1,2-Dihydro-2,2,4-trimethylquinoline, oligomers

Repeated dose toxicity: oral

Administrative data

Endpoint:

chronic toxicity: oral

Remarks:

combined repeated dose and carcinogenicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comprehensive 2 years feeding study conducted according to GLP

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1992

Report date:

1992

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)

Deviations:

not applicable

Remarks:

; althought no guideline was folled this is a comprehensive study conducted similar to actual guidleine

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

1,2-Dihydro-2,2,4-trimethylquinoline, oligomers

EC Number:

500-051-3

EC Name:

1,2-Dihydro-2,2,4-trimethylquinoline, oligomers

Cas Number:

26780-96-1

Molecular formula:

(C12H15N)x

IUPAC Name:

2,2,4-trimethyl-1,2-dihydroquinoline

Details on test material:

Test substance: Flectol Pastilles; purity: 100% product

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Administration / exposure

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

2 years

Frequency of treatment:

daily

Doses / concentrations

Remarks:

Doses / Concentrations:
50, 250, 1000 ppm; approx. 2.3, 11.8 and 48 mg/kg bw (males); approx. 3.1, 15.3 and 63 mg/kg bw (females)
Basis:

No. of animals per sex per dose:

60/sex/dose

Control animals:

yes, concurrent no treatment

Details on study design:

Post-exposure period: no

Results and discussion

Effect levels

Dose descriptor:

NOAEL

Effect level:

ca. 11.8 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: target organs: liver and adrenals

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Analytical verification of stability of the test material, homogeneity and concentration of test material in the diet with satisfactory results.

Compared with their respective controls, survival at the end of the study was greater at the high level in both males (61 ves 40%) and females (59 vs 48%). These results are not indicative of toxicity.

Clinical signs: no compound related findings.

Body weight: significant lower weight was observed for high dose females from week 11 to week 77; no effect in males.

Food consumption: no consistent effect except a statistically significant decrease was observed during the first week of the study.

Ophthalmic examinations: no abnormalities

Clinical pathology:there were no abnormalities in urinanalysis parameters which were attributed to the test material.

Gross pathology: absolute liver weight were increased in high dose males and females; liver weight relative to brain weight was increased in mid dose females; there were no other organ weights attributed to administration of the test material.There were no gross necropsy alterations attributed to administration of the test material.

Microscopic pathology:

The following oservations were reported; statistically significant observations are indicated by an asterics(*)

:

Organ sex control low mid and high dose group

Adrenal

Cystic degen. cortex M 2/60 4/60 4/60 9/60*

Sinusoidalectasia/cyst M 0/60 3/60 3/60 6/60*

Hyperblasis medulla M 12/60 11/60 22/60* 19/60

Liver:

Bile duct prolif. cholangiofibros. M 31/60 33/60 30/60 43/60*

Fucus of celular alteration M 17/60 12/60 22/60 30/60*

Hepathocell. hypert.

centriiobular M 1/60 0/60 0/60 13/60*

F 0/60 0/59 0/59 11/60*

Hepathocell. vacuol. centriiobular F 1/60 3/59 2/59 16/60*

Sinus dilatation F 2/60 3/59 10/59* 17/60*

Thyroid:

Follicular Adenoma/

cystadenoma M 5/60 2/60 4/60 10/60 (not statistically significant)

F 1/60 3/58 0/60 9/59*

Follicular

hyperblasia M 1/60 2/60 2/60 5/60 (no statistics done)

Additional lesions observed were considered to occur spontaneously and, due to the lack of a dose response relationship and/or lack of consistency in the incidences across the various death categories in this study, were not considered related to administration of thetest material.

Cellular proliferation assay:

The mean positive hepathic nuclei/microscopic field was slightly, but statistically significantly, increased in the high dosefemales after 4 days of exposure. The toxicological significanc, if any, of this difference is not known. There were no significant differences in females at one or six months nor there were any differences in males at any time interval.

Applicant's summary and conclusion

Executive summary:

The following effects were considered to be test materia related: effects on body weight of females in the high dose group; histopathologic effects on adrenals in the high dose males; effects on liver weight and liver histopathology in the high dose males and in the mid and high dose females.

The increased incidence of thyroid follicular adenoma/cystadenomas in the high level males and females was considered to have resulted from compound administration, but may have resulted from compensatory mechanisms as a result of the hepathic changes; see discussion of this study in chapter 7.7 carcinogenicity.

The NOAEL for systemic toxicity was considered to be 250 ppm in males and 50 ppm in females.