the length of the adults was measured by digital photography and image analysis and their statistics compared with those of the control animals. The newborn Daphnia magna in each beaker were counted at each daily renewal of the test solutions, inspected for abnormalities in condition, and removed. The following endpoints observed in the reproduction test were evaluated quantitatively:

o Mortality (immobility) of parental generation Daphnia magna;
o Age at first brood o Total number of offspring per replicate;
o Cumulative Number of live offspring per surviving female at the time of recording;
o Intrinsic rate of increase, r;
o Individual length of adults.



RANGE-FINDING STUDY

- Results used to determine the conditions for the definitive study: No acute Daphnia magna immobility was observed at initial concentrations of up to 500 μg/L (clearly above water solubility according to ref. 12) in non-GLP pre-tests conducted at the same testing facilities.

Reference substance (positive control):

no

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

7.8 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

cumulative number of offspring

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

19 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

cumulative number of offspring

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

12 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

cumulative number of offspring

Remarks on result:

other: (2-23 95% CL)

Duration:

21 d

Dose descriptor:

other: EC20

Effect conc.:

62 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

cumulative number of offspring

Remarks on result:

other: (33-350 95% CL)

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

> 63 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

act. ingr.

Basis for effect:

immobilisation

Details on results:

- Mortality of parent animals: 0%

- No. of offspring produced per day per female: see Table 1, no significant difference between control and exposed.

- Body length of parent animals: see Table 1, no significant difference between control and exposed.

- Time to first brood release or time to hatch: see Table 1, no significant difference between control and exposed.

- Other biological observations: it was not possible to determine an EC50 in many cases.

- Effect concentrations exceeding solubility of substance in test medium: not thought to have affected the test by the authors.

Reported statistics and error estimates:

The evaluation of the concentration-effect-relationships and the calculations of effect concentrations were based on mean measured initial concentrations as multiple peak concentrations, as well as on geometric means between mean measured initial and aged (24h) test concentrations. For each endpoint, the NOEC, LOEC, and, if possible, the EC50, EC20 and EC10 were determined. A LOEC and NOEC were calculated by ANOVA followed by Williams' test or an appropriate non-parametric test suggested by the ToxRat program. When the test results showed a concentration-response relationship, the data were analysed by regression using Probit-analysis assuming log-normal distribution of the values using the computer program ToxRat program.

Table 1: Effect of 1 -tetradecanol on growth and survival of D. magna   Treatment (μg/l) Mortality of parents Growth (length)) Age at first brood Cumulative offspring per female Intrinsic rate of increase r % Mean ± SD (mm) Mean± SD (days) Mean± SD (#) Mean ± SD (1/d) Control * 0 4.47 ± 0.32 7.8± 0.8 86.6± 5.7 0.368± 0.0319 24.4 0 4.83± 0.31 7.7± 0.7 84.0± 7.4 0.364± 0.0343 68.6 0 4.50± 0.38 8.1± 0.7 79.7± 9.4 0.347± 0.0328 185.2 0 4.49± 0.27 8.2± 0.8 73.9± 8.5 0.338± 0.0347 500 30 4.73± 0.40 7.9± 0.6 70.4± 8.2 0.338± 0.0241   *thecontrol is also the solvent control (ethanol). The daily transfer of daphnia, although rinsed thoroughly, did cause the re-introduction of bacteria, which increased in number with growth of carapace and resulted in more pronounced losses in the last two weeks of the reproduction studies.   Table 2: Nominal and measured concentrations for 21 days.   Measured concentration (μg/L) results Nominal concentration 24.4 68.8 185.2 500  Fresh media Mean* ±st. dev. (%)  10 ± 49% 51 ± 21%  138 ± 20%  367 ± 31%  Old media Mean* ±st. dev. (%) <LOQ <LOQ 1.2 ± 134% 16 ± 157%  Mean¥ % of nominal (ref. to mean) 1.6 3.6 12.7 76.7 *arithmeticmean of 3 weekly measurements ¥geometricmean of fresh and old means   Table 3.Effect concentrations relative to daily initial concentrations (based on cumulative number of offspring).   Endpoint  μgtest item/L  EC10 70   EC20 270  LOEC  51  NOEC  9.8

Validity criteria fulfilled:

yes

Conclusions:

A reliable 21 d NOEC repro value of 7.8 ug/L has been identified for the effect of the test substance on the cumulative number of offspring of D. magna.

