Morpholine, 4-C12-14-alkyl derivs.

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12 March 2015 - 29 July 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study has been performed according to OECD/EC guidelines and GLP principles.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Version / remarks:

(May 2008)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.26 (Sub-Chronic Oral Toxicity Test: Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Version / remarks:

(September 1998)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.3100 (90-Day Oral Toxicity in Rodents)

Version / remarks:

(August 2009)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

dated 6 May 2013

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Morpholine, 4-C12-14-alkyl derivs.

EC Number:

800-906-3

Cas Number:

1402434-48-3

Molecular formula:

Not applicable

IUPAC Name:

Morpholine, 4-C12-14-alkyl derivs.

Test material form:

other: liquid

Details on test material:

- Name of test material (as cited in study report): C12-14-alkylmorpholine
- Substance type: Organic
- Physical state: light yellow liquid
- Storage condition of test material: At room temperature
- Specific gravity/ density: Approximately 0.87 at 25°C

Test animals

Species:

rat

Strain:

other: Crl:WI(Han)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany
- Age at study initiation: Approximately 6 weeks
- Weight at study initiation: 139-174g (males), 117-138g (females) (main study), 126-142g (dose range finding study)
- Fasting period before study: Animals were only deprived of food overnight (with a maximum of 24 hours) prior to scheduled necropsy
- Housing: Group housing of 5 animals per sex in Macrolon cages (MIV type, height 18 cm), except during locomotor activity monitoring, when animals were housed individually in a Hi-temp polycarbonate cage (for dose range finding study: 3 rats/cage)
- Diet: Pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiäten GmbH, Soest, Germany), ad libitum (except during locomotor activity monitoring, when no food was available and overnight before sacrifice (maximum 24 hours))
- Water: tap water, ad libitum (except during locomotor activity monitoring, when no water was available)
- Acclimation period: At least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19.4 - 22.2
- Humidity (%): 44 - 87
- Air changes (per hr): at least 10
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 12 March 2015 To: 29 July 2015

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
Formulations (w/w) were prepared daily within 6 hours prior to dosing, and were homogenized to visually acceptable levels (stored at room temperature). Adjustment was made for specific gravity of the test substance (0.87) and vehicle (0.92). No correction was made for the purity/composition of the test substance. Formulations were placed on a magnetic stirrer during dosing.

VEHICLE
- Justification for use and choice of vehicle (if other than water): Based on trial formulations performed at WIL Research Europe and on information from the Sponsor.
- Amount of vehicle: 5mL/ kg bw (actual dose volumes were calculated weekly according to the latest body weight)

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Accuracy, homogeneity and stability were determined for formulations prepared for in week 1, week 6 and week 13. Duplicate samples (approximately 500 mg), which were taken from the formulations using a pipette, were accurately weighed into volumetric flasks of 20 or 50 ml. For determination of accuracy, samples
were taken at middle position (50% height) or at top, middle and bottom position (90%, 50% and 10% height). The samples taken at 90%, 50% and 10% height were also used for the determination of the homogeneity of the formulations. For determination of stability, additional samples were taken at 50% height and stored at room temperature under normal laboratory light conditions for 6 hours. The volumetric flasks were filled up to the mark and extracted with methanol. The shaking time was 15 seconds. The extracts were further diluted to obtain an end solution of methanol and concentrations within the calibration range. Analyses were conducted according to a validated method (WIL Research project 508440).

The accuracy of preparation was considered acceptable if the mean measured concentrations are 90-110% of the target concentration for solutions, or 85-115% for suspensions. Homogeneity was demonstrated if the coefficient of variation is ≤ 10%. Formulations were considered stable if the relative difference before and after storage is maximally 10%.

