Butanone

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:

1998

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)

Version / remarks:

reliability scoring based on 2002 guideline

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

-Sampling method: water samples were collected from mid-depth of each test chamber at test inititation and at test termination to measure concentrations of the test substance. The samples were placed in glass scintillation vials and analyzed immediately.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- A primary stock solution was prepared by mixing the test substance directly with dilution water at a concentration of 4.00 mg MEK/mL. The primary stock was inverted at least 20 times to aid in solubilization of the test substance. Five test solutions were prepared by proportional dilution of the primary stock with dilution water. All test solutions appeared clear and colourless

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: daphnids
- Strain: not reported
- Source: Wildlife International Ltd., Easton Maryland
- Age at study initiation (mean and range, SD): 24 hours
- Feeding during test; none



ACCLIMATION
- Acclimation period: 14 days for parents
- Acclimation conditions (same as test or not): same
- Type of food: a mixture of yeast, Carophyll, and trout chow

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

None

Hardness:

132 mg/L as CaCO3

Test temperature:

20 +/- degrees Celsius

pH:

8.2 to 8.6

Dissolved oxygen:

exceeded 60%

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal - 52, 86, 144, 240, and 400 mg/L
Measured (arithmetic mean of duplicate measurements at T0 and T48h)- 48, 68, 136, 234, and 345 mg/L
Measured (geometric mean of duplicate measurements at T0 and T48h)- 47, 64, 136, 233, and 340 mg/L
As the concentration of MEK in the 86 mg/L test vessels fell to 52% at T48h, endpoints were calculated on arithmetic mean basis. As these are close to the geometric mean concentrations, this is deemed suitable.

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL beakers with a depth of 6.8 cm.
- Type: closed with headspace
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 1


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The water used for culturing and testing was freshwater obtained from a well approximately 40 meters deep located on the Wildlife International Ltd. site. The well water is characterized as moderately-hard water. The well water was passed through a sand filter to remove particles greater than approximately 25 micro meters, and pumped into a 37800-L storage tank where the water was aerated with spray nozzles. Prior to use, the water again was filtered (0.2 micro meters) to remove microorganisms and particles.
- Total organic carbon: < 1 mg C/L
The water used for culturing and testing was freshwater obtained from a well approximately 40 meters deep located on the Wildlife International Ltd. site. The well water is characterized as moderately hard water. The water is routinely monitored to ensure there will be no interferences with ecotoxicity testing.

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

308 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% CI of 280 and 339 mg/l

Duration:

48 h

Dose descriptor:

EC0

Remarks:

no mortality/immobility concentration

Effect conc.:

136 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

68 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

behaviour

Remarks:

lethargy

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 345 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

Daphnids in the negative control, 48 and 68 mg/L (arithm mean) treatment groups appeared healthy and normal throughout the test. After 48-hours of exposure, mortality/immobility in the 136, 234 and 345 mg /L treatment groups was 0, 5 and 75% respectively. Although no mortality/immobility occurred in the 136 mg/L treatment group, 10% of the daphnids were observed to be lethargic at test termination.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

None

Validity criteria fulfilled:

yes

Description of key information

The substance was not acutely toxic to Daphnia magna when tested according to OECD TG 202 (Daphnia sp. Acute Immobilisation Test). The 48-hour EC₅₀ in Daphnia magna was 308 mg/L based on arithmetric mean measured concentrations.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

308 mg/L

Additional information

Three studies addressing short-term toxicity to aquatic invertebrates are presented in the dossier. Please refer to the document attached to Section 13 for further discussion of the key study.

Short-term toxicity to aquatic invertebrates.001 – Daphnia – 1998 – key: Acute toxicity to Daphnia magna was assessed according to OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test), and in compliance with GLP. Daphnia were exposed under static conditions to the substance at concentrations of 52, 86, 144, 240, and 400 mg/L (nominal) in freshwater. The test was performed with 10 daphnia per vessel and 20 daphnia per concentration. The vessels were closed with headspace. For each concentration, the percentage of immobilisation at 24 hours and 48 hours was recorded, and test concentrations were confirmed by GC analysis. The following validity criteria were met: immobilisation in the control did not exceed 10% at the end of the test; dissolved oxygen concentrations remained above 60% of the air saturation value at the end of the test; pH did not vary by more than one unit throughout the test; and the concentrations of the test substance remained close to, or within 80% of the initial concentration throughout the test for 4 out of 5 concentrations. The arithmetic mean of the measured concentrations were 48, 68, 136, 234, and 345 mg/L which were used to express the results of the test. After 48 hours immobility in the 136, 234 and 345 mg/L treatment groups was 0, 5 and 75% respectively.   Under the conditions of the test, the 48-hour EC₅₀ was 308 mg/L, and therefore the substance was not acutely toxic to Daphnia magna.

Short-term toxicity to aquatic invertebrates.002 - Daphnia - 1982: Acute toxicity to Daphnia magna was not assessed according to a specific guideline, however; it appears to follow OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test) but was not conducted according to GLP (pre-dates GLP). The Daphnia were exposed to the substance under static conditions for 24 hours and the 24-hour EC₅₀ for immobility was determined to be 7060 mg/L. This lower toxicity over a shorter exposure period is in keeping with the result of the key study.

Short-term toxicity to aquatic invertebrates.003 - Daphnia - 1977: Acute toxicity to Daphnia magna was not assessed according to a specific guideline, however; it appears to follow OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test) but was not conducted according to GLP (pre-dates GLP). The Daphnia were exposed to the substance under static conditions for 24 hours and the 24-hour EC₅₀ for immobility was determined to be 8890 mg/L. This lower toxicity over a shorter exposure period is in keeping with the result of the key study.