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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Link to relevant study record(s)

Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
07.04.2017 to 10.04.2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Experimental test result performed using standard test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Principles of method if other than guideline:
Aim of this study was to evaluate the nature of chemical when comes in contact with the test organism. Test was conducted according to the OECD guideline 201.
GLP compliance:
not specified
Specific details on test material used for the study:
- Name of test material (as cited in study report): Hydrogen potassium phthalate
- Molecular formula : C8H5O4K
- Molecular weight : 204.221 g/mol
- Smiles notation : c1(c(cccc1)C(=O)[O-])C(O)=O.[K+]
- InChl : 1S/C8H6O4.K/c9-7(10)5-3-1-2-4-6(5)8(11)12;/h1-4H,(H,9,10)(H,11,12);/q;+1/p-1
- Substance type:Organic
- Physical state:Solid
Analytical monitoring:
not specified
Vehicle:
not specified
Details on test solutions:
The stock solution 220 mg/l was prepared by dissolving white powder in OECD growth medium. Test solutions of required concentrationas were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name:
- Strain: 86.81 SAG
- Source (laboratory, culture collection): Institute of botany of the ASCR
- Initial biomass concentration: 5x10(3) cells /ml
- Method of cultivation: No data available

ACCLIMATION - No data available
- Acclimation period:
- Culturing media and conditions (same as test or not):
- Any deformed or abnormal cells observed:
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Test temperature:
23±2°C
pH:
Test at highest concentration:
Control:
Nominal and measured concentrations:
0, 77, 100, 130, 170 and 220 mg/l concentrations were used.
Details on test conditions:
TEST SYSTEM
- Test vessel: 50 ml Glass vessel
- Type (delete if not applicable): closed (with air permeable stopper)
- Sample volume: 15 ml
- Initial cells density: 5x10(3) cells/ml
- No. of vessels per concentration (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: Continuous
- Light intensity and quality: 6000-8000 lx

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: microscope with counting chamber Cyrus I or electronic particle counter.
- Other: ErC50 was calculated using non-linear regression by the software Prism 4.0
Reference substance (positive control):
yes
Remarks:
Potassium dichromate (K2Cr2O7)
Key result
Duration:
72 h
Dose descriptor:
other: ErC50
Effect conc.:
329.5 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95 % CI was 246.7 to 440.1 mg/l
Results with reference substance (positive control):
- Results with reference substance valid
- EC50: 0.75 mg/L (24 hours)
Reported statistics and error estimates:
ErC50 was calculated using non linear regression by the software Prism 4.0
Validity criteria fulfilled:
yes
Conclusions:
Based on the growth rate inhibition of algae Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) due to the exposure of chemical the ErC50 was determine to be 329.5 mg/l.
Executive summary:

Aim of this study was to evaluate the nature of chemical test chemical when comes in contact with the test organism Desmodesmus subspicatus (previous name: Scenedesmus subspicatus). Test was conducted according to the OECD guideline 201. The stock solution 220 mg/l was prepared by dissolving white powder in OECD growth medium. Test solutions of required concentrationas were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. Various concentrations 0, 77, 100, 130, 170 and 220 mg/l were used in the study. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration ErC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determine after an exposure period of 72 hrs. The median effective concentration (ErC50) for the test substance Hydrogen potassium phthalate, in algae was determined to be 329.5 mg/L on the basis of growth rate inhibition effects in a 72 hour study. Based on the ErC50 value, indicates that the substance is likely to be non-hazardous to aquatic algae and cannot be classified as per the CLP classification criteria.

Description of key information

study was conducted to evaluate the nature of chemical test chemical when comes in contact with the test organism Desmodesmus subspicatus (previous name: Scenedesmus subspicatus). Test was conducted according to the OECD guideline 201. The stock solution 220 mg/l was prepared by dissolving white powder in OECD growth medium. Test solutions of required concentration as were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. Various concentrations 0, 77, 100, 130, 170 and 220 mg/l were used in the study. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration ErC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determine after an exposure period of 72 hrs. The median effective concentration (ErC50) for the test substance Hydrogen potassium phthalate, in algae was determined to be 329.5 mg/L on the basis of growth rate inhibition effects in a 72 hour study. Based on the ErC50 value, indicates that the substance is likely to be non-hazardous to aquatic algae and cannot be classified as per the CLP classification criteria.

Key value for chemical safety assessment

EC50 for freshwater algae:
329.5 mg/L

Additional information

Summarized result for the toxicity of test chemicalhydrogen potassium phthalate (CAS no. 877-24-7)on the growth of aquatic algae and cyanobacteria are as follows:

 

In the first experimental report, study was conducted to evaluate the nature of chemical test chemical when comes in contact with the test organism Desmodesmus subspicatus (previous name: Scenedesmus subspicatus). Test was conducted according to the OECD guideline 201. The stock solution 220 mg/l was prepared by dissolving white powder in OECD growth medium. Test solutions of required concentration as were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. Various concentrations 0, 77, 100, 130, 170 and 220 mg/l were used in the study. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration ErC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determine after an exposure period of 72 hrs. The median effective concentration (ErC50) for the test substance Hydrogen potassium phthalate, in algae was determined to be 329.5 mg/L on the basis of growth rate inhibition effects in a 72 hour study. Based on the ErC50 value, indicates that the substance is likely to be non-hazardous to aquatic algae and cannot be classified as per the CLP classification criteria.

