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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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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  µm3

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   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=5.4x105

 

294

 

265

 

254

 

µ = 1.33

 

288

 

292

 

254

 

x= 272

50 ppb

277

278

292

288

237

250

N=5.4x105

 

268

 

280

 

260

 

µ = 1.33

 

230

 

204

 

191

 

x=216

100 ppb

259

245

206

206

191

198

N=4.3x105

 

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).

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