2,4,7,9-tetramethyldec-5-yne-4,7-diol

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

1992

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

adopted 1984

GLP compliance:

yes

Specific details on test material used for the study:

Identification 2,4,7,9-Tetramethyl-5-decyne-4,7-diol
CAS RN 126-86-3
Description White solidified mass
Batch 11029
Purity 98.3 %
Test substance storage: In refrigerator in the dark
Stability under storage conditions : Stable
(up to 40°C)
Expiry date: 21 June 2000 (allocated by NOTOX, 1 year after receipt of the test substance

Analytical monitoring:

yes

Details on sampling:

During the final test samples were taken from three concentrations, i.e. 1.0, 10 and 100 mg/l
and the negative control at t=0 h and 72 h.

Details on test solutions:

The batch of 2,4,7,9-TETRAMETHYL-5-DECYNE-4,7-DIOL tested was a 98.3% pure, white
solidified mass and completely soluble in test medium at the concentrations tested. Preparation
of test solutions started with heating the test substance for approximately one hour in a water
bath at 90 °C. The appearance of the substance changed to a clear yellow viscous liquid.
Immediately after pre-heating, the test substance was used to prepare solutions at 100 mg/l in
test medium. Magnetic stirring was applied to dissolve the test substance in the test medium.
The 100-mg/l solutions were used to prepare the lower test solutions by dilution. The final test
solutions were all clear and colourless. After preparation, volumes of 50 ml were added to each
replicate of the respective test concentration.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

Algae stock cultures were started by inoculating growth medium with algal cells from a pure culture on agar. The suspensions were continuously aerated and exposed to light (4000-9000 lux) in a climate room at a temperature of 23 + 2°C.
Preculture: 3 days before the start of the test, cells from the algal stock culture were inoculated in culture medium at a cell density of 2.104 cells/ml. The pre-culture was maintained under the same conditions as used in the test. The cell density was measured immediately before
use.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

Hardness (Ca+Mg) 0.24 mmol/l (24 mg CaCO3/l)

Test temperature:

23 +/- 2 °C

pH:

t = 0 hours: 8.0 to 8.1
t = 72 hour: 8.0 to 10.2

Nominal and measured concentrations:

nominal concentrations: 1.0, 2.2, 4.6, 10, 22, 46 and 100 mg/L
Measured concentrations were > 100 % of nominal in all samples analysed. Based on a recovery experiment simultaneously performed, the measured values indicated that the actual concentrations were in agreement with nominal and remained stable during the test period.

Details on test conditions:

Controls: Test medium without test substance or other additives (blank).
Replicates:
3 replicates of each test concentration.
6 replicates of the blank control.
1 replicate of the highest concentration without algae

Test vessels: 100 ml, all-glass
Milli-Q water: Tap water purified by reverse osmosis and then
passed over activated carbon and ion-exchange
cartridges (Millipore Corp., Bedford, Mass., USA).

Medium: M2-medium according to the ISO-Standard "Algal
growth inhibition test" Nov. 1989; formulated using
Milli-Q water preventing precipitation

Cell density: A volume of 0.67 ml of an algal suspension was
added to each replicate providing a cell density of 10E4
cells/ml.
Test duration: 72 hours

Illumination:Continuously using TLD-lamps of the type 'GroLux' of
30 Watt (Sylvania) yielding 3300-3700 lux, with a light
intensity within the range of 60 to 120 CL~.m-2.sn-o',t
varying by more than 20%.

Incubation: During incubation the algal cells were kept in
suspension by continuous shaking.

At the beginning of the test, cells were counted by microscope, using a counting chamber.
Thereafter cell densities were determined by spectrophotometric measurement of samples at
720 nm using a Lambda Spectrophotometer (Perkin-Elmer, Illinois, USA), with a cuvette of 5 cm
path-length. Algal medium was used as blank

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

39 mg/L

95% CI:

>= 19 - <= 81

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: based on the data recorded during the last 48 hours of exposure (24-72h)

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

82 mg/L

95% CI:

> 39 - <= 170

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

15 mg/L

95% CI:

> 7 - <= 31

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1 mg/L

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1.8 mg/L

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

15 mg/L

Basis for effect:

biomass

Details on results:

A more time related response appeared by comparison of the reduction of growth rate for
different time intervals.

For the total test period, the EC50 for growth rate reduction (ErC50: 0-72h) was 82 mg/l with a
95 % confidence interval ranging from 39 to 170 mg/l. The EC10 for growth rate reduction
(ErC10: 0-72h) was 15 mg/l with a 95 % confidence interval ranging from 7 to 30 mg/l.

However, based on the data recorded during the last 48 hours of exposure (24-72h) the EC50
for growth rate reduction (ErC50: 24-72h) was 39 mg/l with a 95 % confidence interval ranging
from 19 to 81 mg/l. The EC10 for growth rate reduction (EC10: 24-72h) was not different from
the (ErC10: 0-72h): 15 mg/l with a 95 % confidence interval ranging from 7 to 31 mg/l.

The NOEC for cell growth inhibition and growth rate reduction was 1.0 mg/l. However, a
recovery of growth was observed during the last 48 hours of exposure with a NOEC of 4.6 mg/l
for growth rate.

