Fatty acids, C16-18

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

weight of evidence

Study period:

29 Feb - 02 Mar 2000

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP - Guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes

Remarks:

according to the Japanese GLP Standard

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
PHYSICO-CHEMICAL PROPERTIES
- Melting point: 63 °C
- Boiling point: 351 °C
- Water solubility: 0.82 mg/L (at 25 °C)
- log Pow: 5.64

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 10 mg/L
- Sampling method: 2 mL was sampled by each test vessel
- Sample storage conditions before analysis: analysis was conducted immediately after sampling, no storage

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: test substance is diluted in dilution water
- Controls: dilution water with/withour vehicle
- Chemical name of vehicle: HCO-50
- Concentration of vehicle in test medium: 100 mg/L
- Evidence of undissolved material: test water was slightly white-coloured.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Source: breed in-house (origin: Incorporated Administrative Agency, National Institute for Environmental Studies, Tsukuba, Japan)
- Age at study initiation: max. 24 hours
- Feeding during test: no

ACCLIMATION
- Acclimation period: 19 days
- Acclimation conditions: similar to test condition (animals per unit volume: acclimation condition: 20 - 50 animals/L, test condition: 5 animals/100 mL)
- Type and amount of food: Chlorella vulgaris, 0.1 - 0.2 mgC/day
- Health during acclimation: mortality was low and no males and no resting egg were observed.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

250 mg/L (as CaCO3) - M4 medium

Test temperature:

19.7 - 20.5 °C (20 ± 1 °C )

pH:

7.4 - 7.8

Dissolved oxygen:

6.6 - 9.0 mg/L (more than 60% oxygen saturation)

Nominal and measured concentrations:

nominal concentration: 10 mg/L
measured concentration (geometric mean): 4.8 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL beaker
- Material, fill volume: glass, 100 mL
- No. of organisms per vessel: 5
- No. of vessels per concentration: 4
- No. of vessels per control: 4
- No. of vessels per vehicle control: 4

TEST MEDIUM / WATER PARAMETERS
- Test medium: OECD M4 medium
- Culture medium different from test medium: same medium

OTHER TEST CONDITIONS
- Photoperiod: 16 hours light, 8 hours dark

EFFECT PARAMETERS MEASURED: immobility

TEST CONCENTRATIONS
- Range finding study: performed
- Test concentrations: 100 mg/L
- Results used to determine the conditions for the definitive study: EC50 for 48 hours: > 100 mg/L

Reference substance (positive control):

yes

Remarks:

potassium dichromate (reagent grade)

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 4.8 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

> 4.8 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: no abnormality was observed
- Mortality of control: 0%
- Other adverse effects control: 0%

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- EC50: 0.60 mg/L

Table 1: Measured concentration of palmitic acid

Nominal Concentration (mg/L)	Measured Concentration (mg/L)		Geometric Mean During 24 Hours (mg/L)
	0 Hour new	48 Hours old
Control	<0.8	<0.8	-
Dispersant Control	<0.8	<0.8	-
10	6.9	3.3	4.8

new: freshly prepared test solutions

old: test solutions after 48 hours exposure period

Table 2: Mortality or immobility of Daphnia magna

Measured Concentration (mg/L)	Cumulative number of immobilized Daphnia (Percent Immobility)
	24 Hour	48 Hours
Control	0 (0)	0 (0)
Dispersant Control	0 (0)	0 (0)
4.8	1 (5)	0 (0)

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

weight of evidence

Study period:

not reported

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Original report not available and documentation insufficient for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

The substance was tested on Artemia salina using the LC50 assay method.

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

not specified

Test organisms (species):

Artemia salina

Test type:

not specified

Water media type:

saltwater

Limit test:

no

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

> 20 mg/L

Remarks on result:

other: No test duration of this short-term test is given in the publication but is assumed that the test duration might be similar to the duration of the freshwater tests.

Reference 3

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

weight of evidence

Study period:

26 Apr - 27 Apr 1989

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable, well documented study report which meets basic scientific principles

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: 1 g of the test substance was desolved in 10 mL TBA (tertiary butyl alcohol). From this solution 3.2, 1.0, 0.32 and 0.1 mL were diluted to 10 mL with TBA. In this way concentrated solutions of the test substance in TBA containing 100,000, 32,000, 10,000, 3,200 and 1,000 mg/L were prepared. From these concentrated TBA solutions 0.32 mL (32 mg/L test solution) or 0.1 mL (other test solutions) were mixed with 1 L of dilution water. All test solutions and control solutions were vigorously stirred with an magnetic stirrer for 16 h at 15 °C and then filtered through a wad of perlon.
- Controls: 8 blank controls, 2 solvent controls ( 0.1 mL and 0.32 mL)
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): tertiary butyl alcohol (TBA)
- Concentration of vehicle in test medium (stock solution and final test solution): 0.32 and 0.1 mL respectively
- Evidence of undissolved material (e.g. precipitate, surface film, etc): flocs and particles, thus the test medium was filtered through a wad of perlon

