Sodium 3-(p-anilinophenylazo)benzenesulphonate

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:

08-08-2017 - 11-08-2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Experimental test result performed using standard test guidelines

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

no

Specific details on test material used for the study:

- Name of test material : sodium 3-[(4-anilinophenyl)diazenyl]benzenesulfonate
- Molecular formula : C18H14N3O3S.Na
- Molecular weight: 375.383 g/mol
- Smiles notation : c1(Nc2ccccc2)ccc(\N=N\c2cc(ccc2)S(=O)(=O)[O-])cc1.[Na+]
- InChl : 1S/C18H15N3O3S.Na/c22-25(23,24)18-8-4-7-17(13-18)21-20-16-11-9-15(10-12-16)19-14-5-2-1-3-6-14;/h1-13,19H,(H,22,23,24);/q;+1/p-1/b21-20+;
- Substance type: Organic
- Physical state: Solid

Analytical monitoring:

no

Vehicle:

yes

Details on test solutions:

The test solution was prepared in aseptic condition. The test item Sodium 3-(panilinophenylazo) benzenesulphonate was prepared by adding 4 mg of test item in 250 ml of BBM to get the final concentration of 16 mg/L. This stock solution was kept for stirring for 30 minutes to obtain a homogenous solution for the experiment. The test concentrations were chosen according to the available data of the test item. The concentrations chosen were set up to the water solubility limit. The remaining test solutions were prepared by dilution from the above stock solution. To have a better growth and visibility of cells, the initial of the culture was kept 1 X 104cells/ml. Care was taken to have a homogeneous solution for the experiment.

Test organisms (species):

Chlorella vulgaris

Details on test organisms:

The fresh water green alga Chlorella vulgaris, was used as the test organism. Sterile, unicellular, liquid cultures of algae.
The culture was examined under the microscope to confirm that it was unicellular, healthy and not contaminated.
The medium to be used for the growth of algae was Bold’s Basal Medium (BBM). It is a medium composed of macronutrients, micronutrients, alkaline EDTA solution and Iron solution. Stock solution of each of these was prepared separately and then a complete medium was prepared and sterilized. De-ionized water was used to prepare the BBM.

Test type:

static

Water media type:

freshwater

Total exposure duration:

72 h

Test temperature:

22 °C ± 2°C.

pH:

6.2 to 6.7

Nominal and measured concentrations:

0.5 mg/L, 1 mg/L, 2 mg/L, 4 mg/L, 8 mg/L, 16 mg/L. All the six concentration were in geometric series spaced by a factor of 2.

Details on test conditions:

Light Quality: White Fluoroscent Light
Light Intensity: 1500Lux
Photoperiod: 16 Hour Light Period : 8 Hour Dark Period
RPM Speed: 120 Revolutions per minute
Water: Deionized Waer
Test vessel size: 100ml
Test solution volume 60ml
Dilution water: Bold’s Basal Medium
Test concentration Six test concentration were: 0.5mg/l,1mg/l,2mg/l,4mg/l,8mg/l,16mg/l
Replicates per concentration: Three replicates for Control; Two replicates for each test concentration

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

7.927 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: calculated from equation through probit analysis

Details on results:

The microscopic observations were also noted in each of the experimental flasks. All the cells appeared healthy, round and green throughout the test duration in the control and in the experimental flask also no significant changes were observed.

Average specific growth rate and percentage inhibition after an interval of 72 hours:

	CONTROL		0.5mg/l		1 mg/l		2 mg/l		4 mg/l		8 mg/l		16 mg/l
Average Specific Growth rate (μ)	R1	0.31	R1	0.27	R1	0.26	R1	0.20	R1	0.18	R1	0.16	R1	0.12
	R2	0.29	R2	0.29	R2	0.23	R2	0.18	R2	0.15	R2	0.15	R2	0.13
	R3	0.29
Mean of Avg. Specific growth rate	0.30		0.28		0.25		0.19		0.16		0.16		0.13
Percentage Inhibition (%I)	-		6.04		16.40		36.23		44.31		47.00		57.30

 

pH values at 0 Hours and after 72 Hours of test item exposure to algae

Test vessels and test concentration	0 Hours	72 Hours
CONTROL
Replicate1	6.4	6.5
Replicate2	6.4	6.4
Replicate3	6.4	6.6
Average	6.4	6.5
0.5 mg/l
Replicate1	6.5	6.7
Replicate2	6.5	6.6
1 mg/l
Replicate1	6.5	6.5
Replicate2	6.4	6.5
2 mg/l
Replicate1	6.2	6.6
Replicate2	6.4	6.4
4 mg/l
Replicate1	6.3	5.6
Replicate2	6.4	6.6
8 mg/l
Replicate1	6.5	6.6
Replicate2	6.3	6.6
16 mg/l
Replicate1	6.3	6.7
Replicate2	6.2	6.7

Validity criteria fulfilled:

yes

Conclusions:

After 72 hours of exposure to test item Sodium 3-(p-anilinophenylazo)benzenesulphonate (CAS No.587-98-4) to various nominal test concentrations, EC50 was found to be 7.9267 mg/l graphically and through probit analysis.

