Registration Dossier

Toxicological information

Repeated dose toxicity: oral

Currently viewing:

Administrative data

Endpoint:
chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
29 Jan 2003 - 21 Oct 2005
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Cross-referenceopen allclose all
Reason / purpose for cross-reference:
reference to same study
Reason / purpose for cross-reference:
reference to other study
Reason / purpose for cross-reference:
other: reference to review article

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2006
Report date:
2006

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)
Version / remarks:
adopted in 1981
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method B.33 (Combined Chronic Toxicity / Carcinogenicity Test)
Version / remarks:
adopted in 1987
Qualifier:
according to guideline
Guideline:
other: EPA OPPTS 870.4300 (Combined Chronic Toxicity / Carcinogenicity)
Version / remarks:
adopted in 1998
Qualifier:
according to guideline
Guideline:
other: M.A.F.F. in Japan, notification 12 Nousan n°8147 guideline
Version / remarks:
adopted in 2000
GLP compliance:
yes (incl. QA statement)
Remarks:
Secrétariat du Groupe Interministeriel des Produits Chimiques, Paris, France
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
(5-hydroxy-1,3-dimethyl-1H-pyrazol-4-yl)[2-(methylsulfonyl)-4-(trifluoromethyl)phenyl]methanone
EC Number:
609-256-3
Cas Number:
365400-11-9
Molecular formula:
C14H13F3N2O4S
IUPAC Name:
(5-hydroxy-1,3-dimethyl-1H-pyrazol-4-yl)[2-(methylsulfonyl)-4-(trifluoromethyl)phenyl]methanone
Test material form:
solid: crystalline
Specific details on test material used for the study:
STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Homogeneity and stability of the test substance in the diet: analytically confirmed

Test animals

Species:
rat
Strain:
Wistar
Remarks:
Rj:WI (IOPS HAN)
Details on species / strain selection:
no data provided
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: R. Janvier (Le Genest St Isle, France)
- Age at study initiation: 7 weeks
- Weight at study initiation: mean group weights: 286 - 289 g (males), 193 - 196 g (females)
- Fasting period before study: no
- Housing: individually in suspended, stainless steel and wire mesh cages
- Diet: A04CP1-10 from S.A.F.E. (Scientific Animal Food and Engineering, Augy, France), ad libitum
- Water: filtered and softened tap water from the municipal water supply, ad libitum
- Acclimation period: 22 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24
- Humidity (%): 40 - 70
- Air changes (per hr): 10 to 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 29 Jan 2003 To: 05 Sep 2003

Administration / exposure

Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on oral exposure:
PREPARATION OF DIETARY MIXTURES:

DIET PREPARATION
- Rate of preparation of diet (frequency): The test substance formulations were prepared to cover the dietary requirements over 4-weekly periods.
- Mixing appropriate amounts with (Type of food): A04CP1-10 from S.A.F.E.
- Storage temperature of food: at ambient temperature

VEHICLE
- No vehicle was used
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The stability of the test substance in the diet has been demonstrated in a previous and recent 90-day rat study (M-102924-01-2). The stability of the test substance at 2 and 15000 ppm in the diet was verified for up to at least 82 days, when kept at ambient temperature, which covered the period of storage and usage in this study.

The homogeneity of the test substance in diet was verified from the first loads at 25, 250, 1000 and 2500 ppm on the first formulation (F1) and on the first loads at 25 and 2500 ppm of formulations F6, F12, F14, F20 and F26, to demonstrate adequate formulation procedures.
The concentration was checked for all loads at all dose levels for formulations F1, F2, F3, F6, F9, F12, F14, F17, F20, F23 and F26.

Results:
- Homogeneity Analysis: 82* - 115% of nominal concentration
- Concentration Analysis: 85 - 112% of nominal concentration
* 3/266 samples were slightly outside the in-house target range of 85 - 115% of nominal concentration. This minor deviation was not considered to have affected the integrity of the study.
Duration of treatment / exposure:
6 months
Frequency of treatment:
daily, 7 days a week
Doses / concentrationsopen allclose all
Dose / conc.:
25 ppm
Remarks:
equivalent to 1.4 and 1.8 mg/kg bw/day in males and females, respectively
Dose / conc.:
250 ppm
Remarks:
equivalent to 14 and 19 mg/kg bw/day in males and females, respectively
Dose / conc.:
1 000 ppm
Remarks:
equivalent to 58 and 77 mg/kg bw/day in males and females, respectively
Dose / conc.:
2 500 ppm
Remarks:
equivalent to 143 and 191 mg/kg bw/day in males and females, respectively
No. of animals per sex per dose:
10
Control animals:
yes, plain diet
Details on study design:
- Dose selection rationale: Dose levels were selected based on the results from a previous 90-day dietary study in the rat (M-102924-01-2) where dietary administration of up to 7000 ppm in males and 12000 ppm in females resulted in increased plasma cholesterol and triglycerides, increased liver and kidney weights, yellow calculi in the urinary tract, urothelial hyperplasia, centrilobular hepatocellular hypertrophy, and diffuse thyroid follicular cell hyperplasia. The NOAEL in the rat 90-day study was 30 ppm, with a LOAEL of 1000 ppm.

