Benzene, C10-13-alkyl derivs.

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:

Nov 1999 to Mar 2000

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

Analytical monitoring:

yes

Vehicle:

yes

Details on test solutions:

Acetone was used as a solvent (1 mL/L).

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Source: Ecotoxicology Dpt. of Centro Nacional de Sanidad Ambiental. Instituto de Salud Carlos lll 28220. Majadahonda (Madrid)

Test type:

not specified

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

(Ca + Mg) ≤ 0.6 mmol /L

Test temperature:

22 ± 1

pH:

7.1 ± 0.1

Nominal and measured concentrations:

- Nominal concentrations: 25, 50 and 100 µg/L.
- Measured concentrations: 23, 25 and 98 µg/L respectively.

Details on test conditions:

- Initial cells density: 1.0E+04
- Determination of cell concentrations: Coulter Counter
- No. of vessels pre treatment: 3
- No. of vessels pre controls: 2 - 5
- The composition of algae mediumis provide in Table 1 in "Any other information on materials and methods incl. tables".

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 50 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

100 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

An overview of the results is provided in Table 2 to Table 7 in "Any other information on results incl. tables"
- No effects were found for LAB C10 - C13 at 50 µg/L (solubility as measured in study for C12 LAB: 37.6 µg/L).
- EC50 values were above 100 µg/L for all the tested substances.

Table 2. Results of cell concentration s for LAB CAS 67774 -74 -7

Cell concentrations for LAB CAS 67774-74-7                              Time                 72 hours                              Replicates          3                              Controls             6                              Nº                      1.0E+04 cell/mL                              Threshold           8                              Cell Diameter     3.340 µm                              Cell Volume      19.48  µm^3
Controls
C - 1		C – 2		C – 3		C – 4		C – 5		C - 6
198		207		244		211		208		247
220		210		217		224		210		233
201		205		245		221		230		235
206		207		235		220		216		238
F = 2000   x = 220             S=13.6    N = 4.4 x 10^5   µ = 1.30
LAB – CAS  67774-74-7
	1		x		2	x	3		x
	267				281		259				x = 269
25 ppb	273		278		261	269	268		260		N=5.4x10^5
	294				265		254				µ = 1.33
	288				292		254				x= 272
50 ppb	277		278		292	288	237		250		N=5.4x10^5
	268				280		260				µ = 1.33
	230				204		191				x=216
100 ppb	259		245		206	206	191		198		N=4.3x10^5
	245				209		211				µ = 1.25

Table 3. Results of cell concentrations for LAB C10

Cell concentrations for LAB C10                              Time                 72 hours                              Replicates         2                              Controls            2                              Nº                     1.0E+04 cell/mL                              Threshold          8                              Cell Diameter    3.340 µm                              Cell Volume      19.48 µm3
Control
C-1			C-2
335			356
341			353
375			381
350			363
F= 2000; X= 357; S= 9.19; N= 7.1 E+05; µ = 1.42
LAB – C10
ppb	1	Mean	2	Mean
25	212	224	267	272	x = 248 µ = 1.30 N = 5E+05
	222		274
	238		274
50	282	256	284	252	x = 254 µ = 1.30 N = 5.1 E+05
	229		234
	258		238
100	261	245	183	215	x = 230 µ = 1.27 N = 4.6E+05
	228		239
	248		223

Table 4. Results of cell concentrations for LAB C12

Cell concentrations for LAB C12                              Time                 168 hours (Prolonged)                              Replicates         3                              Controls            5                              Nº                     1.0E+04 cell/mL                              Threshold          8                              Cell Diameter    3.340 µm                              Cell Volume      19.48 µm3
Control
C -1		C - 2			C - 3		C - 4			C - 5
4033		2469			2251		3241			2551
4168		2499			2115		3309			2619
4347		2469			2243		3392			2661
4182		2479			2203		3314			2610
Annuled F= 2000; X= 2651; S= 573.12; N= 5.3 E+06; µ = 0.89
LAB – C12
ppb	1		Mean	2		Mean		3	Mean
25	2357		2440	2616		2609		3359	3359		x = 2802 µ = 0.9 N = 5.6E+06
	2439			2532				3396
	2525			2679				3322
50	2378		2432	2119		2223		2235	2285		x = 2313 µ = 0.87 N = 4.6E+06
	2510			2210				2320
	2410			2341				2302
100	2562		2482	3191		3183		3196	3079		x = 2914 µ = 0.9 N = 5.8E+06
	2452			3188				3069
	2423			3172				2973