Duration of treatment / exposure:

at least 90 days

Frequency of treatment:

Once daily

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0, 30, 100 and 300 mg/kg bw (main study)
Basis:
actual ingested

Doses / concentrations 2

Remarks:

Doses / Concentrations:
300 and 600 mg/kg bw/day (dose range finding study)
Basis:
actual ingested

No. of animals per sex per dose:

10 (main study);
3 females (dose range finding study)

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dose levels were based on a 14-day range finding study (for details see below)

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: At least twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: At least once daily after dosing from start of treatment onwards. Once prior to start of treatment and at weekly intervals, this was also performed outside the home cage in a standard arena.

FUNCTIONAL OBSERVATIONS:
During week 12 of treatment, the following tests were performed on the first 5 animals/sex/group after dosing at no specific time point, but within a similar time period after dosing for the respective animals:
- hearing ability, pupillary reflex (L/R), static righting reflex;
- fore- and hind-limb grip strength (recorded as the mean of three measurements);
- locomotor activity (recording period: 1 hour under normal laboratory light conditions, using a computerized monitoring system, total movements and ambulations are reported).

BODY WEIGHT: Yes
- Weekly

FOOD CONSUMPTION :
- Weekly

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: Yes

WATER CONSUMPTION
- Subjective appraisal was maintained during the study, but no quantitative investigation introduced as no effect was suspected.

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: at pretest and week 13
- Dose groups that were examined: all

HAEMATOLOGY: Yes
- Time schedule for collection of blood: At the end of the treatment
- Anaesthetic used for blood collection: Yes (isoflurane)
- Animals fasted: Yes, animals were deprived of food overnight (for a maximum of 24 hours), but water was available.
- How many animals: all animals


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: At the end of the treatment
- Anaesthetic used for blood collection: Yes (isoflurane)
- Animals fasted: Yes, animals were deprived of food overnight (for a maximum of 24 hours), but water was available.
- How many animals: all animals

URINALYSIS: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
All animals were necropsied and descriptions of all macroscopic abnormalities were recorded.

HISTOPATHOLOGY: Yes
The following slides were examined by a pathologist:
- all tissues collected at the scheduled sacrifice from all control and high dose animals,
- lung, stomach, duodenum, jejunum (including Peyer’s patches if detectable), ileum (including Peyer’s patches if detectable), caecum, colon, rectum and mesenteric lymph node of all animals of low and mid dose groups (males and females), based on (possible) treatment-related changes in these organs in high dose group rats,
- kidneys and prostate gland of all males of low and mid dose groups, based on (possible) treatment-related changes in these organs in high dose group animals,
- thyroid glands of all females of low and mid dose groups, based on (possible) treatment-related changes in this organ in high dose group animals,
- all gross lesions.

Statistics:

The following statistical methods were used to analyze the data:
- If the variables could be assumed to follow a normal distribution, the Dunnett-test (many-to-one t-test) based on a pooled variance estimate was applied for the comparison of the treated groups and the control groups for each sex.
- The Steel-test (many-to-one rank test) was applied if the data could not be assumed to follow a normal distribution.
- The Fisher Exact-test was applied to frequency data.
- The Kruskal-Wallis nonparametric ANOVA test was applied to motor activity data to determine intergroup differences.
All tests were two-sided and in all cases p < 0.05 was accepted as the lowest level of significance. Group means were calculated for continuous data and medians were calculated for discrete data (scores). Test statistics were calculated on the basis of exact values for means and pooled variances. Individual values, means and standard deviations may have been rounded off. Therefore, two groups may display the same printed means for a given parameter, yet display different test statistics values.

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Food efficiency:

effects observed, treatment-related

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

no effects observed

Ophthalmological findings:

no effects observed

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

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

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
No mortality occurred during the study period. All animals treated at 300 mg/kg bw/day showed hunched posture and slight piloerection from week 8 onwards (and incidentally in week 2 (one male) and weeks 4-5 (three females)). Salivation was noted after dosing in all treated groups. The incidence, severity and time of onset indicated a dose-related response and was considered to be a physiological response related to the irritant properties of the test substance. In addition, several males and females at 300 mg/kg bw/day had focal erythema, scabs and/or scales at their mouth for several days or weeks during the study. Other clinical signs (alopecia, scabs, scales (neck, back, flank or cheek), a wound in the neck, and swelling and focal erythema of one ear) occurred within the range of background findings to be expected for rats of this age and strain and, at the incidence observed, these were considered to be unrelated to treatment. The weekly arena observations did not reveal any clinical signs in addition to those noted at the daily observations.