- Rationale for animal assignment (if not random): On the day of randomization, animals were allocated to dose groups using a computerized randomization procedure that ensured a similar body weight distribution among groups for each sex. Selected animals were in a weight range from
243 to 325 g for the males and 169 to 221 g for the females at the start of exposure to the test substance, i.e., within ±20% of the mean body weight on the day of randomization. Any animal deemed unsuitable for selection based on weight, ophthalmological abnormalities or health status was not used for the study.

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: animals were checked for moribundity and mortality twice daily (once daily on weekends or public holidays). Clinical signs were recorded at least once daily.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: detailed physical examinations including palpation for masses were performed weekly from study day 1.

BODY WEIGHT: Yes
- Time schedule for examinations: at least weekly during the acclimatization period then weekly for the first 13 weeks of study, approximately every 4 weeks thereafter and prior to necropsy.

FOOD CONSUMPTION AND COMPOUND INTAKE:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/animal/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes

FOOD EFFICIENCY:
- 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: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations:
all animals: during acclimatization (indirect ophthalmoscopy)
all surviving animals: after approximately 3 and 6 months (indirect ophthalmoscopy and slit lamp)
- Dose groups that were examined: all

HAEMATOLOGY: Yes
- Time schedule for collection of blood: blood analyses were performed on all surviving animals in weeks 28/29.
- Anaesthetic used for blood collection: Yes (isoflurane)
- Animals fasted: Yes
- Parameters examined: hematocrit, hemoglobin, leukocyte count, erythrocyte count, platelet count, prothrombin time, leukocyte differential count, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, mean corpuscular volume, reticulocyte count

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: blood analyses were performed on all surviving animals in weeks 28/29.
- Animals fasted: Yes
- Parameters examined: calcium, chloride, magnesium, inorganic phosphorus, potassium, sodium, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, gamma glutamyltransferase, albumin, creatinine, urea, total cholesterol, glucose, total bilirubin, total protein, triglycerides

URINALYSIS: Yes
- Time schedule and for collection of urine: prior to allocation of the animals to treatment groups, urinalysis was performed on thirty males and thirty females. Urinalysis was performed on all surviving animals in weeks 13/14 and 26/27/28.
- Metabolism cages used for collection of urine: not specified
- Animals fasted: Yes (diet and water)
- Parameters examined: appearance, volume, specific gravity/osmolality/refractive index, pH, sediment (microscopic), protein, glucose, ketones, bilirubin, blood/red blood cells, urobilinogen, creatinine

NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes
Necropsy included the examination of external surfaces, all orifices, all major organs, tissues and body cavities. All significant macroscopic abnormalities (including masses and their regional lymph nodes when possible) were recorded, sampled and examined microscopically.

ORGAN WEIGHTS: Yes (see Table 1)

HISTOPATHOLOGY: Yes (see Table 1)
Histopathology examinations were performed as follows:
- all organs and tissue samples from animals sacrificed or dying during the treatment period
- all organs and tissue samples from animals of control and high dose groups
- liver, lung, kidney, thyroid gland, urinary bladder, pancreas and eye from animals of the intermediate dose groups
- gross abnormalities from all animals
For all unscheduled sacrificed or dead animals on study, the cause of death was determined when it was possible.
Initial examinations were performed by the Principal Investigator in Histopathology. Following the initial examination, a review pathologist undertook an independent « peer-review » of representative slides and diagnoses according to standardized operating procedures. The diagnoses presented in this report represent the consensus opinion of the two pathologists.
Statistics:
See "Any other information on materials and methods incl. tables"

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Treatment-related clinical signs consisted of an increased incidence of white area on the eye at the three highest dose levels in both sexes. In addition, there was an increased incidence of soiled fur/soiling around the anogenital region at the two highest dose levels in both sexes (see Table 3).

