N-(2-chloroethyl)-4-[(2,6-dichloro-4-nitrophenyl)azo]-N-ethyl-m-toluidine

Endpoint summary

Description of key information

Based on the results of combined 28-day repeated dose toxicity study with the reproduction/developmental toxicity screening test, the following No Observed Adverse Effect Levels (NOAELs) of DISPERSE BROWN 27 were established:

Parental NOAEL: 150 mg/kg, based on changes in several haematology parameters and spleen at 500 mg/kg in females (The treatment related changes observed in the thyroid hormones were excluded in determining the NOAEL).

Reproduction NOAEL: at least 500 mg/kg.

Developmental NOAEL: 150 mg/kg, based on decreased body weight gain in male and female pups at 500 mg/kg (The treatment related changes observed in the thyroid hormones were excluded in determining the NOAEL).

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

repeated dose toxicity: oral, other

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28 days

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Deviations:

yes

Remarks:

None of the deviations were considered to have impacted the overall integrity of the study or the interpretation of the study results and conclusions.

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

None of the deviations were considered to have impacted the overall integrity of the study or the interpretation of the study results and conclusions.

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

None of the deviations were considered to have impacted the overall integrity of the study or the interpretation of the study results and conclusions.

GLP compliance:

yes

Limit test:

yes

Specific details on test material used for the study:

The batch of Disperse Brown 27 (4852-1501) tested was a brown powder with a purity of 99.7 %

Species:

rat

Strain:

Wistar

Details on species / strain selection:

The Wistar Han rat was chosen as the animal model for this study as it is an accepted rodent species for toxicity testing by regulatory agencies. Charles River Den Bosch has general and reproduction/developmental historical data in this species from the same strain and source. This animal model has been proven to be susceptible to the effects of reproductive toxicants.

Sex:

male/female

Details on test animals or test system and environmental conditions:

At initiation of dosing, males were 10 weeks old and weighed between 256 and 293 g and females were 13 weeks old and weighed between 193 and 214 g.
A health inspection was performed before the initiation of dosing.
The total number of animals used in this study was considered to be the minimum required to properly characterize the effects of the test item. This study has been designed such that it does not require an unnecessary number of animals to accomplish its objectives.
At this time, studies in laboratory animals provide the best available basis for extrapolation to humans and are required to support regulatory submissions. Acceptable models which do not use live animals currently do not exist.
This type of study plan was reviewed and agreed by the Laboratory Animal Welfare Officer and the Ethical Committee of Charles River Den Bosch as required by the Dutch Act on Animal Experimentation (February 1997).

The animals were allowed to acclimate to the Test Facility toxicology accommodation for 8 days prior to start of the pre-test period (females) or 8 days before the commencement of dosing (males).

A total of 40 females was selected at randomization before initiation of the pre-test phase. Any selected female without a regular estrous cycle at the end of the pre-test phase was replaced by one of the 8 additional females having regular estrous cycles. A total of 40 females with regular estrous cycles continued in the study. The supernumerary females were removed from the study and their estrous cycle results were kept in the raw data but were not reported.
Animals were assigned to groups by a computer-generated random algorithm according to body weights, with all animals within ± 20% of the sex mean. Males and females were randomized separately.

Prior to start of the pre-test period (females) or treatment period (males), each animal was identified using earmark and tattoo. Prior to the pre-test period, reserve females were numbered R1 through R8 at random by indelible marker. Any reserve female replacing an allocated female prior to treatment received identification by earmark and tattoo.
Pups were identified on postnatal day (PND) 1. They were randomized per litter and individually identified by means of subcutaneous injection of Indian ink. When general hair growth blurred the identification, the pups were identified by tattoo on the feet.

Route of administration:

oral: gavage

Details on route of administration:

The oral route of administration was selected because this is a possible route of human exposure during manufacture, handling or use of the test item.

Vehicle:

propylene glycol

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

A dose control system (DCS) was used as additional check to verify the dosing procedure according to Standard Operating Procedures.

