Trimethylamine, N-oxide

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study, however, no GLP, no analytical monitoring

Cross-reference

Reason / purpose for cross-reference:

read-across source

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

See attached document in section 13 "Assessment reports" for justification and rationale of the analogy approach

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

190.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

115.06 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Validity criteria fulfilled:

yes

Conclusions:

Based on the analogy approach, the target substance and source substance are expected to have same behavior in aquatic compartment. Hence, the EC50 values were derived for the trimethylamine N-oxyde from experimental results on the souce substance trimethylamine. The EC50 for the target substance were defined at 190.5 and 115.6 mg/L, respectively based on growth rate and biomass.

Executive summary:

Based on their physico-chemical properties, the two substances showed similarity on their structure except the oxygen in the TMAO. Both of the two substances are soluble in water. The partition coefficient n-octanol and water values for the two substances are lower than 0. The two substances could be found in environmental aqueous compartments due to their physico-chemical properties. Additionally, Henry’s law constant were calculated. The transfer from water to air compartments is considered to be slow, even negligible. QSAR were performed on TMAO (ready biodegradability and toxicity to fish, daphnia and algae). Similar results were found for target compared to experimental values obtained on the source substance : readily biodegradable (by Biowin and Vega), fish acute toxicity > 100 mg/L (Ecosar and Vega), daphnia acute toxicity: 10-100 mg/L (Ecosar and Vega), algae acute toxicity >100 mg/L (Ecosar), daphnia chronic.

The algae toxicity is expected to be the same for the two substances.

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1988

Report date:

1988

Reference 2

Reference Type:

other company data

Title:

Unnamed

Year:

2008

Report date:

2008

Reference 3

Reference Type:

other company data

Title:

Unnamed

Year:

2002

Report date:

2002

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: DIN 38412, part 9

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Trimethylamine

EC Number:

200-875-0

EC Name:

Trimethylamine

Cas Number:

75-50-3

Molecular formula:

C3H9N

IUPAC Name:

N,N-dimethylmethanamine

Details on test material:

trimethylamine in 45 % aqueous solution

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Strain: 86.81

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

no data

Test conditions

Hardness:

no data

Test temperature:

20 °C

pH:

uninoculated: 8.1 - 8.5
inoculated: 8.5 - 9.9

Dissolved oxygen:

no data

Salinity:

no data

Nominal and measured concentrations:

Nominal test concentrations: 7.81, 15.83, 31.25, 82.5, 125, 250, 500 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks (250 ml) plugged with gas permeable silicon-sponge caps
- Type (delete if not applicable): open
- Material: glass
- Fill volume: 100 ml
- Initial cells density: 10 000 cells/ml
- No. of vessels per concentration (replicates): 6
- No. of vessels uninoculated control (replicates): 6
- No. of vessels control (replicates): 1
- medium: OECD-medium
- flasks were incubated in an incubation chamber for 72 h
- flasks were shaken once a day to hold cells in suspension
- illumination: permanent artificial light
- light intensity: approx. 120 µE/(m2*s)

Preparation of stock solution:
1 g test substance/litre (sterile bidest. water; test substance is volatile; fluid appeared clear; conductivity: 13 µS/cm, pH 10.2); stock solution was diluted in test medium to reach the final test concentrations.
- tubes were shaken once a day to hold cells in suspension
- illumination: permanent artificial light
- light intensity: approx. 120 µE/(m2s)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: fluorimeter (in vivo chlorophyll-a fluorescence at 685 nm as a size for the biomass (pulsed excitation with light flashesurements) after 0, 24, 48, 72 and 96 h

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

150 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

recalculated

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

86 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

recalculated

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

90.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks:

recalculated

Effect concentrations 4

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

42.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks:

recalculated

Any other information on results incl. tables

During the 96 h exposure to trimethylamine fluorescence values (given as % of control) were as follows (average of 6 replicates):

Nominal concentration (mg/l)	24 h	48 h	72 h	96 h
7.81	109.92	111.63	130.69	108.36
15.83	102.52	89.67	108.69	98.84
31.25	93.01	96.3	112.76	87.79
82.5	72.93	97.84	74.17	54 .96
125	42.28	37.17	32.54	28.37
250	11.63	1.82	0.55	0.7
500	0	-0.13	0	-0.02

pH values:

Nominal test concentrations	test start; not inoculated	96 h; not inoculated	96 h; inoculated
control	8.0	8.2	9.8
7.81	9.7	8.5	8.5
15.63	9.4	8.4	8.5
31.25	9.1	8.3	9.0
62.5	8.8	8.2	9.5
125	8.5	8.2	9.9
250	8.3	8.1	9.9
500	8.1	8.2	9.9

Treatment [mg/L]	Growth rate inhibition [%]	Biomass decrease [%]	Yield Decrease [%]
Control	0.0	0.0	0
7.81	-5.9	-23.3	-31.1
15.63	-1.4	-1.5	-8.8
31.25	-4.0	-5.8	-13.0
62.50	6.5	29.2	26.1
125	26.0	67.8	68.4
250	122.8	102.3	100.9
500	235.8	103.1	101.1

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Executive summary:

Scenedesmus subspicatus was exposed in this study to trimethylamine. Two effects were investigated based on the growth rate as well as on biomass; values were recalculated; therefore nominal results are reported. The concentration is based on the test material. The test duration was 72 hours. For growth rate an EC50 of 150 mg/L and an EC10 of 86 mg/L is reported. Taken the biomass into account, an EC50 of 90.6 mg/L and an EC10 of 42.6 mg/L is recalculated.