Isobutyric acid

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Basic data given, comparable to guideline study with acceptable restrictions (no analytical monitoring)

Qualifier:

according to guideline

Guideline:

other: German industrial standard test guideline DIN 38412, part 11

Principles of method if other than guideline:

Method used is comparable to OECD TG 202 (Daphnia sp., Acute Immobilisation Test)

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Source: Daphnia magna Straus was originally supplied from "Institut National de Recherche Chimique Appliquee" and has been bred from 1978 in the Laboratories of BASF
- Age at study initiation (mean and range, SD): 2-24 hours

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

2.63 mmol/L (total hardness)

Test temperature:

20 °C

pH:

lowest test substance concentration: 7.89
highest test substance concentration: 4.28
pH-values were nearly stable over the test period

Dissolved oxygen:

8.16 - 9.2

Nominal and measured concentrations:

Nominal test concentrations (mg/L): control, 15.625, 31.3, 62.5, 125, 250, 500

Details on test conditions:

TEST SYSTEM
- Test vessel: reagent tubes with flat bottom, 10 ml test volume
- Type (delete if not applicable): open / closed
- Fill volume: 20 ml
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: artificial freshwater.
- Ks up to pH 4.3:= 0.9 ± 0.1 mM
- Conductivity: 600 - 700 µS/cm
- Intervals of water quality measurement: pH values after 0 and 48 h


OTHER TEST CONDITIONS
- Photoperiod: 16:8 hours day night regime
- Light intensity: 5 - 6 µE/(m2 * s) (400 -750 nm)


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Mobility after 3, 6, 24 and 48 hours

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

31.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

51.25 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% CL: 38.28 - 64.22 mg/L

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

125 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Mortality of control: 0 / 20

Mobility of Daphnids

 

Concentration [mg/L]	Number of mobile test animals after
	3 h	6 h	24 h	48 h
0 (controls)	20	20	20	20
15.625	20	20	20	20
31.3	20	20	20	20
62.5	20	20	15	4
125	14	7	0	0
250	0	0	0	0
500	0	0	0	0

 

Validity criteria fulfilled:

yes

Conclusions:

In a Daphnia immobilization test, the LC50 of isobutyric acid was determined to be 51.25 mg/L.

Executive summary:

Isobutyric acid was tested on the waterflea Daphnia magna in a 48-h acute toxicity test similar to OECD TG 202 under static conditions at concentrations of 0 (water control), 15.625, 31.3, 62.5, 125, 250, and 500 mg/L. Immobilization and other toxic effects were observed 3, 6, 24, and 48 h after initiation of the test.

The 48-h EC50 was determined to be 51.25 mg/L (BASF AG, 1989).

 

This acute toxicity study with Daphnia is acceptable and satisfies the information requirements for an acute toxicity study with freshwater invertebrates.

Description of key information

In a valid Daphnia acute immobilization test similar to OECD TG 202, the EC50 of isobutyric acid was determined to be 51.25 mg/L (BASF AG, 1989)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

51.25 mg/L

Additional information

This endpoint is covered by two studies. One study is a valid 48-h acute Daphnia immobilization test (BASF AG, 1989). The second study (Hüls, 1979) cannot be used for assessment of this endpoint due to critical deviations from requirement of actual test guidelines (test period only 24 h).

 

BASF AG 1989

 

Isobutyric acid was tested on the waterflea Daphnia magna in a 48-h acute immobilization test similar to OECD TG 202 under static conditions at concentrations of 0 (water control), 15.625, 31.3, 62.5, 125, 250, and 500 mg/L. Immobilization and other toxic effects were observed 3, 6, 24, and 48 h after initiation of the test.

 

The 48-h EC50 was determined to be 51.25 mg/L (BASF AG, 1989).