Duration of treatment / exposure:

The test item and vehicle were administered to the appropriate animals by once daily oral gavage 7 days a week for a minimum of 28 days. Males were treated for 29 days, up to and including the day before scheduled necropsy. This included two weeks prior to mating, during the mating and post-mating.

Frequency of treatment:

Dose administered every day

Dose / conc.:

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

Remarks:

Dose Concentration (mg/mL): 0

Dose / conc.:

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

Remarks:

Dose Concentration (mg/mL): 10

Dose / conc.:

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

Remarks:

Dose Concentration (mg/mL): 30

Dose / conc.:

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

Remarks:

Dose Concentration (mg/mL): 100

No. of animals per sex per dose:

10 females and 10 males per dose

Control animals:

yes, concurrent vehicle

Details on study design:

The dose levels in this study were selected to be 0, 50, 150 and 500 mg/kg/day, based on the results of a 10-day dose range finder in which dose limiting effectswere observed at 1000 mg/kg (No mortality observed at 1000 mg/kg).

Based on the results of this dose range finder, dose levels selected for the main study were 50, 150 and 500 mg/kg.
Since no clear peak effect of occurrence of clinical signs was observed in the dose range finder, clinical observations (clinical signs and arena) were conducted and functional observations were started in the main study shortly after dosing at no specific time point, but within a similar time period after dosing for the respective animals.

Observations and examinations performed and frequency:

mortality/ moribundity, clinical signs, functional observations (5 selected animals/sex/group), body weight, food consumption, estrous cycle length and regularity, clinical pathology (5 selected animals/sex/group), serum level of thyroid hormone T4 (F0-males), gross necropsy findings, organ weights and histopathologic examinations.

Other examinations:

mating and fertility indices, precoital time, number of implantation sites, gestation index and duration, parturition, maternal care, sex ratio and early postnatal pup development (mortality, clinical signs, body weight, anogenital distance, areola/nipple retention, serum level of thyroid hormone T4 (PND 13-15 pups) and macroscopy).

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Red discoloration of the faeces occurred at 500 m/kg in all animals from Day 7 onwards, Orange discoloration of the tail was noted at 150 mg/kg (in all males and four females, starting on Day 19) and 500 mg/kg (in all animals, starting on Day 11). Incidentally, a few treated animals showed brown discoloration of the mouth. This discoloration was considered to reflect the color of the test item (a brown powder). Piloerection was noted in four females treated at 500 mg/kg on Days 9 and 10.
Salivation seen after dosing among animals treated with the test item, in a dose-related manner, was considered to be a physiological response rather than a sign of systemic toxicity considering its slight severity and the time of occurrence (i.e. shortly after dosing). No additional clinical signs were noted during the weekly arena observations. Any other clinical signs noted incidentally occurred within the range of background findings to be expected for rats of this age and strain which are housed and treated under the conditions in this study and showed no dose-related trend. At the incidence observed, these were considered to be unrelated to treatment.

Mortality:

no mortality observed

Description (incidence):

