Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide

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:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

In the definitive test from each test concentration and the control the samples of fresh solutions were taken at exposure initiation and the samples of old solutions were taken at exposure termination (i.e. pooled replicates)

Vehicle:

no

Details on test solutions:

In the definitive test 128.11 mg of the test item was weighed into a glass flask (analytical balance SBC22, Scaltec) [SOP/W/7] and quantitatively transferred into a glass flask of 2 L capacity by multiple washing with test medium. The stock mixture of total volume of 1280 mL was heterogeneous with visible not dissolved parts of the test item. Therefore, the stock mixture was heated for 2 hours at 50oC in a water bath and then sonicated for 30 min (ultrasonic bath, Sonic-10, Polsonic [SOP/W/78]). The non-dissolved part of the mixture was separated by filtration thorough a conditioned nitrocellulose membrane filter (filter type HAWG, 0.45 µm pores, Millipore) [SOP/W/37]. The filtrate was a homogeneous and transparent solution and was used as the highest test concentration. The lower test concentrations were prepared by sequential dilutions with the test medium in a ratio 1 : 1, volume per volume (as given in Table 1). The generated solutions were treatments named: an undiluted filtrate of a loading of 100 mg/L and its 2-fold dilution, 4-fold dilution, 8-fold dilution and 16-fold dilution.

Test organisms (species):

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

Details on test organisms:

The unicellular green algae Pseudokirchneriella subcapitata (Reinsch) Korshikov (syn. Selenastrum capricornutum Prinz) used for testing originated from the standard laboratory culture of the Institute of Industrial Organic Chemistry, Branch Pszczyna, Department of Ecotoxicology, Laboratory of Aquatic Toxicology according to OECD 201 recommendations [SOP/W/65]. Algae Pseudokirchneriella subcapitata SAG 61.81. on agar bevels were received from the Algae Collection University of Göttingen, Germany.

Test type:

static

Water media type:

freshwater

Total exposure duration:

72 h

Test temperature:

22.2 – 23.1

pH:

7.3 - 9.5

Details on test conditions:

light intensity: 8186 – 8730 lx, constant illumination and shaking

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 2.01 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1.56 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Results with reference substance (positive control):

ErC50 (72h) = 2.75 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:

1.56 mg/L