1,2-dichlorobenzene

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

other: US EPA (1971): Algal Assay Procedure - Bottle Test. National Eutrophication Research Program, Corvallis, 82 ppg

Deviations:

yes

Remarks:

Test vessels were modified according to Galassi and Vighi (1981) in order to maintain constant concentration and to allow the sampling of the culture medium without opening the vessel

Principles of method if other than guideline:

Additionally to the growth inhibition test, a physiological test was carried out in order to determine the EC50 (3 h) on the efficiency of photosynthesis measuring the 14C uptake. A Selenastrum algal biomass, corresponding to 0.1 mg dry weight was inoculated into light and dark bottles (100 mL) containing AAPBT medium and different concentrations of the test material in three replicates each. The samples were incubated for 3 h after addition of 1 mL 14C-NaHCO3 solution. At the end of the incubation the contents of each bottle were filtered through 0.45 µm membrane filters and the radioactivity efficiency was calculated by the channels ratio method. The assimilation coefficients (photosynthesis/unit biomas) were calculated as disintegration per minute (counts/min mg algal dry weight).

GLP compliance:

not specified

Analytical monitoring:

yes

Vehicle:

not specified

Test organisms (species):

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

Test type:

not specified

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

2.2 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

not specified

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

EC0

Effect conc.:

< 0.88 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

not specified

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

EC100

Effect conc.:

17 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

not specified

Basis for effect:

growth rate

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

10 mg/L

Nominal / measured:

not specified

Conc. based on:

not specified

Basis for effect:

other: photosynthesis inhibition

Conclusions:

The EC50 (96 h) for growth inhibition of Selenastrum capricornutum (now: Pseudokirchneriella subcapitata) was determined in a laboratory study using the Algal Assay Procedure - Bottle Test (US EPA, 1971) to be 2.2 mg/L. Furthermore, the EC0 (96 h) could not be determined (< 0.88 mg/L) and the EC100 (96 h) was 17.0 mg/L.
Additionally, the EC50 (3 h) for photosynthesis inhibition was reported to be 10.0 mg/L.

Executive summary:

Calamari et al (1983).

The EC50 (96 h) for growth inhibition of Selenastrum capricornutum (now: Pseudokirchneriella subcapitata) was determined in a laboratory study using the Algal Assay Procedure - Bottle Test (US EPA, 1971) to be 2.2 mg/L. Furthermore, the EC0 (96 h) could not be determined (< 0.88 mg/L) and the EC100 (96 h) was 17.0 mg/L.

Additionally, the EC50 (3 h) for photosynthesis inhibition was reported to be 10.0 mg/L.

Description of key information

The 96h EC50  for growth inhibition of Selenastrum capricornutum (now: Pseudokirchneriella subcapitata) was determined in a laboratory study by Calamari et al (1983) using the Algal Assay Procedure - Bottle Test (US EPA, 1971).  The 96h EC50 was determined to be 2.2 mg/L, however a NOEC (96 h) could not be determined (< 0.88 mg/L).  The EC100 (96 h) was determined as 17.0 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

2.2 mg/L

Additional information

The 96 h EC50 for growth inhibition of Selenastrum capricornutum (now: Pseudokirchneriella subcapitata) was determined in a laboratory study by Calamari et al (1983) using the Algal Assay Procedure - Bottle Test (US EPA, 1971). The 96 h EC50 was determined to be 2.2 mg/L, however a NOEC (96 h) could not be determined (< 0.88 mg/L). The EC100 (96 h) was determined at 17.0 mg/L.