Reddish Blue

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

16 September 2009 to 25 October 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Compliant to OECD 407 and GLP guideline

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2011

Report date:

2011

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.7 (Repeated Dose (28 Days) Toxicity (Oral))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Details on test material:

Name: Reddish Blue

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

Species and strain: CRL: (WI) BR rats
Source: TOXI COOP Ltd., Cserkesz u. 90. 1103 Budapest, Hungary
Hygienic level: SPF at arrival; standard laboratory conditions during the study
Justification of strain: Wistar rat as a rodent is one of the standard strains for repeat-dose toxicity studies
Number of animals: 35 male and 35 female rats
5 rats/sex/group, 4 Main groups (Groups 1 to 4);
5 rats/sex/group, 2 Recovery groups (Groups 1 and 4)
5 rats/sex/group, 1 Positive control group (Group 5)
Age of animals: Young adult rats, 7-8 weeks old at onset of treatment
Body weight: The weight variation did not exceed +/- 20 percent of the mean weight/sex at onset of treatment with the test item; 289-349 g males, 194-247 g females
Acclimation period: 14 days


Animal health: Only healthy animals were used for the test, as certified by the veterinarian. Females were nulliparous and non-pregnant.
Cage type: Type III. polypropylene/polycarbonate
Bedding: Lignocel® Hygienic Animal Bedding produced by J. Rettenmaier & Söhne GmbH+Co.KG, D-73494 Rosenberg Holzmühle 1 Germany, and Laboratory Animal Bedding produced by Brandenburg Holzfaserstoffe Gmbh& Co.KG, Arkeburger Str. 31, 49424 Goldenstedt, Germany.
Light: 12 hours daily, from 6.00 a.m. to 6.00 p.m.
Temperature: 20.8 – 24.9°C
Relative humidity: 32%-69%
Ventilation: 15-20 air exchanges/hour
Housing/Enrichment: Rodents were group-housed (up to 5 animals/sex/cage), to allow social interaction, and with deep wood sawdust bedding, to allow digging and other normal rodent activities.

The temperature and relative humidity were recorded twice daily; no deviations from the intended range occurred during the study.


Animals received ssniff® SM R/M-Z+H "Autoclavable complete feed for rats and mice – breeding and maintenance" produced by ssniff Spezialdiäten GmbH, D-59494 Soest Germany ad libitum, and tap water from municipal supply, as for human consumption from 500 ml bottle ad libitum.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

polyethylene glycol

Details on oral exposure:

The test item was formulated in the vehicle (1:1 PEG 400 and Sterile Distilled Water mixture) at 7.81, 31.25 and 125 mg/mL in the Central Dispensary of CiToxLAB Hungary Ltd. Formulations were prepared at the appropriate frequency for use within 72 hours as documented in the raw data, while stored refrigerated, according to stability assessment results.

The dose volume administered was 8 mL/kg.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analysis of formulations (concentration, homogeneity) and assessment of test item stability in this vehicle under the conditions employed in the study was performed in the Analytical Laboratory of CiToxLAB Hungary Ltd.

Concentration and homogeneity of formulations were evaluated by UV-HPLC method on duplicate samples collected from the top, middle and bottom of test item solutions, and one sample from the control taken and analyzed fresh during the first and last weeks of treatment. Dose formulations were homogenous. The measured (actual) concentrations varied between 102% and 106% of the nominal concentrations. No test item was detected in the control solution samples.

Duration of treatment / exposure:

28 days

Frequency of treatment:

daily

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
7.81, 31.25 and 125 mg/mL
Basis:
other: nominal in vehicle

Doses / concentrations 2

Remarks:

Doses / Concentrations:
62.5, 250, and 1000 mg/kg/day
Basis:
other: nominal and analytical

No. of animals per sex per dose:

Groups 1 to 4: 5 animals/sex/main group
Groups 1 and 4: 5 animals/sex/recovery group
Group 5: 5 animals/sex positive control for MNT

Control animals:

yes, concurrent vehicle

Details on study design:

Rationale for dose-selection: Acute oral toxicity testing of Reddish Blue at a dose level of 2000 mg/kg in the rat did not result in any signs of test item-related toxicity. The median lethal dose level (LD50) was above 2000 mg/kg for oral administration in the female rat. Based on these results and due to experience with similar compounds, dose levels of 62.5, 250, and 1000 mg/kg/day were selected for use in the study.