Executive summary:

The effect of test item Sodium 3-(p-anilinophenylazo)benzenesulphonate, CAS No. 587-98-4 was studied on the growth of fresh water green alga Chlorella vulgaris. The study was conducted following OECD guideline 201- Alga, growth inhibition test. The test concentration chosen for the study were 0.5 mg/L,1 mg/L,2 mg/L,4 mg/L,8 mg/L,16 mg/L. The test concentrations were prepared using stock solution of the test item using mineral media. The green alga was exposed to the test concentration for a period of 72 hours to observe average specific growth rate and % growth inhibition under the effect of the test item. EC50 calculated graphically through probit analysis was observed to be 7.9267 mg/L.

Thus, it was concluded that the Sodium 3-(p-anilinophenylazo)benzenesulphonate (Cas no. 587-98-4) is toxic to aquatic invertebrates, hence it can be considered to be classified as Aquatic chronic 2 as per the CLP classification criteria for aquatic environment.

Description of key information

After 72 hours of exposure to test item Sodium 3-(p-anilinophenylazo)benzenesulphonate (CAS No.587-98-4) to various nominal test concentrations, EC50 was found to be 7.9267 mg/l graphically and through probit analysis.

Thus, it was concluded that the Sodium 3-(p-anilinophenylazo)benzenesulphonate (Cas no. 587-98-4) is toxic to aquatic algae, hence it can be considered to be classified as Aquatic chronic 2 as per the CLP classification criteria for aquatic environment.

Key value for chemical safety assessment

EC50 for freshwater algae:

7.927 mg/L

Additional information

Four studies, considered as key and supporting studies, including predicted data from validated tools and experimental data for toxicity to aquatic algae endpoint of test chemical Sodium 3-(p-anilinophenylazo)benzenesulphonate (CAS 587 -98 -4) with relevant read across which is close to target using log Kow as primary descriptor were summarised as follows:

 

In a key study, the effect of test item Sodium 3-(p-anilinophenylazo)benzenesulphonate, CAS No. 587-98-4 was studied on the growth of fresh water green alga Chlorella vulgaris. The study was conducted following OECD guideline 201- Alga, growth inhibition test. The test concentration chosen for the study were 0.5 mg/L,1 mg/L,2 mg/L,4 mg/L,8 mg/L,16 mg/L. The test concentrations were prepared using stock solution of the test item using mineral media. The green alga was exposed to the test concentration for a period of 72 hours to observe average specific growth rate and % growth inhibition under the effect of the test item. EC50 calculated graphically through probit analysis was observed to be 7.9267 mg/L.

 

Supporting data included prediction for target by Danish QSAR database, Using Battery algorithm model of Danish QSAR, the toxicity of Sodium 3-(p-anilinophenylazo)benzenesulphonate. EC50 was estimated to be 2.64 mg/l to Pseudokirchneriella s. at 72h.

 

Above experimental and predicted results for target assisted by experimental data of read across chemical 2-[({[(4,6-dimethoxypyrimidin-2-yl)carbamoyl]amino}sulfonyl)amino]-N,N-dimethylbenzamide) (Cas no.213464-77-8) fromEPA Office of Pesticides Program Databaseindidcates that the Effective concentration to 50% of Anabaena flosaquae is 3.8 mg/L.Population (Abundance) as effect of measurement.

 

One another read across N'(3,4Dichlorophenyl) N,Ndimethylurea (Diuron) (Cas No. 330 -54 -1) from Science of the Total Environment.463/464:469-477, suggest the 50% Effective concentration to Sellaphora minima for Diuron is 2.606 mg/L when exposed for 96 hrs. It can be concluded that the Diuron is toxic to aquatic algae.

 

Thus based on the effect concentration from key study which is 7.9267 mg/l gives the conclusion that test substance Sodium 3-(p-anilinophenylazo)benzenesulphonate (CAS 587 -98 -4) is toxic to aquatic algae at environmentally relevant concentrations and can be considered to be“aquatic chronic 2”as per the CLP classification criteria.