The changes observed in the eye were considered to be as a consequence of the mode of action ofthe test substance, that in mammals inhibits a key enzyme involved in the catabolism of tyrosine and provokes a specific tyrosinaemia in the rat. The tyrosinemia and the resulting corneal lesions are not relevant to man.
Mortality:
mortality observed, treatment-related
Description (incidence):
The mortality rate at 2500 ppm in males was slightly higher than in the control group (4/75 deceased animals versus 1/75 in the control). The mortality rate in the remaining male treated groups was very low and similar to the control group. No deaths occurred in females.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
At 2500 and 1000 ppm, during the first week of treatment, mean body weight was reduced by 3% (p < 0.05) and 2%, respectively, in males, whilst mean cumulative body weight gain was reduced by 16% (p < 0.01) and 18% (p < 0.01), respectively, compared to controls (see Table 4). Thereafter, mean body weight gain was consistently lower than in controls by up to 56% and 60%, respectively, the effect being statistically significant on several occasions. At the end of the treatment period, mean body weight was reduced by 6% (p < 0.01) and 5% (p < 0.01), respectively, and mean cumulative body weight gain was reduced by 10% (p < 0.01) and 9% (p < 0.01), respectively, compared to controls. In females, there was no treatment-related effect on mean body weight, body weight gain and cumulative body weight gain. The few minor differences from controls which attained statistical significance were sporadic and were considered to be chance findings reflecting the number of comparisons made.
At 250 ppm, during the first week of treatment, mean body weight was reduced by 2% in males, whilst mean cumulative body weight gain was reduced by 14% (p < 0.01), compared to controls.Thereafter mean body weight, body weight gain and cumulative body weight gain were comparable to controls. The few minor differences reaching statistical significance were considered to reflect inter-individual variation rather than a treatment-related effect. In females, there was no treatment-related effect on mean body weight, body weight gain and cumulative body weight gain. The few minor differences from controls which attained statistical significance were sporadic and were considered to be chance findings reflecting the number of comparisons made.
At 25 ppm, there was no treatment-related effect on mean body weight, body weight gain and cumulative body weight gain in either sex over the first 6 months of treatment. The few minor differences from controls which attained statistical significance were sporadic and were considered to be chance findings reflecting the number of comparisons made.

There was no relevant change in terminal body weights of treated animals when compared to controls.
Food consumption and compound intake (if feeding study):
no effects observed
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
effects observed, treatment-related
Description (incidence and severity):
Treatment-related findings noted in weeks 23/24 consisted of corneal opacity, neovascularisation, oedema of the cornea, and "snow flake-like" corneal opacity at 2500 and 1000 ppm in both sexes and 250 ppm in males, as well as neovascularisation of the cornea and "snow flake-like" corneal opacity in females at 250 ppm.
Haematological findings:
no effects observed
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
In males, higher mean total cholesterol concentrations were observed at 2500, 1000 and 250 ppm. The higher values noted at 25 ppm after 7 months were within historical control data (2.02 ± 0.47), and as cholesterol concentration at 25 ppm returned to normal levels for the remainder of the study (12-month and carcinogenicity phase), this increase was considered not to be treatment-related.

In females at month 7, when compared to the controls, statistically significant differences were noted at 2500, 1000 and 250 ppm in total cholesterol and triglyceride concentrations. However in the absence of a clear dose-effect relationship and in view of the variation of the individual values, these changes were considered not to be relevant.
Urinalysis findings:
effects observed, treatment-related
Description (incidence and severity):
When compared to the control groups, a tendency towards higher ketone levels was observed at 2500 and 1000 ppm in both sexes.
Lower mean pH values were noted in males at 2500, 1000 and 250 ppm throughout the study. In females lower mean pH values were noted only in week 13/14, at 2500 ppm (-10%, p<0.01), 1000 ppm (-6%, p < 0.01) and 250 ppm (-6%, p < 0.01). Correlated with the lower mean pH values, lower amounts of crystals were generally observed in the urine. Additionally, when compared to the controls, a tendency towards higher protein levels was seen in males at week 26/28 at all dietary levels tested. In the absence of an adverse kidney histopathology these findings were considered not adverse.
Other statistically significant differences were considered not to be relevant in view of their sporadic occurrence and/or the absence of a clear dose-effect relationship.
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
In males only, mean liver weights were found to be statistically significantly increased at 2500, 1000 and 250 ppm (see Table 5) . These changes were correlated with histopathological changes and were thus regarded as treatment-related.
In males only, mean absolute and relative kidney weights were found statistically significantly higher at 2500 and at 1000 ppm (see Table 6). The change was not statistically significant at 250 ppm, but due to a dose-response, it was considered to be treatment-related at 2500, 1000 and 250 ppm.
Mean thyroid gland weights were found to be higher at 2500 ppm in both sexes and at 1000 and 250 ppm in males (see Table 7). At 2500 ppm in males, mean thyroid gland to body weight ratio was higher and statistically different when compared to controls and was considered to be treatment-related.
Other organ weight changes were considered to be incidental in origin.
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
a/ Unscheduled deaths
One control male rat was killed for humane reasons on day 156. A palpable mass on the right kidney corresponding to a tubular cell carcinoma was found at necropsy.
All others gross changes were considered to be incidental and not treatment-related.