Reference 3

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

1. HYPOTHESIS FOR THE CATEGORY APPROACH
The hypothesis is that the category members have similar structures and long-term toxicity to aquatic invertebrates effects which vary in strength across the category, forming a regular pattern (Scenario 4 in the RAAF). The interpretation of the observed trends of variation of this property across the category is discussed in the endpoint summary.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Please refer to the test material identity information within each endpoint study record and to the endpoint summary. The source chemicals and the target chemical are linear aliphatic alcohols which are members of the long chain linear aliphatic alcohol Category.

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 predictable trends (see point 3).
There are no impurities present at above 1% which are not category members or which would affect the properties of the substance.

3. CATEGORY JUSTIFICATION
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 context of trends observed 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 one or more members of the category with the same chain length, for which the comparability is strongest (in view of the similar physico-chemical properties of the source and target substances as well as similar position in terms of category trends). In addition, the information requirement is extrapolated based on read-across from members of the category with shorter chain length, providing evidence of the range of values expected for the registration substance.

4. DATA MATRIX
A data matrix for the C6-24 alcohols Category is attached in Section 13.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

20.6 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

reproduction

Remarks on result:

other: R/A from C18 branched

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

47.6 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

reproduction

Remarks on result:

other: R/A from C18 branched

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

> 47.6 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

other: reproduction and survival

Remarks on result:

other: R/A from C18 branched

Duration:

21 d

Dose descriptor:

EL10

Effect conc.:

12 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

cumulative number of offspring

Remarks on result:

other: R/A from C15 for PNEC derivation

Description of key information

Long-term toxicity to aquatic invertebrates: 21 d NOEC >LoS for effects of structural analogue octadecanol, branched on reproduction of Daphnia magna in accordance with guideline EPA OPPTS 850.1300 (Daphnid Chronic Toxicity Test). Alcohols with chain length carbon number >C15 are not expected to be toxic at the limit of solubility (expert judgement).

A 21-d EC₁₀ of 0.012 mg/l has been determined for the effects of pentadecan-1-ol (CAS 629-76-5, C15) on reproduction of Daphnia magna (Fraunhofer, 2005).

Additional information

A reliable 21-day NOEC (reproduction) value of 0.0206 mg/L (arithmetic mean measured concentration) has been determined for the effects of octadecanol branched on the number of reproductive young produced per day of the freshwater cladoceran Daphnia magna (ABC, 1999). This study has been selected as key as it is the lowest reliable value available for this substance. The water solubility of the substance has been estimated to be 0.0056 mg/L (Fisk, 2010), therefore the NOEC is above the limit of solubility (>LoS). An EC₁₀ value was not determined in the test.

This test was conducted with the closely related substance octadecanol branched (a single methyl branch group in the 2-position). This type of branched structure is termed 'essentially linear' and the physicochemical, toxicological and ecotoxicological properties and behaviour do not differ significantly between such structures and their linear analogues, which additionally have identical molecular weights. It is therefore possible to read-across between the two substances. The difference in composition is dependent on the manufacturing process which may create linear alcohols or simple mono-branched structures. Direct read-across from octadecanol branched to octadecan-1-ol (CAS 112-92-5) is scientifically justified and they should be regarded as the same substance.

In a second study, a 21 day NOEC value 0.98 mg/L has been determined for the effects of octadecan-1-ol on reproduction of Daphnia magna (Henkel, 1992).The water solubility of octadecan-1-ol is 0.0011 mg/L at 25˚C [SIDS dossier on 1-octadecanol, 1993b; Budavari, 1996], therefore the substance is non-toxic at the Limit of Solubility (LoS), i.e. >0.0011 mg/L (>LoS).

No aquatic toxicity is expected at chain lengths >C15, therefore a study on long-term toxicity of aquatic invertebrates to pentadecan-1-ol (CAS 629-76-5, C15) has been read across for the purpose of setting indicative aquatic PNECs for use in assessing risk to the sediment and terrestrial compartments, using the equilibrium partitioning method.

A 21-day EC₁₀ of 0.012 mg/l has been determined for the effects of pentadecan-1-ol (CAS 629-76-5, C15) on reproduction of Daphnia magna (Fraunhofer, 2005).

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

Linear LCAAs

Data are available from 21-day Daphnia magna reproduction tests conducted generally in accordance with standard test guideline OECD 211 with single carbon chain length alcohols: 1-octanol (Kuhn et al., 1989), 1-decanol, 1-dodecanol, 1-tetradecanol, 1-pentadecanol (Fraunhofer Institute, 2005a-d respectively) 1-octadecanol (Henkel KGaA, 1992), pentadecanol branched and octadecanol branched (ABC 1999a and 1999c respectively). Some modifications to the test guideline procedures took place in the Henkel studies in order to reduce losses of test substance due to the extensive and rapid biodegradation of the alcohols. Details of the modifications to the guideline are provided in the IUCLID dossiers and in the CSR.

