3,4,5-trihydroxybenzoic acid

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Remarks:

Some details are missing on validation criteria. unsure whether the endpoint is growth rate

Qualifier:

according to guideline

Guideline:

other: US EPA Algal, Selenastrum capricornutum, growth test Method 1003.0. In: Short-term methods for estimating the chronic toxicity of effluent and receiving waters to freshwater organisms. EPA 600/4-89/001, Cincinnati OH

GLP compliance:

no

Analytical monitoring:

no

Remarks:

results based on nominal concentrations

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

24 ± 1°C

pH:

7.45

Nominal and measured concentrations:

full range starting around 0.35 and ending around 14 mg/L

Details on test conditions:

6 concentrations in triplicate
the test also investigated the effect of the level of P (phosphorus) levels, here only the results at 6 µM of P are provided since this is the recommended value in test media

Reference substance (positive control):

not required

Key result

Duration:

72 h

Dose descriptor:

IC50

Effect conc.:

2.19 mg/L

Basis for effect:

growth rate

Remarks on result:

other: result at 6 µM of P, the recommended value. unsure whether the endpoint is growth rate

Key result

Duration:

72 h

Dose descriptor:

IC10

Effect conc.:

> 1 - <= 1.5 mg/L

Basis for effect:

growth rate

Remarks on result:

other: result at 6 µM of P, the recommended value. unsure whether the endpoint is growth rate

Details on results:

72h inhibition (unsure whether the endpoint is growth rate) at pH 7.45 and 1 mg/L of test item in medium:
- IC50: 2,19 mg/L
- IC10 graphically determined as ranging > 1-1,5 mg/L

Validity criteria fulfilled:

not specified

Conclusions:

Algae IC50-(72h) of the test item is 2,19 mg/L, and the IC10 ranges > 1-1.5 mg/L. It is unsure whether the endpoint is growth rate.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Remarks:

Some details are missing on test medium and validation criteria. Moreover the exposure duration is 48h instead of 72h recommended. The initial pH is too low (6.5) compared to 7.5-8.1 recommended.

Qualifier:

no guideline followed

Principles of method if other than guideline:

The test technique used is a closed-system algal toxicity test.
Algal inoculum under a steady state was transferred into 300mL BOD bottles containing dilution water (with growth medium) and toxicants. The bottles were then placed on an orbital shaker operated at 100 rpm.
The algal growth rate based on cell density counts was then evaluated.
The population density of the algae was determined using an electronic particle counter (Culter Electronics, Luton, UK).
All chemicals used were of reagent grade and were tested at least twice, i.e., range finding test and definitive test. For the definitive test, one control and 6 (or 7) different treatments were performed in triplicate.
Probit analysis was applied to determine the concentration–response relationship and the median effective concentration (EC50). One-tail Dunnett’s procedure was applied for the estimation of NOEC and LOEC values at 5% level of significance.

GLP compliance:

no

Analytical monitoring:

no

Remarks:

initial concentrations only

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Test type:

static

Water media type:

other: Dilution water

Limit test:

no

Total exposure duration:

48 h

Test temperature:

24 ± 1 °C

pH:

6.5

Nominal and measured concentrations:

Concentration range: 0.40 to 38.4 mg/L

Reference substance (positive control):

not required

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

15.9 mg/L

Basis for effect:

growth rate

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

3.2 mg/L

Basis for effect:

growth rate

Validity criteria fulfilled:

not specified

Conclusions:

Algae growth rate EC50-(48h) and NOEC of the test item are respectively 15.90 mg/L and 3.20 mg/L.

Description of key information

Two study reports in which representative guideline test organism (Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum) are available with the following endpoints:

• Algae IC50-(72h) of the test item is 2,19 mg/L, and the IC10 ranges from > 1 to < 1.5 mg/L. It is unsure whether the endpoint is growth rate
• Algae growth rate EC50-(48h) and NOEC of the test item are respectively 15.90 mg/L and 3.20 mg/L

Based on these endpoints, gallic acid is not classified for aquatic hazards.

Key value for chemical safety assessment

EC50 for freshwater algae:

2.19 mg/L

EC10 or NOEC for freshwater algae:

1 mg/L