During the acclimation period, the animals were assigned to their respective dose groups by randomization based on body weights. Animals were randomly allocated to the control and dose groups based on the most recent actual body weight. SPSS/PC+ software was used in order to verify homogeneity/variation among/within groups. Males and females were randomized separately.

The dosing solutions were administered daily for 28 days by oral gavage, using a bulb tipped gastric gavage needle attached to a syringe. The first day of treatment was regarded as Day 0. The oral route of administration was selected because it is the most likely route for possible human exposure. A constant volume of 8 mL/kg body weight was administered to all test-item treated and the vehicle/control rats.

The positive control rats (Group 5) for the Mammalian Erythrocyte Micronucleus Test were administered Cyclophosphamide by oral gavage, at a dose level of 30 mg/kg bw on Day 27, at 10 mL/kg, 3 mg/mL, approximately 24 hours prior to scheduled necropsy on Day 28.

The actual volume administered was calculated and adjusted based on each animal’s most recent body weight.

Positive control:

Ten Wistar rats (5 male and 5 female), Group 5, served as the positive control group for the Mammalian Erythrocyte Micronucleus Test (MNT). They were treated with 30 mg/kg bw/day Cyclophosphamide by oral gavage (dose volume, 10 mL/kg, concentration, 3 mg/mL) on Day 27, approximately 24 hours prior to scheduled necropsy on Day 28.

Examinations

Observations and examinations performed and frequency:

Clinical Observations and Functional Observation Battery
Animals were inspected for signs of morbidity and mortality twice daily (at the beginning and end of each working day). General clinical observations were made once a day, after the treatment at approximately the same time, and daily during the recovery period. Detailed clinical observations were made on all animals outside the home cage in a standard arena, once prior to the first exposure and once weekly thereafter. Observation was performed on the skin, fur, eyes and mucous membranes, autonomic activity (lachrymation, piloerection, pupil size, respiratory pattern, occurrence of secretions and excretions), circulatory and central nervous system, somatomotor activity and behaviour pattern, changes in gait, posture and response to handling. Special attention was directed towards the observation of tremors, convulsions, salivation, diarrhoea, lethargy, sleep and coma.
Sensory reactivity to different type of stimuli (e.g. auditory, visual and proprioceptive), assessment of grip strength and motor activity were conducted on all animals towards the end of treatment period on Day 26. General physical condition and behaviour of animals were tested. A modified Irwin test was performed. A detailed assessment of any potentially treatment-related neurotoxic effects was made on the basis of these measurements.


Oestrus cycle evaluation
Prior to necropsy, vaginal smears were taken from all females, stained with 1% aqueous methylene blue solution and examined with a light microscope, in order to provide information regarding the stage of oestrus cycle at the time of sacrifice and assist in histological evaluation of oestrogen sensitive tissues.

Body weight measurement
Individual body weight was recorded with precision of 1 g at randomization (Day 7), on the first day of treatment (Day 0), then at least weekly and prior to necropsy (fasted for scheduled necropsy).


Food consumption measurement
Animal food consumption was determined by re-weighing the non-consumed diet with a precision of 1 g on Day 0 (pre-treatment, start on Day -7) then at least weekly. The weekly and mean daily food consumption was calculated.


CLINICAL PATHOLOGY
Blood samples for clinical pathology evaluation (haematology, coagulation, and clinical biochemistry) were collected immediately prior to the scheduled necropsy, by heart puncture under pentobarbital anaesthesia. After an overnight period of food deprivation of animals, three samples were taken from each animal: one for haematology (1.2 mL blood; tube contained K3-EDTA as anticoagulant, 1.6 mg/mL blood), one for determination of blood clotting times (1.2 mL blood; APTT and PT; tube contained sodium citrate as anticoagulant) and the third one to obtain serum samples (at least 2.4 mL blood as practical, in a tube with no anticoagulant) for clinical chemistry.

