tert-pentylbenzene

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 12 October 2007 to 11 April 2008.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP Guideline study.

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0, 6.25, 12.5, 25, 50 and 100 % of a saturated stock solution.
- Sampling method: At test initiation bulk solutions were sampled. After 24 hours samples were taken from the test flasks in which all water fleas were immobile. After 48 hours samples were taken from all remaining test flasks.
- Sample storage conditions before analysis: 2-8°C.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: An amount of 200 mg tertiary-amylbenzene was dissolved in 2 litres Elendt M4 medium. This stock solution was continuously stirred and placed at a temperature of 20°C. On the day of test initiation the stock solution was filtered with filter paper (S&S 595 1/2) to remove undissolved
test substance.
- Controls: Controls with test medium were included.
- Evidence of undissolved material: No.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Source: Aquasense b.v., Amsterdam, The Netherlands
- Age at study initiation: 0 - 24 hours
- Method of breeding: Waterfleas are cultured in vessels with 2 liter spring water. They are fed with algal suspension of Chlorella vulgaris.
- Feeding during test: not applicable

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

Not applicable

Hardness:

No measurement.

Test temperature:

19.8 - 20.9°C

pH:

Controls: 7.8 - 8.3
Test concentrations: 7.7 - 8.3

Dissolved oxygen:

Controls: 7.9 - 8.8 mg/l
Test concentrations: 7.7 - 8.8 mg/l

Nominal and measured concentrations:

See Table 1.

Details on test conditions:

TEST SYSTEM
- Type: closed
- Material, size, headspace, fill volume: closed (glass) flasks with a volume of 250 ml were completely filled with test solution.
- Aeration: No.
- Renewal rate of test solution: No.
- No. of organisms per vessel: 10 water fleas.
- No. of vessels per concentration: 3 replicates.
- No. of vessels per control: 3 replicates.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Elendt M4 medium prepared from purified water.
- Culture medium different from test medium: No.

OTHER TEST CONDITIONS
- Adjustment of pH: No.
- Photoperiod: 16 hours light/8 hours dark

EFFECT PARAMETERS MEASURED: The number of mobile and immobile water fleas and the number of water fleas showing sublethal effects was recorded 24 and 48 hours after test initiation.

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

1 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

2.2 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

mobility

Details on results:

See Table 2.

Table 2: Immobility of Daphnia magna during the acute toxicity test

Mean measured concentration (mg/l)	Number of immobile fleas		Number of water fleas tested	Percentage of immobility after 48 hours
	24 h	48 h
n.d.	0	0	30	0
0.62	0	0	30	0
1.0	0	0	30	0
2.0	5	5	30	16.7
3.8	30	30	30	100
7.2	30	30	30	100

Validity criteria fulfilled:

yes

Conclusions:

Under the test conditions, the EC50/48h value based on immobility was 2.2 mg/L.

Executive summary:

The acute toxicity of Tertiary-amylbenzene to water fleas (Daphnia magna) was tested following OECD Guideline 202 and according to GLP.

Based on a preliminary test the study was conducted at 0, 6.25, 12.5, 25, 50 and 100% of the filtrated stock solution. Because tertiary-amylbenzene will volatilise from the test solutions, the test was conducted in closed (glass) flasks with a volume of 250 mL. Three flasks, each completely filled with test solution, were prepared per concentration and 10 water fleas were added to each glass beaker. the water fleas were exposed for 48 hours to the test solutions.

It was demonstrated that the concentration of tertiary-amylbenzene has been maintained within 12.5% of the measured initial concentration throughout the test. The biological endpoints of the test are based on the average of the measured concentrations being 0, 0.62, 1.0, 2.0, 3.8 and 7.2 mg/L.

No immobility was observed in the control glass beakers. The No Observed Effect Concentration (NOEC) based on immobility was 1.0 mg/L. The EC50/48h value based on immobility was 2.2 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

2.2 mg/L