Fatty acids, C16-18

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

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

Adequacy of study:

key study

Study period:

14 Sep - 05 Oct 2006

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Deviations:

yes

Remarks:

hardness of test water was lower than that recommended by the Guideline

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: 61.7 °C
- Boiling point: 390 °C
- Vapour pressure: 0.998 mmHg (154 °C)
- Water solubility: 0.00072% (20 °C)
- Solubility: freely soluble in diethyl ether, soluble in ethanol

Analytical monitoring:

yes

Details on sampling:

- Concentrations: control, vehicle control, nominal concentration: 0.510 mg/L
- Sampling method: test water was sampled from one vessel in each group at day 0, 1, 7, 8, 14 and 15.
- 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: stock solution (5100 mg/L) was prepared with test substance and vehicle at the study initiation by shaking with hands. Stock solution was stable in a refrigerator > 21 days. Test water was prepared with dilution water and stock solution and mixed for 1 minute with a magnetic stirrer.
- Controls: dilution water with/without vehicle
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): N, N- dimethyl formaldehyde (DMF)
- Concentration of vehicle in test medium (final test solution): 0.1 mg/L
- Evidence of undissolved material: not observed

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Source: Incorporated Administrative Agency, National Institute for Environmental Studies, Tsukuba, Japan
- Age at study initiation: max. 24 hours
- Feeding during test: yes
- Food type: Chlorella vulgaris
- Amount: 0.15 mgC / day

ACCLIMATION
- Acclimation period for parental animals: 2 - 4 weeks
- Acclimation conditions: same as test
- Type and amount of food: Chlorella vulgaris, 0.1 - 0.2 mgC/day
- Health during acclimation: < 5% mortality in 2 weeks before exposure and no males and no ephippia was observed

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

21 d

Hardness:

46 - 52 mg/L (CaCO3)

Test temperature:

19.8 - 20.1 °C (20 ± 1 °C)

pH:

7.3 - 7.9

Dissolved oxygen:

7.1 - 8.5 mg/L (> 60% of saturated oxygen)

Nominal and measured concentrations:

nominal concentration: 0.51 mg/L
measured concentration (time weighted mean): 0.22 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL beaker
- Type: closed (covered with teflon-sheet)
- Material, fill volume: glass, 80 mL
- Renewal rate of test solution: once in 24 hours
- No. of organisms per vessel: 1
- No. of vessels per concentration: 10
- No. of vessels per control: 10
- No. of vessels per vehicle control: 10

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: aerated tap water charcoal-treated and dechlorinated with sodium thiosulfate, in Yokohama, Japan
- Culture medium different from test medium: parental animals were cultured in same dilution water 48 hours before exposure.
- Intervals of water quality measurement: every 6 months

OTHER TEST CONDITIONS
- Adjustment of pH: not adjusted
- Photoperiod: 16 hours in light, 8 hours in dark
- Light intensity: < 800 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
immobility, mortality for parental animals, number of offspring

TEST CONCENTRATIONS
- Justification for using less concentrations than requested by guideline: water solubility was 0.51 mg/L
- Range finding study: acute toxicity test was performed
- Test concentrations: 0.510 mg/L (nominal concentration)
- Results used to determine the conditions for the definitive study: EC50 for 48 hours: >0.510 mg/L

Reference substance (positive control):

yes

Remarks:

potassium dichromate (reagent grade)

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

> 0.22 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

based on cumulative number of juveniles produced per adult

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

> 0.22 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

based on cumulative number of juveniles produced per adult

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

> 0.22 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

based on cumulative number of juveniles produced per adult

Details on results:

- Mortality of parent animals after 21 days: control: 10%, solvent control: 10%, 0.22 mg/L (time weighted mean measured cencentration): 10%
- Cumulative no. of offspring produced per female: see table 1
- Number of males and females (parental): 10 females in each group
- Time to first brood release or time to hatch: 8 - 9 days

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- EC50: 0.75 ± 0.14 mg/L

Reported statistics and error estimates:

Student-t test and Welch-t test

Table 1: Cumulative number of juveniles produced per adult alive for 21 days

Nominal Concentration, mg/L (Measured (a) Concentration, mg/L)	Mean Cumulative Numbers of Living Young after 21 Days(Mean ± S.D.)	Inhibition rate (%)	Significant difference
Control	119.6 ± 10.5
Solvent control	119.8± 7.9
0.510 (0.22)	128.7 ± 13.4	-7.4	-

(a): Time-weighted mean measured concentration

-: Indicates no significant difference

Description of key information

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

Additional information

For the members of the fatty acid category four chronic tests are available conducted with pure homologues of different chain lengths. The tested homologues were: decanoic acid (C10 - CAS 334-48-5), lauric acid (C12 - CAS 143-07-7), myristic acid (C14 - CAS 544-63-5) and palmitic acid (C16 - CAS 57-10-3). As palmitic acid (C16) is one of the main components of the fatty acid mixture under consideration a read-across is performed to a study conducted for this pure homologue. For stearic acid no chronic test is available.

Fatty acid homologue	NOEC (as reported in the study)	Water solubility*	Test design and species	Reference
C16 - CAS 57-10-3 palmitic acid	0.22 mg/L (measured, twa concentrations)	< 0.05 at 20 °C	21 d, semi-static,Daphnia magna	NITE, 2008
C18 - CAS 57-11-4 stearic acid	--	insoluble	No chronic test available

* see category justification

For the evaluation of chronic effects of palmitic acid (C16: CAS 57 -11 -4) on aquatic invertebrates, daphnids were tested in a limit-test over a period of 21 days (NITE, 2008). The semi-static experiment was conducted according to OECD 211 in compliance with GLP-requirements. The used test concentration of 0.51 mg/L (nominal) corresponding to a mean measured value (time weighted mean) of 0.22 mg/L was above the reported water solubility limit. No effects were observed on daphnids at this test concentration and thus the NOEC is reported to be 0.22 mg/L.

Concluding from the results reported for palmitic acid C16 no chronic risk is expected for the considered mixture.