Bromoacetic acid

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

August 1991 to March 1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study was performed according to the OECD guideline 202 and the laboratory was GLP certified while analytical measurements were not performed. However, the test material is not poorly soluble and not volatile under the test conditions.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1992

Report date:

1992

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Bromoacetic acid

EC Number:

201-175-8

EC Name:

Bromoacetic acid

Cas Number:

79-08-3

Molecular formula:

C2H3BrO2

IUPAC Name:

2-bromoacetic acid

Test material form:

solid: crystalline

Details on test material:

- Name of test material (as cited in study report): Monobromoacetic acid
- Substance type: Hygroscopic white yellow crystals
- Physical state: Solid
- Analytical purity: > 98%
- Lot/batch No.: 9271763
- Storage condition of test material: stored at room temperature

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Refer to section 4 : Physical and chemical properties

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:
The medium was prepared from concentrated stock solutions in Milli-Q filtered water. The medium was sterilized by micropore filtration.
The profile of the culture medium is:
NH4CI= 15 mg/L
MgCl2.6H2O= 12 mg/L
CaCl2.2H2O= 18 mg/L
MgSO4.7H2O= 15 mg/L
KH2PO4= 1.6 mg/L
FeCI3.6H2O= 80 µg/L
Na2EDTA.2H2O= 100 µg/L
H3B03= 185 µg/L
MnCl2.4H2O= 415 µg/L
ZnCI2= 3 µg/L
CoCI2.6H2O= 1.5 µg/L
CuC12.2H2O= 0.01 µg/L
Na2MoO4.2H2O= 7 µg/L
NaHCO3= 150 mg/L --> and not 50 mg/L as specified in the OECD guideline.
The pH of this medium after equilibration with air is approximately 8.

- Stock solutions were prepared by dissolving (after warming to approximately 50-60°C), 1.02 g test substance in 500 ml (range finding test) or 21.2 mg test substance in 100 ml algal medium (growth inhibition test).

From these stock solutions, appropriate dilutions were prepared in algal medium to yield final concentrations of 0.01, 0.10, 1.0, 10, 100 and 1000 mg/L (range-finding test) or 0.056,0.10,0.18,0.32,0.56,1.0 and 1.8 mg/L (growth inhibition test).

Test organisms

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Selenastrum capricornutum
- Strain: ATCC 22662
- Source (laboratory, culture collection): Supplied by the 'American Type Culture Collection', c/o Sales Department, 12301 Parklawn Drive. Rockville, Maryland 20852, USA.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

4 d

Test conditions

Hardness:

No data

Test temperature:

23+/-1°C

pH:

without algae: 8.1-8.4
After 3 days with algae: 8.3-8.4
However, after 4 days of incubation the pH were found to increase with algal cell density: 8.3-10.6

Dissolved oxygen:

No data

Nominal and measured concentrations:

Nominal concentration : 0.056, 0.10, 0.18, 0.32, 0.56, 1.0, and 1.8 mg/L
No measured concentrations

Details on test conditions:

TEST SYSTEM
- Test vessel: 200 ml conical test flasks
- Type (delete if not applicable): closed - with silicone sponge caps, autoclaved and coded.
- Material: shaken (l00 rpm) in a Gallenkamp orbital shaker.
- Initial control cells density: 1.0 x10^4 cells/ml (--> density expected in all test vessels)
- No. of replicates: The test was carried out in duplicate with two controls with algae only, and a single background series containing test substance without algae.

GROWTH MEDIUM/TEST MEDIUM / WATER PARAMETERS
Cf. details on test solution

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Light intensity and quality: The light intensity radiated by the fluorescent lamps was within the standard range 60-120 µmol/s/m2 (measured with a Bottemanne Weather Instruments Photosynthetic Radiometer RA200 Q).

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
One sample was taken from each flask after 0, 23, 47.5, 71.5 and 92.5 h, and the number of algal cells per mI in the samples was determined.
* EC50: The number of algae in the test series was obtained by subtraction of the number of particles in the background control series (without algae) from the number of particles in the test series. The mean values were used for further calculations.
In this study the EC values with respect to the inoculum viability (EeC50), assuming a counting error proportional to the number of cells were calculated by means of a parametric model developed by Kooijman et al. (1983).
EC values with respect to the area under the growth curve (Et,C values) were calculated by linear interpolation of a plot of the percentage reduction in growth (lA) against the log concentration of the test substance.
* NOEC: estimated by visual comparison of the measured and calculated growth curves of the treated algal suspensions with those of the controls.

