Maleic acid

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study. The substance caused a decrease in pH of the test solution at the highest test concentrations. The test was repeated with the two highest test concentration (pH was adjusted).

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Maleic acid

EC Number:

203-742-5

EC Name:

Maleic acid

Cas Number:

110-16-7

Molecular formula:

C4H4O4

IUPAC Name:

but-2-enedioic acid

Details on test material:

- Name of test material (as cited in study report): Maleic acid
- Analytical purity: 99.7 %
- Lot/batch No.: LPMS3A1015

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution was prepared by mixing 250 mg o with 25 ml test medium. The test solutions were prepared separately by dilution of the stock solution.

Test organisms

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Source (laboratory, culture collection): Norwegian Institute for Water Research, Oslo, Norway

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Test temperature:

22.6 - 23.4 °C

pH:

initial test: 4.64 - 8.31
repeated test: 7.72 - 8.36

Nominal and measured concentrations:

Nominal test concentrations:
2, 5, 12.5, 31.25 and 78.13 mg/l

Mean measured concentrations:
2.04, 5.13, 12.78, 31.76, 79.72 mg/l

Repeated test:
31.25 and 78.13 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel: conical flasks (250 ml)
- Fill volume: 150 ml
- Initial cells density: 10000
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: the test medium was prepared according to OECD guideline 201


OTHER TEST CONDITIONS
- Adjustment of pH: yes at 31.25 and 78.13 mg/l
- Photoperiod: continous illumination
- Light intensity and quality: 7240 - 7390 Lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: cell growth (haemocytometer) after 24, 48 and 72 hours of exposure.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.5

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

11.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

22.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

74.35 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

The substance caused a decrease of the pH in the test medium. Diefferences in the algal grwoth between the initial test and the repeated test were ascribed to the low pH at test concentrations of 31.25 and 78.13 mg/l in the initial test.