4-chloro-7H-pyrrolo[2,3-d]pyrimidine

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

effects on growth of green algae

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From February 26, 2021 to March 05, 2021

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

28 July 2011

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch number: 4419-190704
Purity: 99.3%

Analytical monitoring:

yes

Details on sampling:

Analysis of the concentration of the test item was performed by HPLC in 0 hour fresh solution and 72 hours old solutions in control and each test group.

Vehicle:

no

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: alga
- Strain:
- Source (laboratory, culture collection): The stock alga was originally introduced from CTI Chemical Safety Evaluation Research Center (SUZHOU) CO., LTD
- Age of inoculum (at test initiation): The age of preculture at inoculation of the definitive test was four days.
- Method of cultivation: cultured continually under the same conditions as growth test in the facility.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

21-24 oC

Nominal and measured concentrations:

Nominal 10, 18, 32, 56 and 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: flask
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume:
- Aeration: no
- Initial cells density: 5×103 cell/mL
- No. of vessels per concentration (replicates): 3 replicates
- No. of vessels per control (replicates): 3 replicates

GROWTH MEDIUM
- Standard medium used: yes
- Detailed composition if non-standard medium was used:

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH:
- Photoperiod:
- Light intensity and quality: The continuous and uniform light was used; the light intensity was 4440-8880 Lux for cool white light.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
The algal biomass in each flask was inspected daily (at 24h, 48h and 72h) during the test period. The biomass was measured by manual cell counting with microscope and counted 4 times.
The health conditions of the cells were also determined with microscope, and any abnormal signs were recorded.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.8
- Justification for using less concentrations than requested by guideline:
- Range finding study
- Test concentrations: 1, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study:

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol (3,5-DCP) as reference item was tested for EC50 as a means of assuring that the test conditions are reliable twice a year in the laboratory.

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

39.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

16.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Details on results:

After the 72-hour exposure period, the mean growth yield of control cultures was 5.04×105 cell/mL, and the cell density of control cultures increased by a factor of 101 in the control replicates. The mean coefficient of variation for section-by-section specific growth rate in control cultures was 30.1%. The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures was 14.0%. The results met the requirements of the test validity.
During the 72-hour test duration, there was no abnormal appearance of the algae observed in control replicates and replicates of each test group.
After 72 hours exposure, there was no significant inhibition of algae growth rates and yield at 10 mg/L. There was no significant difference in algae growth rate and growth yield between the control group and the test group of 10 mg/L (p>0.05, t-test). There was inhibition of algae growth rates and growth yield at other test concentrations. The inhibition rates increased with the increasing of test concentration.

Results with reference substance (positive control):

72 hour EyC50 of 3,5-DCP to Pseudokirchneriella subcapitata was 0.82 mg/L with the 95% confidence limits 0.65 ~ 1.0 mg/L and 72 hour ErC50 was 1.4 mg/L with the 95% confidence limits 0.97 ~ 2.1 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

The 72-hour effect concentration of average specific growth rate (ErC50) of and yield (EyC50) of the test item to Pseudokirchneriella subcapitata were 39.8 mg/L and 16.9 mg/L, the NOEC for growth rate and yield were 10 mg/L.

Executive summary:

An alga growth inhibition study of the test item was conducted over a 72-hour exposure period in a static system, according to OECD Guideline 201 under GLP.

According to the results and based on nominal concentration, the 72-hour effect concentration of average specific growth rate (E_rC₅₀) of and yield (E_yC₅₀) of the test item to Pseudokirchneriella subcapitata were 39.8 mg/L and 16.9 mg/L, the NOEC for growth rate and yield were 10 mg/L.

Description of key information

An alga growth inhibition study of the test item was conducted over a 72-hour exposure period in a static system, according to OECD Guideline 201 under GLP.

According to the results and based on nominal concentration, the 72-hour effect concentration of average specific growth rate (E_rC₅₀) of and yield (E_yC₅₀) of the test item to Pseudokirchneriella subcapitata were 39.8 mg/L and 16.9 mg/L, the NOEC for growth rate and yield were 10 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

39.8 mg/L

EC10 or NOEC for freshwater algae:

10 mg/L