Haematology and Blood Clotting Times
The following parameters were evaluated in all animals:
Red Blood Cell (erythrocyte) count, White Blood Cell (leukocyte) count, Haemoglobin concentration, Haematocrit, Mean Corpuscular (erythrocyte) Volume, Mean Corpuscular (erythrocyte) Haemoglobin, Mean Corpuscular (erythrocyte) Haemoglobin Concentration, Red Cell (erythrocyte) volume (%) Distribution Width, Platelet (thrombocyte) count, Mean Platelet Thrombocyte volume, Reticulocyte count, Neutrophil, Lymphocyte, Monocyte, Basophil, Eosinophil, Large Unstained Cells, Partial Thromboplastin Time, Prothrombin Time,


Clinical chemistry
The following parameters were evaluated in all animals:
Glucose Blood sugar concentration, T-BIL Total Bilirubin concentration, Urea Urea concentration, Chol. Cholesterol concentration, Creat. Creatinine concentration, Phos. Phosphorus concentration, Sodium concentration, Potassium concentration, Calcium concentration, Chloride concentration, Total Protein concentration, Albumin concentration, Alb/glob ratio, Aspartate Aminotransferase activity, Alanine Aminotransferase activity, Alkaline. Phosphatase – activity, Gamma Glutamyltransferase -activity, Bile acids

Sacrifice and pathology:

Terminal procedures
Following blood sample collection for clinical pathology evaluation, necropsy and macroscopic examination was performed on every Main Study or Recovery animal euthanized at the end of the treatment or recovery periods, with the exception of positive control Group 5 animals (Mammalian Erythrocyte Micronucleus Test in Bone Marrow Cells), for which bone marrow was collected from the right femur immediately after euthanasia, after which the carcasses were discarded without further examination. Surviving animals were euthanized by exsanguination under pentobarbital anaesthesia.

Macroscopic examination
After exsanguination the external appearance was examined, cranium, thoracic and abdominal cavities were opened and the appearance of the tissues and organs was observed macroscopically.
Any abnormality was recorded with details of the location, colour, shape and size, as appropriate.

On completion of the macroscopic examination and organ weight measurements according to OECD 407 were evaluated.

Organ weight measurement
The following organs were weighed and recorded: with precision of 0.01 g, liver, kidneys, testes, epididymides, uterus, including cervix, prostate, seminal vesicle with coagulating glands as a whole, thymus, spleen, brain and heart; with precision of 0.001 g, ovaries, adrenals.
Paired organs were weighed together. Absolute organ weights were measured, and relative organ weights to the body and brain weights were calculated and are reported.

Histopathology
Full histopathology was performed in Group 1 (Control) and Group 4 (High Dose), main and recovery animals and on all organs and tissues with macroscopic findings. Representative tissue samples were embedded into paraffin and slides were prepared, then stained with haematoxylin-eosin/phloxine and examined with light microscope. As no microscopic findings recorded in High Dose animals were considered potentially treatment-related, no further histology examination was performed on other tissues or organs from the lower dose levels.

Statistics:

Data were collected using the software PROVANTIS v.7 or recorded on the appropriate forms from the relevant SOPs of LAB Research Ltd., then tabulated using the software PROVANTIS v.7, Microsoft Office Word and/or Excel, as appropriate.

Numerical data obtained during the conduct of the study were subjected as appropriate to calculation of group means and standard deviations. The statistical analysis was performed using SPSS PC+4.0 software. The heterogeneity of variance between groups was checked by Bartlett's homogeneity of variance test. Where no significant heterogeneity was detected, a one-way analysis of variance was carried out. If the obtained result was positive, Duncan's Multiple Range test was used to assess the significance of inter-group differences. Where significant heterogeneity was found, the normal distribution of data was examined by Kolmogorov-Smirnov test. If the data was not normal distributed, the non-parametric method of Kruskal-Wallis One-Way analysis of variance was used. If there was a positive result, the inter-group comparisons were performed using Mann-Whitney U-test. The frequency of clinical observations and necropsy and histopathology findings was calculated as applicable.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food efficiency:

no effects observed

Ophthalmological findings:

no effects observed

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

no effects observed

Behaviour (functional findings):

no effects observed

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Details on results:

CLINICAL SIGNS AND MORTALITY
No adverse effects

Black discoloration of the faeces was noted at all the dose levels tested from Day 1 (1000 and 250 mg/kg bw/day) or Day 2 (62.5 mg/kg bw/day) onwards. The discoloration of the faeces persisted in the 1000 mg/kg bw/day recovery animals for 2 days after the last dose administration (on Days 28 and 29); thereafter no test item-related effects were noted until completion of the 14-day recovery period. In addition, grey urine was noted during the treatment period at 250 and 1000 mg/kg bw/day after Day 1 up to and including Day 28. These changes were ascribed to elimination of Reddish Blue or its metabolites through faeces and/or urine (cage side observations) and an expected staining effect.

