Potassium benzoate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

supporting study

Study period:

7 days

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 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 metal salts of organic acids, the cation is generally critical to determine the solubility in biological or environmental media and if the key physico-chemical properties are equivalent, the potential for hazard and environmental fate will be equivalent; this is especially so for potassium and sodium salts that share similar solubility and dissociation characteristics.The cation is only critical in determining hazard if this is itself hazardous, but if the metal cations are present in the diet or are ‘essential’ elements for health, then there should be little to differentiated long-term hazards.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Research into validity of a test to cover single-cell organisms over 7 days. Concluded to be a valid method, but not following specific guidelines

GLP compliance:

no

Specific details on test material used for the study:

Not specified

Analytical monitoring:

not specified

Vehicle:

no

Test organisms (species):

Scenedesmus quadricauda

Details on test organisms:

Cultured in synthetic water media

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

7 d

Remarks on exposure duration:

Longer then normal OECD study, but considered valid for classification purposes

Hardness:

Not specified

Test temperature:

27 C

pH:

Non-adjusted

Dissolved oxygen:

Not specified

Nominal and measured concentrations:

Not specified

Reference substance (positive control):

no

Key result

Duration:

7 d

Dose descriptor:

EC10

Effect conc.:

ca. 1 630 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

The figures reported are for the 'onsets of inhibition' and this has been taken as being roughly equivalent to an EC10

Validity criteria fulfilled:

not specified

Conclusions:

Although methods and results are not speific, the headline result suggests low toxicity of benzoate acid to algae.

Executive summary:

Considered non-hazardous.

Description of key information

The effects of benzoic acid, sodium benzoate and potassium salts have been considered in this review.

The toxicity to sodium benzoate (IC50 30 mg/l) appears significantly greater than the toxicity of benzoic acid, suggesting that the salts may be more bioavailable than the acid.

The toxicity of potassium was estimated from different sources and in most cases was stimulating to growth at concentrations even in excess of 100 mg/l.

The benzoate has been used to assess the toxicity of potassium benzoate and is used to estimate a PNEC.

It is considered conservative to use the IC50 of 30 mg/l to set a figure for estimating PNEC.

Key value for chemical safety assessment

EC50 for freshwater algae:

30 mg/L