1-(2,4-dimethylphenylazo)-2-naphthol

Repeated dose toxicity: oral

Administrative data

Endpoint:

chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Data is from publication.

Data source

Reference

Reference Type:

publication

Title:

CHRONIC TOXICITY STUDIES ON FOOD COLOURS. PART II. OBSERVATIONS ON THE TOXICITY OF FD & C GREEN NO. 2 (LIGHT GREEN SF YELLOWISH), FD & C ORANGE NO. 2 (ORANGE SS) AND FD & C RED NO. 32 (OIL RED XO) IN RATS.

Author:

M. G. ALLMARK, H. C. GRICE AND W. A. MANNELL

Year:

1956

Bibliographic source:

J. Pharma. Pharmacology; Vol. 8, Pg. no. 417-424, 1956

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: As mention below

Principles of method if other than guideline:

Repeated dose oral toxicity study was conducted on male and female rats for a period of 44 weeks by oral feed for FD&C Red No. 32.

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

1-(2,4-dimethylphenylazo)-2-naphthol

EC Number:

221-490-4

EC Name:

1-(2,4-dimethylphenylazo)-2-naphthol

Cas Number:

3118-97-6

Molecular formula:

C18H16N2O

IUPAC Name:

1-(2,4-dimethylphenylazo)-2-naphthol

Test material form:

solid: crystalline

Details on test material:

- Name of test material (as cited in study report):FD&C Red No. 32.
- Molecular formula: C18H16N2O
- Molecular weight : 276.337 g/mol
- Substance type: Organic
- Physical state: Solid
- Smiles : Cc1ccc(N=Nc2c(O)ccc3ccccc23)c(C)c1
- InChI: 1S/C18H16N2O/c1-12-7-9-16(13(2)11-12)19-20-18-15-6-4-3-5-14(15)8-10-17(18)21/h3-11,21H,1-2H3/b20-19+

Specific details on test material used for the study:

- Name of test material (as cited in study report):FD&C Red No. 32.
- Molecular formula: C18H16N2O
- Molecular weight : 276.337 g/mol
- Substance type: Organic
- Physical state: Solid
- Smiles : Cc1ccc(N=Nc2c(O)ccc3ccccc23)c(C)c1
- InChI: 1S/C18H16N2O/c1-12-7-9-16(13(2)11-12)19-20-18-15-6-4-3-5-14(15)8-10-17(18)21/h3-11,21H,1-2H3/b20-19+

Test animals

Species:

rat

Strain:

not specified

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: No data available
- Age at study initiation: 5 to 6 weeks old
- Weight at study initiation: 40-360g
- Fasting period before study: No data available
- Housing: The animals were kept in groups of two to a cage.
- Diet (e.g. ad libitum): Diet ad libitum
- Water (e.g. ad libitum): Water ad libitum
- Acclimation period: No data available

Administration / exposure

Route of administration:

oral: feed

Vehicle:

other: rodent Diet

Details on oral exposure:

VEHICLE
- Justification for use and choice of vehicle (if other than water): No data available
- Concentration in vehicle: 0,0.03,0.75and 1.5% (0,30,75and 1500mg/kgbw/day)
- Amount of vehicle (if gavage): No data available
- Lot/batch no. (if required): No data available
- Purity: No data available

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

44 weeks

Frequency of treatment:

Daily

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

30 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

75 mg/kg bw/day (nominal)

Doses / concentrations 4

Dose / conc.:

1 500 mg/kg bw/day (nominal)

Remarks:

0,0.03,0.75and 1.5%

No. of animals per sex per dose:

Total number-120
0 mg/kgbw/day 20 male and female rats
30 mg/kgbw/day 20 male and female rats
75 mg/kgbw/day 20 male and female rats
1500mg/kgbw/day 20 male and female rats

Control animals:

yes, concurrent vehicle

Details on study design:

No data available

Positive control:

Not specified.

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: No data available
- Cage side observations checked in table [No.?] were included:
Mortality was observed.

DETAILED CLINICAL OBSERVATIONS: No data available
- Time schedule: No data available

BODY WEIGHT: Yes
- Time schedule for examinations: Body weight of the test animal was recorded weekly.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes, food consumption of the test animal was recorded weekly.
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No data available

FOOD EFFICIENCY: Yes
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: Yes

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No data available
- Time schedule for examinations: No data available
OPHTHALMOSCOPIC EXAMINATION: No data available
- Time schedule for examinations: No data available
- Dose groups that were examined: No data available

HAEMATOLOGY: Yes, haematology determinations were made for 20 weeks on groups of male and female rats at the dose level of 30mg/kg bw/day.
A slight modification of the pyridine-haemochromogen method of Rimington was used and the mean values of the final determinations were made.
- Time schedule for collection of blood: No data available
- Anaesthetic used for blood collection: No data available
- Animals fasted: No data available
- How many animals: No data available
- Parameters checked in table [No.?] were examined: Blood haemoglobin parameter was examined.

