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Ecotoxicological information

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:
2.12.-22.12.1992
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study was accepted by authorities in context of ELINCS notification.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1993
Report date:
1993

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Qualifier:
according to guideline
Guideline:
other: Directive 87/302/EEC: Algal Inhibition Test
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
2-(phenylmethoxy)naphthalene
EC Number:
405-490-3
EC Name:
2-(phenylmethoxy)naphthalene
Cas Number:
613-62-7
Molecular formula:
C17H14O
IUPAC Name:
2-(benzyloxy)naphthalene
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
- Name of test material (as cited in study report): BNE
- Substance type: organic
- Physical state: white powder
- Analytical purity: 99.8%
- Impurities (identity and concentrations):
- Expiration date of the lot/batch: August 31, 1994
- Storage condition of test material: at room temperature in the dark

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
- Concentrations:
- Sampling method: duplicate samples from test solutions and blank control at t = 0 h and t = 96 h plus reserve samples
- Sample storage conditions before analysis: at -20 °C until analysis, if not anaöysed on day of sampling

Test solutions

Vehicle:
no

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Scenedesmus subsoicatus
- Strain: 86.61 SAG
- Source (laboratory, culture collection):
- Age of inoculum (at test initiation):
- Method of cultivation:

ACCLIMATION
- Acclimation period:
- Culturing media and conditions (same as test or not):
- Any deformed or abnormal cells observed:

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h

Test conditions

Test temperature:
19 - 21 °C
pH:
at 0 h: 8.0 - 8.6
at 72 h: 7.7 - 7.9
Nominal and measured concentrations:
see Table 1 under Any other information on materials and methods incl. tables
Details on test conditions:
TEST SYSTEM
- Test vessel: 100 ml, all glass
- Initial cells density: 10000 cells/ml
- Control end cells density: 342000 cells/ml
- Replicas: 3 per test concentration
6 per control (test medium without test substance or any other additives)
- No. of vessels per vehicle control (replicates):

GROWTH MEDIUM
- Standard medium used: yes ISO-medium formulated acc. to the International Standards "Algal growth inhibition test" (November, 1989)
in Milli-Q water without visible precipitation.


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Tap water purified by reverse osmosis and subsequently passed over activated carbon and
- Preparation of test media: The test media were prepared using a supersaturated stock solution of 1 g/l in medium.
This stock was stirred for 16 hours. After stirring, the stock still contained undisso1ved particles and
was filtered through a paper filter (Schleicher and Schuell 604).
The filtrate was used for the preparation of the different test concentrations.
The final volume of the test solutions was 50 ml per vessel.
At the start of the test all test solutions were clear.

OTHER TEST CONDITIONS
- Photoperiod: continously using TLD-lamps of 18 W (Philips, Spain)
- Light intensity: 6000 - 8000 lux


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: at the start of the test counting by microscope, using a counting chamber;
thereafter by spectrophotometric measurement at 720 nm with a cuvette of 5 cm path-length
and algal medium as a blank
- observation interval: 24 h


TEST CONCENTRATIONS
- Spacing factor for test concentrations: approx. 1.8
- Justification for using less concentrations than requested by guideline:
- Range finding study: A supersaturated test solution (2g/l, nominal) was stirred for 22h.
After this period the test substance was filtered through a paper filter and 1%, 10% and 100% of the filtrate were tested.
- Test concentrations: As the results of the range-finding test showed that the filtrate of a supersaturated solution did not induce any effect on
cell growth: a filtrate (100%) of a supersaturated solution and solutions containing 10%, 18%, 32% and 56% of the filtrate,
were tested.

Reference substance (positive control):
yes
Remarks:
potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
> 90 µg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
90 µg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
> 90 µg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
90 µg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
- Exponential growth in the control (for algal test): yes
Results with reference substance (positive control):
- Results with reference substance valid? yes
- EC50:
The nominal 72-hour EC50 for growth inhibition (EBC50:0-72h) was 0.44 mg/1, the 95% confidence interval ranging from 0.33 to 0.5B mg/1.
The nominal 72-hour EC50 for growth rate reduction (ERC50:24-72h) approximated 1.0 mg/1.

Any other information on results incl. tables

TABLE 2:Mean cell densitiesl

Concentration %-filtrate2

Mean cell densities during exposure

0h3

24h

48h

72h

96h

0

1.00

3.13

8.5

19.3

34.2

10

1.00

2.46

7.8

18.9

41.6

18

1.00

2.57

6.4

11.7

24.6

32

1.00

2.51

8.6

24.6

51. 7

56

1.00

2.85

9.0

21.8

44.7

100

1.00

2.79

8.7

17.6

37.1

1A variation of±0.1 is acceptable owing to rounding off by the program used for calculations.

2100%-filtrate corresponded with a mean measured concentration of 90 µg/l.

3Number of cells inoculated at t=0: 1.0x10^4 cells/ml.·

 

TABLE 3: Percentage inhibition of cell growth and percentage reduction of growth rate.

Concentration %-filtrate1

Cell growth (0-72h) Growth rate (24-72h) Reduction

 

 

Cell growth (0-72h)

Growth rate (24-72h)

Concentration %-filtrate1

Area (A) mean

Inhibition (%)

mean µ

Reduction(%)

0

1069.70

0

0.03317

0

10

1114.59

-4.2

0.03908

-18

18

707.54

34

0.03082

7.1

32

1394.05

-30

0.04266

-29

56

1259.72

-18

0.03812

-15

100

1059.24

1

0.03582

-8.0

-----------------------------------------------------------~----

1100%-filtrate corresponded with a mean measured concentration of 90 µg/1.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
Temperature of climate room varied from 20 to 23°C. Such a slight deviation of the protocol led range did not invalid the results of the test.
Conclusions:
Under the conditions of the present study with Scenedesmus subspicatus, 2-(phenylmethoxy)naphthalene did not reduce cell growth of this fresh water algae species significantly at exposure concentrations up to and including 90 µg/l, corresponding with an actual starting concentration of 117 µg/l.
Both the nominal 96-hour EC50 for growth inhibition (EbC50: 0-96h)
and the nominal EC50 for growth rate reduction (ErC50: 24-96h) were > 90 µg/l, i.e. higher than the maximum solubility of BNE in water.
The No Observed Effect Concentration for both growth inhibition (NOEbC) and
growth rate reduction (NOErC) was found to be higher than the maximum solubility of 2-(phenylmethoxy)naphthalene in water (ca. 70 µg/l).

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