Tin sulphide

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:

2010-01-26 to 2010-02-02

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

GLP and guideline compliant study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

AAP medium without chelating agent was used.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The soluble fraction was prepared from a nominal concentration of 100 mg/L. 53.74 mg and 50.89 mg of test item were weighed out and filled up to 537.4 mL and 508.9 mL of modified AAP medium in glass flasks of 1 L capacity. The glass flasks were shaken for 24 h at room temperature. In order to separate the insoluble fraction, filtration though nitrocellulose membrane 0.45 μm was performed. Both filtrates were mixed. 800 mL of filtrate and 800 mL of modified AAP medium were inoculated with 1.84 mL of algae pre-culture to obtain initial algae density of 1 x 104cells/mL. The test concentration and control were divided into six replicates.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata (Reinsch) Korshikov (syn. Selenastrum capricornutum Prinz)
- Source: the standard laboratory culture of Institute of Industrial Organic Chemistry, Branch Pszczyna, Department of Ecotoxicology, Laboratory of Aquatic Toxicology
- Method of cultivation: Algae were cultured on agar bevels and in liquid cultures. For the preliminary tests algae cultured in full AAP medium were used. However, for the definitive test algae from bevels were transferred into fresh modified AAP medium (without EDTA). The algae were incubated in 250 mL Erlenmeyer flask in 21 - 24°C in constant illumination (pre-culture). The algae culture in modified medium was renewed (inoculated to a new medium) once a week in sterile conditions.
A pre-culture was started four days before the experiment. The pre-culture was used for inoculation of the test concentrations and the control.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Hardness:

not applicable

Test temperature:

21.5 – 21.8°C

pH:

7.19 - 7.77

Dissolved oxygen:

not applicable

Salinity:

not applicable

Nominal and measured concentrations:

The measured concentration in samples collected at test initiation was 0.034 mg/L (nominal: 100 mg/L).
In samples collected at the end of the experiment (t72) the content of tin sulfide was below limit of quantification (LoQ = 0.006 mg/L). It can not be excluded that interactions with ingredients of treatment after 72 h of exposure in the test conditions caused that content of tin ion in soluble fraction was below LoQ.

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer glass flasks
- Initial cells density: 1x 10Exp4 cells/mL
- No. of vessels per concentration (replicates): 6

GROWTH MEDIUM
- Standard medium used: The AAP medium (US EPA) recommended by OECD Guideline No 201 was modified in order to exclude chelating agent and used as the culturing medium for test organism and the diluent/solvent for the test item.

TEST MEDIUM / WATER PARAMETERS
- Intervals of water quality measurement: At the beginning and the end of the test pH values were measured in pooled replicates.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: constant illumination
- Light intensity and quality: fluorescent light, 7733 – 7863 lx

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: counting at 24, 48 and 72 hours of exposure
- Other: At the end of the test the microscopic observations of algae cell morphology were performed.

TEST CONCENTRATIONS
- Range finding study: In the first preliminary test soluble fractions of nominal concentrations were applied: 0.1-100 mg/L. In the second preliminary test soluble fractions of nominal concentrations of the test item were used: 6.25-100 mg/L.
- Results used to determine the conditions for the definitive study: The results of the preliminary tests did not show growth inhibition of algae in the soluble fractions of the concentrations used.

Reference substance (positive control):

yes

Remarks:

3,5 dichlorophenol

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 34 µg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 34 µg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 34 µg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: No effects up to highest concentration, prepared as soluble fraction from nominal concentration of 100 mg/L.

Details on results:

The microscopic observations did not show any changes in the algae morphology in comparison to the control.

Results with reference substance (positive control):

First reference test in full AAP medium: The ErC50/72 h value was 3.42 mg/L and EyC50/72 h value was 1.02 mg/L.
Second reference test in modified AAP medium: The ErC50 value was 1.91 mg/L and EyC50 value was 0.83 mg/L.

Reported statistics and error estimates:

statistic comparative Fisher’s test

Validity criteria fulfilled:

yes

Conclusions:

In a growth inhibition test on Pseudokirchneriella subcapitata according to OECD guideline 201 no effects were observed with a saturated solution of tin sulfide. Therefore, the 72-hr EC50 is > 34 µg a.i./L and the 72-hr NOEC is >= 34 µg a.i./L. These concentrations are well above the limit of water solubility.

Executive summary:

In a 72-hour toxicity study, the cultures of Pseudokirchneriella subcapitata were exposed to tin sulfide at a measured concentration of 34 µg a.i./L (a saturated solution of tin sulfide prepared from nominal concentration of 100 mg/L) under static conditions in accordance with the OECD 201 guideline. No effects were observed, neither on growth rate, biomass reduction or changes in cell morphology . The tested concentrations are well above the limit of water solubility.

Description of key information

Tin sulfide causes no toxic effects up to the limit of water solubility.

Key value for chemical safety assessment

EC50 for freshwater algae:

0.034 mg/L

Additional information

In the key study, tin sulfide was testsed as WAF at concentrations above the limit. There was no reduction in algae growth (according to statistic comparative Fisher’s test).

In a 72 -h test with aquatic algae tin sulfide caused no toxic effects up to the limit of water solubility.

This is supported by a result from two read across substances (SnS2 and SnCl2).