Reported statistics and error estimates:

For determination of the NOEC and the ECS0 the approaches recommended in the OECD
guideline (201, adopted 7 June 1984) were used. An effect was considered to be significant if
statistical analysis of the data obtained for the test concentrations compared with those
obtained in the negative control revealed significant reduction of growth or inhibition of growth
rate (ANOVA, Tukey test, Williams' test, TOXSTAT Release 3.5, 1996, D.D. Gulley, A.M.
Boelter, H.L. Bergman). Additionally, the EC10 was determined to meet the recommendations as
put down in "A Review of Statistical Data Analysis and Experimental Design in OECD Aquatic
Toxicology Test Guidelines" by S. Pack, August 1993.

2,4,7,9-Tetramethyl-5-Decyne-4,7-Diol affected growth of the
fresh water algae species Selenastrum capricornutum
significantly at 2.2 mg/l and higher. The NOEC for cell
growth inhibition and growth rate reduction was 1.0 mg/l.
However, a recovery of growth was observed during the last
48 hours of exposure with a NOEC of 4.6 mg/l for growth
rate. 

 19 to 81).

Validity criteria fulfilled:

yes

Remarks:

The pH-value deviated by more than 1.5 units during the test in the lowest dose levels and the solvent control, but this was related to a relatively high rate of algal growth. Hence, this deviation did not affect the validity criterion for algal growth.

Conclusions:

2,4,7,9-Tetramethyl-5-Decyne-4,7-Diol affected growth of the fresh water algae species Selenastrum capricornutum significantly at 2.2 mg/l and higher. The NOEC for cell growth inhibition and growth rate reduction was 1.0 mg/l. However, a recovery of growth was observed during the last 48 hours of exposure with a NOEC of 4.6 mg/l for growth rate.

Executive summary:

 

2,4,7,9-Tetramethyl-5-Decyne-4,7-Diol affected growth of the fresh water algae species Selenastrum capricornutum significantly at 2.2 mg/l and higher. The NOEC for cell growth inhibition and growth rate reduction was 1.0 mg/l. However, a recovery of growth was observed during the last 48 hours of exposure with a NOEC of 4.6 mg/l for growth rate. The batch of 2,4,7,9-Tetramethyl-5-Decyne-4,7-Diol tested was a 98.3 percent pure, white solidified mass and was completely soluble in test medium at the concentrations tested. Preparation of test solutions started with heating the test substance for approximately one hour in a water bath at 90 degrees C. The appearance of the test substance changed to a clear yellow viscous liquid. After a range-finding test, a final test was performed exposing exponentially growing algal cultures to 2,4,7,9-Tetramethyl-5-Decyne-4,7-Diol concentrations ranging from 1 to 100 mg/l, increasing with a factor of 2.2. The initial cell density was 104 cells/ml. The total test period was 72 hours. Samples for analysis were taken at 1.0, 10 and 100 mg/l at the start and the end of the test. Measured concentrations were greater than 100 percent of nominal in all samples analysed. Based on a recovery experiment simultaneously performed, the measured values indicated that the actual concentrations were in agreement with nominal and remained stable during the test period. A more time related response appeared by comparison of the reduction of growth rate for different time intervals. For the total test period, the EC50 for growth rate reduction (ErC50: 0-72h) was 82 mg/l with a 95 percent confidence interval ranging from 39 to 170 mg/l. The EC10 for growth rate reduction (ErC10: 0-72h) was 15 mg/l with a 95 percent confidence interval ranging from 7 to 30 mg/l. However, based on the data recorded during the last 48 hours of exposure (24-72h) the EC50 for growth rate reduction (ErC50: 24-72h) was 39 mg/l with a 95 percent confidence interval ranging from 19 to 81 mg/l. The EC10 for growth rate reduction (ErC10: 24-72h) was not different from the (ErC10: 0-72h): 15 mg/l with a 95 percent confidence interval ranging from 7 to 31 mg/l.

Description of key information

For the total test period, the EC50 for growth rate reduction (ErC50: 0-72h) was 82 mg/l with a
95 % confidence interval ranging from 39 to 170 mg/l. The EC10 for growth rate reduction
(ErC10: 0-72h) was 15mg/l with a 95 % confidence interval ranging from 7 to 30 mg/l.

However, based on the data recorded during the last 48 hours of exposure (24-72h) the EC50
for growth rate reduction (ErC50: 24-72h) was 39 mg/l with a 95 % confidence interval ranging
from 19 to 81 mg/l. The EC10 for growth rate reduction (ErC10: 24-72h) was not different from
the (ErC10: 0-72h): 15 mg/l with a 95 % confidence interval ranging from 7 to 31 mg/l.
The NOEC for cell growth inhibition and growth rate reduction was 1.0 mg/l. However, a
recovery of growth was observed during the last 48 hours of exposure with a NOEC of 4.6 mg/l
for growth rate.

Key value for chemical safety assessment

EC50 for freshwater algae:

82 mg/L

EC10 or NOEC for freshwater algae:

15 mg/L