N-methylaniline

Long-term toxicity to fish

Administrative data

Endpoint:

fish short-term toxicity test on embryo and sac-fry stages

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study without detailed documentations.

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1993

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 212 (Fish, Short-term Toxicity Test on Embryo and Sac-Fry Stages)

GLP compliance:

not specified

Remarks:

.

Test material

Test material information

Constituent 1

Reference substance name:

N-methylaniline

EC Number:

202-870-9

EC Name:

N-methylaniline

Cas Number:

100-61-8

Molecular formula:

C7H9N

IUPAC Name:

N-methylaniline

Details on test material:

- Name of test material (as cited in study report): N-methylaniline (100-61-8)
- Physical state: solved in reconstituted water
- Analytical purity: reagent grade
- Supplier: Merck, 6100 DarmstacE/FR Germany

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

No details specified.

Test organisms

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Common name: Zebrafish
- Strain: Brachydanio rerio
- Source: West Aquarium, 3/422 Bad Lauterberg/FR Germany

METHOD FOR PREPARATION AND COLLECTION OF FERTILIZED EGGS
- Numbers of parental fish to induce spawning: 4 females, 8 males
- Method of collection of fertilised eggs: the spawn was collected on the bottom of a glass box covered by a steel wire-net containing some small green glass trees
- Subsequent handling of eggs: the eggs were separated and cultured at 25°C individually using micro plates (Nunc, Roshilde/Denmark) containing 100 µL reconstituted water.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Remarks on exposure duration:

Until hatching.

Post exposure observation period:

Not applicable.

Test conditions

Hardness:

200 mg/L

Test temperature:

25°C

pH:

8 ± 0.2

Dissolved oxygen:

No data.

Salinity:

2 mM CaCI₂.2 H.O, 0.078 mM KCI, 0.5 mM MgSO₄.7 H₂O, 0.77 mM NHCO₃, in demineralized water

Nominal and measured concentrations:

7 concentrations between 0.1-5 µmol/L

Details on test conditions:

TEST SYSTEM
- No. of fertilized eggs/embryos per vessel: 12
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1

EFFECT PARAMETERS MEASURED: marked signs of development, e.g. abnormalities, and deaths during the 96 h test period.

Reference substance (positive control):

not required

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

0.2 µmol/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Oedematous enlargement of the pericardial space with retardation of heart development and reduced blood flow , deformation of the skeleton and the muscle apparatus and general retardation of the embryo development.

Effect concentrations 2

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

0.71 µmol/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: 95% CL: 0.69-0.72

Effect concentrations 3

Duration:

96 h

Dose descriptor:

other: LC100

Effect conc.:

1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

Mortality/survival at embryo and larval stages:
- no deaths or morphological changes were observed in the controls
- an obvious association excisted between malformations and death
Type of morphological abnormalities:
- oedematous enlargement of the pericardial space with retardation of heart development and reduced blood flow
- deformation of the skeleton and the muscle apparatus
- general retardation of the embryo development

Reported statistics and error estimates:

- oedematous enlargement of the pericardial space in about 20 % of all treated embryos
- deformation of the skeleton and muscle apparatus in approximately one third of all treated embryos
- retardation of body development in about 20 % of all treated embryos

Any other information on results incl. tables

Table 1: Comparison of the toxicity of N-methylaniline to embryonal development of Danio rerio with the results for aniline and N,N-dimethylaniline:

	Dimension	Concentration range	NOEL	LC50	95%-C.I.	LC100	Ratio-NOEL
Aniline	mmol	0.2 - 20	1	9.3	9.2-9.5	17	2.E-04
N-Methylaniline	umol	0.1 - 5	0.2	0.71	0.69-0.72	1	1
N,N-Dimethylaniline	umol	0.08 - 4	0.33	1.51	1.49-1.54	2	0.6

Hence, the fish-embryotoxicity of N-methylaniline is four orders of magnitude higher compared to aniline, whereas it is in the same range as N,N-dimethylaniline.

Applicant's summary and conclusion

Validity criteria fulfilled:

not applicable

Remarks:

only similar to guideline

Conclusions:

In this study N-methylaniline was found highly toxic to Zebrafish embryo, with a NOEC of 0.2 µmol/L or 21 ug/L and a LC50 of 0.71 µmol/L or 76 ug/L.

Executive summary:

Zebra-fish embryos exposed for 96 h were more sensitive to methylanilines than to Nmethylamine, N,N-dimethylamine, 2-aminoethanol, and isopropylamine. N-methylanilie, like aniline and N,N-dimethylaniline, produced malformations in the fish embryos with lesions mainly of the heart or skeleton. Besides mortality, effects observed were: a general retardation of the embryo development and oedematous enlargement of the pericardial space with retardation of heart development and reduced blood flow. In addition, exposure to N-methylaniline caused a deformation of the skeleton and the muscle apparatus. The underlying cause of death could not be determined explicitly although an obvious association between malformations and death existed. The NOEL for N-methylaniline was 0.2 µmol/L, while the NOEL for aniline was 1 mmol/L. In conclusion: The embryotoxicity of aniline is enhanced considerably by its alkylation to N-methylaniline or N,N-dimethylaniline. However, NH2-substitution of alkyl compounds leads to agents with less embryotoxicity.