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Source: in-house culture
- Age at study initiation: less than 24 h
- Feeding during test: none

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

47 h

Hardness:

one solution with 215 and another with 54 mg CaCO3/L

Test temperature:

20 ± 1 °C

pH:

7.4 - 8.3, measured at test start and test end

Dissolved oxygen:

> 7.6mg/L, measured at test start and test end

Nominal and measured concentrations:

Nominal:
10 and 32 mg/L (water hardness of 215 mg/L CaCO3)
0.1, 0.32, 1.0, 3.2, 10, 32 mg/L (water hardness of 54 mg/L CaCO3)

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 150 mL glass beaker with 100 mL test medium
- Aeration: no aeration
- No. of organisms per vessel: 5 ddaphnids
- No. of vessels per concentration: 4 beakers for each test
- No. of vessels per control: 8
- No. of vessels per vehicle control: 2 (0.32 and 0.1 mg/L)

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: prepared from ground water

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

EFFECT PARAMETERS MEASURED: immobilisation after 23 and 47 h

Reference substance (positive control):

no

Duration:

47 h

Dose descriptor:

EC50

Effect conc.:

> 32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Mortality of control: no immobilities in blank and solvent control

No immobilities occurred within the water solubility of 0.09 mg test substance/L

Description of key information

A PNEC is not derived since no adverse effects were observed in acute tests in the range of the water solubility of the test substances.

Additional information

Studies are available for the pure homologue members of the fatty acid category. In addition some studies are summarized for certain fatty acid mixtures. Generally it could be stated that toxicity of fatty acids to aquatic organisms increases with increasing chain length up to the water solubility limit at a chain length of C12. For longer chains, no effects at saturation are observed.

For the fatty acid mixture under consideration, which contains as main homologues C16 and C18, read-across is performed to studies available for the pure homologues C16 (palmitic acid, CAS 57 -10 -3) and C18 (stearic acid, CAS 57 -11 -4). For the evaluation of the mixture only studies available for the pure homologues which were determined as key studies or used to cover the endpoint via weight of evidence were chosen for read-across. All linked studies conducted with the pure homologues were used in a weight of evidence approach to cover the endpoint "short-term toxicity to invertebrates" for the considered fatty acid mixture.

Fatty acid homologue	EC50 (as reported in the study)	Water solubility*	Test design and species	Reference
C16 - CAS 57-10-3 palmitic acid	> 4.8 mg/L (measured, geom. mean)	< 0.05 at 20 °C	48 h, static,Daphnia magna	NITE, 2000a
C18 - CAS 57-11-4 stearic acid	> 32 mg/L (nominal)	insoluble	47 h, static,Daphnia magna	Hooftman, 1991
	> 20 mg/L (nominal)		Artemia salina, saltwater	Curtis et al., 1970

* see category justification

Palmitic acid (C16: CAS 57 -10 -3) was tested on daphnids in a 48 h static test (NITE, 2000a) under GLP. In the limit test a nominal test concentration of 10 mg/L (corresponding to a measured concentration (geom. mean) of 4.8 mg/L) was used. No effects on mobility of daphnids could be observed during the test period of 48 h. Thus the EC50 is reported to be above 4.8 mg/L (measured concentration) which is far above the limit of water solubililty (see table above and category justification).

For the evaluation of toxic effects of stearic acid (C18: CAS 57 -11 -4) on aquatic invertebrates two studies were taken into account. The static test was conducted on daphnids over 47 hours according to the EU method C.2 in compliance with GLP requirements (Hooftman, 1991). Different concentrations were tested in the study using test water of different hardness. In this study the EC50 -value was reported to be above 32 mg/L (nominal). This result is in line with the EC50 given in the other available study for stearic acid (C18: CAS 57 -11 -4). In the publication of Curtis et al. (1970) Artemia salina were tested. The authors reported an EC50 > 20 mg/L. However, the authors did not mention the test duration and hence the study was only rated with a reliability of 4. Nevertheless, the result of the study indicates that no toxic effects were observed which is in line to the results obtained from the freshwater study. Therefore it might be concluded that the test duration might have been similar to the duration of the freshwater test. Both tests demonstrate the lack of adverse effects in aquatic invertebrates caused by stearic acid.

Concluding from the results reported for the pure homologues C16 and C18 no toxic effects on invertebrates within the range of water solubility are expected for the considered fatty acid mixture.