Tetrabutylammonium bromide

Toxicity to aquatic plants other than algae

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic plants other than algae

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Data is from peer reviewed journal

Justification for type of information:

Data is from peer reviewed journal

Qualifier:

according to guideline

Guideline:

other: Refer below principle

Principles of method if other than guideline:

Standard Method:-
Tests were conducted in 15-ml Petri dishes over 96 h. In petri dish approximately two fronds of L. minor (a single colony) with roots cut to less than 1 mm was added . Then the root length was measured and the number of new fronds were counted at the end of the experiment.For each Petri dish,
the combined root length was divided by the number of fronds to calculate the mean root length per frond, which were used as metric of root growth.Root growth was normalized to frond number since roots must grow from fronds and because preliminary tests showed that this parameter was
sensitive to concentrations of chemicals below the concentration that would cause effects on frond number. The cultures were maintained and tests was conducted in continuous light from four 122- cm, wide-spectrum General Electric (Cleveland, OH, USA) plant and aquarium bulbs suspended 20 cm above the fronds.

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

not specified

Test organisms (species):

Lemna minor

Details on test organisms:

Lemna minor strain number 492 from the University of Toronto Culture Collection (derived from Landolt 7730). Prior to tests, cultures were maintained for one month in growth medium. No sexual reproduction was observed in the cultures.

Test type:

not specified

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Details on test conditions:

fronds with roots cut to <1 mm placed in Petri dish; exposed to title comp. under continuous lighting for 96 h;

Reference substance (positive control):

not specified

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

51.4 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

frond number

Remarks on result:

other: Range of EC50- 35.62–91.62 mg/L

Details on results:

Frond growth is the number of new fronds produced per replicate during the test.

Validity criteria fulfilled:

not specified

Conclusions:

After the exposure of test chemical for 96 hrs, EC50 was observed to be at 51.4 mg/l. Hence, it is said to have low toxicity for aquatic plants in aquatic chronic category 3.

Executive summary:

Tests were conducted in 15-ml Petri dishes over 96 h. In petri dish approximately two fronds of L. minor (a single colony) with roots cut to less than 1 mm was added . Then the root length was measured and the number of new fronds were counted at the end of the experiment.For each Petri dish, the combined root length was divided by the number of fronds to calculate the mean root length per frond, which were used as metric of root growth.Root growth was normalized to frond number since roots must grow from fronds and because preliminary tests showed that this parameter was sensitive to concentrations of chemicals below the concentration that would cause effects on frond number. The cultures were maintained and tests was conducted in continuous light from four 122- cm, wide-spectrum General Electric plant and aquarium bulbs suspended 20 cm above the fronds. Lemna minor strain number 492 from the University of Toronto Culture Collection. Prior to tests, cultures were maintained  for one month in growth medium. No sexual reproduction was observed in the cultures. The concentration (and 95% confidence interval) at which a 50% reduction in growth (the EC50) occurred was calculated for both frond growth (measured as number of new fronds) and root length per frond using the sigmoidal dose–response (variable slope) equation in the ligand-binding response macro for Sigmaplot 7.0. After the exposure of test chemical for 96 hrs, EC50 was observed to be at 51.4 mg/l. Hence, it is said to have low toxicity for aquatic plants in aquatic chronic category 3.

Description of key information

Tests were conducted in 15-ml Petri dishes over 96 h. In petri dish approximately two fronds of L. minor (a single colony) with roots cut to less than 1 mm was added . Then the root length was measured and the number of new fronds were counted at the end of the experiment. For each Petri dish, the combined root length was divided by the number of fronds to calculate the mean root length per frond, which were used as metric of root growth. Root growth was normalized to frond number since roots must grow from fronds and because preliminary tests showed that this parameter was sensitive to concentrations of chemicals below the concentration that would cause effects on frond number. The cultures were maintained and tests was conducted in continuous light from four 122- cm, wide-spectrum General Electric plant and aquarium bulbs suspended 20 cm above the fronds. Lemna minor strain number 492 from the University of Toronto Culture Collection. Prior to tests, cultures were maintained  for one month in growth medium. No sexual reproduction was observed in the cultures. The concentration (and 95% confidence interval) at which a 50% reduction in growth (the EC50) occurred was calculated for both frond growth (measured as number of new fronds) and root length per frond using the sigmoidal dose–response (variable slope) equation in the ligand-binding response macro for Sigmaplot 7.0. After the exposure of test chemical for 96 hrs, EC50 was observed to be at 51.4 mg/l. Hence, it is said to have low toxicity for aquatic plants in aquatic chronic category 3.

Key value for chemical safety assessment

EC50 for freshwater plants:

51.4 mg/L

Additional information

Based on the various experimental data for the target chemical study have been reviewed to determine the nature of test chemical on the growth of aquatic plants. The studies are as mentioned below:  

 

In the first experimental study from peer reviewed journal toxicity were measured. Tests were conducted in 15-ml Petri dishes over 96 h. In petri dish approximately two fronds of L. minor (a single colony) with roots cut to less than 1 mm was added. Then the root length was measured and the number of new fronds were counted at the end of the experiment. For each Petri dish, the combined root length was divided by the number of fronds to calculate the mean root length per frond, which were used as metric of root growth. Root growth was normalized to frond number since roots must grow from fronds and because preliminary tests showed that this parameter was sensitive to concentrations of chemicals below the concentration that would cause effects on frond number. The cultures were maintained and tests was conducted in continuous light from four 122- cm, wide-spectrum General Electric plant and aquarium bulbs suspended 20 cm above the fronds. Lemna minor strain number 492 from the University of Toronto Culture Collection. Prior to tests, cultures were maintained for one month in growth medium. No sexual reproduction was observed in the cultures. The concentration (and 95% confidence interval) at which a 50% reduction in growth (the EC50) occurred was calculated for both frond growth (measured as number of new fronds) and root length per frond using the sigmoidal dose–response (variable slope) equation in the ligand-binding response macro for Sigmaplot 7.0. After the exposure of test chemical for 96 hrs, EC50 was observed to be at 51.4 mg/l. Hence, it is said to have low toxicity for aquatic plants in aquatic chronic category 3.

 

Above study was supported by the second study from peer reviewed journal 2008. Toxicity value of test cheimical in terms of root length per frond to Lemna minor is EC50: 32.66 mg/L. Hence, the substance is said to have low toxicity to aquatic plants in aquatic chronic category 3.

 

Thus based on the above studies, chemical consider to be toxic and classified as aquatic chronic 3 as per the CLP classification criteria.