1,3-difluorobenzene

Toxicity to aquatic algae and cyanobacteria

Administrative data

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

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 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

1,3-difluorobenzene

EC Number:

206-746-5

EC Name:

1,3-difluorobenzene

Cas Number:

372-18-9

Molecular formula:

C6H4F2

IUPAC Name:

1,3-difluorobenzene

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

yes

Details on test solutions:

The primary stock solution used in the range-finding test was prepared by dissolving 0.0250 g of the test substance in 250 mL with OECD medium, resulting in a concentration of 100 mg.L-1. The stock solution of 10 mg.L-1 was prepared from dilution of the primary stock solution.

The primary stock solution used in the definitive test was prepared by dissolving 0.1 g of the test substance in 1000 mL with OECD medium, resulting in a concentration of 100 mg.L-1. The stock solution of 10 mg.L-1 was prepared from dilution of the primary stock solution.

From these initial stock solutions, a series of dilutions was prepared in order to obtain the desired tested concentrations

Test organisms

Test organisms (species):

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

Study design

Test type:

static

Water media type:

brackish water

Limit test:

yes

Total exposure duration:

72 h

Test conditions

Test temperature:

22.1 to 22.3oC

pH:

8.1-8.3

Reference substance (positive control):

yes

Results and discussion

Effect concentrations

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

65.95 mg/L

Details on results:

The 72-hours EyC50 value for alga Pseudokirchneriella subcapitata exposed to 1,3-Difluorobenzene was 29.72 mg.L-1 and the 72-hours ErC50 value was 65.95 mg.L-1. The highest test substance concentration with no observed significant adverse effect (NOEC) on algal growth was 10 mg.L-1 and the lowest test substance concentration at which was observed significant reducing effect on growth (LOEC) was 32 mg.L-1.

Any other information on results incl. tables

Table 12 –Cells Concentration, Yield of Biomass and Yield Inhibition, Growth Rate, and Growth Rate Inhibition of Cells Compared to the Control at 24, 48, and 72 Hours at Each Tested Concentration, in the Definitive Test.

 

Test period (hours)	Nominal concentration (mg.L^-1)	Obs*	Cells concentration (cells.mL^-1)			Cells concentration average (cells.mL^-1)	Yield (y) (cells.mL^-1)	Yield inhibition (Iy) (%)	Growth rate (µ) (day^-1)	Growth rate inhibition (Iµ) (%)
			R1	R2	R3
24	Control	NM	30000	20000	30000	26667	21667	0	1.6740	0
	0.32	NM	30000	30000	30000	30000	25000	0	1.7918	0
	1	NM	20000	30000	30000	26667	21667	0	1.6740	0
	3.2	NM	30000	30000	20000	26667	21667	0	1.6740	0
	10	NM	30000	20000	30000	26667	21667	0	1.6740	0
	32	NM	20000	20000	20000	20000	15000	31	1.3863	17
	100	NM	10000	10000	10000	10000	5000	77	0.6931	59
48	Control	NM	160000	140000	160000	153333	148333	0	1.7116	0
	0.32	NM	180000	150000	160000	163333	158333	0	1.7432	0
	1	NM	150000	170000	180000	166667	161667	0	1.7533	0
	3.2	NM	170000	150000	150000	156667	151667	0	1.7223	0
	10	NM	150000	170000	160000	160000	155000	0	1.7329	0
	32	NM	100000	70000	90000	86667	81667	45	1.4263	17
	100	NM	20000	20000	10000	16667	11667	92	0.6020	65
72	Control	NM	680000	700000	710000	696667	691667	0	1.6456	0
	0.32	NM	690000	720000	710000	706667	701667	0	1.6504	0
	1	NM	720000	690000	700000	703333	698333	0	1.6488	0
	3.2	NM	710000	680000	710000	700000	695000	0	1.6472	0
	10	NM	700000	720000	670000	696667	691667	0	1.6456	0
	32	NM	300000	320000	290000	303333	298333	57	1.3685	17
	100	NM	30000	20000	20000	23333	18333	97	0.5135	69

R1, R2 and R3 = replicates.

* NM = None morphological effects observed.

 

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The 72-hours EyC50 value was 29.72 mg.L-1 and the 72-hours ErC50 value was 65.95 mg.L-1. The highest test substance concentration which no observed significant adverse effect (NOEC) on algal growth was 10 mg.L-1 and the lowest test substance concentration at which was observed significant reducing effect on growth (LOEC) was 32 mg.L-1.