Diphenylamine

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:

other: Basic data given: comparable to guidelines

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

not specified

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:
Freshly produced medium was prepared from deionised water, and nutrients were- added according to IS0 (1989). An exponentially growing culture of algae acclimated to the test conditions for at least 24 h before the test start was used as inoculum.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Method of cultivation: batches exposed to a dilution series of the test substance under continuous shaking (120 rpm)

ACCLIMATION
- Acclimation period: 24 h
- Culturing media and conditions (same as test or not): freshly produced medium from deionised water + nutrients according to ISO

Test type:

not specified

Water media type:

not specified

Limit test:

no

Total exposure duration:

72 h

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 ml glass flasks
- Initial cells density:4.6 x 10^3
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates):6

GROWTH MEDIUM
- Standard medium used: yes

Reference substance (positive control):

not specified

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

2.17 mg/L

Nominal / measured:

estimated

Conc. based on:

other: as NVOC in stock

Basis for effect:

growth rate

Remarks on result:

other: 95 % CL: 2.01-2.36

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.37 mg/L

Nominal / measured:

estimated

Conc. based on:

other: as NVOC in stock

Basis for effect:

growth rate

Results with reference substance (positive control):

no data

Applying the EU classification criteria for environmental danger, the following classification of diphenylamine can be proposed: N: R50/53, i.e. "Very toxic to aquatic organisms and may cause long-term effects in the aquatic environment"

Validity criteria fulfilled:

not specified

Remarks:

details of the results not available

Conclusions:

The 72-hour EC50 for growth inhibition of K. subcapitata was estimated to be 2.17 mg/L

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Does not meet important criteria of today standard methods: data on test substance, testing methodology

Qualifier:

no guideline followed

Principles of method if other than guideline:

1) Haematococcus pluvialis cells were grown under optimal growth conditions in the presence of the absence of diphenylamine (30 µM) for 96 h to determine the effects of diphenylamine on growth (cell number, chlorophyll content, dry weight and rate of oxygen evolution and uptake)
2) Cells at the logarithmic growth phase were incubated with or without diphenylamine (30 µM), then the pigment composition was analysed by HPLC to determine the effects of diphenylamine on astaxanthin accumulation

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: dissolving pure crystalline diphenylamine in 70 % basic ethanol
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): ethanol

Test organisms (species):

Haematococcus pluvialis

Test type:

not specified

Water media type:

not specified

Total exposure duration:

14 d

1) Growth showed no significant differences between two treatments

2) Addition of diphenylamine resulted in yellow cells

Validity criteria fulfilled:

not applicable

Conclusions:

Under the conditions of study, diphenylamine did not cause any toxic effect to growth at the concentration tested but inhibited accumulation of astaxanthin under phosphate starvation, leading to accumulation of bêta-carotene

Description of key information

EC50 72 hr (growth rate): 2.17 mg/l for Selenastrum capricornutum (OECD 201)

Key value for chemical safety assessment

EC50 for freshwater algae:

2.17 mg/L