Arsenic acid

Toxicity to microorganisms

Administrative data

Endpoint:

toxicity to microorganisms

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The test is conducted according to a protocol different of the OECD guidelines. However the result is considered as reliable enough to validate the endpoint.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1976

Report date:

1976

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

DIN 38412-8 (Pseudomonas Zellvermehrungshemmtest)

Deviations:

yes

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

di-Natriumhydrogenarsenat

IUPAC Name:

di-Natriumhydrogenarsenat

Details on test material:

- Name of test material (as cited in study report):di-natriumhydrogenarsenate
- Molecular formula (if other than submission substance): Na2HAsO4 7h2O

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
no additionnal data

Sampling and analysis

Analytical monitoring:

no

Details on sampling:

not relevant

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: the test solution is first neutralized, using as few soda as possible. No data on test substance dissolution.
- Eluate: bidistilled water
- Differential loading:The dilution of the stock solution is made with a factor of 2 exp 0 to 2exp14 the first container contains 160 mL of the test substance solution and the further containers of the serie contains 80 mL of the previous solution and 80 mL of distilled water.
- Controls: test medium
- Chemical name of vehicle (organic solvent, emulsifier or dispersant):none
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)):not relevant
- Evidence of undissolved material (e.g. precipitate, surface film, etc):no information

Test organisms

Test organisms (species):

Pseudomonas putida

Details on inoculum:

- Laboratory culture: internal culture
- Method of cultivation: on agar gel in test tubes
- Preparation of inoculum for exposure: the cultures are rinsed from the Agar gel using NaCl solution.
- Pretreatment:
- Initial biomass concentration: so that when mixed in a 1+ 9 dilution with NaCl, the extinction value is 10 times higher than that of a Formazin Standard suspension.

Study design

Test type:

static

Water media type:

not specified

Limit test:

no

Total exposure duration:

16 h

Post exposure observation period:

none

Test conditions

Test temperature:

25 °C

pH:

neutral

Dissolved oxygen:

no data

Salinity:

no data

Nominal and measured concentrations:

from the stock solution, dilutions of 2 exp 0 to 2 epx 14 are performed.

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): open / closed
- Material, size, headspace, fill volume: 160 mL
- Aeration: none, the test containers are closed with artificial material.

No additional data on test organisms number



OTHER TEST CONDITIONS
- Adjustment of pH: yes
- Photoperiod:
- Light intensity:

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Cell increase reduction is measured through primary light absorption after correction with the dissolved substance absorption and protection from diffuse reflexion.

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

16 h

Dose descriptor:

EC10

Effect conc.:

18 other: mg arsenate/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Effect concentrations 2

Duration:

16 h

Dose descriptor:

EC10

Effect conc.:

4.18 other: mg As/L

Nominal / measured:

nominal

Basis for effect:

growth inhibition

Details on results:

no

Results with reference substance (positive control):

no reference substance

Any other information on results incl. tables

For the determination of the effect concentration, the following procedure is used:

A halflogarith graph is used, with on X the substance concentrations and on Y the extinction values.

Calculation is made of the mean value of the extinction for test concentrations at which the cultures where non affected (neither stimulation nor inhibition) This is the point A . The allowed standard deviation is 3%. The mean value of the extinction in the three test cultures of the lowest toxic substance concentration is calculated. This is the point B. The 3 points A, B, and A-3 % are reported on a halflogarithm Y ax. The corresponding concentrations are a, b, and c. "c" is the concentration that corresponds to the beginning of the cell increase reduction.

Applicant's summary and conclusion

Validity criteria fulfilled:

not applicable

Remarks:

not applicable as the assessment of effects is not made theough gaz consumption

Conclusions:

Under the conditions of the test, the test substance showed a EC3% of 18 mg/L.

Executive summary:

The toxicity of the substance di-sodiumhydrogenarsenate was tested on the bacteria pseudomonas putida. The organisms were exposed to different concentrations of the test substance, with dilution factors from 2⁰to2¹⁴.The inhibitory effect of the test substance on the organisms was measured through turbidimetric measurement. Cell increase reduction is measured through primary light absorption after correction with the dissolved substance absorption and protection from diffuse reflexion. A graphic assessment of the results was performed in order to derive the concentration at which the test substance starts reduce the cell number increase, i.e. when effects of more than 3% are observed.

The resulting EC3% is 18 mg/L for the tested substance.

This corresponds to 6.75 mg/L As element. (Calculation of the assessor).