No mortality occurred during the study period among animals treated with the test item. One female of the control group (no. 45) died after blood sampling on the day of scheduled necropsy. Aspiration of blood, as evidenced by the presence of alveolar blood at marked degree, with correlating dark red discoloration of the lungs recorded at necropsy was probably the cause of death for this animal.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Males treated at 500 mg/kg showed reduced body weight gain (statistically significant) throughout the treatment period, resulting in statistically significantly reduced mean body weights at Days 8 and 15 of the mating period (5% difference from control). In females at 500 mg/kg, body weight gain was reduced during the pre-mating phase (reaching statistical significance at Day 1 of the mating period) and gestation (statistically significant at Days 7-14 post-coitum). During lactation, body weight gain of 500 mg/kg females tended to be higher (not statistically significant) than that of controls. Mean body weights of 500 mg/kg females were slightly lower (up to 6%) compared to controls, but statistical significance was reached only at Day 13 of the lactation. No treatment-related changes in body weights or body weight gain were noted in rats treated up to 150 mg/kg. An incidental, statistically significant difference noted in 50 mg/kg females (lower weight gain at Day 7 post-coitum) was considered unrelated to treatment due to the lack of a dose-related trend.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Food consumption (before and after allowance for body weight) was reduced at 500 mg/kg in females during the first week of gestation. The differences from controls (about 10-15%) were generally statistically significant. In addition, lower food consumption (before and after allowance for body weight) was noted during the first week of the pre-mating period for the 500 mg/kg females housed in one of the cages.
No treatment-related changes in food consumption were noted in males up to 500 mg/kg and in females up to 150 mg/kg. The statistically significantly lower relative food consumption noted in 150 mg/kg females between Days 0-4 post-coitum was considered an incidental finding as similar differences were not observed at later time points. In addition, a large amount of crumbled feed pellets was observed at the bottom of the cage of female no.43 in the afternoon of Day 4 of lactation. As a result, the value for food consumption over days 4-76 of lactation for this animal was affected and excluded from interpretation. Since this food spillage was a one-time event in a control animal, no importance was attached to this finding.

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

The following changes in haematology parameters parameters (red and white blood cell parameters, number of platelets) distinguished treated animals from control animals. The differences were statistically significant unless indicated otherwise. Relative changes in mean values (or fold change) compared to the control group are indicated between parentheses.

• Lower number of red blood cells in females at 150 and 500 mg/kg (8 and 14%, respectively). In males, the number of red blood cells tended to be lower (6%) at 500 mg/kg but statistical significance was not achieved.
• Lower haemoglobin concentration in females at 150 and 500 mg/kg (6% at both dose levels). In males, haemoglobin concentration tended to be lower (4%) at 500 mg/kg but statistical significance was not achieved.
• Higher number of reticulocytes in females at 150 and 500 mg/kg (1.5x and 1.9x of control, respectively) and in males at 500 mg/kg (1.5x of control).
• Higher mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH) in females at 500 mg/kg (14 and 9%, respectively).
• Lower (4%) mean corpuscular haemoglobin concentration (MCHC) in females at 500 mg/kg.

The statistically significant difference in MCHC (4% lower) noted in females at 50 mg/kg was considered to be unrelated to treatment due to the lack of a clear dose-related trend and corroborating changes in other red blood cell parameters.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

The following statistically significant changes distinguished treated animals from control animals. Relative changes in mean values (or fold change) compared to the control group are indicated between parentheses.

• Higher (1.8x of control) mean plasma activity of alanine aminotransferase (ALAT) in females at 500 mg/kg.
• Higher total bilirubin concentration in females at 150 and 500 mg/kg (1.5x and 2.0x of control, respectively).
• Higher (16%) potassium concentration in females at 500 mg/kg. The other statistically significant differences noted in treated animals were considered unrelated to treatment as they occurred in the absence of a dose-related trend and all group mean values were within the normal background range for rats of the same strain an age.

Male and female PND 13-15 pups at 50 and 150 mg/kg showed statistically significantly higher serum total T4 levels than pups of the control group (about 1.7x and 1.5x of control, respectively). Mean total T4 levels at 500 mg/kg were about 1.2x higher than controls (not statistically significant). It might by argued that these differences were unrelated to treatment because their magnitude decreased with increasing dose levels of the test item. However, the differences at 50 and 150 mg/kg exceeded normal background variation3. Moreover, differences were consistent across sexes.
The serum TSH levels in male and female PND 13-15 pups were considered not affected by treatment. A relatively large variation of the individual TSH values was observed within some of the treated dose groups, i.e. female pups at 50 mg/kg and male and female pups at 500 mg/kg. However, a correlation with the changes in total T4 levels individual PND 13-15 male and female pups was not observed. The results of total T4 and TSH in F1-male

