3-(2,2-dimethyl-3-hydroxypropyl)toluene

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

Study period:

25 to 28 September 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

adopted 1984

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Niedersächsiches Umweltministerium Hannover

Analytical monitoring:

yes

Details on sampling:

- Concentrations: control, 6.25, 12.5, 25, 50 and 100 mg/L. Samples were taken at start (0h) and end of the study (72h).
- Sample storage conditions before analysis: Samples were stored at 7 +/- 2°C until start of analysis, if necessary.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
-Stock solutions were freshly prepared eith test medium. For dispersion they were treated with ultrasound for 30 min at room temperature.

Test organisms (species):

Scenedesmus sp.

Details on test organisms:

TEST ORGANISM
- Common name: Scenedesmus subspicatus
- Strain: CHODAT SAG 86.81
- Source (laboratory, culture collection): Sammlung von Algenkulturen (SAG), Pflanzenphysiologisches Institut der Universität Göttingen
- Age of inoculum: A four day old preculture was used
- Method of cultivation: Fresh stocks were prepared every month an Z-Agar. Light intensity amounted 35-70 pE/m2 -s for 24 h per day

ACCLIMATION
- Culturing media and conditions (same as test or not): Nutrient medium Z according to LÜTTGE et al. (1994)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

After 72 h 0.5 mL alga suspension from the mean measured concentration levels 31 — 64 - 131 mg/L were transferred to 10 mL untreated fresh medium and allowed to grow for further 4 d to determine whether the effect of the test item was reversible.

Test temperature:

23 +/- 2°C

pH:

7.88 (0h) - 7.93 (72h) (100 mg/L)
8.04 (0h) - 8.76 (72h) (6.25 mg/L)
control: 8.01 - 8.73

Nominal and measured concentrations:

Nominal: 6.25 - 12.5 - 25 - 50 - 100 mg/L
Measured: 7.2 - 15 - 31 - 64 - 131 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Plastic cuvettes (50 mm diameter), transparent, with top, volume: 20 mL, test volume: 10 mL
- Type (delete if not applicable): open
- Initial cells density: approx. 1x10^4 cells/mL
- Control end cells density: 0h: 8825; 72h: 594880 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to guideline

OTHER TEST CONDITIONS
- Photoperiod: 24h
- Light intensity and quality: Nominally 60 - 120 µE/m2 *s (according to the EEC Guideline)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable):
- Determination of cell concentrations: [counting chamber; electronic particle counter; fluorimeter; spectrophotometer; colorimeter]: Cell density was measured via Chlorophyll-a-fluorescence (excitation at 435 nm, emission at 685 nm); Chlorophyll-impulsfluorometer (KLEINFELD)
- Chlorophyll measurement: Chlorophyll-fluorescence was determined at the beginning, after 24, 48 and 72 h

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study: yes; concentrations: 0.1, 1, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

Potassium dichromate p.a.

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

27 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

7.2 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

19 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

7.2 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): no

Results with reference substance (positive control):

- Results with reference substance valid? yes
- EC50 (growth rate): 0.85 mg/L

Reported statistics and error estimates:

Statistical analysis was performed by using SigmaPlot and SigmaStat (SPSS Inc.)

Evaluation after 72h

Statistical significant differences ov biomass integrals and growth rates compared to control values are marked (+), not significant differences are marked (-)

Test item concentration		Replicate No.	Biomass integral	Inhibition of biomass [%]	Growth rate	Rate-related inhibition [%]
Nominal [mg/L]	Mean measured [mg/L]
100	131	1	-1259	*100.00	0	*100.00
		2	-2030	*100.00	0	*100.00
		3	-1023	*100.00	0	*100.00
		Mean	(+) -1437	*100.00	(+) 0	*100.00
50	64	1	14774	96.65	0.1	92.87
		2	15813	96.42	0.1	92.64
		3	18837	95.73	0.09	93.72
		Mean	(+) 16474	96.27	(+) 0.1	93.07
25	31	1	82916	81.21	0.53	61.96
		2	79782	81.92	0.55	60.82
		3	81207	81.59	0.50	64.17
		Mean	(+) 81301	81.57	(+) 0.53	62.34
12.5	15	1	285486	35.29	1.19	15.48
		2	306440	30.54	1.24	11.70
		3	281028	36.3	1.23	12.37
		Mean	(+) 290984	34.04	(+) 1.22	13.2
6.25	7.2	1	470588	-6.67	1.43	-1.93
		2	489754	-11.02	1.45	-3.37
		3	472132	-7.02	1.42	-1.46
		Mean	(+) 477490	-8.24	(-) 1.44	-2.25
Control		1	435230		1.37
		2	435645		1.37
		3	435749		1.39
		4	426952		1.39
		5	465184		1.46
		6	448183		1.46
		Mean	441158		1.40

 inhibitions > 100 are given as 100.00

Validity criteria fulfilled:

yes

Conclusions:

The ErC50 (72h) was determined to be 27 mg/L and the NOEC to be 7.2 mg/L (mean measured concentrations) in an OECD 201 test.

Description of key information

ErC50 (72 h): 27 mg/L based on growth inhibition of Scenedesmus subspicatus (OECD 201)

NOEC(growth rate) (72 h): 7.2 mg/L based on growth inhibition of Scenedesmus subspicatus (OECD 201)

Key value for chemical safety assessment

EC50 for freshwater algae:

27 mg/L

EC10 or NOEC for freshwater algae:

7.2 mg/L

Additional information

The available test with algae was performed with the freshwater green algal species Scenedesmus subspicatus according to the OECD Guideline 201 (1984) in a 72 -hour static test. The nominal concentrations of the test item of 6.25, 12.5, 25, 50 and 100 mg/L were tested in parallel with a control. The mean measured concentrations were 7.2, 15, 31, 64 and 131 mg/L.

The biological results were related to the mean measured concentrations of the test item. The biological results (based on mean measured concentrations) of the study were as follows: 72 h EC50 (based on growth rate): 27 mg/L; 72 h NOEC (based on growth rate / biomass): 7.2 mg/L; 72 h EC50 (based on biomass) 19 mg/L.