HAEMATOLOGY
1000 mg/kg bw/day:
Lower red blood cell count (RBC), haemoglobin concentration (HGB) and mean corpuscular (erythrocyte) haemoglobin concentration (MCHC)
Higher mean corpuscular (erythrocyte) volume (MCV), red cell (erythrocyte) volume (RDW), platelet (PLT) and reticulocyte count (Retic.)

ORGAN WEIGHTS
Statistically higher spleen and lower testes and epididymides mean absolute and relative weights were noted at 1000 mg/kg bw/day.

GROSS PATHOLOGY
Bilaterally small testes and/or epididymides were observed in 4/5 High Dose males and spleen enlargement was recorded in 4/5 High Dose males and 4/5 High Dose females.

HISTOPATHOLOGY: NON-NEOPLASTIC
Bilateral diffuse mild tubular atrophy/degeneration in the testes and bilateral mild to moderate reduction of the sperm content accompanied with ductal cell debris and apoptotic bodies in the epididymides were noted in High Dose male rats.
Extramedullary haematopoiesis of the spleen was observed with minimal severity in 9/10 Control and mild severity in 10/10 High Dose Main rats. Although this finding could be a common background change in the young animals, the higher severity of extramedullary haematopoiesis in the spleen observed in High Dose animals compared to controls (mild versus minimal) was considered to be potentially related to the treatment with Reddish Blue. In addition, from the Mid dose 250 mg/kg bw/day group, 6/10 animals showed minimal severity and 4/10 mild severity of extramedullary haematopoiesis of the spleen.

Effect levels

1

Dose descriptor:

NOEL

Effect level:

62.5 mg/kg bw/day (actual dose received)

Based on:

act. ingr.

Sex:

male/female

Basis for effect level:

other: see 'Remark'

2

Dose descriptor:

NOAEL

Effect level:

250 mg/kg bw/day (actual dose received)

Based on:

act. ingr.

Sex:

male/female

Basis for effect level:

other: see effects in NOEL: at 250 mg/kg bw, the effects on hematology were questionable; increase in the severity of extramedullary haematopoiesis in the spleen was minimally and did not affect the animals adversely.

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Reddish Blue administered daily by oral gavage for 28 days in Wistar rats did not result in mortality, clinical signs, changes in body weight, food consumption, coagulation parameters, clinical chemistry parameters or oestrus cycle at dose levels of 62.5, 250, or 1000 mg/kg bw/day during either the treatment or 14-day recovery/observation periods.

Haematological changes considered related to treatment and suggesting a regenerative anaemia were observed in the 1000 mg/kg bw/day animals and possibly at the 250 mg/kg bw/day at the end of the treatment period although the findings were not present following the 14 day recovery period.

Macroscopic changes including small testes and/or epididymides and spleen enlargement were observed at 1000 mg/kg bw/day and correlated with the organ weight and microscopic changes. The microscopic changes in the testes consisted in bilateral diffuse mild tubular atrophy/degeneration in the testes and bilateral mild to moderate reduction of the sperm content accompanied with ductal cell debris and apoptotic bodies in the epididymides. These changes were also noted in animals following the recovery period, however with a slightly reduced severity in recovery animals, indicating a possible tendency to recover after cessation of the treatment. In the spleen, a slight increase in the severity of extramedullary haematopoiesis was noted at 1000 and 250 mg/kg bw/day and was considered correlated with the spleen response to the slight regenerative anaemia in these animals. Recovery animals showed no such effects.

In conclusion, under the conditions of this study, the no observed effect level (NOEL) for Reddish Blue is considered to be 62.5 mg/kg bw/day the no observed adverse effect level (NOAEL) is considered to be 250 mg/kg bw/day.

Executive summary:

The toxicity of Reddish Blue when administered daily for 28 days by oral gavage to CRL:(WI)BR rats was investigated. The reversibility of any treatment-related changes was evaluated following a 14-day recovery period. In addition, the test item was evaluated for genotoxic effects by evaluating the induction of micronuclei in bone marrow erythrocytes of treated and control animals.