 

The results of the tests are given in the table below. Summary statistics for each test are presented as both NOEC and EC₁₀. The 1-octanol and 1-octadecanol studies are reliability 2, valid with restrictions; the other studies are reliability 1.

Table      Long-term (21-d) aquatic toxicity of long chain alcohols to Daphnia magna.

Chain length	CAS	Survival EC10 (µg/L)	Reproduction EC10 (µg/L)	Water solubility (µg/L)
C8	111-87-5	1000	1000	551,000 at 25°C
C10	112-30-1	340	210	39,500
C12	112-53-8	33	13	1930 at 20°C
C14	112-72-1	130	6.3	191 at 25°C
C15	629-76-5	>63	12	102 at 25°C
C15b	N.A.	>178 (LOEC)	64 (LOEC)	0.07 mg/L (estimate)
C18	112-92-5	980* (NOEC)	980* (NOEC)	1.1 at 25°C
C18b	N.A.	>48	48	0.0056 mg/L (estimate)

EC10s are based on mean measured concentrations in fresh and old media.

* no analytical analysis performed: nominal concentration

The study with C18 determines a NOEC of 0.98 mg/L, corresponding to the lowest concentration tested. Should a lower exposure concentration have been tested, it is likely that the NOEC would also be lower.

 

A pattern of increased toxicity with increasing chain length is apparent up to C14. The NOEC and EC₁₀ values then increase from C14 to C15. This is almost certainly the result of the concentration exceeding the solubility of the substance (Rufli et al. 1998). Based on the trends observed in these data it is expected that the NOEC for long-term effects on mortality and reproduction would be above the solubility limit of linear alcohols with carbon numbers >C15 Schäfers et al. (2009).

 

This is also discussed in the attached ECOTOXICITY Alcohols C6-24 Category report.

 

 

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

Linear LCAAs

Data of an acceptable quality are available for 21-day reproduction studies with Daphnia magna for the single carbon chain length LCAAs 1-octanol (Kuhn et al., 1989), 1-decanol, 1-dodecanol, 1-tetradecanol, 1-pentadecanol (Fraunhofer Institute, 2005a-d respectively), pentadecanol branched (ABC 1999a) and octadecanol branched (ABC 1999c). The data were obtained generally in accordance with standard test guideline OECD 211. However some modifications to the normal guideline procedures were necessary to reduce losses of test substances due to the extensive and rapid biodegradation of the LCAAs. The following changes to typical protocols were therefore adopted to enable the performance of high-quality and meaningful studies:

 

Vessels were closed, to reduce entry of bacteria from the atmosphere;

Gentle aeration of test vessels was required as degradative losses of LCAAs resulted in unacceptably low dissolved oxygen concentrations;

Test solution renewals were made daily, with confirmatory analysis on both renewed and initial test solutions;

Static renewal was determined to be the best exposure regime for long chain aliphatic alcohols as this reduced the transfer of LCAAs -degrading or consuming microbes (as compared to flow-through systems, where it becomes increasingly difficult to discourage acclimation and bio film formation; see Brixham Environmental Laboratory, AstraZeneca, 2004);

Saturated alcohol stock solutions were prepared daily for each test concentration. This involved a detailed preparatory method to reduce the possibility of insoluble material being present in the tests (Fraunhofer Institute, 2005a, b);

Daphnia magna were carefully rinsed with each daily transfer to reduce bacterial cross over to fresh exposure solutions. As Daphnia magna grow in size, this becomes less effective; and,

Dilution water and test vessels were autoclaved prior to use each time (Fraunhofer Institute, 2005a, b, c, d).

 

Algae have been found to metabolize LCAAs and this is an unavoidable occurrence in long-term studies with Daphnia magna fed with algae. No modifications could be made to counter this without conducting further research into an alternative diet.

 

In spite of the guideline modifications significant losses of test substance still occurred. It was therefore necessary to report the results both in terms of the mean of the measured concentrations in the fresh media and the mean of the measured concentrations in the fresh and old media. The test substance renewal interval was 24 hours. Survival and reproduction endpoints have been summarised using standard statistical techniques. Conclusions for each test are presented as both NOEC and EC₁₀. The 1-octanol and 1-octadecanol study are reliability 2, valid with restrictions; the other studies are reliability 1.

 

The effect of LCAAs on Daphnia magna survival is generally less sensitive than the effect on reproduction. A pattern of increased toxicity with increasing chain length is also apparent. In the octanol study, the most sensitive and only reported effect was on time to first brood release which occurred at 1000 µg/L (nominal concentration). For comparison of results across chain lengths and structure activity models the response for survival and reproduction was assumed to be equal to the effect on time to first brood.