Table 5. Results of cell concentrations for LAB C14

Cell concentrations for LAB C14                              Time                 72 hours                              Replicates         3-2                              Controls            5                              Nº                     1.0E+04 cell/mL                              Threshold          8                              Cell Diameter    3.340 µm                              Cell Volume      19.48 µm3
Control
C -1		C - 2			C - 3		C - 4			C - 5
785		620			726		721			739
784		708			669		793			784
716		678			649		786			756
761		668			681		766			760
F= 2000; X= 727; S= 48.38; N= 1.45 E+06; µ = 1.65
LAB – C14
ppb	1		Mean	2		Mean		3	Mean
25	743		717	821		842					x = 779 µ = 1.6 N = 1.5E+06
	717			859
	692			847
50	741		728	750		753					x = 740 µ = 1.6 N = 1.48E+06
	710			728
	735			783
100	705		718	645		620		807	819		x = 719 µ = 1.6 N = 1.4E+06
	719			611				854
	740			604				798

 Table 6. Results of growth inhibition for LAB CAS 67774 -74 -7

Inhibition of growth rate
Sample : Commercial LAB  CAS Nº 67774-74-7
Concentration ppb	Inhibition %
25	-2.3
50	-2.3
100	3.8

 

Table 7. Results of growth inhibition for LAB-C10, LAB-C12, LAB-C14

Inhibition of growth rate
Samples:  LAB-C10, LAB-C12, LAB-C14
Concentration ppb	Inhibition %
	LAB-C10	LAB-C12	LAB-C14
25	8.4	-1.1	3.1
50	8.4	2.2	3.1
100	10.5	-1.1	3.1

 

Validity criteria fulfilled:

yes

Conclusions:

Based on the findings, the 72-hr NOErC was determined to be ≥50 µg/L and ErC50 values were > 100 µg/L for all substances tested. This is higher than the measured solubility limit for C12 LAB of 37.6 µg/L.

Executive summary:

This study examined the toxicity of linear alkyl benzenes to aquatic algae, Scenedesmus subspicatus. The study was conducted according to OECD TG 201 and in compliance with GLP. The algae was exposed to concentrations of 25, 50 and 100 µg/L of test substance for 72 hrs. During this time, readings of the growth rate were taken. Tests were also done on C10, C12, and C14 linear alkyl benzenes in addition to commercial LAB. Based on the findings, the 72-hr NOErC was determined to be ≥ 50 µg/L and  ErC50 values were > 100 µg/L for all substances tested. This is higher than the measured solubility limit for C12 LAB of 37.6 µg/L.

Description of key information

All available data was assessed and the key study was condisered to be the worst-case and selected for CSA. The other study was included as supporting information.

A 72-hour short-term toxicity test of the test subtsance to freshwater algae (Scenedesmus subspicatus) was conducted according to OECD Guideline No. 201. The NOErC was determined to be ≥ 50 µg/L and  ErC50 value was > 100 µg/L.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

50 µg/L

Additional information

The key study examined the toxicity of various LABs to aquatic algae. Tests were also done on C10, C12, and C14 linear alkyl benzenes in addition to the commercial LAB. Scenedesmus subspicatus was exposed to the test substances for 72 hours. During this time, readings of the growth rate were taken. The nominal concentrations tested were 25, 50 and 100 µg/L, with corresponding measured concentrations of 23, 25, and 98 µg/L, respectively, for the C12-LAB. The 72-hr EC50 values for all substances were >100 µg/L (nominal), which is higher than the measured solubility limit for C12-LAB (37.6 µg/L).