b/ Terminal sacrifice:
Enlarged liver was observed in a proportion of male animals in all treated groups (3/10 males at 2500 ppm, 1/10 males at 1000 ppm, 4/10 males at 250 ppm, and 2/10 males at 25 ppm). Prominent lobulation was observed at a higher incidence in treated males than in controls. These findings were correlated with centrilobular hypertrophy and were considered to be treatment-related.
A higher incidence of eye opacity was found in treated animals at 2500 ppm and in treated males at 1000 and 250 ppm. This finding was correlated with relevant microscopic findings and was considered to be treatment-related.
All others gross changes were considered to be incidental and not treatment-related.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
a/ Unscheduled deaths
One control male was killed for humane reasons and a malignant tubular cell carcinoma of the kidney was found at microscopy.

b/ Terminal sacrifice:
Effects of treatment were seen in the eyes, liver and pancreas of both sexes and thyroid glands and kidneys of males.

In the eyes, unilateral or bilateral inflammation of the cornea with regenerative hyperplasia and neovascularisation were seen in both sexes treated at 2500 and 1000 ppm and males at 250 ppm.

In the liver, centrilobular hepatocellular hypertrophy was noted in both sexes at 2500, 1000 or 250 ppm and in males at 25 ppm. The incidence of centrilobular vacuolation was higher than controls in males at 2500, 1000 or 250 ppm. These were considered to reflect an adaptive response to treatment rather than an adverse effect.

In the thyroid gland, a higher incidence of altered basophilic colloid was noted in males at 2500, 1000 and 250 ppm when compared with controls. Increased follicular diameter and brown pigment in follicular cells was observed with a higher incidence in males at 2500 ppm. The alteration of colloid and brown (lipofuscin) pigmentation were considered not to be adverse findings since these findings were observed in the controls and reflect a normal age-related physiological process associated with the rapid turnover of colloid which is unique to the rat.

In the kidney, there was a marginally higher incidence and severity of chronic progressive nephropathy in males dosed at 2500 ppm in comparison with controls. This finding was considered having no relevance for extrapolation in human risk assessment, as chronic nephropathy has been described to be a rodent-specify entity.

In the pancreas, diffuse degeneration/atrophy of acinar tissue was recorded in 7/10 males and 8/10 females dosed at 2500 ppm, and 1/9 females dosed at 1000 ppm.

A variety of spontaneous changes was noted in control and treated animals with no indication of an effect of treatment. The spectrum of these findings is mainly consistent with changes commonly encountered in laboratory rats of this age kept under laboratory conditions.
Histopathological findings: neoplastic:
no effects observed
Description (incidence and severity):
The only tumor noted was a malignant tubular cell carcinoma of the kidney observed for a control animal.
Other effects:
not examined
Details on results:
Corneal opacities, occasionally accompanied by neovascularization and their histopathological correlates (keratitis, reactive epithelial hyperplasia, and vascularization) are considered a rat-specific phenomenon. Corneal changes were not seen in other species chronically treated with the test substance (i.e. mice and dogs). The test substance is an inhibitor of the HPPDase enzyme and induces increased plasma tyrosine levels. This effect is more pronounced in rats than in mice and dogs. Experimentally induced hypertyrosinemia has been shown to induce snow flake-like corneal lesions in rats but not in mice (M-210983-01-2). In mice and humans, even under conditions of strong HPPD inhibition, tyrosine concentrations will not increase to levels high enough to induce ocular toxicity and hence, this toxicity observed in the rat is inappropriate for extrapolation to humans (ECETOC TR No. 99).

