1,2,3,4-tetrahydronaphthalene

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:

other: Guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

Cited as Directive 92/69/EEC, C.3

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Parallel samples without algae were analysed for the test item after 0 and 72 hours

Vehicle:

no

Details on test solutions:

1 g test substance/l was stirred in deionized water for 18 hours and filtered. The resulting concentration  was 63 mg/l. The maximum concentration tested  was 17 mg/l. No vehicle or  solvent was used.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

- Strain: Scenedesmus subspicatus (CHODAT (86.81 SAG))
- Source/supplier: Origin: Institute "Wasser-, Boden- und Lufthygiene",  Berlin; further bred inhouse
- Laboratory culture: A preculture is seeded from a stock culture by transfer 3 days prior to begin of test. Test cultures were established from these
precultures.
- Controls: yes (0 mg test substance/l)
- Initial cell concentration: approximately 20,000 cells/ml

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

24 +/- 2 degree C

pH:

8.8-8.9 (study start); 
7.9-9.4 (end of study)

Nominal and measured concentrations:

1.20; 2.0; 3.6; 6.0; 10.0; 17.0 mg/l (nominal)  
 1.05; 1.8; 3.3; 5.7;  9.1; 16.1 mg/l (measured at 0 hours)   
0.99; 1.7; 3.2; 5.4;  8.7; 15.1 mg/l (measured at 72 hours)   
Since the analytical concentrations after 0 hours deviated by less than 20% from the nominal concentrations and the values at 72 hours indicate  stability, nominal concentrations were used for the evaluation.

Details on test conditions:

- Renewal of test solution: no
- Exposure vessel type: Sterile-aerated Erlenmeyer flasks on light benches
- Number of replicates: 5 (test substance) or 8 (control)
- Intensity of irradiation: approx. 8000 lux, white

TEST PARAMETER: Light absorption at 685 nm, related to cell density via  calibration curve

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

3.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

3.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

7 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Duration:

72 h

Dose descriptor:

EC90

Effect conc.:

13 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

5.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

11 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC90

Effect conc.:

25 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: extrapolated

Details on results:

Statistical method: Probit analysis (Cavalli-Sforza, 1972)

RESULTS: EXPOSED AND CONTROL
- Cell density data: 
  Cells/ml after 0; 24; 48; 72 hours (mean)
  -----------------------------------------
  Control:       2;  6; 22;  90 (x 10,000)
   1.2 mg/l:     2;  7; 27; 108 (x 10,000)
   2.0 mg/l:     2;  7; 23;  96 (x 10,000)
   3.6 mg/l:     2;  6; 21;  84 (x 10,000)
   6.0 mg/l:     2;  5; 14;  52 (x 10,000)
  10.0 mg/l:     2;  5;  6;  17 (x 10,000)
  17.0 mg/l:     2;  3;  3;   6 (x 10,000)

Validity criteria fulfilled:

not specified

Conclusions:

The lowest 72 h-EC50 (biomass) was determined as 7.0 mg/L, 72 h-EC50 (growthrate) was determined as 11.0 mg/L indicating that the test item may be toxic to algae.

Executive summary:

In a 72 hour toxicity study, the cultures of Scenedesmus subspicatus were exposed to Tetrahydronaphthalene at nominal concentrations of 1.20; 2.0; 3.6; 6.0; 10.0 and 17.0  mg/L under static conditions in accordance with EU Method C3. The following endpoints were derived:

Growth rate:
72 hr ErC50:  11.0 mg/L    95% CL: n.a.

72 hr ErC10:  5.3 mg/L    95% CL: n.a.

72 hr NOEC:  not available

Biomass:

72 hr EbC50:  7.0 mg/L 95% CL.: n.a.

72 hr EbC10:  3.8 mg/L 95% CL.: n.a.

72h NOEC. 3.6 mg/L

 

The study is classified as "reliable without restrictions".

Description of key information

The growth inhibition on the freshwater alga Desmodesmus subspicatus was tested by Scholz (1994) over a period of 72 h according to accepted guidance documents (OECD guideline 201). Algae were exposed to 6 concentrations between 1.2 mg/L and 17 mg/L and one control. Since the analytical results indicate the stability of the test item, the results are based on the nominal test item concentrations. Based on the growth rate, the ErC50 of 11 mg/L and a 72 h ErC10 of 5.3 mg/L were determined. Based on biomass development, the EbC50 of 7 mg/L and a 72 h EbC50 of 3.8 mg/L were determined. The NOEC based on cell growth (biomass) was assessed to be 3.6 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

11 mg/L

EC10 or NOEC for freshwater algae:

5.3 mg/L

Additional information

Based on biomass development an EbC50 (72 h) of 7.0 mg/L and a 72 h-EbC10 of 3.8 mg/L were determined. Based on growth rate an ErC50 of 11.0 mg/l and a 72 h-ErC10 of 5.3 mg/l were determined. The NOEC based on cell growth (biomass) was assessed to be 3.6 mg/l.