Uric acid

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Version / remarks:

OECD, 2006: The Organisation for Economic Co-operation and Development (OECD) Guidelines for Testing of Chemicals, Section 2, OECD 201, Fresh Water Alga and Cyanobacteria, Growth Inhibition Test, adopted by the Council on March 23, 2006 (Annex 5 corrected on July 28, 2011).

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

1

Reference substance name:

Uric acid

EC Number:

200-720-7

EC Name:

Uric acid

Cas Number:

69-93-2

Molecular formula:

C5H4N4O3

IUPAC Name:

7,9-dihydro-1H-purine-2,6,8(3H)-trione

Test material form:

solid: particulate/powder

Details on test material:

It was manufactured by MOLAR CHEMICALS Ltd.

Sampling and analysis

Analytical monitoring:

yes

Test organisms

Test organisms (species):

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

Details on test organisms:

Name of the Organism : Pseudokirchneriella subcapitata
Strain Number : ATCC 22662
Origin and Source of Culture : American Type Culture Collection, 10801, University of Boulevard, Manassas, Virginia, 20110-2209, USA
Subculture Maintained at : Section - Ecotoxicology
Jai Research Foundation
Valvada, Dist. Valsad, Gujarat
Date of Receipt (at JRF) : March 10, 2017
Date of Last Subculture : March 05, 2018
Method of Cultivation : Static condition

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Remarks on exposure duration:

Exponentially growing cultures of P. subcapitata were exposed to nominal test concentrations of 0.0 (Control), and 60.0 mg/L. The algal cultures were assessed for the growth by visual cell count at 24, 48, and 72 h.

Test conditions

Test temperature:

21 - 23 °C

pH:

7.00 – 8.19

Details on test conditions:

Test Conditions
Temperature (°C) : 21 - 23 °C (APPENDIX 3)
Test Duration : 72 h
Mean Illumination (Lux) : 6540 – 6643 (± 15% of the mean value) (APPENDIX 3)
pH Value Range : 7.00 – 8.19 (APPENDIX 2)
Culturing Apparatus : 250 mL conical flask
Test Concentrations : Control [0.0] and 60.0 mg uric acid/L
Initial Mean Number of Cells/mL : 6010

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 60 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 60 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

< 60 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

EC50, NOEC and LOEC: Greater than 60.0 mg uric acid/L

Growth Inhibition, EC50 Values, NOEC and LOEC
There was no significant alteration observed in algal growth (biomass), yield and growth rate of uric acid exposed group as compared to control group. The uric acid does not inhibit the growth of alga (Pseudokirchneriella subcapitata) up to the concentration of 60.0 mg/L. The EC50, NOEC and LOEC value was greater than 60.0 mg/L.

Results with reference substance (positive control):

See it in appendix 1.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

 CONCLUSION:   EC50, NOEC and LOEC:Greater than 60.0 mguric acid/L

Test Culture Conditions
The pH and temperature rangedwithin7.00 - 8.19 and 21 - 23 °C respectively. Mean illumination values rangedwithin6540 – 6643 lux (APPENDICES 1 & 2). All parameters were within the guideline limits.

 Algal Cell Count
In the control, cell growth in numbers was observed more than 114.8 times over 72 h exposure period [as per OECD 201 (2006) at least 16 times in control] (TABLE 1).
The coefficient of variance of average specific growth rate during the whole test period (0-3) in replicate control culture was found to be 0.63 %. The mean coefficient of variation for day 0-1, 1-2 and 2-3 in control culture was found to be 11.61.Thus coefficient of variation is within the guidelines limit(TABLE 1).

Analysis of Test Concentrations
The stability of uric acid in test media was performed during method validation (JRF Study N° 228-2-13-18992) and uric acid in test media was stable up to 72 h (>80% of nominal concentration). Test media was analysed for uric acid active ingredient concentration and stability to monitor the concentration and stability of test solution at 0 and 72 h during main study. The active ingredient concentration of uric acid in test media was within acceptable limit (>80% of nominal concentration) (APPENDIX 7).

Growth Inhibition, EC50Values, NOEC and LOEC
There was no significant alteration observed in algal growth (biomass), yield and growth rate of uric acid exposed group as compared to control group. The uric acid does not inhibit the growth of alga (Pseudokirchneriella subcapitata) up to the concentration of 60.0 mg/L. The EC50, NOEC and LOEC value was greater than 60.0 mg/L.

 Validity Criteria of the Study
The coefficient of variation of average specific growth rates during the test period in the replicate control cultures was 0.63%. Thus, the validity criterion was met.
The cell concentration in the control cultures increased exponentially by a factor of 114.8within the test period. Thus, thevalidity criterion was met.
The mean coefficients of variation forday 0-1, 1-2, and 2-3in control culture was 11.61%.Thus, the validity criterion was met.

 CONCLUSION:   EC50, NOEC and LOEC:Greater than 60.0 mguric acid/L

Executive summary:

EXECUTIVE SUMMARY:This study was performed to assess the effects on the growth of the algaPseudokirchneriella subcapitatacaused by exposure under static conditions to the uric acid.

Exponentially growing cultures ofP. subcapitatawere exposed to nominal test concentrations of 0.0 (Control), and 60.0 mg/L. The algal cultures were assessed for the growth by visual cell count at 24, 48, and 72 h.

The stability ofuric acidin test media was performed during method validation (JRF StudyN°228-2-13-18992) anduric acidin test media was stable up to 48 h (>80% of nominal concentration). Test media was analysed foruric acidactive ingredient concentration and stability to monitor the concentration and stability of test solution at 0 and 72 h during main study. The active ingredient concentration ofuric acidin test media was within acceptable limit (>80% of nominal concentration).

There was no significant alteration observed in algal growth (biomass), yield and growth rate ofuric acidexposed group as compared to control group. Theuric aciddoes not inhibit the growth of alga (Pseudokirchneriella subcapitata) up to the concentration of 60.0 mg/L.The EC₅₀, NOEC and LOEC value was greater than 60.0 mg/L.