Malonic acid

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2001

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Justification for type of information:

Succinic acid may be used as an analogue for malonic acid, based on the following considerations. Firstly, dicarboxylic acids are naturally occurring metabolic products of fatty acid oxidation, and are rapidly beta-oxidised. A category approach for short-medium chain dicarboxylic acids, including malonic acid and succinic acid, has been validated and used by various bodies including the Cosmetics Ingredient Review Panel and the European Food Safety Authority.Disodium succinate may be used as an analogue for succinic acid as there is no significant difference in toxicity expected between succinic acid and disodium succinate, since both substances will dissociate into succinate ion under physiological conditions.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes

Specific details on test material used for the study:

Disodium succinate hexahydrate (CAS No.: 6106-21-4, Nakarai Kagaku, Inc. (Japan), Lot. No.: MOT9476, Purity = 100.2%

Analytical monitoring:

yes

Details on test solutions:

Test chemical was refrigerated. The stability of the chemical was confirmed by IR spectrum. The IR spectrum at the end of the test was same at the start of test.

Test organisms (species):

Selenastrum sp.

Details on test organisms:

Species : Selenastrum capricornutum (Algae)Supplier/Source: Obtained from American Type Culture Collection and reproduced in aseptic cultureMethod of Cultivation: SterileStain Number: ATCC22662Pre-culture (duration, medium, etc.): Test alga was pre-incubated for 3 days under the same method of test in OECD medium

Test type:

static

Water media type:

freshwater

Total exposure duration:

72 h

Test temperature:

water temperature: 23.0 - 23.6ºC

pH:

pH: 7.7 - 7.9 (at the start of the test)10.3 - 10.5 (at the end of the test)

Details on test conditions:

Medium: OECD mediumExposure Vessel Type: 100 mL Medium in a 500mL Erlenmeyer Flaskwith silicon cap (open system)Vehicle/Solvent and Concentrations: Any solvent was not used.Number of Replicates: 3Initial Cell Number: 10,000 cells/mLLight Condition: 4,000 - 5,000 lux, continuouslyShaking: 100 rpm

Reference substance (positive control):

yes

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 998 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

> 998 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 998 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

> 998 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Results with reference substance (positive control):

EbC50 (0-72 hr) for a reference substance (potassium dichromate) was 0.427 mg/L.

Reported statistics and error estimates:

Data Analysis: The calculated inhibition rate at the highest concentration based on growth rate inhibition and biomass were less than 50%, therefore the EC50 was more than the highest concentration. The NOEC values were determined by analysis of variance (ANOVA).Method of Calculating Mean Measured Concentrations (i.e. arithmetic mean, geometric mean, etc.): time-weighted mean

Percent Growth Inhibition of Selenastrum capricornutum

Measured Conc mg/L	Area under the growth curves (Average)
	Area A (0-72hr)	Inhibition (%)* IA (0-72hr)
Control	25,400,000	---
247	27,900,000	-10.2
501	28,600,000	-12.8
998	28,300,000	-11.7

 

Mean Measured Conc. mg/L	Growth rates and percent inhibition (Average)
	Rate u(24-48hr)	Inhibition(%) Im(24-48hr)	Rate u(0-72hr)	Inhibition(%) Im(0-72hr)
Control	0.0771	---	0.0665	---
247	0.0778	-0.875	0.0642	3.37
501	0.0779	-0.954	0.0650	2.21
998	0.0771	-0.138	0.0660	0.745

Growth Curves: During the test period algae grew almost linearly(log scale) in each concentration.

Measured Concentrations: The tested concentrations were measured at the start and the 72nd hour. For all of them, the deviations from the nominal concentration were less than +/-20%.

Nominal conc. mg/L	Measured Conc., mg/L		Mean* mg/L	Percent of nominal
	0 Hour	72 Hour		0 Hour	72 Hour
Control	<15.0	<15.0	---	---	---
250	249	246	247	99.7	98.3
500	504	498	501	101	99.6
1,000	1,000	997	998	100	99.7

*: Mean measured concentration (time-weighted mean)

Validity criteria fulfilled:

yes

Conclusions:

In an algal growth inhibition test (OECD TG 201, open system), the acute toxicity results (72 h ErC50 and 72 h EbC50) to Selenastrum capricornutum were were determined to be >998 mg/L by both the biomass method and the growth rate method. Disodium succinate was considered to be not toxic to algae according to EU classification criteria.

Executive summary:

In an algal growth inhibition test (OECD TG 201, open system), the acute toxicity results (72 h ErC50 and 72 h EbC50) to Selenastrum capricornutum were were determined to be >998 mg/L by both the biomass method and the growth rate method. Disodium succinate was considered to be not toxic to algae according to EU classification criteria.

Description of key information

In an algal growth inhibition test (OECD TG 201, open system), the acute toxicity results (72 h ErC50 and 72 h EbC50) to Selenastrum capricornutum were were determined to be >998 mg/L by both the biomass method and the growth rate method. Disodium succinate was considered to be not toxic to algae according to EU classification criteria.

Key value for chemical safety assessment

EC50 for freshwater algae:

998 mg/L

EC10 or NOEC for freshwater algae:

998 mg/L