Chromium (III) propionate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Type of information:

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

Adequacy of study:

supporting study

Study period:

24 hour, plate method

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

As with all inorganic salts, the significance for toxicity or environmental assessment is the presence of specific ions that will form when in solution or when in biological systems.In the case of Cr III salts, the counter ion will have an effect on solubility and this is itself dependant on the type of media being used and in particular the pH of that media. It is generally accepted that in the case of metal salts, testing with salts that are soluble in the respective test media will ensure maximum exposure of the metal ions. This will include chlorides and nitrates as being more soluble and will indeed have relevance when dissolved in acid media, such as if ingested.Read-across to other chromium III salts is therefore considered valid as long as the exposure in the test system is greater than wold be expected for the substance under review for registration.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Streaked nutrient agar method adopted from Mgbemena et al. (2012).

GLP compliance:

no

Specific details on test material used for the study:

Laboratory grade

Vehicle:

no

Details on test solutions:

0, 5, 50, 100, and 500 mg/L CrCl3

Test organisms (species):

other: Azotobacter S8, Bacillus subtilis, Pseudomonas putida

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

24 h

Remarks on exposure duration:

To allow significant growth of cultures

Details on test conditions:

Incubated 24 hours at 37 C

Reference substance (positive control):

no

Duration:

24 h

Dose descriptor:

NOEC

Effect conc.:

ca. 5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Key result

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

ca. 50 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Duration:

24 h

Dose descriptor:

EC100

Effect conc.:

ca. 100 - 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Details on results:

Lowest concentration to significnatly inhibit the growth of Azotobacter S8, Bacillus subtilis and Pseudomonas putida was found to be ranging from 50 to 100 mg/L Chromium(III).

Validity criteria fulfilled:

not specified

Conclusions:

Lowest concentration to significnatly inhibit the growth of Azotobacter S8, Bacillus subtilis and Pseudomonas putida was found to be ranging from 50 to 100 mg/L Chromium(III).

Executive summary:

Scientifically valid study examining effects on growth in three species of bacteria

Description of key information

Scientifically valid study shows limited inhibition of bactial growth at approximatley 50 mg/l equivalent of the hydroxide or chloride, with inhibition of specific bacterial strains starting at concentrations > 5 mg/l Cr III.

However, enhancement of growth at lower concentrations (essential element)

Propionic acid rapidly biodegrades and as it is also present in living cells, it is estimated to be less hazardous to plants than the chromium.

Propionic acid has biocidal properties as a food preservative at high concentrations.

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L

Additional information

Testing performed on other Cr III salts.

Inhibition of < 25% at 100 mg/l Cr Propionate by extrapolating from chromium figures.