Dioxybenzone

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018-01-19 - 2018-03-28

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study according to guidelines

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

April 2004

GLP compliance:

yes (incl. QA statement)

Remarks:

March 2015

Test material

Test material information

Constituent 1

Reference substance name:

Dioxybenzone

EC Number:

205-026-8

EC Name:

Dioxybenzone

Cas Number:

131-53-3

Molecular formula:

C14H12O4

IUPAC Name:

2-(2-hydroxybenzoyl)-5-methoxyphenol

Test material form:

solid: particulate/powder

Specific details on test material used for the study:

Name: 2,2’ -Dihydroxy-4-methoxybenzophenone
Batch/Lot Number: CM70314A1
Description: Yellow powder
Expiry Date: 14 March 2019
Purity: 99.8%
Storage Conditions: Room Temperature, protected from light

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 100, 50.0, 25.0, 12.5 and 6.25 % of a filtrate at a loading rate of 100 mg test item/L
- Sampling method: Control and test solutions were sampled in duplicate at the start of exposure and at 48h.
- Sample storage conditions before analysis: All samples were stored in amber glass bottles in the dark at a temperature of ≤ -18°C after sampling and before shipment.

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
As the test item is poorly water-soluble, the following approach was used taking into account aspects of ISO 14442 (2006), Water quality -- Guidelines for algal growth inhibition tests with poorly soluble materials, volatile compounds, metals and waste water, and OECD 2000, Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures. OECD Series on Testing and Assessment Number 23. ENV/JM/MONO(2000)6.
A stock solution was prepared at a nominal loading rate of 100 mg/L as described below by adding 0.10038 mg of the test item to 1000 mL of the test medium. This stock solution was stirred with 600 rpm for 48 hours at ambient temperature in the dark.
Thereafter this stock solution was filtered, using a glass fibre filter with an average retention capacity of 0.40 µm (MN 85-220). The initial 150 mL of the filtrate were discarded. Visual inspection of the flask showed a clear slightly yellow solution without Tyndall effect.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Strain/clone: M10
- Source: Daphnia magna STRAUS (clone M10), a water flea, cultured at ECT Oekotoxikologie GmbH since December 22, 2011
- Age of parental stock: < 35 days
- Feeding during test: none

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test conditions

Hardness:

254 mg/L CaCO3

Test temperature:

20.3 - 21.0 °C

pH:

7.7 - 7.9

Dissolved oxygen:

89 - 93 % of air saturation
7.9 - 8.2 mg/L

Conductivity:

676 µS/cm

Nominal and measured concentrations:

control and 100, 50.0, 25.0, 12.5 and 6.25 % of a filtrate at a loading rate of 100 mg test item/L (nominal concentrations)
(measured concentrations)

Details on test conditions:

TEST SYSTEM
- Test vessel:100-mL glass beakers, closed by watch glass
- Material, size, headspace, fill volume: 50-60 mL fill volume
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Test medium: Elendt medium M4

OTHER TEST CONDITIONS
- Adjustment of pH: None
- Photoperiod: 16h light / 8h dark
- Light intensity: 580-638 lx

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

21.1 other: % of filtrate at 100 mg test item/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Effect concentrations 2

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

ca. 4.27 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

act. ingr.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: Sublethal observations on the mobile daphnids were recorded. At 25% of filtrate at 100 mg test item/L reduced swimming activity was observed after 24 h and in respectively one test vessel at 12.5 and 25.0% of filtrate at 100 mg test item/L after 48 h.
- Mortality of control: 0%
- Other adverse effects in controls: None

Validity criteria:
% of immoible daphnids in the control was less than 10% (0%) and dissolved oxygen concentration in control and test vessels at the end of the test were greater than 3 mg/L (> 7.9 mg/L)

Results with reference substance (positive control):

24h EC50 0.74 mg/L
The results of this reference test are acceptable and the test conditions are reliable and the sensitivity of the test system could be demonstrated.

Any other information on results incl. tables

Table 1: Cumulative number of immobile Daphnia magna after 24 and 48 h

nominal concentration	total number of introduced daphnids	total number of immobilised daphnids	immobilised daphnids (% of introduced)	total number of immobilised daphnids	immobilised daphnids (% of introduced)
[%*]		[24 h]	[24 h]	[48 h]	[48 h]
Control	20	0	0.0	0	0.0
6.25	20	0	0.0	0	0.0
12.5	20	0	0.0	0	0.0
25.0	20	13	65.0	19	95.0
50.0	20	20	100.0	20	100.0
100	20	20	100.0	20	100.0

*% of filtrate at 100 mg test item/L

Table 2: Summary of measured concentrations

% of a saturated solution with a loading rate of 100 mg/L	Sample name	Test period [d]	Age of test matrix [d]	Measured conc (mg/L)
0	0530	0	0	<LOD
6.25	0532	0	0	1.25
12.5	0534	0	0	2.57
25	0536	0	0	4.78
50	0538	0	0	10.3
100	0540	0	0	20.6
0	0543	2	2	<LOQ
6.25	0545	2	2	1.18
12.5	0547	2	2	2.38
25	0549	2	2	4.76
50	0551	2	2	10.2
100	0553	2	2	20.1

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The EC50 value for daphnids exposed to the test item was ca. 4.27 mg/L.

Executive summary:

The acute toxicity of the dioxybenzone was tested according to OECD guideline 202 and GLP conditions.

A clear concentration-response relationship was observed. The following EC_xvalues were determined based on nominal concentrations in % of filtrate at 100 mg test item/L:

EC10: 18.5 % of filtrate at 100 mg test item/L; ca. 3.73 mg/L

EC20: 19.3 % of filtrate at 100 mg test item/L; ca. 3.90 mg/L

EC50: 21.1 % of filtrate at 100 mg test item/L; ca. 4.27 mg/L