Hydrocarbons, C7-C9, isoalkanes

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Adopted according to OECD SIDS (public available peer reviewed source) and respective study summary. The original source is not available and has not been reviewed.

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

Individual treatment solutions were prepared by adding the test substance, via syringe, to 17 L of laboratory blend water in 20 L glass carboys that were sealed to minimize volatile loss of test material. The stock solutions were mixed for 24 hours with a vortex of <10% (1-2 cm vortex). Mixing was performed using a magnetic stir plate and teflon stir bar. After mixing, the solutions were allowed to settle for one hour and the Water Accommodated Fraction (WAF) was then siphoned from the bottom of the mixing vessel and added to the test vessels. Siphons were placed in the carboys prior to adding the test material.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: rainbow trout
- Source: Thomas Fish Co.
- Age at study initiation (mean and range, SD): approximately 5 weeks
- Length at study initiation (length definition, mean, range and SD): mean total length = 3.4 cm
- Weight at study initiation (mean and range, SD): mean wt. = 0.297 g

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Test temperature:

15.4 – 16.0°C

pH:

7.5 - 8.7 (7.6 to 8.7 for "new" solutions and 7.5 to 8.4 for "old" solutions)

Dissolved oxygen:

5.0 – 9.7 mg/L (8.0 to 9.7 mg/L for "new" solutions and 5.4 to 7.7 mg/L for "old" solutions)

Nominal and measured concentrations:

0, 0.9, 2.0, 10.0, 22.0, and 50.0 mg/L (nominal)
non-detected, 0.05, 0.12, 0.33, 0.36, 0.47 mg/L (measured)

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type: closed
- Material, size, headspace, fill volume: 4.0 L aspirator bottles containing 4.5L of solution sealed with no headspace
- Renewal rate of test solution (frequency/flow rate): Approximately 80% of each solution was renewed daily from a freshly prepared WAF.
- No. of organisms per vessel: 7
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
- Biomass loading rate: 0.46 g fish/L

OTHER TEST CONDITIONS
- Photoperiod: 16 hrs light and 8 hrs dark
- Light intensity: 73 ft. candles

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

LL50

Effect conc.:

18.4 mg/L

Nominal / measured:

nominal

Conc. based on:

other: Water Accomodated Fraction (WAF)

Basis for effect:

mortality (fish)

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

0.11 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

other: Water Accomodated Fraction (WAF)

Basis for effect:

mortality (fish)

Reported statistics and error estimates:

Probit procedure of SAS

Sublethal observations / clinical signs:

Tab.: Fish Total Mortality

Nominal Loading (mg/L)	Fish Total Mortality
	24h	48h	72h	96h
Control	0	1	1	1
0.9	0	2	2	0
2.0	0	2	2	1*
10.0	0	7	7	8
22.0	1	9	9	11
50.0	6	13*	21*	21*

* 2 non-test related mortalities

Validity criteria fulfilled:

not specified

Conclusions:

The acute toxicity, as measured by mortality to rainbow trout (Oncorhynchus mykiss), was evaluated in freshwater. Under the conditions of this study, the test substance produced acute lethal toxicity to Oncorhynchus mykiss at 18.4 mg/L, based on nominal loading of the test substance in water.

Executive summary:

The acute toxicity, as measured by mortality to rainbow trout (Oncorhynchus mykiss), was evaluated in freshwater. Under the conditions of this study, the test substance produced acute lethal toxicity to Oncorhynchus mykiss at 18.4 mg/L, based on nominal loading of the test substance in water.

Description of key information

LL50 (96 h) = 18.4 mg/L (Oncorhynchus mykiss)

Additional information

A study conducted according to OECD 203 guideline is available on the acute toxicity to fish for hydrocarbons, C7-C9, isoalkanes (CEFIC 1995). The acute toxicity, as measured by mortality to rainbow trout (Oncorhynchus mykiss), was evaluated in freshwater by using water accomodated fractions (WAFs).

In this methodology, different loadings of the substance are added to the test medium and equilibrium between the water and the hydrocarbons is achieved according to their specific water solubility. The hydrocarbon concentrations at equilibrium will be characteristic of the loading of the substance, and therefore toxicity values from WAF studies are expressed as effect loadings or lethal loadings (EL or LL), not as concentrations. These effect loadings are used to determine environmental classifications. The WAF methodology is widely accepted for the testing of complex hydrocarbon substances and other UVCBs, and it has been incorporated in different guidance documents, including the REACH guidance (see draft decision response letter in Section 13).

Under the conditions of this study, the test substance, hydrocarbons, C7-C9, isoalkanes produced acute lethal toxicity to Oncorhynchus mykiss at 18.4 mg/L (CEFIC 1995) based on nominal loadings of the test substance in water.