FUNCTIONAL OBSERVATIONS
Hearing ability, pupillary reflex, static righting reflex and grip strength were not affected by treatment. Motor activity data showed a similar habituation profile for all groups with high activity in the first interval that decreased over the duration of the test period. The mean values for total movements were lower in females at 30 and 300 mg/kg bw/day than in controls (not statistically significantly different from controls). In absence of a dose-related response this was not considered treatment related.

BODY WEIGHT AND WEIGHT GAIN
Males treated at 300 mg/kg bw/day gained less body weight than controls from initiation of treatment. The differences from the control group were statistically significant from day 8 onwards. Mean body weight gain of males at 300 mg/kg bw/day were statistically significantly lower from day 22. The difference from controls gradually increased in the course of the study (relative difference mean body weight on day 91: 16%). The mean body weights in males treated at 100 mg/kg bw/day were slightly lower than those in controls after about four weeks of treatment. The differences were small (relative differences day 36- 91: 5-7%), not statistically significant and not accompanied by statistically significant changes in body weight gain. Therefore, the slightly lower mean body weights in males at 100 mg/kg bw/day were considered not to be toxicologically relevant. An isolated, statistically significant difference in mean body weight gain noted on day 8 in males at 30 mg/kg bw/day was not considered to be related to treatment. Body weights and body weight gain of treated females remained in the same range as controls over the study period.

FOOD CONSUMPTION
In males food consumption before correction for body weight was similar between treated and control animals. Food consumption after correction for body weight was higher in males treated at 300 mg/kg bw/day than in controls from week 2 onwards. In females higher food consumption values (before and after correction for body weight) were noted at 300 mg/kg from week 2 onwards.

OPHTHALMOSCOPIC EXAMINATION
No ophthalmology findings were noted that were considered to be related to treatment.

HAEMATOLOGY
Absolute and differential neutrophil counts were increased in males at 100 and 300 mg/kg bw/day with respectively 20% and 60% (absolute, only statistically significant at 300 mg/kg bw/day) and with respectively 57.3% and 69.7% (differential count,both statistically significant)). Females showed the same reaction, with statistically significant increase in absolute neutrophil count at 300 mg/kg bw (with 150%), and in differential neutrophil count (with respectively 56.5% and 10.8% at 100 and 300 mg/kg bw/ day). This effect was most likely related to local inflammatory responses (see below). The differential lymphocyte count was statistically significantly decreased in males and females in these groups (with respectively -8.9% and -10.6% at 100 and 300 mg/kg bw/day in males and with respectively -6.3% and -11.8% at 100 and 300 mg/kg bw/day in females). Furthermore, absolute and differential monocyte count was statistically significantly increased at 300 mg/kg bw/day (with 50% in males and 61.5% in females (relative values)). In females, white blood cell count was affected (-30.2%, -20.8% and +13.2% for respectively 30, 100 and 300 mg/kg bw/day, statistically significant only at 30 mg/kg bw/day). Further statistically significant effects in females were increased reticulocytes at 300 mg/kg bw/day (+25%, absolute) and increased activated partial thromboplastin time at 300 mg/kg bw/day in females and increased prothrombin time in males at 100 mg/kg bw/day. As the higher percentage of reticulocytes was not accompanied by changes in other red blood cell parameters and the values were in the normal range for rats of this strain and age, these findings were considered not to be toxicologically relevant.
Further findings in males that were statistically different from the control group were increased mean corpuscular haemoglobin values at 30 and 100 mg/kg bw/day (respectively -1.3% and -0.9%) and prothrombin time at 100 mg/kg bw/day (-7.8%). In absence of dose-relationship of these responses and in consideration of the minor severity, these effects were not found to be adverse.