TEST CONCENTRATIONS
* Range finding study
- Test concentrations: 0.01, 0.10, 1.0, 10, 100 and 1000 mg/L
- Results used to determine the conditions for the definitive study: The inhibiting effects could be expected at concentration higher than 0.1 mg/L

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

4 d

Dose descriptor:

EC50

Effect conc.:

0.28 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: inoculum viability

Remarks on result:

other: 0.24-0.32 mg/L

Effect concentrations 2

Duration:

4 d

Dose descriptor:

EC10

Effect conc.:

0.09 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: inoculum viability

Effect concentrations 3

Duration:

4 d

Dose descriptor:

EC90

Effect conc.:

0.89 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: inoculum viability

Effect concentrations 4

Duration:

4 d

Dose descriptor:

EC50

Effect conc.:

0.29 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: area under the growth curve

Remarks on result:

other: 0.18-0.32 mg/L

Effect concentrations 5

Duration:

4 d

Dose descriptor:

EC10

Effect conc.:

0.17 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: area under the growth curve

Remarks on result:

other: 0.10-0.18 mg/L

Effect concentrations 6

Duration:

4 d

Dose descriptor:

EC90

Effect conc.:

1.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: area under the cell growth

Remarks on result:

other: 1.0-1.8 mg/L

Effect concentrations 7

Duration:

4 d

Dose descriptor:

NOEC

Effect conc.:

0.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: By visual comparison of the measured and the calculated growth curves of algal suspensions exposed to the test substance with those of the algal controls

Details on results:

Microscopic examination of the cells at the start and the end of the incubation period revealed no abnormalities at the concentrations tested.

Reported statistics and error estimates:

The model of Kooijman et al (1983) assumes that:
1. The number of cells in each culture increases exponentially.
2. The growth rate or the number of actively growing cells in the inoculum decreases according to a logistic function of the natural logarithm of test substance concentration.
The following equations were used:
N(t,c) = Eb - E(c) + E (c) exp (tR(C))
or when no effect is expected on the inoculum, i.e. E(c) = Eb:
N(t,c) = Eb exp (tR(C)
or when no effect is expected on the growth rate, i.e. R(c) = Rb
N(t,c) = Eb - E(c) + E(c) exp (tRbl
where
N(t,c) = number of cells.m1-1 at time t and concentration c of the test substance
E(c) = inoculum; number of cells.m1-1 in the culture containing concentration c of the test substance at t = 0
R(c) = the growth rate at concentration c of the test substance
R b and Eb = growth rate and inoculum, respectively, of the untreated cells.
In addition,
R(c) = Rb (1 + exp (Rg (In c - R))-1
and
E(c) = Eb (1 + exp (Rg (In c - E)))-1
where
Re and He = natural logarithm of the respective EC50 values.
Rg and Eg = the gradient of the functions for, respectively, the growth rate and the and the inoculum.

The parameters Eb, Ee, Eg, Rb, Re, and Rg were calculated by a weighted least square fitting of the model to the results.
Calculations and curve plottings were perfonned by computer program on a HP 320 computer.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The toxicity of monobromoacetic acid to the fresh-water green alga Selenastrum capricornutum was determined in a growth inhibition test according to the OECD Guideline no. 201. The test duration was extended to four days.

The EC50 with respect to inoculum viability (EeC50) was found to be 0.28 mg/L, with a 95% confidence interval of 0.24-0.32 mg/L. The EC50 with respect to the area under the growth curve (EbC50) was found to be 0.29 mg/L (in the range 0.18-0.32 mg.!-!).
The NOEC was estimated to be 0.10 mg/L.
The concentrations given are nominal concentrations of the test substance monobromoacetic acid.

Executive summary:

The toxicity of monobromoacetic acid to the fresh-water green alga Selenastrum capricornutum was determined in a growth inhibition test according to the OECD Guideline no. 201 and the OECD principles of Good Laboratory Practice.

The test duration was extended to four days.

The concentrations of monobromoacetic acid tested were 0.056, 0.10, 0.18, 0.32, 0.56,1.0 and 1.8 mg/L. The algal growth was detennined by electronic particle counting. The effect values were calculated using a parametric model assuming a counting error proportional to the number of cells.

The EC50 with respect to inoculum viability (EeC50) was found to be 0.28 mg/L, with a 95% confidence interval of 0.24-0.32 mg/L. The corresponding EeC10 and EeC90 values were 0.09 mg/L and 0.89 mg/L respectively.

The EC50 with respect to the area under the growth curve (EbC50) was found to be 0.29 mg/L (in the range 0.18-0.32 mg/L). The corresponding EbC10 and EbC90 values were 0.17 mg/L (0.10-0.18 mg/L) and 1.6 mg/L (1.0-1.8 mg/L) respectively.

The no-observed-effect-concentration (NOEC) with respect to the effects referred to above was estimated to be 0.10 mg/L.

The concentrations given are nominal concentrations of the test substance monobromoacetic acid.