Thyroid hormone analyses:
Increased levels of total T4 in were observed F0-male and female rats at all dose levels. The results and the percentages of increase relative to controls are presented in the text table below:
Males Females

Dose level (mg/kg): Cont 50 150 500 Cont 50 150 500
Total T4 4.67 6.16 5.64 6.17 4.17 5.70 6.56 6.88
% Total T4 increase 32 21 32 37 57** 65**
( relative to cont)
**: P<0.01

Whereas in treated males, the increase in level of total T4 varied between 21%-32% and a dose response relationship was not apparent, a dose related increase was observed in treated females, starting at a 37% increase in the 50 mg/kg dose group and achieving levels of statistical significance for the 57% in the 150 mg/kg and 68% in the 500 mg/kg dose group.

Urinalysis findings:

not examined

Behaviour (functional findings):

effects observed, non-treatment-related

Description (incidence and severity):

Hearing ability, pupillary reflex and static righting reflex were normal in all examined animals. Grip strength was not affected by treatment. The variation in motor activity did not indicate a relation with treatment. All groups showed a similar habituation profile with a decreasing trend in activity over the duration of the test
period. In the absence of a dose-related response and statistical significance, the intergroup differences noted in females (about 40% lower mean values for total movements and ambulations at 50 and 500 mg/kg) were considered to be unrelated to treatment. All mean values were within the normal range for rats of the same strain and age1.

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Statistically significant, test item-related higher weights of the spleen, liver and kidneys were noted at 500 mg/kg.

• Spleen: Higher absolute and relative weights at 500 mg/kg in both sexes (statistically significant except for the absolute weight in females). Mean spleen weights were also higher in females at 150 mg/kg but not statistically significantly.
• Liver: Higher relative weight (statistically significant) at 500 mg/kg in males.
• Kidneys: Higher relative weight (statistically significant) at 500 mg/kg in males.

No further changes in organ weights were noted. The statistically significantly higher thyroid weight (absolute and relative to body weight) in males at 150 mg/kg was considered unrelated to treatment due to the absence of a dose-related trend.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Test item-related macroscopic findings consisted of orange discoloration of the adipose tissue of all animals treated with the test item, and orange discoloration of the skin of the tail of all males at 150 and 500 mg/kg and of 6/10 females at 500 mg/kg. There was no microscopic correlate for this discoloration, the orange color disappeared during histology processing. The remainder of the recorded macroscopic findings were within the range of background gross observations encountered in rats of this age and strain. These findings were therefore considered to be unrelated to treatment.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Test item-related microscopic findings were noted in the spleen of both sexes and in the thyroid gland, liver and kidneys of males.

Test item-related findings in the spleen consisted of:
• An increased incidence and severity of extramedullary hematopoiesis in males at 500 mg/kg (minimal-slight) and in females at 150 and 500 mg/kg (minimal-moderate).
• An increased incidence and severity of pigmentation in males at 500 mg/kg and in females at 150 and 500 mg/kg (minimal-slight).

The minimal severities recorded for these findings in the remaining dose groups were considered within background pathology for rats of this age and strain.

An increased incidence of minimal follicular cell hypertrophy was noted in the thyroid gland of males at 500 mg/kg, accompanied by a minor increase in incidence and severity (up to
slight degree) of colloid alteration. There were no test item related microscopic alterations in the thyroid gland of the F1-pups.

Centrilobular hepatocellular hypertrophy (at a minimal degree) was noted in the liver of 2/5 males at 500 mg/kg.

An increased incidence and severity of hyaline droplet accumulation was present in the kidneys of males at 50, 150 and 500 mg/kg (minimal-moderate). The remainder of the recorded microscopic findings were within the range of background pathology encountered in rats of this age and strain. There was no test item-related alteration in the prevalence, severity, or histologic character of those incidental tissue alterations.

