Naphthenic acids

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II) (January 2012)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

no

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

Not relevant

Hardness:

Not reported

Test temperature:

23.2-24.2°C

pH:

6.8-8.9

Dissolved oxygen:

Not relevant

Salinity:

Not reported

Nominal and measured concentrations:

Nominal WAF loading rates: 0 (control), 2.5, 5, 10, 20 and 80 mg/L naphthenic acids

72h mean measured:
96h mean measured:

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 ml Erlenmeyer flasks
- Test volume: 100 ml
- No. of organisms per vessel: Flasks were inoculated with 1 ml of pre-culture of Pseudokirchneriella subcapitata (1*10E+06 cells/ml)
Initial cell concentration: 1x10E+04cells/ml . Positions were randomized on a daily basis.
- No. of vessels per concentration (replicates): 6 replicates and 1 extra vessel of 1l for analytical measurements at 72h. Three replicates were pooled for analytical measurements at 96h.

GROWTH MEDIUM
- Algal nutrient medium prepared to ASTM E1217-97a recipe

OTHER TEST CONDITIONS
- Continuous lightning
- Light intensity and quality: 4357-4527 lux (cool white fluorescent lighting).
- Orbital shaker (100 rpm)
- Temperature and pH were recorded in all parent solutions, at 72h in the extra 1l vessels and at 96 hours in 1 replicate.


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Microscopic counting using a hemacytometer at 24, 48, 72 and 96 hours after incubation


TEST CONCENTRATIONS
- Spacing factor for test concentrations:
- Justification for using less concentrations than requested by guideline:
- Range finding study
- Test concentrations:
- Results used to determine the conditions for the definitive study:

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

ca. 41.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL 40-42

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

ca. 23.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 95% CL 23-25

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 29.6 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: 95% CL 29-30

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 17.7 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

biomass

Remarks on result:

other: 95% CL 17-19

Duration:

96 h

Dose descriptor:

EL50

Effect conc.:

ca. 43.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL 42-45

Duration:

96 h

Dose descriptor:

EL50

Effect conc.:

ca. 24.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 95% CL 24-26

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

ca. 29.9 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: 95% CL 29-31

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

ca. 18.1 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

biomass

Remarks on result:

other: 95% CL 17-19

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

ca. 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: growth rate and biomass

Duration:

72 h

Dose descriptor:

LOELR

Effect conc.:

ca. 20 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: growth rate and biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 7.38 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

other: growth rate and biomass

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

ca. 15 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

other: growth rate and biomass

Duration:

96 h

Dose descriptor:

NOELR

Effect conc.:

ca. 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: growth rate and biomass

Duration:

96 h

Dose descriptor:

LOELR

Effect conc.:

ca. 20 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: growth rate and biomass

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

ca. 7.41 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

other: growth rate and biomass

Duration:

96 h

Dose descriptor:

LOEC

Effect conc.:

ca. 14.8 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

other: growth rate and biomass

Details on results:

No confidence limits are reported in the HPVIS document. The 95% CL are taken from the ‘Naphthenic acids category analysis and hazard characterizaton’. Report submitted to the US EPA by the American Petroleum Institute petroleum HPV testing Group www.petroleumhpv.org. Consortium Registration, May 14, 2012.

Reported statistics and error estimates:

Not specified

The appearance of the alga cell was normal.

Validity criteria fulfilled:

yes

Conclusions:

The growth rate of the unicellular algae (species: Pseudokirchneriella subcapitata) is evaluated during 72 hours of exposure to the water accommodated fractions (WAF) of naphthenic acids. Test was performed according to OECD TG 201, in a static set up. WAFs were produced with loading rates 0 (control), 2.5, 5, 10, 20 and 80 mg/L naphthenic acids. The measured concentrations were (at 72 h): The results of the study showed that WAF has inhibiting effects on the growth rate of the unicellular algae Pseudokirchneriella subcapitata. The ErLC50 is 41.3 mg/l (load) and ErC50 is 29.6 mg/l (measured) for 72 hours of exposure.

The test is performed according to GLP principles and standard test procedures. The quality of the test and test results are highly reliable.

Executive summary:

The effect of the water accommodated fraction (WAF) of naphthenic acids (NA) on the growth rate of the unicellular algal species Pseudokirchneriella subcapitata was measured during a 72 hours exposure period. WAFs were prepared using loading rates of 0 (control), 2.5, 5, 10, 20 and 80 mg/l naphthenic acids. The measured concentrations were <MQL (control), 1.69, 3.48, 7.38, 15, 28.9 and 44.9 mg/l naphthenic acids.

