p-toluidine

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:

1994-1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP - Guideline study

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1998

Reference 2

Reference Type:

secondary source

Title:

p-Toluidine - CAS No: 106-49-0 - SIDS Initial Assessment Report.

Author:

OECD

Year:

2005

Bibliographic source:

UNEP Publications

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

This standard procedure also fulfils the requirenments of ISO 6341 and 92/69/EEC standard methods.

Principles of method if other than guideline:

Details on method:
In total 17 aniline compounds were tested for inhibition of the mobility of the freshwater crustacean Daphnia magna.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

p-toluidine

EC Number:

203-403-1

EC Name:

p-toluidine

Cas Number:

106-49-0

Molecular formula:

C7H9N

IUPAC Name:

4-methylaniline

Details on test material:

- Name of test material (as cited in study report): p-Toluidine
- CAS No.: 106-49-0
- Supplier: Merck
- Lot. No.: 380216
- Purity [%]: >99
- Storage condition of test material: in the dark at 3-5 °C at VKI (testing laboratory).
The test substances were received in the period from December 1993 to February 1994.

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Samples from the control and from the lowest, medium and highest test concentrations were taken at the beginning of the test and after 24 hours, as well as at the beginning and end of the second exposure period (at 24 hours and 48 hours). For some substances 50 ml and for others 200 ml test solution was transferred directly to a 50 ml, respectively a 200 ml measuring flask and spiked with 250 µl of a 100 ppm solution of aniline-d5 in methanol as an internal standard. 0.5 ml, respectively 2.0 ml of 6 M NaOH was added in order to increase the pH-level above 11, and 5 or 20 g NaCl was added to facilitate out-salting of the test substance. As organic phase, tert-butyl methyl ether was added until a total of about 1 ml non-aqueous phase, and the mixture was vigorously shaken for 5 minutes. After separation of the phases, the organic phase was sampled and stored at 4°C until transportation to the analyzing laboratory, DTI Kemiteknik.

Test solutions

Vehicle:

no

Details on test solutions:

Freshly produced ISO-medium was used in the tests. The medium was prepared from deionised water, and salts were added to the water according to the standard procedure (ISO 6341). The pH was adjusted to 7.8 ± 0.1 and the hardness to 250 ± 25 mg/l expressed as CaCO3. An appropriate amount of test substance was weighed into the test medium. In order to facilitate the dissolution, the mixture was ultrasonicated for 5 min. followed by magnetic stirring for 22 hours. After settling of possible remaining particles for 1-2 hours, aliquots were sampled from the mid-fraction of the stock solution for preparation of the individual test concentrations.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

breeding of Daphnia magna:
A strain of Daphnia magna (Straus) was isolated from Lake Langedam, Birkerod in 1979 and has been cultured at VKI since then. The animals are cultured in water from Lake Bradebaek at 20°C and fed three times every day with Selenastrum or Chlorella and a supply of yeast once or twice every week. Every week, a new culture is started with young animals.

senstivity of Daphnia magna:
The relative sensitivity of this strain is in the same order of magnitude as other clones of Daphnia magna as demonstrated in the international ring test (OECD, 1995). In addition according to the method, 24 h acute toxicity tests on the reference substance potassium dichromate (K2Cr2O7) were performed regularly to check the sensitivity of the test animals. The refence substance was tested in the following nominal concentrations: 0.4, 0.7, 1.0, 1.4, 2.0, and 3.0 mg/l.

Young Daphnia magna (less than 24 hours old) from this culture were used in the tests.

Study design

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test conditions

Hardness:

250 ± 25 mg/l

Test temperature:

20 ± 1 °C (continuous recodring during test)

pH:

Control: 7.9 (0 h), 7.9 (24 h), 7.9 (48 h)
0.40 mg/l: 8.1 (0 h), 7.8 (24 h), 7.9 (48 h)
0.80 mg/l: 8.1 (0 h), 7.8 (24 h), 7.9 (48 h)
1.60 mg/l: 8.1 (0 h), 7.8 (24 h), 7.9 (48 h)

Dissolved oxygen:

Control: 96 (0 h), 98 (24 h), 99 (48 h)
0.40 mg/l: 95 (0 h), 98 (24 h), 99 (48 h)
0.80 mg/l: 95 (0 h), 98 (24 h), 98 (48 h)
1.60 mg/l: 95 (0 h), 98 (24 h), 98 (48 h)

Nominal and measured concentrations:

nominal concentrations: 0 (control), 0.02, 0.05, 0.10, 0.20, 0.40, 0.80, and 1.60 mg/l
measured concentrations:
control: 0.0344 mg/l (meas. mean 0-24h)
control: 0.0172 mg/l (meas. mean 24-48 h)
0.02 mg/l: 0.0063 mg/l (meas. mean 0.24 h)
0.02 mg/l: 0.00485 mg/l (meas. mean 24-48 h)
0.2 mg/l: 0.13895 mg/l (meas. mean 0-24 h)
0.2 mg/l: 0.13585 mg/l (meas. mean 24-48 h)
1.6 mg/l: 1.07155 mg/l (meas. mean 0-24 h)
1.6 mg/l: 1.078125 mg/l (meas. mean 24-48 h)

Details on test conditions:

A light-dark cycle with 16 h light and 8 h darkness was maintained throughout the test period.

Reference substance (positive control):

yes

Remarks:

potassium dichromate (K2Cr2O7)

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

0.67 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: CL: 0.57-0.81

Effect concentrations 2

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.12 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: CL: 0.10-0.16

Effect concentrations 3

Duration:

24 h

Dose descriptor:

EC10

Effect conc.:

0.497 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: CL: 0.321-0.641

Effect concentrations 4

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: CL: 0.85-1.21

Effect concentrations 5

Duration:

24 h

Dose descriptor:

other: EC90

Effect conc.:

1.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: CL: 1.28->1.6

Effect concentrations 6

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

0.073 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: CL: 0.013-0.103

Effect concentrations 7

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.183 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: CL: 0.152-0.230

Effect concentrations 8

Duration:

48 h

Dose descriptor:

other: EC90

Effect conc.:

0.293 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: CL: 0.244-0.387

Reported statistics and error estimates:

EC50 values based on both nominal and measured concentrations for the acute toxicity of p-toluidine and the reference substance (K2Cr2O7) were calculated by using the standard procedure Probit (SNV, Version 2.3).

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Executive summary:

Pedersen (1998):

A test on the acute toxicity of p-toluidine to the invertebrate Daphnia magna was performed according to the OECD TG 202 in a semistatic test system. For a test period of 48 hours an EC50 value of 0.12 mg/l based on measured concentrations was reported (Pedersen et al., 1998).