Octan-1-ol

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

Study conducted according to sound scientific principles, no GLP or details on analytical monitoring conducted are reported.

Qualifier:

according to guideline

Guideline:

other: Federal Environment Agency (1984)

Deviations:

yes

Remarks:

analyitcal monitoring sampling days were reduced to 2.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Deviations:

not specified

GLP compliance:

not specified

Analytical monitoring:

yes

Details on sampling:

- Sampling method: Samples were taken twice from selected concentration levels of the test series during the test period and analysed chemically. The first sampling was taken before the 7th day previous to any offspring appearance, the second sample was taken between day 16 and day 21. No further details on analytical methods were presented.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: the test substance was dispersed to make up a stock solution of 200 mg/L, then gradual serial dilutions (corresponding to a ratio of 1:2) of the stock solution were made to produce the concentration range tested.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM

- Common name: water flea

- Strain: IRCHA

- Age of parental stock: maintained in accordance with the procedure practised since 1978

- Feeding during test

- Food type: Tetramin-Haupfutter (fish feed) and activated sludge.


ACCLIMATION

- Type and amount of food: dry algae Scenedsmus spp. 9g of feed were suspended in 1000 mL tap water and 2 mL were added to each 2 L cultures.

- Feeding frequency: daily



METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES: pipette

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Test temperature:

25 +/- 1 C

pH:

average: >7

Dissolved oxygen:

>69%

Nominal and measured concentrations:

Nominal: 0.4 to 50 mg/L

Details on test conditions:

TEST SYSTEM

- Test vessel: beakers

- Material, size, fill volume: 400 ml glass beakers filled with 250 mL test water.

- Aeration: none

- No. of organisms per vessel: 5

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

- No. of vessels per control: 4

- Biomass loading rate: 1 animal/50ml


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: deionised water was used to prepare standard artificial medium (synthetic fresh water) as stated by DIN - German Institute of Standardisation

- Culture medium different from test medium: yes, culture medium was de-chlorinated tap water

- Intervals of water quality measurement: 3 times / week


OTHER TEST CONDITIONS

- Photoperiod: 7am to 4pm

- Light intensity: fluorescent lamps - Philis TL 40/25W


EFFECT PARAMETERS MEASURED: mortality, reproduction rate and appearance of offspring, daily.

Reference substance (positive control):

no

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

1 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

other: Mortality, reproduction rate, and appearance of offspring

Details on results:

- Mortality of parent animals: 7.1%

- Time to first brood release or time to hatch: 7-8 days for the appearance of first offpsring.

- Brood size: 88 offspring

Reported statistics and error estimates:

Student's t-test and U-test for deterimining the NOEC of reproduction rate and parent mortality.

Primarily, the results were expressed with reference to the nominal concentration. If however, the chemical analysis showed a loss of tested 

substance greater than 20%, then the lowest analysed concentration (minimum value) obtained during the test was also reported for the NOEC.
The 21-d NOEC based on nominal concentrations was 1.6 mg/L.
The 21-d NOEC based on the minimum value for 1-Octanol was 1.0 mg/L.

The most sensitive endpoint was the appearance of first offspring.

Validity criteria fulfilled:

yes

Conclusions:

A reliable 21 day reproduction NOEC value of 1.0 mg/L has been determined for the effects of the test substance on reproduction and survival of the freshwater test organism Daphnia magna.

Description of key information

Long-term toxicity to invertebrates: 21 d NOEC: 1 mg/L (measured) for the effects of the test substance on mortality of Daphnia magna (guideline: Federal Environment Agency (1984)).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

1 mg/L

Additional information

A reliable 21 day reproduction NOEC value of 1.0 mg/L has been determined for the effects of octan-1-ol (CAS 111-87-5) on reproduction and survival of the freshwater test organism Daphnia magna. An EC₁₀ value was not reported (Kuhn et al., 1989). The study reflects the only reliable value that is available for this endpoint and has been selected as key.

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.