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Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms, other
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Data is from peer reviewed journal
Justification for type of information:
Data is from peer reviewed journal
Qualifier:
according to guideline
Guideline:
other: Refer below principle
Principles of method if other than guideline:
To study the toxicity of Phthalates to the Marine Dinoflagellate Gymnodinium breve
GLP compliance:
not specified
Specific details on test material used for the study:
- Name of test material: 1,2-Benzenedicarboxylic acid, monopotassium salt
- Molecular formula: C8 H6 O4.K
- 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
Details on sampling:
- Concentrations: 0,1,10, 20, 50, 100, 200, 500, 1000 and 1000 ppm
- Sampling method: Potassium hydrogen phthalate is prepared by 1% solutions of these compounds in distilled water, i.e. 1.0 g of the compound in I00 ml of distilled water.
- Sample storage conditions before analysis: 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. I000 foot-candles) in a 25˚ constant room temperature. Special care was taken to insure uniform light on test portions to avoid variability of relative chlorophyll a values.
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Potassium hydrogen phthalate is prepared by 1% solutions of these compounds in distilled water, i.e. 1.0 g of the compound in I00 ml of distilled water.
- Controls: Yes
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): distilled water
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): 0.1, 0.2, 0.5, 1.0 ml in distilled water.
Test organisms (species):
other: Dinoflagellate Gymnodinium breve
Details on inoculum:
- Laboratory culture: Yes
- Method of cultivation: Gymnodinium breve that were grown in an artificial sea water medium--NH-15 were used and were transferred 14 days prior to use so that they would be in an active logarithmic growth phase.
- Initial biomass concentration: 1000 and 5000 G. breve per milliliter.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Hardness:
No data
Test temperature:
25˚C
pH:
7.6
Dissolved oxygen:
No data
Salinity:
No data
Conductivity:
No data
Nominal and measured concentrations:
No data
Details on test conditions:
TEST SYSTEM
- Test vessel: Artificial sea water medium--NH-15.
- No. of organisms per vessel: 1000 and 5000 G. breve per milliliter.
- No. of vessels per concentration (replicates): 10
- No. of vessels per control (replicates): 3
- No. of vessels per vehicle control (replicates): 2
- Biomass loading rate: The cultures contained between 1000 and 5000 G. breve per milliliter at the time the assays were started.

OTHER TEST CONDITIONS
- Adjustment of pH: Yes, pH 4.2 adjusted to pH 7.6
- Photoperiod: Constant
- Light intensity: cool-white fluorescent lights (incident light ca. I000 foot-candles)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Relative chlorophyll a values were observed.
Key result
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
498.52 - 997 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Details on results:
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: The pH of these media (4.2) to be responsible, thus an additional assay was carried out in which the pH of the one percent solution of potassium hydrogen phthalate was adjusted to 7.6 with potassium hydroxide (yielding the dipotassium salt in situ) before adding aliquots to the culture portions.This adjustment alleviated the observed toxicity.
Reported statistics and error estimates:
Values were obtained by plotting on semilog paper the concentration of test material (ppm) versus the growth rate (linear axis of graph), expressed as a percentage of the growth of a "no-add" control. The concentration values (ppm) which caused a 50 percent growth reduction.
Validity criteria fulfilled:
no
Conclusions:
EC50 for Potassium hydrogen phthalate was found to be 498.52 and 997 mg/l when tested on Marine Dinoflagellate Gymnodinium breve for 96 hours.

Executive summary:

In a study of toxicity of Phthalates to the Marine Dinoflagellate Gymnodinium breve the effect of Potassium hydrogen phthalate was evaluated. The test substance was tested in a concentration of 0,1,10, 20, 50, 100, 200, 500, 1000 and 1000 ppm. The results show Median growth when concentration of test material (ppm) versus the growth rate (linear axis of graph), expressed as a percentage of the growth of a "no-add" control at 498.52 and 997 mg/l. Therefore, EC50 of Potassium hydrogen phthalate was considered to be be 498.52 and 997 mg/l when tested on Marine Dinoflagellate Gymnodinium breve for 96 hours.

Description of key information

EC50 for Potassium hydrogen phthalate was found to be 498.52 and 997 mg/l when tested on Marine Dinoflagellate Gymnodinium breve for 96 hours.

Key value for chemical safety assessment

EC50 for microorganisms:
498.52 mg/L

Additional information

In a study of toxicity of Phthalates to the Marine Dinoflagellate Gymnodinium breve the effect of Potassium hydrogen phthalate was evaluated. The test substance was tested in a concentration of 0,1,10, 20, 50, 100, 200, 500, 1000 and 1000 ppm. The results show Median growth when concentration of test material (ppm) versus the growth rate (linear axis of graph), expressed as a percentage of the growth of a "no-add" control at 498.52 and 997 mg/l. Therefore, EC50 of Potassium hydrogen phthalate was considered to be be 498.52 and 997 mg/l when tested on Marine Dinoflagellate Gymnodinium breve for 96 hours.