Tetrabutyltin

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:

Not provided

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

no guideline available

Principles of method if other than guideline:

The first test was for algal population; growth and enumeration of algae was performed after toxicant exposure. In the algal toxicity tests, concentration response was estimated with a derivation of the moving average angle method becuase algae response relationships differ from animal tests. The second test to determine lethal organotin concentrations were performed by counting and classifying dead cells after toxicant exposure. In the third test, two algal species were exposed to the toxicant to determine if they could adapt to TPTO and TBTO concentrations.

GLP compliance:

not specified

Analytical monitoring:

yes

Vehicle:

yes

Details on test solutions:

- Chemical name of vehicle (organic solvent, emulsifier or dispersant): 0.01 mL of nanograde acetone

Test organisms (species):

Skeletonema costatum

Details on test organisms:

TEST ORGANISM
- Source (laboratory, culture collection): University of Rhode Island, Kingston
- Method of cultivation:maintained in artificial seawater medium fortified with trace metals, vitamins and nutrient salts.
- Exposure of algae was made after 48 h growth

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

20 °C

pH:

8.1

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 150 mL capacity, with stainless steel closures
- Initial cell density: 2500 cells/mL
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- No. of vessels per vehicle control (replicates): 1

GROWTH MEDIUM
- Standard medium used: yes
- Detailed composition if non-standard medium was used:artificial seawater growth medium fortified with trace metals, vitamins and nutrient salts.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:algae from inoculum stock cultures were added to 50 mL of growth medium

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod:72 hours
- Light intensity and quality:150 µE/ m^3/sec photosenthtically active radiation from cool white fluorescent tubes
- pH: 8.1

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: enumerated on hemocytometer and fluorescence measured on a Perkin-Elmer Model 210 fluorescence spectrophotometer (exciter wavelength 430 nm, analyzer wavelength 672 mm)

Reference substance (positive control):

not specified

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

17 µg/L

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

other: LC50

Effect conc.:

> 500 µg/L

Conc. based on:

test mat.

Basis for effect:

other: Cell death

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

186 µg/L

Conc. based on:

test mat.

Basis for effect:

other: Cell death

Validity criteria fulfilled:

not specified

Conclusions:

The EC50 of tetrabutyltin was 17 µg/L when tested with S. costatum for growth rate.
The EC50 and LC50 for tetrabutyltin on cell death of S. costatum are 186 and >500 µg/L respectively.

Executive summary:

The EC50 of tetrabutyltin was 17 µg/L when tested with S. costatum for growth rate.

The EC50 and LC50 for tetrabutyltin on cell death of S. costatum are 186 and >500 µg/L, respectively.

The EC50 values reported for tests on cell death are greater than those of growth tests because biomass at the time of exposure was greater. Extensive death of cells at or near the EC50 concentration may indicate greater hazard than when the LC50 far exceeds the EC50. These data show that populations of algae exposed to relatively high concentrations of organotins (up to 50 µg/L) over a short period of time may recover without input of new cells. However, the data do not show whether recovery was due to adaptation of surviving cells or loss of toxicant from the medium by volatilization, adsorption to dead cells or to walls of exposure vessels, degradation or a combination of these factors.

Description of key information

The 72 hour EC50 of Tetrabutyltin was 17 µg/L when tested with S. costatum for growth rate.

Key value for chemical safety assessment

EC50 for freshwater algae:

17 µg/L

Additional information

Once study is available. The EC50 of tetrabutyltin was 17 µg/L when tested with S. costatum for growth rate. The EC50 and LC50 for tetrabutyltin on cell death of S. costatum are 186 and >500 µg/L, respectively.

The EC50 values reported for tests on cell death are greater than those of growth tests because biomass at the time of exposure was greater. Extensive death of cells at or near the EC50 concentration may indicate greater hazard than when the LC50 far exceeds the EC50, These data show that populations of algae exposed to relatively high concentrations of organotins (up to 50 µg/L) over a short period of time may recover without input of new cells. However, the data do not show whether recovery was due to adaptation of surviving cells or loss of toxicant from the medium by volatilization, adsorption to dead cells or to walls of exposure vessels, degradation or a combination of these factors.