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Toxicity to aquatic algae and cyanobacteria

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toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No inhibitory effect even with the highest concentration. EL50 not reached. Based on WAFs.
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
according to guideline
ISO 10253 (Water quality - Marine Algal Growth Inhibition Test with Skeletonema costatum and Phaeodactylum tricornutum)
Principles of method if other than guideline:
Guideline study
GLP compliance:
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
No test surrogate material is tested
Analytical monitoring:
Details on sampling:
Not applicable (no analytical monitoring)
Details on test solutions:
The test solutions were prepared as water accomodated fractions (WAFs). They were prepared by direct addition of the required nominal amounts, followed by stirrring for approximately 20 hours. The preparations were then allowed to stand for appromately 1 h, before withdrawing a sample by siphon from the middle of the water phase, avoiding incorporation of floating/settled material.
Test organisms (species):
Skeletonema costatum
Details on test organisms:
- Common name: Skeletonema costatum
- Age of inoculum (at test initiation): at least 4 days
- Method of cultivation: Stock culture in laboratory at ca. 20°C at constant illumination

- Acclimation period: 4 days
- Culturing media and conditions: same as test
Test type:
Water media type:
Limit test:
Total exposure duration:
72 h
Post exposure observation period:
No post exposure observation
Not relevant (seawater study)
Test temperature:
19.5 °C
8.07 - 8.81
Dissolved oxygen:
No data provided
No data provided
Nominal and measured concentrations:
10096, 20063, 30025, 60085 and 100204 mg/L (ppm). These concentrations are based after weighing the test substance in the algal culture medium.
Details on test conditions:
- Test vessel:
- Type: closed (all flasks looselys covered with aluminium foil caps)
- Material, size, headspace, fill volume: borosilicate glass conical flasks, 80 mL test medium
- Aeration: Not provided in the study report
- Initial cells density:10^4 cells/ml
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 4

- Standard medium used: yes

- Sterile test conditions: No
- Adjustment of pH: Yes
- Photoperiod: continuous light
- Light intensity and quality: 4 x 40W tubes mounted at a distance of 40 cm directely above the test area

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: counting chamber

- Spacing factor for test concentrations: 1.8
Reference substance (positive control):
Water-soluble chemical 3',5-dichlorophenol
72 h
Dose descriptor:
Effect conc.:
> 10 000 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: Not relevant
Details on results:
- Exponential growth in the control (for algal test): yes
Results with reference substance (positive control):
72 h LC50 = 3.83 mg/L
Reported statistics and error estimates:
Not relevant as the EL50 is greater than the highest tested concentration.

No remarks

Validity criteria fulfilled:
No growth inhibition at concentrations up to 10,000 mg/L
Executive summary:

The test procedure followed is described in the ISO/DIS 10253 « Water quality » - Marine algal growth inhibition test with Skeletonema costatum and Phaeodactylum tricornutum”, 1991.

Skeletonema costatum was used as test organism.

The organisms are exposed to Water Accomodated Fractions (WAFs) of test substance H383 -96.

The exposure of Skeletonema costatum to concentrations up to 10,000 mg/l for 72 h does not inhibit algal growth (based on growth rate measurements).

Description of key information

As the substance is poorly soluble in water, most of the studies are performed using Water accomodated fractions (WAFs) and all the results are

based on nominal loadings. Thus, the values indicated below as NOECs are actually NOELRs (No observed effect loading rates). No study could lead to the calculation of EL50.

Key value for chemical safety assessment

Additional information

Many study reports were available for this end-point, all dealing with the toxicity of the substance “Hydrocarbons, C14-C18, n-alkanes, isoalkanes, cyclics, < 2% aromatics” on algae growth rate. All the studies used the marine species Skeletonema costatum. None of the studies allowed calculating 48h-EL50 that was never reached. All LL50 are superior to 10000 mg/L based on WAF studies.