Reproductive performance
Two couples had no offspring: 1/10 couples at 50 mg/kg (female/male no. 53/13) and 1/10 couples at 500 mg/kg (female/male no. 71/31). The females of these couples were not
pregnant despite evidence of mating. One female at 150 mg/kg (no. 64, mated with male no. 24) had total litter loss at Day 3 of lactation. Male no. 31 (500 mg/kg) showed moderate tubular atrophy with germ cell degeneration in the testes and reduced luminal sperm with luminal cell debris in the epididymides which accounted for the lack of offspring. This animal showed degenerative spermatogenic stages. As this can be seen as a background finding in testes of rats of this age and strain and was
recorded in only a single male, this was considered to be an incidental finding unrelated to treatment. For the two other couples, no abnormalities were seen in the reproductive organs and mammary gland which could account for their lack of offspring or total litter loss. There were no morphological findings in the reproductive organs of either sex which could be attributed to the test item, and stage aware evaluation of the testes did not show any indication for abnormal spermatogenesis.

Histopathological findings: neoplastic:

not examined

Key result

Dose descriptor:

NOAEL

Remarks:

Parental

Effect level:

> 150 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

haematology

Remarks on result:

other:

Remarks:

No specific organ was targeted

Key result

Dose descriptor:

NOAEL

Remarks:

Reproduction

Effect level:

>= 500 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No reproduction toxicity was observed up to the highest dose level tested (500 mg/kg).

Remarks on result:

other:

Remarks:

No specific organ was targeted

Key result

Dose descriptor:

NOAEL

Remarks:

Developmental

Effect level:

>= 150 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

Remarks on result:

other:

Remarks:

No specific organ was targeted

Critical effects observed:

no

System:

other: No specific organ was targeted

Organ:

other: No specific organ was targeted

Conclusions:

based on the results of this combined 28-day repeated dose toxicity study with the reproduction/developmental toxicity screening test, the following No Observed Adverse Effect Levels (NOAELs) of DISPERSE BROWN 27 were established:
Parental NOAEL: 150 mg/kg, based on changes in several haematology parameters and spleen at 500 mg/kg in females (The treatment related changes observed in the thyroid hormones were excluded in determining the NOAEL).
Reproduction NOAEL: at least 500 mg/kg.
Developmental NOAEL: 150 mg/kg, based on decreased body weight gain in male and female pups at 500 mg/kg (The treatment related changes observed in the thyroid hormones were excluded in determining the NOAEL).

Executive summary:

Wistar Han rats were treated with DISPERSE BROWN 27 by daily oral gavage at dose levelsof 50, 150 and 500 mg/kg (10 rats/sex/dose level). Concurrent controls (10 rats/sex) received the vehicle, propylene glycol, alone. Males were treated for two weeks prior to mating, during mating, and up to termination (for 29 days). Females that delivered offspring were treated for two weeks prior to mating, during mating, during post-coitum, and 13-15 days of lactation (mostly for 50 -56 days). Females without healthy offspring were treated for 43 or 46 days.

Formulation analysis showed that the dosing formulations were prepared accurately and homogenously, and confirmed stability upon storage for at least 5 hours at room temperature under normal laboratory light conditions. Accuracy, homogeneity and stability of dosing formulations were demonstrated by analyses.

Parental results: Treated rats showed red discoloration of the faeces (at 500 mg/kg) and orange discoloration of the skin of the tail (starting at 150 mg/kg) and of adipose tissue (at all dose levels). This discoloration likely represented the test item (a brown powder) and/or test item metabolite(s). In the absence of correlating microscopic alterations, this discoloration was regarded as nonadverse. Slight salivation was noted after dosing at all dose levels (in a dose-related manner), and was considered to be a physiological response to administration of the test item. Piloerection was incidentally seen at 500 mg/kg in females, but considered not to be toxicologically relevant based on its temporary presence. Reduced body weight gain was observed at 500 mg/kg in males throughout the treatment period and in females during the pre-mating phase and gestation. The resulting reductions in mean body weights did not exceed 6% in comparison with the concurrent controls. These small changes in body weight (gain) were considered to be non-adverse.