 

Reddish Blue, the vehicle or cyclophosphamide were administered to seventy Wistar rats (20 male and 20 female Main animals, 10 male and 10 female Recovery animals, and 5 male and 5 female positive control animals)according to the following experimental design:

 

Group No.		Group Designation	Dose Level (mg/kg/day)		Conc. (mg/mL)	Dose volume (mL/kg)	Number of Animals
							Main			Recovery
							Male		Female	Male		Female
1		Control	0		0	8	5		5	5		5
2		Low Dose	62.5		7.81		5		5	-		-
3		Mid Dose	250		31.25		5		5	-		-
4		High Dose	1000		125		5		5	5		5
Mammalian Erythrocyte Micronucleus Test Positive Control Group Animals*
Group			Cyclophosphamide					Male			Female
No	Designation		(mg/kg/day)	(mg/mL)		(mL/kg)
5	Positive Control		30	3		10		5			5

*administered approximately 24 hours prior to scheduled necropsy

 

Main animals underwent necropsy on Day 28 (start of treatment, Day 0), after 28 days of treatment. Recovery animals were treated for 28 consecutive days and were euthanized and subjected to necropsy after a 14-day recovery period. Control animals received the vehicle item solution only (1:1 PEG 400 and Sterile Distilled Water mixture), at the same volume as the high dose animals. No correction for purity ofReddish Bluewas applied.

 

Ten Wistar rats (5 male and 5 female), Group 5, served as the positive control group for the Mammalian Erythrocyte Micronucleus Test (MNT). They were treated with 30 mg/kg bw/day Cyclophosphamide by oral gavage (dose volume, 10 mL/kg, concentration, 3 mg/mL) on Day 27, approximately 24 hours prior to scheduled necropsy on Day 28.

 

Parameters measured during the study includedsigns of morbidity and mortality twice daily,observation of clinical signs, performed daily (general, cage side observations, after the dose administration), or weekly (detailed observations), a modified Irwin test conducted on Day 26, weekly determination of body weight and food consumption. Prior to necropsy, the oestrus cycle of all females was evaluated by examination of vaginal smears. In addition, blood was collected prior to terminal necropsy, for clinical pathology (haematology, coagulation and clinical chemistry) assessment. At termination, necropsy with macroscopic examination was performed. Weights of selected organs were recorded and representative tissues/organs were sampled and preserved in appropriate fixatives. 

 

Histopathology evaluation was conducted on tissues and organs retained in fixative and processed to slides from the control and high dose animals (1000 mg/kg bw/day), on all organs with macroscopic findings from the low and mid dose groups (62.5 and 250 mg/kg bw/day, respectively), on all testes and epididymides from the mid dose 250 mg/kg bw/day malesand on all spleens from the 62.5 and 250 mg/kg bw/day male and female animals.

 

Analysis of formulations (concentration, homogeneity) and assessment of test item stability in this vehicle in the conditions employed on the study was performed in the Analytical Laboratory of CiToxLAB Hungary Ltd. 

 

Stability tests (CiToxLAB study code 09/128-316AN) at concentrations from approximately 1 to 125 mg/mL in the vehicle(1:1 PEG 400 and Sterile Distilled Water mixture)indicated an up to 24 hour stability at room temperature. In addition, under refrigerated conditions (5±3°C), the solutions were stable for up to 72 hours, with a recovery of 98% and 103%, at 1 and 125 mg/mL, respectively (acceptance range: 100% ± 10%). Concentration and homogeneity of formulations were evaluated by UV-HPLC method on duplicate samples collected from the top, middle and bottom of test item solutions, and one sample from the control taken and analyzed fresh during the first and last weeks of treatment. Dose formulations were homogenous. The measured (actual) concentrations varied between 102% and 106% of the nominal concentrations.No test item was detected in the control solution samples.These results were considered suitable for the study purposes.  

 

Following 28-days of treatment with Reddish Blue at dose levels up to and including 1000 mg/kg bw/day, no test item related mortality or systemic adverse effects were noted in CRL:(WI)BR rats. Black discoloration of the faeces was noted at all the dose levels tested from Day 1 (1000 and 250 mg/kg bw/day dose level, males and females) or Day 2 onwards (62.5 mg/kg bw/day dose level, males and females). The discoloration of the faeces persisted in the 1000 mg/kg bw/day recovery animals for 2 days after the last dose administration (on Days 28 and 29); thereafter no test item-related effects were noted until completion of the 14-day recovery period. In addition, grey urine was noted during the treatment period at 250 and 1000 mg/kg bw/day between Days 1 and 28. These changes were ascribed to elimination of Reddish Blue or its metabolites through faeces and/or urine (cage side observations) and an expected staining effect. 

