2-(phenylmethoxy)naphthalene

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 guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: Directive 87/302/EEC: Algal Inhibition Test

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

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 concentrations

Effect concentrations 1

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

Effect concentrations 2

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

Effect concentrations 3

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

Effect concentrations 4

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).