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Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
26.04.1999 - 29.04.1999
Reliability:
1 (reliable without restriction)
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
Official Journal of the European Communities, L383 A, Part C.3, Algal inhibition test. 19 December 1992
GLP compliance:
no
Specific details on test material used for the study:
- Analytical purity: 99.97%
- Physical state: clear colourless liquid
- Lot/batch No.: MEHQ25 Batch 662
- Storage condition of test material: refrigerator
- Supllier ICI Acrylics
-Date of revieve: 09/12/98
Analytical monitoring:
yes
Details on sampling:
- Sampling method: At the start of the test, samples were taken of each test solution, using the excess remaining after filling the test vessels, and were analysed for the concentration of the test substances, calibrated against mixed standards.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: All test concentrations were prepared by the direct addition of an appropriate weight of the relevant test substance to sterile medium to a final volume of 1000 mL.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: green alga Selenastrum capricornutum Printz
- Strain: ATCC 22662
- Method of cultivation: maintained under axenic conditions
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
Daily temperature measurements in the two incubators used (recorded using a mercury-in-glass thermometer) ranged from 23.9 to 24.2°C. The hourly temperature measurements, recorded automatically, ranged from 23.5 to 23.8°C.
pH:
At the start of the test the pH of the test solutions ranged from 8.19 to 8.39 and at the end of the test the range was 6.76 to 9.68. During the course of the test the pH of the control solutions increased by 0.92 to 1.35 units. This increase was due to the high algal cell densities allied to the fast growth rates (the mean control values for the algal cell densities in the individual incubators increased by × 228 and × 284 over the course of the test). A high orbital shaking rate (160 rpm) was used to minimise this pH shift.
Nominal and measured concentrations:
Test concentrations (nominal): 4.5, 10, 22, 50, 110 mg/L (and a control)
Test concentrations (measured): 3.6, 9.7, 22, 49, 110 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type: closed (airtight,teflon faced disc/crimp closures
- Material, size, headspace, fill volume: borosilicate glass bottles of 50 mL nominal capacity filled completely (approximately 60 mL of test solution)
- Initial cells density: 0.106 x E4 cells per mL
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 4


GROWTH MEDIUM
- Standard medium used: used medium is described by Miller et al. 1978
- Detailed composition if non-standard medium was used:
1) To approximately 900 mL of distilled water add 1 mL of solutions Al, A2, A3 and B.
2) Make up to 1 liter with distilled water.
3) Autoclave at 103 kPa for 15 minutes, allow to cool. (This procedure causes a slight volume loss through the evaporation of distilled water which is replaced by sterile addition).
4) Add 7.67 mL of solution C (aseptic technique)
- Solution A1: NaNO3 12.75 g, MgCl2,6H70 6.082 g, CaC12.2H20 2.205 g, Distilled water to 500 mL
- Solution A2: MgSO4.7H2O 7.35 g, Distilled water to 500 mL
- Solution A3: K2HPO4.3H2O 0.684 g, Distilled water to 500 mL
- Solution B (Micronutrients): H3BO3 0.093 g, MnCl2.4H2O 0.208 g, FeCl3.6H2O 0.080 g, Na2EDTA.2H2O 0.150 g, ZnCl2 1.64 mg, CoCl2.6H2O 0.714 mg, Na2MoO4.2H2O 3.63 mg, CuCl2.2H2O 0.006 mg, Distilled water to 500 mL
- Solution C: NaHCO3 7.5 g, Distilled water to 500 mL


OTHER TEST CONDITIONS
- Photoperiod: 24 hours per day
- Light intensity and quality: The light intensity, measured once during the study, was 8,250 lux in incubator 1 and 7,390 lux in incubator 2 (by cosine receptor). This was also measured in terms of quantum response and was 97.8 and 85.8 μE m-2 s-1 respectively.
- Other: orbital shaking at 160 rpm, in Gallenkamp type INR-401 orbital incubators.


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 110 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 110 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
49 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
110 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
% Loss in concentration of test substance over test period: 6 to 13%
Reported statistics and error estimates:
Statistical analysis: One-way analysis of variance (ANOVA), and Dunnett's procedure was used to identify significant differences (P = 0.05) from the control.

MEAN GROWTH RATES OVER THE TEST PERIOD AND PERCENTAGES OF THE CONTROL

 

Mean measured conc of methyl methacrylate

(mgr')

Mean growth rate

 

(0 - 3days)

%

of control

Control

1.810

-

3.6

1.812

100

9.7

1.812

100

22

1.910

106

49

1.729

96

110

1.666

92

There were no significant differences from the control (P = 0.05)

Validity criteria fulfilled:
yes
Conclusions:
EC50 (72h) based on growth was > 110 mg/l
NOEC (72h) based on growth was 110 mg/l
Executive summary:

In a 72 hour acute toxicity study, the cultures of Pseudokircheriella supcapitata were exposed to methyl methacrylate at measured concentrations of 3.6, 9.7, 22, 49, 110 mg/L under static conditions in acc. with OECD 301 (adopted 12 December 1992). Substance loss during the test was 6 -13 %.

EC50 (72h) based on growth was > 110 mg/l

NOEC (72h) based on growth was 110 mg/l

Description of key information

The ErC50(72h)for MMA in algae was >  110 mg/L.
The NOEC (72h) for growth of algae was 110 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
110 mg/L
EC10 or NOEC for freshwater algae:
110 mg/L

Additional information

In a reliable guideline study according to OECD guideline 201 with Pseudokirchneriella subcapitata and an exposure period of 72 hours an EC50 of >110 mg/L was established based on the inhibition of the growth rate. In the same study a NOEC of 110 mg/L was determined. Based on these results methyl methacrylate is of low toxicity to algae.