Hydrocarbons, C12-C16, n-alkanes, isoalkanes, cyclics, aromatics (2-25%)

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

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

Adequacy of study:

key study

Study period:

Sept. 6, 1996-Dec. 9, 1996

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

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Samples were taken during the equilibration phase (WAF preparation: media allowed to settle for about 1 hour) and at the end of the period of use 24 hours later.
All extractions for each test were performed on the day of the samples being taken and all determinations carried out on the same or following day.

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
Water accomodated fractions of Shellsol H were produced by stirring water appropriate to the test organisms and Shellsol H from 49 hours, leaving the contents of the vessel to stand at least for 1 hour and running off the aqueous phase for use as the test medium.
To enable the Shellsol H to be added at low loading rates, it was added o the growth medium as a solution in acetone and the stirred to prepare the WAF.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Strain: Axenic strain (ATCC 22662)
- Source (laboratory, culture collection): American type culture collection, Maryland, Ohio, U.S.A.
- Age of inoculum (at test initiation): in exponential growth phase
- Method of cultivation: Cultures are made by adding 1.5% (m/v) agar to liquid medium, then autoclaving. While cooling, it is then poured into 9 cm sterile petri dishes. After setting, the cultures are streaked onto the plates and kept under constant illumination at 18-22 °C in an incubator. The cultures are renewed every two weeks. Liquid medium cultures are initiated from the agar plate cultures with cells transferred on a sterile loop. 100 ml cultures are grown in 250 ml Erlenmeyer flasks for up to 4 days. These cultures are also maintained under constant illumination at 21-25 °C in an incubator.

Test type:

static

Limit test:

no

Total exposure duration:

72 h

Test temperature:

19-26 °C

pH:

7.4-9.6

Salinity:

Not applicable (freshwater test)

Nominal and measured concentrations:

Nominal loading rate: 0, 0.1, 0.3, 1.0, 3.0, 10, 30 and 100 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): sealed
- Material, size, headspace, fill volume: 300 ml Erlenmeyer flask with two teflon marbles added for stirring, placed in a cooled orbital incubator (100 cycles/min)
- initial cell concentration: 5000 cells/ml
- No. of vessels per concentration (replicates): 3 flasks inoculated for control + 1 used for background particle counts
- No. of vessels per vehicle control (replicates): 6 flasks inoculated for controls + 1flask used for background particle counts
- No. of vessels per control (replicates): 3 flasks inoculated for controls + 1 flask used for background particle counts

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The water comes from two pumping stations (Highstead and controlled by the Mid Kent Water Company. The water is obtained from bore holes in the chalk of the North Downs. The only chemical treatment prior to its arrival in the laboratory is chlorination to 0.1 mg/l. In the laboratory, the water is filtered (PAL MDY 1001 Y400) to remove all particles larger than 15 µm (90% of particles greater than 10µm) and passed through activated carbon filters (Cuno model CT) to remove chlorine and organic conatminants. Both particle and activated carbon filter cartridges are renewed as recommended by the manufacturers. Heat exchange units (stainless steel and perspex) are used to adjust the temperature of the water.
- Intervals of water quality measurement: six months


OTHER TEST CONDITIONS
- Photoperiod: constant illumination
- Light intensity and quality: 3000 lux



EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Coulter counter or Coulter multisizer every 24 hrs

Duration:

24 h

Dose descriptor:

EL50

Effect conc.:

10 - 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

24 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

24 h

Dose descriptor:

NOELR

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

24 h

Dose descriptor:

NOELR

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

10 - 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

10 - 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

48 h

Dose descriptor:

NOELR

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

48 h

Dose descriptor:

NOELR

Effect conc.:

3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

10 - 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

10 - 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Validity criteria fulfilled:

yes

Conclusions:

The test substance exhibited 72-hour EbL50 (biomass) and ErL50 (growth rate) values of 10-100 mg/L with the alga, Raphidocelis subcapitata. The 72-hr NOEL values for biomass and growth rate were 3 mg/L, respectively.

Executive summary:

The acute toxicity of water accomodated fractions (aqueous extrats) of Shellsol H has been determined to the unicellular alga Raphidocelis subcapitata (formerly Selenastrum capricornutum).

The test media were prepared by adding quantities of Shellsol H to culture medium appropriate to the test organisms and stirring in sealed vessels for 49 hours). The strirring period was demonstrated as being sufficient to ensure equilibration of the shellsol H and aqueous phases. After stirring the contents of the test vessels were left to settle for about 1 hour before drawing off the WAF for use as the test media in the toxicity tests.

The concentrations of dissolved hydrocarbons (derived from the shellsol H) in the test media was determined during the toxicit tests usig gas chromatography. The analyses showed that the concentration in the test media was <1%% of the loading rate. The reduction in the concentration of dissolved hydrocarbons in the test media during the test was ≤26%.

The acute toxicity to R. subcapitata of water accomodated fractions of Shellsol H prepared at loading ranging from 0.1 to 100 mg/l was determined in a 72h growth inhibition test without renewal of the test media in sealed test vessels. The7h EL50 values (loading rates reducing the area under the growth curves and the average specific growth rates by 50% after 72h exposure) were in the range 10 -100 mg/l.

Description of key information

There is no data available for this substance. However, key data is available for the structural analogue Hydrocarbons, C10-C13, n-alkanes, Isoalkanes, cyclics, aromatics (2-25%). The data for this substance is presented in this dossier. The data is read across to these substances 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, C10-C13, n-alkanes, isoalkanes, cyclics, aromatics (2-25%) presented 72-hour EbL50 (biomass) and ErL50 (growth rate) values within the range if 10-100 mg/L for Raphidocelis subcapitata.  The 72-hr NOEL values for biomass and growth rate were 3 mg/L, respectively. (Based on water accommodated fractions).

Additional information

One study report was available and input as an endpoint record for toxicity to aquatic algae and cyanobacteria.

The study from Shell (1995) examined the acute toxicity of water accomodated fractions (aqueous extrats) of Shellsol H (Hydrocarbons, C10 -C13, n-alkanes, isoalkanes, cyclics, aromatics (2 -25%)) to Raphidocelis subcapitata (formerly Selenastrum capricornutum). The test media were prepared by adding quantities of Shellsol H to culture medium appropriate to the test organisms and stirring in sealed vessels for 49 hours). The strirring period was demonstrated as being sufficient to ensure equilibration of the shellsol H and aqueous phases. After stirring the contents of the test vessels were left to settle for about 1 hour before drawing off the WAF for use as the test media in the toxicity tests. The concentrations of dissolved hydrocarbons (derived from the shellsol H) in the test media was determined during the toxicit tests usig gas chromatography. The analyses showed that the concentration in the test media was <1%% of the loading rate. The reduction in the concentration of dissolved hydrocarbons in the test media during the test was ≤26%. The acute toxicity to R. subcapitata of water accomodated fractions of Shellsol H prepared at loading ranging from 0.1 to 100 mg/l was determined in a 72h growth inhibition test without renewal of the test media in sealed test vessels. The7h EL50 values (loading rates reducing the area under the growth curves and the average specific growth rates by 50% after 72h exposure) were in the range 10 -100 mg/l.