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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:
07 Feb 18 - 17 April 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
CAS#: 53423-65-7
EC#: 258-548-3
Label Identification: Arichem, LLC; 187 Sloss Industries Road; Ariton, AL 36311 USA
Product Sample: Sodium Trichlorobenzene Sulfonate
Lot: 1708-09; Approx 100g
Date & Quantity Received: 29 Jan 18; 109.7 g (GW)
Physical Description: White powder
Storage Conditions: Room temperature
Purity: 100% active ingredient, refer to the Sponsor provided Certificate of Analysis
Analytical monitoring:
no
Remarks:
Substance is a non-volatile solid and known to be stable in water at environmetal pH
Vehicle:
no
Details on test solutions:
The limit test solution was prepared by dissolving 0.1600 g of test item in 800 mL of OECD medium and mixing for approximately 15 minutes. All concentrations were double the desired final concentration until media containing algae cells was added in equal volume to prepared test concentration to achieve the final test concentration of 100 mg/L.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Justification for Species: One of the freshwater alga species specified in the regulations
Source: STILLMEADOW, Inc. cultures
Age: Mass culture initiated 3-7 ± 1 days prior to dosing
Density: Initial cell density was 25,000 cells/mL
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Test temperature:
Target: 24 ±2°C
Actual: 22-25ºC
Dissolved oxygen:
Test containers received constant agitation on shaker table set at approximately 100 cycles/minute
Nominal and measured concentrations:
Range-finding: 1 mg/L, 5 mg/L, 10 mg/L, 50 mg/L and 100 mg/L.
Limit Test: 100 mg/L
Details on test conditions:
Test Room: Environmentally controlled Chamber A
Test Chambers: 250 mL sterile Erlenmeyer flasks with foam stoppers; filled with 100 mL of the appropriate solution
Test/Nutrient Medium: OECD media with a pH of 8.1 ±0.1.
Continuous lighting (3770-4930 lux)
Reference substance (positive control):
yes
Remarks:
Zinc chloride
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Results with reference substance (positive control):
The test was considered valid because the 72 hour terminal control increased by a factor of at least 16 times.

Limit Test Average Growth Rate Results

Test Conc. (mg/L)

Rep

Cell Density x 104cells/mL

Initial pH

Terminal pH

Avg. Growth Rate

24 Hours

48 Hours

72 Hours

Test Medium

control

A

18 a

51

149 c

8.1

8.6

0.057

B

12

33

63 b c

8.4

NA b

C

21 a

46

164 c

8.3

0.058

D

10

37

132 c

8.2

0.055

E

21

43

145 c

8.5

0.056

F

24 a

48

168 c

8.2

0.058

100

A

11

35

185 c

7.6

8.7

0.060

B

10

45

170 c

8.7

0.059

C

19

39

192 c

8.7

0.060

Positive control

A

2

0

1

7.0

7.9

-0.013

B

1

0

1

7.9

-0.013

C

2

0

0

7.9

0.000

Note: All organisms had no observable abnormalities unless otherwise indicated.

Rep: Replicate; (-) NA: Not Applicable

aClump of uncountable cells

bReplicate considered outliers and eliminated from statistical analysis.

cAt 72 hours, control and 100 mg/L solutions appeared green and cells were NOA (No Observable Abnormalities)

Validity criteria fulfilled:
yes
Conclusions:
The EC50 was determined to be >100 mg/L based on growth rate. The growth rathe, cell density, and growth rate curve NOEC was determined to be the limit dose of 100 mg/L.
Executive summary:

In this GLP guidline study conducted according to OECD 201, the substance was evaluated for toxicity to Pseudokirchneriella subcapitata in a 72-hour static limit test at a concentration of 100 mg/L. The growth rate, cell density, and growth curve NOEC was determined to be 100 mg/L and the EC50, based on growth rate, was determined to be >100 mg/L.

Description of key information

In this GLP guidline study conducted according to OECD 201, the substance was evaluated for toxicity to Pseudokirchneriella subcapitatain a 72 -hour static limit test at a concentration of 100 mg/L. The growth rate, cell density, and growth curve NOEC was determined to be 100 mg/L and the EC50, based on growth rate, was determined to be >100 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

The  EC50 was determined to be >100 mg/L based on growth rate.