Thyroid findings (increased weight, histopathological changes comprising changes in colloid, follicular cell hypertrophy and pigment deposition in the follicular epithelium) are considered a non-adverse and rat specific phenomenon. No changes of the thyroid were noted in either mice or dogs, the other two species in which repeated-dose studies with histopathological examination of the thyroid were conducted with the test substance. As the test substance through inhibition of the HPPDase enzyme increases plasma tyrosine concentration in the rat, it is quite possible that some of this increased tyrosine is taken up by the thyroid and stored in the colloid, either as free tyrosine or through either increasing the synthesis of thyroglobulin or altering its composition in terms of number of tyrosine residues per thyroglobulin molecule.
In the absence of signs of altered thyroid functions (such as effects on body weights, fertility and gestation indices or effects on offspring performance in the developmental neurotoxicity study), the observed morphological changes are considered to be non-adverse.

Effect levels

open allclose all
Key result
Dose descriptor:
NOAEL
Effect level:
25 ppm
Based on:
test mat.
Remarks:
equivalent to 1.4 and 1.8 mg/kg bw/day in males and females, respectively
Sex:
male/female
Basis for effect level:
other: no adverse effects observed at 25 ppm
Key result
Dose descriptor:
LOAEL
Effect level:
250 ppm
Based on:
test mat.
Remarks:
equivalent to 14 and 19 mg/kg bw/day in males and females, respectively
Sex:
male/female
Basis for effect level:
other: At 250 ppm, mortality, clinical signs, reduced body weight gain as well as changes in clinical biochemistry and urinalysis were noted.

Target system / organ toxicity

open allclose all
Key result
Critical effects observed:
yes
Lowest effective dose / conc.:
1 000 ppm
System:
gastrointestinal tract
Organ:
pancreas
Treatment related:
yes
Dose response relationship:
yes
Critical effects observed:
yes
Lowest effective dose / conc.:
250 ppm
System:
eye
Organ:
cornea
Treatment related:
yes
Dose response relationship:
yes
Relevant for humans:
no
Critical effects observed:
yes
Lowest effective dose / conc.:
250 ppm
System:
endocrine system
Organ:
thyroid gland
Treatment related:
yes
Dose response relationship:
yes
Relevant for humans:
no
Critical effects observed:
yes
Lowest effective dose / conc.:
2 500 ppm
System:
urinary
Organ:
kidney
Treatment related:
yes
Dose response relationship:
yes
Relevant for humans:
no

Any other information on results incl. tables

Table 2: Mean achieved test item intake per group

Mean achieved test item intake (mg/kg bw/day)

Sex

Males

Females

Dose levels
(ppm)

25

250

1000

2500

25

250

1000

2500

Weeks 1 - 13

1.4

14

58

143

1.8

19

77

191

Weeks 1 - 52

1.1

11

45

114

1.5

15

63

155

Table 3: Treatment-related clinical signs

Incidence of treatment-related clinical signs after 6 months of treatment (first day of appearance)

Sex

Male

Female

Dose level (ppm)

0

25

250

1000

2500

0

25

250

1000

2500

Group size

75

75

75

75

75

75

75

75

75

75

White area on eye

0

1
(40)

38
(13)

41
(13)

48
(6)

0

1
(14)

5
(69)

36
(41)

52
(27)

Soiled fur generalized

0

0

2
(138)

4
(138)

13
(131)

0

0

2
(159)

4
(159)

19
(159)

Soiled fur localized

0

0

0

0

6
(34)0

0

0

0

1
(167)

1
(167)

Soiled anogenital region

0

0

0

1
(68)

2
(111)

0

0

1
(104)

1
(139)

25
(35)

Table 4: Mean body weights and cumulative body weight gains (BWG)

Group mean body weights (BW) and cumulative body weight gains (BWG) (g)

Dose level (ppm)

0

25

250

1000

2500

Males

 

 

 

 

 

Initial BW (Day 1) (%C)

287

287
(100)

288
(100)

289

(101)

286

(100)

BW Week 1 (Day 8) (%C)

336

336

(100)

330

(98)

329

(98)

327*

(97)

BW Week 13 (Day 92) (%C)

548

565

(103)

539

(98)

526*

(96)

529

(97)

BW Week 25 (Day 176) (%C)

632

645

(102)

624

(99)

602**

(95)

597**

(94)

BWG Week 1 (Days 1 to 8) (%C)

49

50

(102)

42**

(86)

40**

(82)

41**

(84)

BWG Weeks 1-13 (Days 1 to 92) (%C)

