A mixture of isomers of: mono-(2-tetradecyl)naphthalenes; di-(2-tetradecyl)naphthalenes; tri-(2-tetradecyl)naphthalenes

Toxicity to aquatic algae and cyanobacteria

Administrative data

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:

other: Reliability rating was 1 because the study followed OECD 201 (Alga Growth Inhibition) test guidelines and was carried out under GLP conditions. Study was well-documented.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

MCP 2484

IUPAC Name:

MCP 2484

Constituent 2

Reference substance name:

A mixture of isomers of: mono-(2-tetradecyl)naphthalenes; di-(2-tetradecyl)naphthalenes; tri-(2-tetradecyl)naphthalenes

EC Number:

410-190-0

EC Name:

A mixture of isomers of: mono-(2-tetradecyl)naphthalenes; di-(2-tetradecyl)naphthalenes; tri-(2-tetradecyl)naphthalenes

Cas Number:

132983-41-6

Molecular formula:

Can vary from C24H36 (mono rxn product) to C52H92 (tri rxn product)

IUPAC Name:

2,3,6-tritetradecylnaphthalene; 2,3-ditetradecylnaphthalene; 2-tetradecylnaphthalene

Details on test material:

- Name of test material (as cited in study report): MCP 2484
- Physical state: liquid, amber-color
- Analytical purity: 100%

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

no

Details on test solutions:

Preparation of WAF Solutions

The test solutions were prepared by adding the test substance (200 mg) to dilution medium (2L) in a glass vessel. The contents of the vessel were stirred with a vortex of approximately 10% for approximately 24 hours and then left to stand for approximately 24 hours. An aliquot (1200 mL) was then removed mid vessel to provide a Water Accommodated Fraction (WAF) at nominal loading rate concentration of 100 mg/L that was used in the test. An aliquot (13.0 mL) of the secondary algal inoculum was added to a portion (800 mL) of the test medium, to give an initial nominal cell density of 1 x 104 cells/mL. An aliquot (100 mL) of the inoculated test medium was added to each of the test vessels.

Test organisms

Test organisms (species):

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

Details on test organisms:

Pseudokirchneriella subcapitata, Strain No. CCAP 278/4 was obtained from the Culture Collection of Algae and Protozoa (CCAP), SAMS Research Services Ltd., Dunstaffnage Marine Laboratory, Dunbeg, Oban, Argyll, Scotland. Cultures were stored in an illuminated refrigerator.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test conditions

Test temperature:

Temperature ranged between 21.9-24.7 C

pH:

PH 7.6 to 8.0

Nominal and measured concentrations:

Limit test: 100 mg/L nominal loading as WAF solution

Details on test conditions:

Alga source and cultures

Pseudokirchneriella subcapitata, Strain No. CCAP 278/4 was obtained from the Culture Collection of Algae and Protozoa (CCAP), SAMS Research Services Ltd., Dunstaffnage Marine Laboratory, Dunbeg, Oban, Argyll, Scotland. Cultures were stored in an illuminated refrigerator. Sterile algal nutrient medium was inoculated with cells aseptically removed from the slope culture; these primary liquid cultures (100 mL) were incubated for approximately three days in an orbital incubator under continuous illumination at nominal temperatures in the range 21 to 25 C. Subsequently, appropriate volumes of these primary cultures were aseptically transferred to fresh sterile algal nutrient medium to prepare secondary liquid cultures; these cultures were incubated, as stated above, for a further three days to provide an inoculum in the log phase of growth, characterised by a cell density of 6.17 x E+5 cells/mL

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

and AUC growth curve

Effect concentrations 2

Duration:

72 h

Dose descriptor:

other: NOEL

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

and AUC growth curve

Any other information on results incl. tables

Based on statistical analysis of cell density data, algal growth was not inhibited by the test substance in this test. In fact, the test group at 100 mg/L nominal loading WAF, showed statistically greater algal growth than the controls. Hence, the test substance does not inhibit algal growth at the nominal loading of 100 mg/L WAF level under the conditions of the test. The 72-hr EL50 value was determined to be >100 mg/L nominal loading and the 72-hr NOEL was estimated to be >100 mg/L nominal loading.

In all samples of the test cultures taken at the start and end of the definitive test, the concentrations of MCP2484 were below the limit of detection of the analytical method (<0.01 mg/L). This was not unexpected based on the limit of aqueous solubility (≤0.001 mg/L measured at 20°C) of the test material.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The test material did not affect the growth of the freshwater alga, Pseudokirchnerella subcapitata, in the presence of up to 100 mg/L nominal loadings (WAF). The 72-hr EL50 value was determined to be >100 mg/L nominal loading and the 72-hr NOEL was estimated to be >100 mg/L nominal loading. No inhibition of algal growth was observed for the test material at its maximal water solubility level under the conditions of this test at the highest test loading of 100 mg/L (nominal).

Executive summary:

The acute toxicity of test material as measured by alga cell growth or inhibition toPseudokirchnerella subcapitatawas evaluated in freshwater. Nominal loadings of the test material did not produce any acute toxicity to alga up to loadings of 100 mg/L relative to controls under the conditions of this study. The 72-hr EL50 value was determined to be >100 mg/L nominal loading and the 72-hr NOEL was estimated to be >100 mg/L nominal loading. Overall, no inhibition of algal growth was observed for the test material at its maximal water solubility level (<0.001 mg/L) under the conditions of this test at the highest test loading of 100 mg/L (nominal).