Benzene, mono-C10-13-alkyl derivs., distn. residues

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:

Dec. 1, 1992-Dec. 3, 1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study.

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Enough test substance was added to create a 1 g/L concentration of test substance in synthetic fresh water, and stirred for 18 hrs. The test medium was then filtered. This solution was then diluted to create the test solutions.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Strain: Straus
- Source: laboratory breed
- Age at study initiation (mean and range, SD): < 24 hrs

Test type:

static

Water media type:

freshwater

Total exposure duration:

48 h

Test temperature:

20 +/- 1°C

pH:

8.1

Dissolved oxygen:

8.1 to 8.3

Nominal and measured concentrations:

Nominal: 0.35, 0.49, 0.70, 0.98, 1.40 mg/L

Details on test conditions:

TEST SYSTEM
- Type: closed
- Material, size, headspace, fill volume: 10 ml flasks covered with glass plates
- Aeration: None
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: 1 organism/ 2 ml


OTHER TEST CONDITIONS
- Photoperiod: darkness


EFFECT PARAMETERS MEASURED: immobilization at 24 and 48 hrs

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

1.4 mg/L

Nominal / measured:

nominal

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 1.4 mg/L

Details on results:

One daphnid was found immobilized in the 0.98 mg/l test group at the 24 hr observation. At the 48 hr observation, there was one daphnid immobilized at the three highest concentrations, 0.70, 0.98, and 1.40 mg/l. Since this effect did not show a dose response, and the number of immobilized daphnia did not exceed 10%, this effect is not considered treatment related.

Number of Immobilized Daphnia

Concentration	24 hrs	48 hrs
Control	0	0
0.35 mg/l	0	0
0.49 mg/l	0	0
0.70 mg/l	0	1
0.98 mg/l	1	1
1.40 mg/l	0	1

Validity criteria fulfilled:

yes

Conclusions:

The 48-hr EC50 for daphnids was > 1.40 mg/L.

Executive summary:

This study examined the potential for the test substance to be toxic to aquatic invertebrates. Groups of 20 daphnids were exposed to concentrations of 0, 0.35, 0.49, 0.70, 0.98, or 1.40 mg/L of test substance. The daphnids were then observed at 24 and 48 hrs after start of exposure for immobilization. At the 24 hr observation, one daphnid at the 0.98 mg/l concentration was immobilized. At the 48 -hr observation one daphnid at the 0.70, 0.98, and 1.40 mg/l concentrations was immobilized. The 48 -hr EC50 was > 1.4 mg/l test substance, which is greater than the water solubility of the test substance.

Description of key information

In the first of two studies conducted to examine the potential for HAB to be toxic to aquatic invertebrates, enough test substance was added to create a 1 g/L concentration of HAB in synthetic fresh water, and stirred for 18 hrs. The test medium was then filtered. This solution was then diluted to create the test solutions. Groups of 20 daphnids were exposed to concentrations of 0, 0.35, 0.49, 0.70, 0.98, or 1.40 mg/L of test substance. The daphnids were then observed at 24 and 48 hrs after start of exposure for immobilization. At the 24 hr observation, one daphnid at the 0.98 mg/L concentration was immobilized. At the 48-hr observation one daphnid in each of the 0.70, 0.98, and 1.40 mg/L concentrations was immobilized. Since this effect did not follow a dose response, and the number of immobilized Daphnia did not exceed 10%, this effect is not considered treatment related. Therefore, the 48-hr EC50 was >1.4 mg/L test substance.

In the second study, 0.3 mL of LABs with varying phenyl positions (Phenyl-C4, Phenyl-C8, Phenyl-C10, Phenyl-C12, Phenyl-C14, Phenyl-C16, Phenyl-C18) were added to 300 ml MilliQ water in a conical flask and stirred for 96 hrs at 20°C.  The phenyl-C10 LAB is the most water soluble single component of HAB.  Groups of 10 daphnids were exposed to concentrations of 12.5, 25, 50, and 100 ug/L of test substance for 144 hrs. The daphnids were observed regularly for immobilization. All 48-96 h EC50 values were higher than the water solubility limit, while the extended 120-144 h EC50 values were at or below the estimated water solubility limit. Results for phenyl-C10, the most water soluble single component of HAB, show that the 48-96 h EC50 values were higher than the water solubility limit (0.0404 mg/L), while the extended 120-144 h EC50 values were below the estimated water solubility limit. Therefore, the 48-hr EC50 is >0.1 mg/L.