CLINICAL CHEMISTRY: No data available
- Time schedule for collection of blood: No data available
- Animals fasted: No data available
- How many animals: No data available
- Parameters checked in table [No.?] were examined: No data available

URINALYSIS: No data available
- Time schedule for collection of urine: No data available
- Metabolism cages used for collection of urine: No data available
- Animals fasted: No data available
- Parameters checked in table [No.?] were examined: No data available

NEUROBEHAVIOURAL EXAMINATION: No data available
- Time schedule for examinations: No data available
- Dose groups that were examined: No data available
- Battery of functions tested: sensory activity / grip strength / motor activity / other: No data available

Other-In the study exposure period was 65 weeks for control animals while it was 44 weeks for treatment group.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes, A complete necropsy was done on all 44-week exposure groups animals. All abnormalities were recorded on the individual animal necropsy forms. Heart, liver, kidney, Spleen, adrenal and testes. from all scheduled sacrifice animals were weighed. The mean weight in mg/g of body weight was calculated for male and female rats at he dose levl of 30mg/kg bw/day for treated group compare to control.


HISTOPATHOLOGY: A detailed examination was made of the haematoxylin-eosin stained paraffin sections of a number of organs including heart, liver, kidney, Spleen, adrenal and testes in male and female rats at he dose levl of 30mg/kg bw/day for treated group compare to control.

Statistics:

Standard deviation was observed.

Results and discussion

Results of examinations

Clinical signs:

not specified

Mortality:

mortality observed, treatment-related

Description (incidence):

Mortality; No mortality was obserserved at the dose level of 30 mg/kg bw/day in treated group compared to control.

Mortality was observed ,by the end of 20 weeks in all the rats on the 1500 mg/kg bw/day level .
Mortality was also observed ,by the end of 40 weeks in all the rats on the 75 mg/kg bw/day level .

Body weight and weight changes:

no effects observed

Description (incidence and severity):

No significant change was observed at the dose level of 30 mg/kg bw/day in treated group compared to control.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

No significant change was observed at the dose level of 30 mg/kg bw/day in treated group compared to control.

Food consumption was affected by the test substance at the dose level of 75and 1500 mg/kg bw/day.

Food efficiency:

no effects observed

Description (incidence and severity):

No significant change was observed at the dose level of 30 mg/kg bw/day in treated group compared to control.

Food efficiency was affected by the test substance at the dose level of 75and 1500 mg/kg bw/day.

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not specified

Haematological findings:

no effects observed

Description (incidence and severity):

No significant change was observed at the dose level of 30 mg/kg bw/day in treated group compared to control.

Clinical biochemistry findings:

not specified

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

No significant changes was observed in mean and final organ weight of male animals Heart, liver, spleen, kidneys and testes at the dose level of 30 mg/kg bw/day in treated group compared to control.
Except in mean organ weight of liver in female rats of 30 mg/kg bw/day significant change was observed.No significant changes was observed in mean organ weight of female animals Heart, spleen, kidneys and testes at the dose level of 30 mg/kg bw/day in treated group compared to control.

Gross pathological findings:

no effects observed

Description (incidence and severity):

No significant changes was observed in male animals Heart, liver, spleen, kidneys and testes at the dose level of 30 mg/kg bw/day in treated group compared to control.

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

No consistent histopathological changes were observed in the tissues or organs of the male and femalerats at the dose level of 30 mg/kg bw/day.

Histopathological findings: neoplastic:

not specified

Other effects:

not specified

Details on results:

Other-In the study exposure period was 65 weeks for control animals while it was 44 weeks for treatment group.

Effect levels

Key result

Dose descriptor:

NOAEL

Effect level:

ca. 30 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No significant mortality occurred in the study. Exposure-related adverse clinical signs were absent. No significant change were observed in body weight, food consumption , food efficiency, hematology, gross pathology and histopathology.

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

CUMULATIVE NUMBER OF DEATHS

Concentration of the colour in diet	Sex	No.of rats	Time in week on test
			2	4	8	12	16	20	24	28	32	36	40	44
FD&C Red No. 32
control	M	20	0	2	3	4	5	7	10	11	11	12	13	13
	F	20	0	0	2	2	3	6	7	7	7	7	7	7
30 mg/kgbw/day	M	20	0	0	2	3	3	7	9	9	9	9	16	18
	F	20	0	0	1	1	5	5	6	6	6	6	8	9
75 mg/kgbw/day	M	20	2	3	4	11	15	15	15	16	17	19	20
	F	20	0	0	0	9	11	13	15	15	15	16	20
1500mg/kgbw/day	M	20	2	8	11	17	19	20
	F	20	0	2	10	18	19	20

Applicant's summary and conclusion

Conclusions:

NOAEL was considered to be 30mg/kg bw/day when male and female rats were exposed to FD&C Red No. 32 repeatedly by oral (feed).

Executive summary:

A study was designed to investigate the chronic repeated dose toxicity effects of FD&C Red No. 32in young male and female rats by an oral route for 44 weeks. The rats were exposed by oral feed for 44 week to the concentrations of 0, 30,75and 1500mg/kgbw/day.No mortality was observed at the dose level of 30mg/kg bw/day in treated group compared to control.Mortality was observed ,by the end of 20 weeks in all the treated rats on the dose level of 1500 mg/kg bw/day .Mortality was also observed ,by the end of 40 weeks in all the rats on the concentration of 75 mg/kg bw/day .No significant change were observed in clinical sign,body weight, food consumption , food efficiency, hematology, gross pathology and histopathology of male and female rats obserserved at the dose level of 30mg/kg bw/day in treated group compared to control. Therefore NOAEL was considered to be 30mg/kg bw/day for FD&C Red No. 32in male and female rats by an oral route for 44 weeks.