Hexanoic acid

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

Study period:

Feb 1973 - Jul 1974

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions

Qualifier:

no guideline followed

Principles of method if other than guideline:

96-hour static test, 10 fish per replicate

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: direct addition to Lake Superior water, thorough mixing by shaking

Test organisms (species):

Pimephales promelas

Details on test organisms:

TEST ORGANISM
- Common name: Fathead minnow
- Source: Environmental Research Laboratory, Duluth
- Age at study initiation (mean and range, SD): 4 to 8 weeks
- Length at study initiation (length definition, mean, range and SD): 1.1 to 3.1 cm
- Feeding during test: no

ACCLIMATION
- Acclimation period: at least 48 hr before the tests, in flowing water 11 cm deep in a holding trough (360 cm long, 58 cm wide, 31 cm deep)
- Type and amount of food: Glencoe trout chow no. 3 granules

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Test temperature:

18 -22 °C

pH:

< 5.9

Dissolved oxygen:

> 4.0 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 3-L cylindrical glass battery jars
- Type (delete if not applicable): closed
- Fill volume: containing 2 L of test water
- Aeration: no
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Lake Superior water
- Culture medium different from test medium: no
- Intervals of water quality measurement: at test start and one to two times during the test

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Complete immobilisation was equated with mortality, measured after 1, 24 48 and 96 hours.

TEST CONCENTRATIONS
- Range finding study: yes
- Test concentrations: 3 to 5 concentrations, spacing factor of 10 or more

Reference substance (positive control):

not specified

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

88 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Description of key information

LC50 (96 h) = 88 mg/L (nominal), similar to OECD 203

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Effect concentration:

88 mg/L

Additional information

Four studies on the short-term toxicity to fish are available for hexanoic acid C6 (CAS 142-62-1). None of the studies were conducted according to todays GLP standards nor following a certain guideline. However, the studies conducted by Mattson (1976) and Brooke et al. (1984) are comparable to the method described in OECD guideline 203. Both studies were conducted similarly, under static conditions using fathead minnows (Pimephales promelas), and determined a LC50 for an exposure period of 96 h. In the study by Mattson (1976) test concentrations were not stated and the LC50 was given as 88 mg/L (nominal). Brooke et al. (1984) exposed fish to concentrations in the range of 148, 247, 412, 686, and 1143 mg/L (nominal) and determined the LC50 to be 320 mg/L. Since the LC50 of 88 mg/L determined by Mattson (1976) is the more critical value, this study was selected as key value.

A further study was conducted by Onitsuka et al. (1989) using Oryzias latipes. The study is well reported, however, the exposure period of 48 h does not meet todays requirements. Nevertheless, the LC50 determined with 235 mg/L is well in the range of the former studies and reported and thus used as supporting study here.

A study by Richterich and Mühlberg (2002) does not meet important criteria of today's standard methods, e.g. exposure duration only 48 h, no control and in the three highest test concentration only one fish per concentration exposed. Therefore this study was disregarded.