Females treated at 150 or 500 mg/kg showed changes (generally dose-dependent) in several haematology parameters, including reductions in the number of red blood cells and haemoglobin concentration and increases in the number of reticulocytes, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and plasma concentration of total bilirubin. Associated findings in the spleen at these dose levels consisted of an increased incidence and severity of extramedullary haematopoiesis (a compensatory response) and pigmentation (mostly at minimal or slight degree), and a related increase in spleen weight. There were no clinical signs indicative of hypoxia, and mean red blood cell and haemoglobin values of treated males and females remained in the normal range. The increases in plasma bilirubin and pigment in the spleen are suggestive of increased destruction of red blood cells.

The combination of effects in the red blood cells and spleen in 500 mg/kg females was considered to be adverse. The red blood cell effects in 150 mg/kg females were less severe and, therefore, regarded as non-adverse. For the same reason, the red blood cell related effects noted in 500 mg/kg males (increases in number of reticulocytes and splenic extramedullary haematopoiesis and pigmentation, tendency to lower number of red blood cells and haemoglobin concentration) were considered non-adverse. Male rats showed an increased incidence and severity (up to moderate degree) of hyaline droplet accumulation (likely representing alpha2u-globulin, a male rat specific protein) in the kidneys starting at 50 mg/kg (with correlating increased relative renal weight at 500 mg/kg). In the absence of indicators of renal tubular damage, this renal change was regarded as nonadverse.

Centrilobular hepatocellular hypertrophy (at minimal degree) was observed in a few males at 500 mg/kg (with correlating increased relative liver weight). In the absence of any degenerative or inflammatory changes, these treatment-related hepatic findings were considered to be non-adverse.

Increased levels of total T4 in were observed F0-male and female rats at all dose levels.

Whereas in treated males, the increases in level of total T4 varied between 21%-32% and a dose response relationship was not apparent, the increases in level of total T4 in treated females were 37%, 57% and 68% in the 37% increase for the 50 mg/kg, 150 mg/kg and 500 mg/kg dose groups respectively, in comparison with controls. No corroborating morphological changes were observed in the thyroid gland in males and females. The slight increased incidence of follicular cell hypertrophy and colloid alteration observed in the thyroid gland in males at 500 mg/kg showed no dose relationship and, also based on the incidence and severity, these changes were considered to be non-adverse. Any conclusion on the adversity of the changes in total T4 could not be evaluated from the results obtained in this study.

Minor changes in clinical biochemistry parameters at 500 mg/kg in females (higher mean plasma levels of alanine aminotransferase and potassium) were considered non-adverse as they remained within normal limits and occurred without corroborating changes in other endpoints.

Reproductive results: No reproduction toxicity was observed up to the highest dose level tested (500 mg/kg).

Developmental results: Body weight gain of male and female pups was reduced at 500 mg/kg, resulting in 11% (males) – 14% (females) lower mean body weights at PND 13. At birth, pup body weights showed no treatment-related changes.

Treatment-related, statistically significantly higher mean serum T4 levels (exceeding the historical control range) were noted at 50 and 150 mg/kg in male and female PND 13-15 pups (about 1.7x and 1.5x of control, respectively). Mean T4 levels at 500 mg/kg were about 1.2x higher compared to controls (not statistically significant and within normal limits). The TSH levels seemed not to be affected and no histopathological changes were observed in the thyroid glands in these pups up to treatment at 500 mg/kg. From these results, it was concluded that the increase levels of total T4 in plasma did not resulted in a (inhibitory) feedback regulation on TSH, which was supported by the absence of histopathological changes in the thyroid glands. Therefore, any conclusion on the adversity of the changes in total T4 could not be evaluated from the results obtained in this study.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

150 mg/kg bw/day

Study duration:

subacute

Species:

rat