The test was performed in controlled conditions. At 0, 24, 48 and 72 hours the number of cells/ml was assessed (hemacytometer). Results were expressed as % inhibition of the growth rate when compared to control growth rate. The effect concentrations were calculated.

Analytical results are available and document on the exposure concentrations and stability of the test substance (identical results after 72 an 96 hours).

The ErLC50 is 41.3 mg/l (load) and ErC50 is 29.6 mg/l (measured) for 72 hours of exposure.

Also effects on biomass are reported, and NOEC/LOEC values. The test has been prolonged up to 96 hours, and effect values are reported for this exposure period as well.

 

The test is performed according to GLP principles and standard test procedures. The quality of the test and test results are highly reliable.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

USEPA TOx database

Principles of method if other than guideline:

Data was taken from a reliable peer-reviewed secondary source.

GLP compliance:

not specified

Test organisms (species):

Navicula seminulum

Test type:

not specified

Water media type:

freshwater

Total exposure duration:

4 d

Nominal and measured concentrations:

unmeasured

Duration:

4 d

Dose descriptor:

EC50

Effect conc.:

>= 26 - <= 80.5 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

other: population growth

The following data have been retrieved from the US EPA ECOTOX database. The original paper ( Final Rep.No.RG-3965(C2R1), U.S.Public Health Service Grant, Acad.of Nat.Sci.,,:89 p.) given for all these data could not be obtained:

Test species	Duration (d)	Chemical Name	Effect	Measured effect	Endpoint	Conc (ug/L)
Navicula seminulum	4	Naphthenic acid	POP	PGRT	EC50	26000
Navicula seminulum	4	Naphthenic acid	POP	PGRT	EC50	42500
Navicula seminulum	4	Naphthenic acid	POP	PGRT	EC50	43500
Navicula seminulum	4	Naphthenic acid	POP	PGRT	EC50	43700
Navicula seminulum	4	Naphthenic acid	POP	PGRT	EC50	45600
Navicula seminulum	4	Naphthenic acid	POP	PGRT	EC50	80500
Navicula seminulum	4	Naphthenic acid	POP	PGRT	EC50	30500
Navicula seminulum	4	Naphthenic acid	POP	PGRT	EC50	41200
Navicula seminulum	4	Naphthenic acid	POP	PGRT	EC50	42700
Navicula seminulum	4	Naphthenic acid	POP	PGRT	EC50	43100
Navicula seminulum	4	Naphthenic acid	POP	PGRT	EC50	66000
Navicula seminulum	4	Naphthenic acid	POP	PGRT	EC50	79000

Validity criteria fulfilled:

no

Conclusions:

The toxicity of naphthenic acids to the freshwater diatom,Navicula seminulum,has been measured. The 96-h EC50 ranged from 26.0 - 80.5 mg/L

Executive summary:

The toxicity of naphthenic acids to populations of the freshwater diatom, Navicula seminulum,has been measured. The 96-h EC50 for growth ranged from 26.0 - 80.5 mg/L.

Description of key information

The growth rate of the unicellular algae (Pseudokirchneriella subcapitata) is evaluated during 72 hours of exposure to the water accommodated fractions (WAF) of naphthenic acids. The ErLC50 is 41.3 mg/l  (load) and ErC50 is 29.6 mg/l (measured) for 72 hours of exposure.

Key value for chemical safety assessment

EC50 for freshwater algae:

29.6 mg/L

Additional information

The growth rate of the unicellular algae (species: Pseudokirchneriella subcapitata) is evaluated during 72 hours of exposure to the water accommodated fractions (WAF) of naphthenic acids. Test was performed according to OECD TG 201, in a static set up. WAFs were produced with loading rates 0 (control), 2.5, 5, 10, 20 and 80 mg/L naphthenic acids. The measured concentrations were (at 72 h): <MQL (control), 1.69, 3.48, 7.38, 15, 28.9 and 44.9 mg/l naphthenic acids. Test conditions were suitable.

The results of the study showed that WAF has inhibiting effects on the growth rate of the unicellular algae Pseudokirchneriella subcapitata. The ErLC50 is 41.3 mg/l (load) and ErC50 is 29.6 mg/l (measured) for 72 hours of exposure.

 

The test is performed according to GLP principles and standard test procedures. The quality of the test and test results are highly reliable.

The toxicity of naphthenic acids to populations of the freshwater diatom, Navicula seminulum,has been measured. The 96-h EC50 for growth ranged from 26.0 - 80.5 mg/L (US EPA Ecotoxicity website).