Zinc dodecyl hydrogen disulphate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

21 Oct - 24 Oct 2014

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION:
The test solution was prepared at 100 mg/L in culture medium. Five test concentrations were then obtained by dilutions.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Source (laboratory, culture collection): in-house culture
- Method of cultivation: algal suspension is kept in culture medium in sterile 250 mL flasks, under stirring with electrical stirrer and continuous light (>4300 lux).

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

none

Test temperature:

23.0 - 23.2 °C

pH:

Control: 7.78 - at test initiation; 8.68 at test end
Test samples: 7.59 at test initiations; 8.93 at test end

Nominal and measured concentrations:

0, 1.02, 2.56, 6.40, 16.0, 40.0 mg/L (nominal for tested product)

Details on test conditions:

TEST SYSTEM
- Test vessel: glass flasks,
- Initial cells density: 10^4
- Control end cells density: 2.15 x 10^6
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
deionized water was used for medium preparation

OTHER TEST CONDITIONS
- Sterile test conditions: yes/no
- Adjustment of pH: no
- Photoperiod: continuous
- Light intensity and quality: fluorescent lamp, 8000 lux


EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: counting chamber; at 24, 48, 72h; microscopic observations for abnormal cell apperance.


TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 0, 0.01, 0.1, 1.0, 10, 100 mg/L

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.747 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.226 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Description of key information

EC50(72 h, growth rate)= 0.747 mg a.i./L (P. subcapitata, nominal, OECD 201)
EC10(72 h, growth rate)= 0.226 mg a.i./L (P. subcapitata, nominal, OECD 201)

Key value for chemical safety assessment

EC50 for freshwater algae:

0.747 mg/L

EC10 or NOEC for freshwater algae:

0.226 mg/L

Additional information

One study on the toxicity of C12-14 AS Zn to aquatic algae P. subcapitata is available (Z&S, 2014). The GLP study was performed according to OECD 201 guideline. Algae were exposed for 72 hours to several test concentrations 0, 1.02, 2.56, 6.40, 16.0, 40.0 mg product/L (nominal values). The tested product had a purity of 26.6% and the remaining was water. The TOC analysis proved that the test concentrations are stable over time. Since no other analytical measurements of the test substance were performed, the results are based on the nominal concentrations. The 72-h EC50 and EC10 values were determined to be 2.813 mg product/L and 0.853 mg product/L. For the active substance the values were 0.747 mg a.i./L and 0.226 mg a.i./L respectively (nominal concentration).