1-bromobutane

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:

24/11/97 to 16/12/97

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

not specified

GLP compliance:

yes

Specific details on test material used for the study:

No further details specified in the study report.

Analytical monitoring:

yes

Details on sampling:

Analytical chemistry and physico-chemical measurements were carried out at the beginning and the end of the test.

Vehicle:

not specified

Details on test solutions:

Not specified

Test organisms (species):

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

Details on test organisms:

Biological reagent: Test organisms are freshwater algae, green unicellular, Pseudokirchneriel! a subcapitata strain CCAP 278/4 (previously named Raphidocelis subcapitata and Selenastrum capricornutum); the strain used was obtained from the Culture Center of Algae and Protozoa.

Test type:

not specified

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Post exposure observation period:

Not specified

Hardness:

Not specified

Test temperature:

23.4 ± 0.9 °C

pH:

During the test, the control pH varied by 0.45 units.

Dissolved oxygen:

Not specified

Salinity:

Not applicable.

Conductivity:

Not specified

Nominal and measured concentrations:

The effect concentrations and NOEC have been calculated using the initial concentrations of n-BUTYL BROMIDE determined by gas chromatography according to the method described in annex to this report.

Details on test conditions:

The study was performed using 120 ml glass bottles stoppered with PTFE bungs and sealed with aluminium caps, containing 50 ml of test solution inoculated with an algal suspension so that the initial cell concentration was equal to 1 x 104 cells/ml. Tests flasks were incubated at 23.4 ± 0.9 °C continuously shaken and constantly exposed to a light intensity of between 6000 and 6900 lux. The algal concentration was measured daily.

Reference substance (positive control):

not specified

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1.93 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

other: biomass & growth rate

Details on results:

The appearance of the test solutions was visually checked at the beginning and at the end of the test. Solutions were found to be clear, colourless. No precipitation was observed at the end of the test.
Microscopic observation confirmed that the algae appeared deformed, turgid in the 3 highest concentrations in comparison to the control: the normal form of the unicellular algae is a crescent shaped cell with an average length of 5-10 μm.

Results with reference substance (positive control):

Not specified

Reported statistics and error estimates:

The No Observed Effect Concentration (NOEC), corresponding to the highest tested concentration where no significant effect was observed in comparison to the control, was determined using a statistical analytical method (Dunnett test).

Validity criteria fulfilled:

yes

Conclusions:

EbC50: 6.9 mg/l
ErC50: 9.98 mg/l
The No Observed Effect Concentration (NOEC): 1.93 mg/l

Executive summary:

The determination of the growth inhibition (chronic toxicity) of the freshwater algae Pseudokirchneriella subcapitata (previously known as Raphidocelis subcapitata and Selenastrum capricornutum) exposed to the test substance n-BUTYL BROMIDE (BROMURE DE n-BUTYLE) for a duration of 72 hours was performed following the method C3 described in Directive 92/69/EEC of the European Commission and in the guideline 201 of the OECD.

 

Algae were exposed to a range of concentrations of n-BUTYL BROMIDE dissolved in dilution water. The toxic effect measured during the assay was the inhibition of cellular multiplication over a time period of 72 hours.

 

The study was performed using 120 ml glass bottles stoppered with PTFE bungs and sealed with aluminium caps, containing 50 ml of test solution inoculated with an algal suspension so that the initial cell concentration was equal to 1 x 10⁴cells/ml. Tests flasks were incubated at 23.4 ± 0.9 °C continuously shaken and constantly exposed to a light intensity of between 6000 and 6900 lux. The algal concentration was measured daily.

Analytical chemistry and physico-chemical measurements were carried out at the beginning and the end of the test.

 

The concentration of test substance causing a 50 % reduction in biomass (EbC50) or in growth rate (ErC50) was determined. The No Observed Effect Concentration (NOEC), corresponding to the highest tested concentration where no significant effect was observed in comparison to the control, was determined using a statistical analytical method (Dunnett test). The results were as follows:

 

Effect concentration and NOEC (mg/l)
	Value	95 % CI
Biomass
EbC50 – 72h	6.9	(4.6 – 9.6)
EbC10 – 72h	2.9	(1.4 – 4.3)
NOECb	1.93	ND
Growth rate
ErC50 – 72h	9.9	(7.8 – 13)
ErC10 – 72h	4.1	(2.9 – 5.4)
NOECr	1.93	ND

CI: 95 % confident interval

ND: not determined

 

The effect concentrations and NOEC shown in the previous table have been calculated using the initial concentrations of n-BUTYL BROMIDE determined by gas chromatography according to the method described in annex to this report.

