N-hexane

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

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

Adequacy of study:

key study

Study period:

17th March 1993 to 22nd January 1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study

Justification for type of information:

A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SBP 60/95 LNH is a C6 -C7 hydrocarbon solvent with a n-hexane content of less than 3%. Being made from hydrogenated feedstock, its aromatics and olefins content is very low.

Analytical monitoring:

no

Details on sampling:

Due to trace concentrations of interfering components, the limit of the analytical method was determined to be 10 mg/L (nominal). Since most of the test concentrations were less than this limit, no sample analysis was done.

Details on test solutions:

Test medium was prepared using laboratory mains supply. Water was filtered and passed through activated carbon. This test medium is mixed with test substance for 22 h, then allowed to settle for 1 h. Aqeous phase was then used in the experiment.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Strain: Walbaum
- Source: Zeals Trout Farm
- Age at study initiation (mean and range, SD): fingerlings
- Length at study initiation (length definition, mean, range and SD): 4.5-5.6 cm
- Weight at study initiation (mean and range, SD): 0.75-1.6 g

ACCLIMATION
- Acclimation period: 7 days
- Type and amount of food: Maintenance ration of Mainstream Trout Food No. 03
- Health during acclimation (any mortality observed): less than 5%

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

284-290 mg/L CaCO3

Test temperature:

14-15 ºC

pH:

7.2-7.8

Dissolved oxygen:

8.8-10.1 mg/L

Nominal and measured concentrations:

Nominal: 0, 1.8, 4, 9, 20, 45, 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 12 L glass aspirators
- Renewal rate of test solution (frequency/flow rate): every 24 h
- No. of organisms per vessel: 7

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Test medium was prepared using laboratory mains supply. Water was filtered and passed through activated carbon.

OTHER TEST CONDITIONS
- Photoperiod: 16 h light/ 8 h dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable):
-Toxic symptoms and mortality at 3, 24, 48, 72, and 96 h

Key result

Duration:

96 h

Dose descriptor:

LL50

Effect conc.:

12 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 7.3-18 mg/L

Duration:

96 h

Dose descriptor:

LOELR

Effect conc.:

4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Details on results:

Fish in the 45 mg/L group showed increased cough frequency and abnormal swimming at the 3-h observation. All fish in the 100 mg/L group were dead by this time. The fish in the 45 mg/L group were deceased by the 24-h observation, and some fish in the 9 and 20 mg/L groups were showing signs of toxicity at this time. By the 48-h observation, 6 fish in the 20 mg/L group were deceased, with the remaining fish showing toxic symptoms. One fish in the 9 mg/L group also still showed toxic symptoms. At the 72-h observation, all fish in the 20 mg/L group were deceased, and two fish in the 9 mg/L group showed toxic symptoms. At the 96-h observation, one fish in the 9 mg/L group showed toxic symptoms, and one fish in this group was dead. No toxic symptoms or mortality were seen fish exposed to concentrations of 4 mg/L or less.

Validity criteria fulfilled:

yes

Conclusions:

The 96-h LL50 for fish is 12 mg/L.

Executive summary:

This study examined the short-term toxicity of the test substance SBP 60/95 LNH to Oncorhynchus mykiss. Groups of 7 fish were exposed to concentrations of 0, 1.8, 4, 9, 20, 45, or 100 mg/L of test substance for 96-h. Test solutions were renewed daily. Fish were observed at 3, 24, 48, 72, and 96 h after exposure. Signs of toxicity and mortality was seen at the two highest concentrations by the first observation. By the 24-h observation, signs of toxicity were seen at concentrations as low as 9 mg/L. By the end of the exposure period, all fish in the 20, 45, and 100 mg/L groups had died, and one fish in the 9 mg/L group was also dead. No mortality or toxic symptoms were seen in the 4 or 1.8 mg/L groups. The 96-h LL50 for fsh is 12 mg/L.

Description of key information

There is data available for this substance. Additionally, key data is available for structural analogue Hydrocarbons, C6-C7, isoalkanes, cyclics, <5% n-hexane. The data is read across to this substance based on analogue read across and a discussion and report on the read across strategy is provided as an attachment in IUCLID Section 13.

Hydrocarbons, C6-C7, isoalkanes, cyclics, <5% n-hexane presented a 96-h LL50 (mortality) for Oncorhynchus mykiss of 12 mg/L.

n-Hexane presented a 48-h LC50 (mortality) for Oryzias latipes of >1000 µg/mL (>1000 mg/L).

Additional information

Two study reports were available and input as endpoint records. The studies were scientifically reliable according to Klimish (Klimish et al., 1997) scoring (Klimish 1 and 2).

The study from Shell (1994) examined the short-term toxicity of the test substance SBP 60/95 LNH (Hydrocarbons, C6-C7, isoalkanes, cyclics, <5% n-hexane) to Oncorhynchus mykiss. Groups of 7 fish were exposed to concentrations of 0, 1.8, 4, 9, 20, 45, or 100 mg/L of test substance for 96-h. Test solutions were renewed daily. Fish were observed at 3, 24, 48, 72, and 96 h after exposure. Signs of toxicity and mortality was seen at the two highest concentrations by the first observation. By the 24-h observation, signs of toxicity were seen at concentrations as low as 9 mg/L. By the end of the exposure period, all fish in the 20, 45, and 100 mg/L groups had died, and one fish in the 9 mg/L group was also dead. No mortality or toxic symptoms were seen in the 4 or 1.8 mg/L groups. The 96-h LL50 for fsh is 12 mg/L.

The study from Tsuji et al. (1986) examined the short-term toxicity of n-hexane to fish. Groups of 10 fish were exposed to 988.5 µg/mL of test substance for 48 h. The exposure temperature was 10, 20, or 30°C. The fish were observed for mortality at 24 and 48 h after start of exposure. The 48-h LC₅₀for fish exposed to n-hexane was >1000 µg/mL.