Reaction mass of methyl acetate and methanol

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II) (January 2012)

Deviations:

not specified

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

no

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: green alga
- Strain: ATCC-22662
- Source (laboratory, culture collection): National Institute Environmental Research, Korea
- Age of inoculum (at test initiation): 7 days
- Method of cultivation: The flasks then were placed on a shaker incubator at 170 rpm and 25°C, with 24 h light supplied via worm white fluorescent tubes, with an average illumination of 30 ± 5µE/m2s.

ACCLIMATION
- Acclimation period:
- Culturing media and conditions (same as test or not): Stock alga was cultivated in 250 mL Erlenmeyer flasks, containing 200 mL sterilized nitrate-enriched BBM medium prepared in triple distilled water, to avoid nitrogen limitation during the high-density culture. The culture flask was agitated on a shaker at 170 rpm, and bubbled with air (1 vvm), without sparger. Light was continuously supplied, with an average of 30 ±5 µE/m2s, using warm-white fluorescent tubes located on top of the shaker. All the flasks were maintained in the shaker incubator at 25 ± 5°C for 7 days.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Test temperature:

25°C

Details on test conditions:

TEST SYSTEM

Experiments were performed in 250 mL Erlenmeyer flasks containing 55 mL of sterilized culture medium, inoculated with 5 mL samples of 7 day cultured algae. Solutions of organic solvents were subsequently added to the test flasks. The organic solvents tested were completely miscible with water, forming a homogeneous phase. Concentrations were adjusted in the range between 0.1 M and 1.26 µM to obtain complete concentration-response curves. At each determined exposure date, the optical density of the algal biomass was estimated at 438 nm using a spectrophotometer. The dry cell weight, corresponding to the optical density, was determined from the linear relationship; dry cell weight (g/L) = 0.329 x optical density. All experiments were performed in duplicate, but the control experiments were conducted in triplicate.

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

ca. 22 000 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth rate

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

Growth inhibition test

GLP compliance:

not specified

Analytical monitoring:

not specified

Test organisms (species):

other: Anabaena sp., A. cylindrica, A. variabilis, A. inaegualis, and Nostoc sp.

Details on test organisms:

TEST ORGANISM
- Common name: blue-green algae
- Strain and Source: Anabaena sp. ATCC 27899, A. cylindrica ATCC 29414, A. variabilis ATCC 29413, and Nostoc sp. ATCC 29105 were obtained from the American Type Culture Collection, Rockville, Maryland, U.S.A., A. inaequalis was obtained from the Department of Botany and Genetics, University of Guelph, Guelph, Ontario, Canada.
- Method of cultivation: Stock cultures were grown in 250 mL Erlenmeyer flasks sealed with cotton bungs and containing 150 mL of an inorganic, nitrogen-free medium (Stratton et al. 1980). Flasks were incubated at 25 ± 1°C and a light intensity of 7 klux on a 12 hour light-dark cycle.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

14 d

Nominal and measured concentrations:

A minimum of 10 concentrations were tested for each species, ranging from 0.6% to 10% methanol by volume (4.74-79.00 g/L).

Details on test conditions:

TEST SYSTEM
- No. of vessels per concentration (replicates): 5 - 10
- experiment repeated 3 - 5 times

Reference substance (positive control):

no

Key result

Dose descriptor:

EC50

Effect conc.:

20 300 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: growth inhibition

Remarks on result:

other: Anabaena cylindrica

Key result

Dose descriptor:

EC50

Effect conc.:

21 170 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: growth inhibition

Remarks on result:

other: Anabaena inaequalis

Key result

Dose descriptor:

EC50

Effect conc.:

24 730 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: growth inhibition

Remarks on result:

other: Anabaena sp.

Key result

Dose descriptor:

EC50

Effect conc.:

43 290 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: growth inhibition

Remarks on result:

other: Nostoc sp.

Description of key information

Based on a read across to the structural analogue Methyl acetate (CAS 79 -20 -9) the 96-hour EC10 and EC50 (growth rate) of the registration substance was determined to be > 120 mg/L. The 72-hour NOEC (growth rate) is considered to be 120 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

120 mg/L

Additional information

No data on short-term toxicity to aquatic invertebrates are available for the registration substance itself, but for the read across source substances Methanol and Methyl acetate.

Methanol

In a static Alga, Growth Inhibition Test according to OECD Guideline 201 withRaphidocelis subcapitataa 96-hour EC50 (growth rate) of 22000 mg/L was determined (Cho et al., 2008).

In a growth inhibition test (non-guideline) by Stratton (1987) the blue-green algae Anabaena sp., A. cylindrica, A. variabilis,  A. inaegualis and Nostoc sp.were exposed for 14 days to a minimum of 10 concentrations, ranging from 0.6% to 10% methanol by volume (4.74-79.00 g/L). The following EC50 values were derived fro growth inhibition:

Anabaena cylindrica: EC50 = 20300 mg/L

Anabaena inaequalis: EC50 = 21170 mg/L

Anabaena sp.: EC50 = 24730 mg/L

Nostoc sp.: EC50 = 43290 mg/L

Methyl acetate

The toxicity of Methyl acetate to algae was tested in a static test sytem for a test period of 72 h according to OECD 201 and in compliance with the GLP principles (Stuhlfaut, 1994). Scenedesmus subspicatus was the test organism. The test was conducted as a limit test with a test concentration of 120 mg/L. The EC50 and EC10 based on growth rate was determined to be > 120 mg/L, based on nominal values. The 72 -hour NOEC based on growth rate as well as on biomass was 120 mg/L (nominal). Hence, Methyl acetate revealed to be non-toxic to algae in this test. All validity criteria of the guideline were fulfilled. The study is hence regarded to be valid.

Conclusion

Based on the most reliable information (Stuhlfaut, 1994) and by applying a worst case approach the 72-hour EC10 and EC50 (growth rate) of the registration substance is considered to be > 120 mg/L, the 72 -hour NOEC (growth rate) to be 120 mg/L..