The behaviour and general condition of the animals were normal during the study. There was no treatment-related effect on motor activity or in the functional observation battery tests across groups of treated male or female animals and no findings indicative of neurotoxicity were observed. 

Evaluation of the vaginal smears prior to necropsy showed the expected distribution of the oestrus cycle phases within the normal population of female Wistar rats. 

There were no toxicologically significant changes in body weight, body weight gain or animal food consumption between the control and test item treated groups. 

There were no changes that could be ascribed to Reddish Blue administration noted in coagulation or clinical chemistry parameters.

Haematological changes including statistically lower red blood cell count, haemoglobin concentration and mean corpuscular (erythrocyte) haemoglobin concentration and statistically higher mean corpuscular (erythrocyte) volume, red cell (erythrocyte) volume, platelet and reticulocyte count mean values were observed in the 1000 mg/kg bw/day males and females and were considered related to treatment, suggesting a regenerative anaemia, possibly with a similar trend at the 250 mg/kg bw/day at the end of the treatment period. No test item related effects were observed after 14 days recovery. 

 

On macroscopic evaluation, small testes and/or epididymides were observed at 1000 mg/kg bw/day, noted in 4/5and 5/5 Recovery males. In addition, spleen enlargement was observed in 8/10 Main animals at 1000 mg/kg bw/day, but not in Recovery animals. These findings were considered related to test item administration and correlated with the organ weight and microscopic changes.

 

On histological examination of testes, tubular atrophy/degeneration and reduction of the sperm content combined with presence of ductal cell debris and apoptotic bodies in the epididymides was observed in all 1000 mg/kg bw/day males, with a slightly reduced severity in recovery animals. At additional histopathological examination of the testes and epididymides from all 250 mg/kg bw/day males, no test item-related changes were noted in these organs.

 

Slightly increased severity of extramedullary haematopoiesis in the spleen with an apparent dose response, associated with haematological and/or organ weight changes, was observed in 1000 mg/kg bw/day and 250 mg/kg bw/day rats when compared to controls (mild versus minimal). The effects observed in the spleen were considered to reflect an adaptive response to the slight regenerative anaemia noted in these animals and be potentially ascribed to the test item administration. At additional histopathological examination of the spleen from all 62.5 mg/kg bw/day animals, no test item-related changes were noted. In Recovery rats, extramedullary haematopoiesis in high-dose animals had a lower incidence than in control-group rats (9/10 Control and 6/10 High Dose Recovery rats) with minimal severity, similar to controls, indicating complete reversibility after 14 days of recovery.

 

No induction of micronuclei in bone marrow erythrocytes was observed, thus, there was no evidence of any genotoxic activity of the test item.

 

In summary, Reddish Blue administered daily by oral gavage for 28 days in Wistar rats did not result in mortality, clinical signs, changes in body weight, food consumption, coagulation parameters, clinical chemistry parameters or oestrus cycle at dose levels of 62.5, 250, or 1000 mg/kg bw/day during either the treatment or 14-day recovery/observation periods.

 

Haematological changes considered related to treatment and suggesting a regenerative anaemia were observed in the 1000 mg/kg bw/day animals and possibly at the 250 mg/kg bw/day at the end of the treatment period although the findings were not present following the 14 day recovery period. 

  

Macroscopic changes including small testes and/or epididymides and spleen enlargement were observed at 1000 mg/kg bw/day and correlated with the organ weight and microscopic changes. The microscopic changes in the testes consisted in bilateral diffuse mild tubular atrophy/degeneration in the testes and bilateral mild to moderate reduction of the sperm content accompanied with ductal cell debris and apoptotic bodies in the epididymides. These changes were also noted in animals following the recovery period, however with a slightly reduced severity in recovery animals, indicating a possible tendency to recover after cessation of the treatment. In the spleen, a slight increase in the severity of extramedullary haematopoiesis was noted at 1000 and 250 mg/kg bw/day and was considered correlated with the spleen response to the slight regenerative anaemia in these animals. Recovery animals showed no such effects.

 

No induction of micronuclei in bone marrow erythrocytes was observed.

 

In conclusion, under the conditions of this study, the no observed effect level (NOEL) for Reddish Blue is considered to be 62.5 mg/kg bw/day the no observed adverse effect level (NOAEL) is considered to be 250 mg/kg bw/day.