 

The appearance of the test solutions was visually checked at the beginning and at the end of the test. Solutions were found to be clear, colourless. No precipitation was observed at the end of the test.

 

Microscopic observation confirmed that the algae appeared deformed, turgid in the 3 highest concentrations in comparison to the control: the normal form of the unicellular algae is a crescent shaped cell with an average length of 5-10 μm.

 

During the test, the control pH varied by 0.45 units.

 

The validity criteria of the study were respected: the increase in cell density (R), measured in the control solution between the end and the beginning of the test, was greater than a factor of 16 (R =57); the final concentrations of n-BUTYL BROMIDE were maintained within the designated limit of 80 % of the initial concentration in non-inoculated flasks.

 

The study was performed according to the principles of Good Laboratory Practice (GLP) as described by OECD.

Description of key information

EbC50: 6.9 mg/l

ErC50: 9.98 mg/l

The No Observed Effect Concentration (NOEC): 1.93 mg/l

 

 

Key value for chemical safety assessment

EC50 for freshwater algae:

9.9 mg/L

EC10 or NOEC for freshwater algae:

1.93 mg/L

Additional information

The determination of the growth inhibition (chronic toxicity) of the freshwater algae Pseudokirchneriella subcapitata (previously known as Raphidocelis subcapitata and Selenastrum capricornutum) exposed to the test substance n-BUTYL BROMIDE (BROMURE DE n-BUTYLE) for a duration of 72 hours was performed following the method C3 described in Directive 92/69/EEC of the European Commission and in the guideline 201 of the OECD.

 

Algae were exposed to a range of concentrations of n-BUTYL BROMIDE dissolved in dilution water. The toxic effect measured during the assay was the inhibition of cellular multiplication over a time period of 72 hours.

 

The study was performed using 120 ml glass bottles stoppered with PTFE bungs and sealed with aluminium caps, containing 50 ml of test solution inoculated with an algal suspension so that the initial cell concentration was equal to 1 x 10⁴cells/ml. Tests flasks were incubated at 23.4 ± 0.9 °C continuously shaken and constantly exposed to a light intensity of between 6000 and 6900 lux. The algal concentration was measured daily.

Analytical chemistry and physico-chemical measurements were carried out at the beginning and the end of the test.

 

The concentration of test substance causing a 50 % reduction in biomass (EbC50) or in growth rate (ErC50) was determined. The No Observed Effect Concentration (NOEC), corresponding to the highest tested concentration where no significant effect was observed in comparison to the control, was determined using a statistical analytical method (Dunnett test). The results were as follows:

 

Effect concentration and NOEC (mg/l)
	Value	95 % CI
Biomass
EbC50 – 72h	6.9	(4.6 – 9.6)
EbC10 – 72h	2.9	(1.4 – 4.3)
NOECb	1.93	ND
Growth rate
ErC50 – 72h	9.9	(7.8 – 13)
ErC10 – 72h	4.1	(2.9 – 5.4)
NOECr	1.93	ND

CI: 95 % confident interval

ND: not determined

 

The effect concentrations and NOEC shown in the previous table have been calculated using the initial concentrations of n-BUTYL BROMIDE determined by gas chromatography according to the method described in annex to this report.

 

The appearance of the test solutions was visually checked at the beginning and at the end of the test. Solutions were found to be clear, colourless. No precipitation was observed at the end of the test.

 

Microscopic observation confirmed that the algae appeared deformed, turgid in the 3 highest concentrations in comparison to the control: the normal form of the unicellular algae is a crescent shaped cell with an average length of 5-10 μm.

 

During the test, the control pH varied by 0.45 units.

 

The validity criteria of the study were respected: the increase in cell density (R), measured in the control solution between the end and the beginning of the test, was greater than a factor of 16 (R =57); the final concentrations of n-BUTYL BROMIDE were maintained within the designated limit of 80 % of the initial concentration in non-inoculated flasks.

 

The study was performed according to the principles of Good Laboratory Practice (GLP) as described by OECD.