 

First study was supported by the second study from experimental report. The study was designed to assess the toxic effects of the test compound Hydrogen potassium phthalate on the green alga Chlorella vulgaris. Test was conducted in compliance with the OECD guideline 201 (Alga, Growth Inhibition Test). The test solution was prepared in aseptic condition. The test item Potassium hydrogen phthalate was prepared by adding 50 mg of test item in 250 ml of BBM to get the final concentration of 200 mg/L. This stock solution was kept for stirring for 30 minutes to obtain a homogenous solution for the experiment. The test concentrations were chosen according to the available data of the test item. The concentrations chosen were set up to the water solubility limit. The remaining test solutions were prepared by dilution from the above stock solution. To have a better growth and visibility of cells, the initial cell density of the culture was kept 1 X 10000 cells/ml. Care was taken to have a homogeneous solution for the experiment. For the assessment of algal growth, the test was conducted in replicates. The control flask was maintained in triplicates as recommended in the OECD guideline and the test concentration were selected in geometric series which were maintained in duplicates. To obtain a quantitative concentration-response relationship by regression analysis, a linearizing transformation of the response data into probit was performed. Using the same, effective concentration (EC) were determined. Algal growth was calculated daily by counting the cells microscopically with the help of hemocytometer. For microscopic observations the cultures were observed daily with the help of a microscope to verify a normal and healthy appearance of the algal culture and also to observe any abnormal appearance of the algae (as may be caused by the exposure of the test item). Apart from this, the cell count of each test vessel was also noted with the help of a microscope and hemocytometer. By spectrophotometer the absorbance values of each test vessel and control vessel was noted at 680nm.The BBM was taken as blank for both control and test vessels. The absorbance value of each vessel was in line with the average specific growth rate. As per OECD 201, the biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72 hr test period. This corresponds to a specific growth rate of 0.92 per day. Thus, the observed specific growth rate in the control cultures during the experiment was 0.333 per day. The mean coefficient of variation for section by section specific growth rates (days 0-1, 1-2 & 2-3, for 72 hr tests) in the control cultures must not exceed 35%. Thus, the observed mean coefficient of variation in the control cultures during the experiment was 21.6%. The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures must not exceed 10%. Thus, the observed coefficient of variation of average specific growth rates during the experiment in control cultures was 3.94%. Hence, the test is considered valid as per OECD guideline, 201. After 72 hours of exposure to test item Hydrogen potassium phthalate to various nominal test concentrations, EC50 was determine to be 19.885 mg/l graphically and through probit analysis. Based on the EC50, it can be concluded that the chemical was toxic and can be consider to be classified as aquatic chronic 3 as per the CLP classification criteria. But as the chemical was readily biodegradable in water thus does not exist for long time in water. Based on readily biodegradable criteria, chemical consider to be nontoxic and not classified as per the CLP classification criteria.

 

 

Similarly in the third study from peer reviewed journal short term toxicity to algae study was carried out for 96 hrs. The study was based on the effects of the test compound on algae in a static fresh water system. 1% solution of test chemical was prepared in distilled water, i.e. 1.0 g of the compound in 100 ml of distilled water. Test chemical conc. used for the study were 1, 10, 20, 50, 100, 200, 500 and 1000 mg/l, respectively (nominal concentrations). Gymnodinium breve was used as a test organism. Cultures of Gymnodinium breve were grown in an artificial sea water medium--NH-15 and were transferred 14 days prior to use so that they would be in an active logarithmic growth phase. Test portions were placed in a single row in test tube racks which were placed 2 inches from 40-watt, cool-white fluorescent lights (incident light ca. 1000 foot-candles) in a 25°C, constant temperature room. Special care was taken to insure uniform light on test portions to avoid variability of relative chlorophyll a values. Microscopic examinations and relative chlorophyll a measurements were carried out as soon as the portions were set up, and 24, 48, 72 and 96 hours thereafter. Initial counts of the culture population level were also carried out prior to setting up the test portions and counts were made of each test portion after 96 hours. Based on the effect of test chemical on the population of the test organism Gymnodinium breve, the 96 hrs NOEC and LOEC value was determined to be 200 and 500 & 1000 mg/l, respectively.

 

Thus based on the above both studies, chemicalhydrogen potassium phthalate (CAS no. 877-24-7)was consider to be nontoxic and not classified as per the CLP classification criteria.