CLINICAL CHEMISTRY
At 300 mg/kg bw/day, in males statistically significant effects included increased aspartate aminotransferase levels (27.6%, in females also an increase of 9.9% was found, but this was not statistically significant), decreased total protein levels (-4.5%) and albumin (-3.2%). Furthermore, glucose levels were statistically significantly decreased at all dose levels (with respectively -16.3%, -16.8% and -20.4%). In females, urea concentration was statistically significantly increased at 300 mg/kg bw/day (20.6%). In males, statistically significant effects on ionic balance were seen: at 100 mg/kg bw/day a slight increase in sodium level was detected, chloride levels were elevated at 100 and 300 mg/kg bw/day and calcium was decreased at 300 mg/kg bw/day. Calcium decrease was also seen in females at highest dose. These changes in clinical chemistry were considered to be of no toxicological significance in the absence of a treatment-related distribution, as most values remained within the range of historical data for rats of this age and strain, as control values were rather high and/or no corroborative changes in other endpoints examined in this study.

ORGAN WEIGHTS
Absolute liver weights of treated males decreased related to dose (with respectively -4.6%, -6.8% and -12.5% for 30, 100 and 300 mg/kg bw/day, only statistically significant for highest dose). Absolute thyroid weights were decreased for male rats at 300 mg/kg bw/day (with -17.6%, statistically significant). Absolute prostate weight was decreased at 300 mg/kg bw/day (with -25.2%, statistically significant). None of these effects in males were also seen for relative organ weights, therefore these observations were not found to be toxicologically relevant. Relative kidney weights were statistically significantly increased in males dosed at 300 mg/kg bw/day (with +19%), furthermore an increase in relative adrenal weight was seen and of the testes (with respectively +36.4% and +15%), statistically significant at 300 mg/kg bw/day. The relative weight of seminal vesicles was increased with dose (with respectively +6.9%, +25.8% and +33% for 30, 100 and 300 mg/kg bw/day, statistically significant only at high dose).
In females, absolute and relative liver weight was statistically significantly increased at 300 mg/kg bw/day (with respectively +15.3% and +17.2%), and also absolute and relative kidney weights (with respectively +15.7% and +18.2%) were increased.

GROSS PATHOLOGY
A test item-related change was observed in the forestomach and consisted of irregular surface in 4/10 males and 3/10 females treated at 100 mg/kg bw/day and in 9/10 males and 9/10 females treated at 300 mg/kg bw/day. Other incidental findings among control and treated animals were within the background range of findings that occur in rats of this age and strain, and their incidence did not show a dose-related trend. These necropsy findings were therefore considered to be unrelated to treatment.

HISTOPATHOLOGY
Local adverse test item-related morphologic alterations were present in the (fore-)stomach of females treated at all dose groups (although at 30 mg/kg bw/day, only one female was affected) and males from 100 mg/kg bw/day onwards, which consisted of squamous cell hyperplasia/hyperkeratosis, erosion/ulceration and/or lymphogranulocytic inflammation of the forestomach and increased basophilia of the proliferation zone (adjacent to limiting ridge) of the glandular mucosa. The mesenteric lymph nodes showed increased macrophage foci in all rats at 300 mg/kg bw/day. These foci were without necrosis or additional inflammatory response. The mesenteric lymph node is directly draining the gastro-intestinal tract and therefore the macrophage foci were regarded to be related to the (local) forestomach changes. Based on this and the slight or moderate severities in all rats at 300 mg/kg/day, the increased macrophage foci were regarded to be adverse. Additional non-adverse test item-related morphologic alterations were noted from 100 mg/kg bw/day onwards in the kidneys of males consisting of hyaline droplet accumulation and follicular cell hypertrophy at low degree in the thyroid glands of females. Furthermore at 300 mg/kg/day effects were see in the intestines of both sexes, consisting of increased apoptosis in the villi of the small intestines (with the duodenum as most affected part) and increased incidence and/or severity of mucosal hypertrophy of the large intestines (most prominent in the cecum). Presumably, these changes represent a response to maintain the protective barrier of the intestinal mucosa. Since these findings were without inflammation or necrosis and recorded severities were generally mild (mostly minimal or mild), these findings were most likely a local non-adverse response.

