4,4'-dihydroxybenzophenone

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:

72 hour exposure

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Version / remarks:

Test conditions according to SOP E203 based on OECD Guideline for testing of chemicals, Freshwater Alga and Cyanobacteria, Growth Inhibition Test reference 201 (2011).

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Lot/Batch Number: 20111104
Purity/Composition: >99.5% CAS # 611-99-4
Chemex reference: ECO 170601

Analytical monitoring:

yes

Vehicle:

yes

Remarks:

Nutrient grwoth medium

Details on test solutions:

Test concentrations (nominal): 0 (control), 6.25, 12.5, 25, 50, and 100 mg/l
Stock solutions were prepared for both the range-finding and definitive tests by addition of the test sample directly to nutrient growth medium in a volumetric flask of adequate volume.
Calculated volumes of the stock solution were added to nutrient growth medium and made to volume to prepare the test concentrations and provide enough solution for testing and subsequent water quality measurements

Test organisms (species):

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

Details on test organisms:

Species: Pseudokirchneriella subcapitata strain: CCAP 278/4 received 22 April 2016.
Source: Culture Collection of Algae and Protozoa SAMS Ltd Scottish Marine Institute, OBAN, Argyll PA37 1QA, Scotland, United Kingdom
Culture conditions: Temperature: 21.4 – 21.7C.
Illumination: 6800 - 9670 lux continuous white light.
Orbiting: set to 200 rpm.
Culture media: Deionised water with added nutrients according to OECD 201

Test type:

static

Water media type:

other: The stocks of culture and tests performed, in nutrient growth medium (OECD 201), prepared by adding appropriate amounts of nutirent stocks to deionised water (sterilised by autoclaving at 120°C for 15 minutes) at an intial pH of 8.25 (adjusted to 8.06)

Total exposure duration:

72 h

Test temperature:

Temperature range within incubator throughout test: 21.0 – 21.9°C
(Required: 21-24±2°C)

pH:

Initial pH at 0 Hours: 8.02 (Required: 8.1±0.1)
pH range in control and test concentrations throughout test: 7.37 – 8.77

Nominal and measured concentrations:

Analytical measurement of the freshly prepared exposure solutions showed that not all the mean measured concentrations were within 20% of nominal concentrations. However analytical measurement of the aged exposure solutions showed that all of the concentrations were within 20% of the initial measured concentrations. Therefore in accordance with OECD Guidelines, the initial measured concentrations have been used in the determination of the EC50 and NOEC values.

Reference substance (positive control):

yes

Remarks:

A separate reference study was run using potassium dichromate as a means of checking the test procedure and sensitivity of the test species. The ErC50 obtained was 1.06mg/l and all validity criteria were met.

Key result

Duration:

72 h

Dose descriptor:

other: EC(r)50

Effect conc.:

42.61 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

other: EC(y)50

Effect conc.:

21.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

12.542 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

32.04 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth rate

Details on results:

Cell densities were measured microscopically by direct cell counts on each test and control replicate, in sextuplicate at 24 hours for the control and triplicate thereafter, and in triplicate at 24, 48 and 72 hours (±2h) for the test concentrations. Average results of the cell density determinations are given in 3.1. All results in this study are calculated from the measured cell densities.
The algal cells were examined microscopically during the determination of the cell density, all cells within the control and all test concentrations appeared normal, no morphological abnormalities were observed.
When observed visually, the control conical flasks appeared clear and colourless at 24 hours, clear and sightly green at 48 hours and pale green at 72 hours. All test conical flasks appeared clear and colourless at 24 hours. 6.25 and 12.5mg/l concentrations appeared clear and slightly green at 48 hours and pale green at 72 hours. 25mg/l appeared clear and slightly green at 48 and 72 hours. 50 and 100mg/l test concentrations were clear and colourless at 48 hours. 50mg/l appeared clear and slightly green at 72 hours and 100mg/l appeared clear and very slightly green at 72 hours.

Validity criteria fulfilled:

yes

Conclusions:

The 72 hour EC(r)50 and EC(y)50 of 4,4 DIHYDROXYBENZOPHENONE to Pseudokirchneriella subcapitata were 42.61 mg/l and 21.40 mg/l respectively.
The 0 to 72-hour NOEC(r) and NOEC(y) was 12.542 mg/l and the 0-72 hour LOEC was 32.04 mg/l .
The algal cells were examined microscopically during the determination of cell concentration. All cells within the control and test concentrations appeared normal, no abnormalities were observed.
All validity criteria for the definitive test were met

Description of key information

The 72 hour EC(r)50 and EC(y)50 of 4,4 DIHYDROXYBENZOPHENONE to Pseudokirchneriella subcapitata were 42.61 mg/l and 21.40 mg/l respectively. The EC50 (r) growth rate value has been used as the key value for this end point.

The 0 to 72-hour NOEC(r) and NOEC(y) was 12.542 mg/l and the 0-72 hour LOEC was 32.04 mg/l .

The algal cells were examined microscopically during the determination of cell concentration. All cells within the control and test concentrations appeared normal, no abnormalities were observed.

All validity criteria for the definitive test were met

Key value for chemical safety assessment

EC50 for freshwater algae:

42.61 mg/L

EC10 or NOEC for freshwater algae:

12.54 mg/L