 

The data indicates that for survival and reproduction, the NOEC and EC₁₀ values increase from C14 to C15. This is almost certainly due to exceeding the limit of water solubility as would be expected from conventional toxicological theory (Rufli et al. 1998). Under these circumstances a more accurate interpretation of the results might be obtained by setting the exposure to the solubility of the substance (i.e. 49 µg/L). This has the effect of lowering the toxicity values but they are still higher than those for the C14 substance. This pattern is not in keeping with the trend of reducing short-term toxicity values (i.e. higher toxicity) observed between the C8 and C14 alcohols. Similarly, the NOEC identified for C18 is a limit value of >980 µg/L but a lower value would have been obtained if a lower loading had been tested. A more accurate NOEC would therefore be obtained by expressing it as greater than the water solubility of the test substance, which is 10 µg/L. This statement is supported by data on C15 and C15 branched, where the NOEC was not achieved at the solubility limit.

 

It must be appreciated that significant uncertainty exists in identifying the true exposure concentrations in the region of the water solubility of a substance. The water solubility values of the LCAAs category decrease with increasing chain length (see section 1.4 for further details.). In a review of aquatic toxicity testing of sparingly soluble compounds Rufli et al. (1998) point out that interpretation of toxicity responses observed above the solubility limit is aggravated by artefacts and that testing should only occur at or below the limit. For LCAAs with carbon numbers greater than C15 there are significant experimental difficulties in producing, maintaining and quantifying exposures of the test substance due to progressively lower solubility, while exceptionally rapid biodegradability would remain unchanged. This explains why there are no data for such substances.

 

However, based on the trends observed in the available data, it is expected that for linear LCAAs with carbon numbers ≥C15 the NOEC for long-term effects on mortality and reproduction would be above the solubility limit (Schäfers et al. 2009).

 

Multi-constituent LCAAs

No measured data are available for multi-constituent substances of different carbon chain length LCAAs.

 

References:

ABC Laboratories (1999a). Chronic toxicity of PMN P98-960 during the complete life-cycle of Daphnia magna under flow-through test conditions. ABC Study No. 45414. Oct.13 1999. ABC Laboratories Inc. 7200 E. ABC Lane, Columbia, Missouri 65202.

 

ABC Laboratories (1999c). Chronic toxicity of PMN P98-963 during the complete life-cycle of Daphnia magna under flow-through test conditions. ABC Study No.45658. Oct.13 1999. ABC Laboratories Inc. 7200 E. ABC Lane, Columbia, Missouri 65202.

 

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.

 

Rufli, H., P. R. Fisk, A. E. Girling, J. M. H. King, R. Lange, X. Lejeune, N. Stelter, C. Stevens, P. Suteau, J. Tapp, J. Thus, D. J. Versteeg, H. J. Niessen. 1998. Aquatic toxicity of sparingly soluble, volatile, and unstable substances and interpretation and use of data. Ecotoxicology and Environmental Safety 39 (2):72-77.

 

Fraunhofer Institute, 2005a. Daphnia magna, reproduction test in closed vessels following OECD 211. C10 fatty alcohol. GLP code: SDA-005/4-21. Fraunhofer Institute for Molecular Biology and Applied Ecology (IME) 57377 Schmallenberg, Germany.

 

Fraunhofer Institute, 2005b. Daphnia magna, reproduction test in closed vessels following OECD 211. C12 fatty alcohol. GLP code: SDA-001/4-21. Fraunhofer Institute for Molecular Biology and Applied Ecology (IME) 57377 Schmallenberg, Germany.

 

Fraunhofer Institute, 2005c. Daphnia magna, reproduction test in closed vessels following OECD 211. C14 fatty alcohol. GLP code: SDA-006/4-21. Fraunhofer Institute for Molecular Biology and Applied Ecology (IME) 57377 Schmallenberg, Germany.

 

Fraunhofer Institute, 2005d. Daphnia magna, reproduction test in closed vessels following OECD 211. C15 fatty alcohol. GLP code: SDA-002/4-21. Fraunhofer Institute for Molecular Biology and Applied Ecology (IME) 57377 Schmallenberg, Germany.

 

Schäfers, C. Boshof, U. Jürling, H. Belanger, S.E. Sanderson, H. Dyer, S.D. Nielsen, A.M. Willing, A. Gamon, K. Kasai, Y. Eadsforth, C.V. Fisk, P.R. Girling, A.E., 2009. Environmental properties of long chain aliphatic alcohols. Part 2: Structure-activity relationship for chronic aquatic toxicity of long-chain alcohols. Ecotoxicology and environmental safety. 72(4): 996-1005.