4-methylstyrene

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 February 28, 2001 to March 02, 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

yes

Remarks:

study conducted in sealed vessels to reduce losses via volatilisation

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

Water used for acclimatization of the test organisms and all toxicity testing was adjusted to hardness 160 to 180 mg/L as CaCO3 and stored in polyethylene tanks were it was aerated and recirculated through particle filters, activated carbon and an ultraviolet sterilizer. Prior to use the pH of dilution water was adjusted <8.0.

A series of solutions were prepared by bringing 3.8, 6.1, 9.6, 15.3, 23.9 mg of the test substance to 4,000 mL dilution water in a sealed amber glass bottles. The solutions were mixed on magnetic stirrers for approximately four hours. The solutions were allowed to settle for approximately one hour and a portion for each solution was transferred into a 250 mL beaker through a spout at the bottom of the mixing vessels. A 250 mL portion of dilution water was also transferred to a glass beaker to serve as a control. Water quality measurements were made and each solution was subdivided into four clear glass 40 mL vials. Five daphnids were indiscriminately added to each vial and the vials, which were filled to capacity to eliminate any head space, were sealed with Teflon-lined cap. Vials remained sealed throughout the 48 hour exposure period.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Age at study initiation: less than 24 hours old
- Method of breeding: laboratory culture
- Feeding during test: no

ACCLIMATION
- Acclimation period:2 days
- Acclimation conditions: same as in the test
- Health during acclimation:at the start of the study all organisms were considered free of disease, injuries and abnormalities

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

Observations were conducted at 24 and 48 hours to determine abnormal behaviour in addition to chanting mortality.

Hardness:

172 mg/L calcium carbonate

Test temperature:

20.1-20.8°C

pH:

7.3-7.7

Dissolved oxygen:

8.4-8.6 mg/L

Nominal and measured concentrations:

Range finding study - nominal concentrations: 0.1, 1.0, 5.0, 10.0 and 100 mg/L
Definitive study - nominal concentrations 0.95, 1.5, 2.4, 3.8 and 6.0 mg/L
Mean measured concentrations: 0.51, 0.81, 1.5, 2.3 and 3.8 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): closed
- Fill volume: 500 mL, no headspace
- Aeration: no aeration
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): as per guideline

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

1.3 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

act. ingr.

Basis for effect:

mobility

Remarks on result:

other: confidence interval 1.0 - 1.6 mg/L

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

1.7 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

act. ingr.

Basis for effect:

mobility

Remarks on result:

other: 95% confidence intervals: 1.4 to 2.1 mg/L

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

0.81 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

act. ingr.

Basis for effect:

mobility

Remarks on result:

other: p<0.05

Reported statistics and error estimates:

48 h LC50 and EC50 were calculated using the moving average method (Stephan et al. 1978). The NOEC was calculated using TOXSTAT 3.3 (Gulley, et al. 1990).

Test substance - measured concentrations in the study.

Nominal concentration (mg/L)	Measured concentration (mg/L)			% of nominal
	0hr	48hr	Mean
0 (control)	ND	ND	ND
0.95	0.53	0.49	0.51	54
1.5	0.85	0.77	0.81	54
2.4	1.6	0.14	1.5	63
3.8	2.5	2.1	2.3	61
6.0	4.1	3.5	3.8	63

ND = not detected above the LOQ

test substance mortality/immobilisation scores.

Measured concentration (mg/L)	Mean % mortality			Mean % immobilised
	0hr	24hr	48hr	0hr	24hr	48hr
0 (control)	0	0	0	0	0	0
0.51	0	0	0	0	0	0
0.81	0	0	0	0	0	0
1.5	0	0	0	0	60	65
2.3	0	100	100	0	0	0
3.8	0	100	100	0	0	0

Validity criteria fulfilled:

yes

Conclusions:

Under the study conditions, the mean measured 48 h EC50 was 1.3 mg/L (95% CI: 1.0 to 1.6 mg/L) and the 48 h LC50 was 1.7 mg/L (95% CI: 1.4 to 2.1 mg/L). The NOEC was 0.81 mg/L (p<0.05).

Executive summary:

A study was conducted to determine the toxicity of the test substance to Daphnia magna according to OECD Guideline 202, in compliance with GLP. The test was performed under static conditions in sealed vials with no head space to minimize loss of the volatile test substance from test solutions. The test was run with five concentrations at a temperature of 20 ± °1C. Nominal concentrations of the test substance were: 0, 0.95, 1.5, 2.4, 3.8 and 6.0 mg/L. Analysis immediately after preparation of the solutions showed a substantial loss of test substance ranging from 54 to 63% of nominal values. These mean measured concentrations were steady throughout the exposure period. Insoluble material was not observed in any of the groups. Under the study conditions, the mean measured 48 h EC50 was 1.3 mg/L (95% CI: 1.0 to 1.6 mg/L) and the 48 h LC50 was 1.7 mg/L (95% CI: 1.4 to 2.1 mg/L). The NOEC was 0.81 mg/L (p<0.05) (Wyskiel, 2000).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

1.3 mg/L

Additional information

A study was conducted to determine the toxicity of the test substance to Daphnia magna according to OECD Guideline 202, in compliance with GLP. The test was performed under static conditions in sealed vials with no head space to minimize loss of the volatile test substance from test solutions. The test was run with five concentrations at a temperature of 20 ± °1C. Nominal concentrations of the test substance were: 0, 0.95, 1.5, 2.4, 3.8 and 6.0 mg/L. Analysis immediately after preparation of the solutions showed a substantial loss of test substance ranging from 54 to 63% of nominal values. These mean measured concentrations were steady throughout the exposure period. Insoluble material was not observed in any of the groups. Under the study conditions, the mean measured 48 h EC50 was 1.3 mg/L (95% CI: 1.0 to 1.6 mg/L) and the 48 h LC50 was 1.7 mg/L (95% CI: 1.4 to 2.1 mg/L). The NOEC was 0.81 mg/L (p<0.05) (Wyskiel, 2000).