Ethanone, 1-(4-methoxyphenyl)-2-[(3-methoxyphenyl)thio]-

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:

Jun 2006 to Feb 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

469-300-0

EC Name:

-

Cas Number:

63675-73-0

Molecular formula:

Hill Empirical Formula: C16H16O3S CAS Empirical Formula: C16H16O3S

IUPAC Name:

1-(4-methoxyphenyl)-2-[(3-methoxyphenyl)sulfanyl]ethan-1-one

Test material form:

solid: particulate/powder

Details on test material:

Lot no: 151105Purity - 101.39%

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

At approximately 24-hour intervals after the start of the incubation period, volumes of test media were removed from each incubated test vessel, and transferred to individually identified cell counting vials. The content of each vial was diluted to a 10 mL final volume with an electrolyte solution. The number of alga cells in duplicate 0.5 mL volumes, drawn into the counter (under vacuum) from each vial, was then determined using a particle counter (22 Coulter Counter®). These values were then used to establish cell densities (cells/ml) for each of the incubated test vessels used in the test.

Test solutions

Vehicle:

yes

Remarks:

Acetone

Details on test solutions:

The dilution media used was algae nutrient medium (EC media). The definitive test was conducted at nominal Beta Ketosulfide concentrations of control, 0.088, 0.159, 0.287, 0.516, 0.929, 1.67 and 3.01 mg/L. The selected concentrations were based on the results of the range-finding test and the practical solubility limit for the test substance.A test medium at a nominal concentration of 100 mg!L, was prepared by weighing 199.98 mg of Beta Kctosulfide into a glass vessel and adding 200 µL of acetone. The vessel contents were then rinsed into a 2-litre volumetric flask and made up to volume with EC medium. The flask contents was then treated with ultrasound for 30 minutes, stirred for 1 hour in the dark and filtered through a 0.45µm pore sized filter. The remaining test media then were prepared by serially diluting the nominal 100 mg!L test medium. Additional aliquots of acetone were added to each test media preparation as it was prepared, to ensure that a solvent loading of 0.1 mUL was achieved in the solvent control a nd in all treatments.The solvent control treatment was prepared by adding 100 µL of acetone to a 1000 mL volumetric flask and making up to volume with EC medium. The control treatment was prepared by adding EC medium only to the test vessels.

Test organisms

Test organisms (species):

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

Details on test organisms:

The test organism, Pseudokirchneriel/a subcapitata (Strain 278/4) was obtained from the CCAP (Culture Collection of Algae and Protozoa) and is a representative species of the freshwater aquatic phytoplankton. This species is recommended for testing in accordance with the OECD regulatory guidelines. The P. subcapitata culture used was derived from the CCAP, SAMS Research Services Ltd., Oban, UK.Prior to testing, duplicate starter cultures were prepared and incubated under test conditions. A start ing alga cell density of 1 x 10^4 algacells/mL was achieved.

Study design

Test type:

semi-static

Water media type:

other: Reverse osmosis water

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

At 72 hours, measured concentrations of Beta Ketosulfide had declined significantly, resulting in overall mean measured concentrations outside 80-120% of the nominal concentrations. Therefore, the toxicity values have been reported in terms of the overal! (geometric) mean measured test conc entrations. The limit of detection for the analytical method was 0.008 mg/L.

Test conditions

Hardness:

Not measured

Test temperature:

23.3-24.3C

pH:

7.7-7.9 initially. Increased to 9.9 after 72 hrs with algal cells

Dissolved oxygen:

Not measured

Salinity:

Not measured

Conductivity:

Not measured

Nominal and measured concentrations:

The overall mean (geometric) measured concentrations of Beta Ketosulfide at the respective nominal concentrations of 0.088, 0.159, 0.287, 0.516, 0.929, 1.67 and 3.01 mg!L were 0.0408, 0.0893, 0.155, 0.290, 0.747, l.57 and 2.76 mg/L, respectively. These values correspond to 46, 56, 54, 56, 80, 94 and 92 % of the nominal concentrations, respectively.

Details on test conditions:

The dilution media used was algae nutrient medium (EC media). The definitive test was conducted at nominal Beta Ketosulfide concentrations of control, 0.088, 0.159, 0.287, 0.516, 0.929, 1.67 and 3.01 mg/L. The selected concentrations were based on the resu lts of the range-finding test and the practical solubility limit for the test substance.A test medium at a nominal concentration of 100 mg!L, was prepared by weighing 199.98 mg of Beta Kctosulfide into a glass vessel and adding 200 µL of acetone. The vessel contents were then rinsed into a 2-litre volumetric flask and made up to volume with EC medium. The flask contents was then treated with ultrasound for 30 minutes, stirred for 1 hour in the dark and filtered through a 0.45µm pore sized filter. The remaining test media then were prepared by serially diluting the nominal 100 mg!L test medium. Additional aliquots of acetone were added to each test media preparation as it was prepared, to ensure that a solvent loading of 0.1 mUL was achieved in the solvent control and in all treatments.The solvent control treatment was prepared by adding 100 µL of acetone to a 1000 mL volumetric flask and making up to volume with EC medium. The control treatment was prepared by adding EC medium only to the test vessels.

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 0.615 mg/L

Basis for effect:

biomass

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 1.21 mg/L

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 0.29 mg/L

Basis for effect:

growth rate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 0.29 mg/L

Basis for effect:

biomass

Details on results:

Toxicity ValuesStatistical comparison of growth (area under the growth curve and specific growth rate data) in the c ontrol and solvent control treatments, revealed no significant differences between the two treatments. Therefore, the ErC5o and EbC.so toxicity values have been detennined by comparison of treatments with combined (pooled) control data.Based on the overall mean measured concentrations of Beta Ketosulfide, the 0 - 72 hour EbC50 and Er C50 toxicity values with corresponding NOEC values are presented in the table below (see any other information on results incl. tables).

Any other information on results incl. tables

follow on from "Details on results" section

 

CI = 95% confidence interval

 

Parameter	Toxicity Values (EC50 and NOEC)   Overall   mean   measured   Beta   Ketosulfide Concentration (mg/l)
0 -72 hour Er C50   NOEC	1.21 (CI = 1.09 -1.34)   0.290
0 -72 hour Eb C50   NOEC	0.615 (CI =0.363 -1.04)   0.290

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity of Beta Ketosulfide, on the growth of the unicellular green algae, Pseudokirchner iella subcapitata was determined during a 72 hour growth inhibition toxicity test.The test was conducted in accordance with the known requirements of OECD Chemical Testing Guideline No. 201 Algae, Growth Inhibition tests (adopted 7 June 1984). In terms of the overall mean measureed concentrations, based on the growth rate toxicity values, Beta Ketosulfide exposure to P. subcapitata was considered to be toxic (where toxicity values > 1mg/ L and <= 10 mg/L) and may cause long term adverse effects in the aquatic environment. For the area under the growth curve (0-72 hour Eb C50), Beta ketosulfide would be consided to be very toxic , as the toxicity value was <= 1mg/L. The toxicity values have already been presented above.

Executive summary:

This test was conducted in accordance with the known requirements of OECD Chemical Testing

Guideline No. 201 Algae, Growth Inhibition Test (adopted 7 June 1984)

The ErC50 (0 -72 hrs) = 1.21, NOEC = 0.290

The EbC50 (0 -72 hrs) = 0.615, NOEC = 0.290