(xylenes and 4-ethylbenzene)sulfonic acids

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:

2005

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well described GLP compliant study conducted to recognized international test guidelines

Justification for type of information:

Read-across from supporting substance (structural analogue or surrogate)

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Sampllng times were a 0h and 48h

Vehicle:

no

Details on test solutions:

Stock solution of 100 mg/L in ISO-medium stired for 5-8 minutes

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: daphnid
- Strain: not indicated
- Source: in-house culture with a known history
- Age at study initiation (mean and range, SD): <24h
- Feeding during test: no

ACCLIMATION
- Acclimation period: in house culture
- Acclimation conditions (same as test or not): yes
- Type and amount of food: suspension of freshwater algae
- Feeding frequency: daily
- Health during acclimation (any mortality observed): not indicated

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

250 mg/L as CaCO3

Test temperature:

19.1-19.7 C

pH:

control - 7.9-8.0
100 mg/L - 5.9-7.2

Dissolved oxygen:

9.2-9.7 mg/L

Nominal and measured concentrations:

nominal - 0 and 100 mg/L
measured - 0 and 103 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: glass
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: glass, 100 mL with 80 mL solution
- Aeration: no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: not indicated

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: ISO-medium with hardness of 250 mg/L as CaCO3 and pH of 8.0 +/- 0.2
- Culture medium different from test medium: no
- Intervals of water quality measurement: 0h and 48h except temperature which is continuously monitored

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 h light
- Light intensity: not indicated

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : immobility including mortality

TEST CONCENTRATIONS
- Spacing factor for test concentrations: limit test

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 103 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

other: immobility including mortality

Details on results:

No immobilization or mortality at 103 mg/L
The pH of the solution at 103 mg/L was initially 5.9 (which is just below the 6.0 guideline limit) at the 0h but increased to 7.2 at 48h. This was not considered to have an effect on the daphnids.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Mortality: no mortality at 0, 0.1, 0.18 or 0.32 mg/L; 5% at 0.56 mg/L, and 100% at 1.0 and 1.8 mg/L
- EC50/LC50: appx 0.75 mg/L
- Other:

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity of the test material (based on active ingredient), as defined by an EC50, is > 100 mg/L which was the only concentration tested.

Description of key information

EC50 for freshwater invertrebrates = 100 mg/L

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

100 mg/L

Additional information

There are 3 short-term acute studies with Daphnia Magna. The key study is a 2005 Guideline (OECD 202) study with a 99.8% analyticaly pure benzenesulfonic acid (CAS No. 98-11-3) conducted under GLPs. It is a well documented limit test with analytical confirmation. There was no mortality or immobility observed at 100 mg/L (nominal) / 103 mg/L measured. The test conditions were confirmed to be valid and the reference substance produced expected results. The 48h-EC50 for 98-11-3 is reported as >100 mg/L.

The 2005 study with benzenesulfonic acid is the only one of the three studies with sufficient details and adherence to OECD guidelines to use to establish the 48h-EC50 of >100 mg/L. The other 2 studies give support to this endpoint value.

There is a 1995 supporting study conducted following OECD 202 but without analytical confirmation and no confirmation of GLP compliance. This limit test was conducted with a 65% pure (in water) benzenesulfonic acid (CAS No, 98-11-3). There was no toxicity observed and the 48h-EC50 is reported as >100 mg/L. There is also a 1983 study of p-toluenesulfonic acid (CAS No. 104-15-4) designated a "weight-of-evidence" study. There were multiple, nominal test concentrations (5000, 1000, 100, 10 and 0), however, the exposure duration was 24 hours instead of the required 48 hours. There was no toxicity in the 0 and 10 mg/L exposures, 5% at 100 mg/L, 35% at 1000 mg/L and 10% at 5000 mg/L. There are insufficient details and no plausible explanation for the lower toxicity at 5000 mg/L. The results indicate the 24h-EC50 is above 1000 mg/L.