261

279*

(107)

252

(97)

237**

(91)

243*

(93)

BWG Weeks 14-25 (Days 92 to 176) (%C)

83

76

(92)

86

(104)

77

(93)

70**

(84)

 

 

 

 

 

 

Females

 

 

 

 

 

Initial BW (Day 1) (%C)

196

193

(98)

193

(98)

194

(99)

193

(100)

BW Week 1 (Day 8) (%C)

214

216

(101)

212

(99)

210

(98)

209

(98)

BW Week 13 (Day 92) (%C)

297

302

(102)

300

(101)

296

(100)

299

(101)

BW Week 25 (Day 176) (%C)

320

328

(103)

330

(103)

327

(102)

331

(103)

BWG Week 1 (Days 1 to 8) (%C)

17

22**

(129)

20

(118)

17

(100)

16

(94)

BWG Weeks 1-13 (Days 1 to 92) (%C)

102

109**

(107)

107

(105)

102

(100)

105

(103)

BWG Weeks 14-25 (Days 92 to 176) (%C)

22

26

(118)

30**

(136)

31**

(141)

33**

(150)

C = control

* Statistically different (p < 0.05) from the control.

** Statistically different (p < 0.01) from the control.

Table 5: Liver weight changes at terminal sacrifice (% change when compared to controls)

 

Males

Females

Dose levels (ppm)

0

25

250

1000

2500

0

25

250

1000

2500

Mean absolute liver weight

11.87

-

13.04

(+10%)

14.49

(+22%)

**

14.03

(+18%)

*

14.84

(+25%)

**

6.93

-

6.89

(-1%)

7.27

(+5%)

7.49

(+8%)

7.26

(+5%)

Mean liver to body weight ratio

1.980

-

2.113

(+7%)

2.425

(+22%)

**

2.426

(+23%)

**

2.551

(+29%)

**

2.192

-

2.253

(+3%)

2.221

(+1%)

2.521

(+15%)

**

2.332

(+6%)

Mean liver to brain weight ratio

538.464

591.628

(+10%)

661.226

(+23%)

**

643.721

(+20%)

**

682.721

(+27%)

**

327.992

333.997

(+2%)

360.662

(+10%)

368.255

(+12%)

364.330

(+11%)

** p < 0.01;* p < 0.05

 

Table 6: Kidney weight changes at terminal sacrifice (% change when compared to controls)

 

Males

Females

Dose levels (ppm)

0

25

250

1000

2500

0

25

250

1000

2500

Mean absolute kidney weight

2.92

-

3.14

(+8%)

3.36

(+15%)

3.56

(+22%)

**

4.10

(+40%)

**

1.94

-

1.97

(+2%)

1.96

(+1%)

2.01

(+4%)

2.01

(+4%)

Mean kidney to body weight ratio

0.494

-

0.509

(+3%)

0.564

(+14%)

0.628

(+27%)

**

0.713

(+44%)

**

0.614

-

0.644

(+5%)

0.600

(-2%)

0.676

(+10%)

0.648

(+6%)

Mean kidney to brain weight ratio

133.429

-

142.407

(+7%)

153.455

(+15%)

164.600

(+23%)

**

189.624

(+42%)

**

91.868

-

95.463

(+4%)

97.291

(+6%)

98.807

(+8%)

101.050

(+10%)

** p < 0.01

Table 7: Thyroid gland weight changes at terminal sacrifice (% change when compared to controls)

Sex

Males

Females

Dose levels (ppm)

0

25

250

1000

2500

0

25

250

1000

2500

Mean absolute thyroid gland weight

0.0219

-

0.0231

(+5%)

0.0246

(+12%)

0.0269

(+23%)

0.0284

(+30%)

0.0167

-

0.0152

(-9%)

0.0155

(-7%)

0.0142

(-15%)

0.0184

(+10%)

Mean thyroid gland to body weight ratio

0.0036

-

0.00376

(+2%)

0.00411

(+12%)

0.00462

(+26%)

0.00488

(+33%)

*

0.00526

-

0.00493

(-6%)

0.00472

(-10%)

0.00474

(-10%)

0.00597

(+13%)

Mean thyroid gland to brain weight ratio

0.99454

-

1.05167

(+6%)

1.11564

(+12%)

1.23055

(+24%)

1.30330

(+31%)

0.78660

-

0.73471

(-7%)

0.76980

(-2%)

0.69975

(-11%)

0.9233E (+17%)

*: p < 0.05

Applicant's summary and conclusion