Effect levels

1

Dose descriptor:

NOAEL

Remarks:

local

Effect level:

< 30 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Local, adverse changes in the stomach (mainly in the forestomach) (seen in a single female at 30 mg/kg bw/day, and in all animals at higher doses) and intestines (at 100 mg/kg bw/day and above).

2

Dose descriptor:

NOAEL

Remarks:

systemic

Effect level:

>= 30 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: see 'Remark'

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Analysis of formulations:

The concentrations analyzed in the formulations of the treatment groups and in the additional formulation of 2 mg/mL were in agreement with target concentrations (i.e. mean accuracies between 97% and 110%). The 2 mg/mL formulation was prepared in week 1 to determine stability over a larger concentration range than used for dosing of the animals.

A small response at the retention time of the test substance was observed in the chromatograms of the control formulation prepared for use in week 13. It was considered not to derive from the formulation since a similar response was obtained in the analytical blanks. In all other formulations of the control group, no test substance was detected.

The formulations of low and high dose groups were homogeneous (i.e. coefficient of variation ≤ 2.4%). Analysis of the 2 mg/mL formulations in week 1 after storage yielded a relative difference of -4.8%.

Based on this, the 2 mg/mL formulations were found to be stable during storage at room temperature under normal laboratory light conditions for at least 6 hours.

Analysis of high dose group formulations in week 1 after storage yielded a relative difference of 15%, most likely caused by analytical issues. Therefore, the storage stability of high dose group formulations was repeated in week 6 and analysis yielded a relative difference of 4.5%. Based on this, the formulations were found to be stable during storage at room temperature under normal laboratory light conditions for at least 6 hours.

Organ Weights

Mean percent weight differences from control groups

	males			females
	30	100	300	30	100	300
Dose level (mg/kg/day):
Kidneys
Absolute	+1	-2	0	-2	+8	+16**
Relative to body weight	+3	+5	+19**	0	+6	+18**
Liver
Absolute	-5	-7	-12*	-2	+4	+15**
Relative to body weight	-3	+1	+5	-1	+3	+17**

*: P≤0.05, **: P≤0.01

Summary Test Item-Related Microscopic Findings: Stomach

	males				females
Dose level (mg/kg/day):	0	30	100	300	0	30	100	300
Forestomach^a	10	10	10	10	10	10	10	10
Squamous cell hyperplasia / Hyperkeratosis
Minimal	0	0	4	0	0	0	3	0
Slight	0	0	2	0	0	1#	1	2
Moderate	0	0	3	6	0	0	6	8
Marked	0	0	0	4	0	0	0	0
Erosion/ulceration
Minimal	0	0	2	1	0	1#	2	1
Slight	0	0	0	0	0	0	1	0
Inflammation
Minimal	0	0	4	1	0	0	3	1
Slight	0	0	4	6	0	1#	2	7
Moderate	0	0	0	2	0	0	3	2
Glandular Stomach^a	10	10	10	10	10	10	10	10
Increased basophilia of the proliferation zone (adjacent to limiting ridge)
Minimal	0	0	0	2	0	0	0	3

^a = Number of tissues examined from each group.

# = Female no. 57.

Applicant's summary and conclusion

Conclusions:

In a 90-day oral NOAEL for local effects < 30 mg/kg bw/day based on minimal to slight forestomach lesions observed in one female animal at 30 mg dose level.
Systemic NOAEL is 30 mg/kg bw/day, based on lower body weight (males only), slight changes in absolute and relative neutrophil counts indicative of inflammation, and slight increased kidney weights and liver weight at 100 mg/kg bw/day, that are more pronounced at 300 mg/kg bw in females.

Executive summary:

A 90-day oral repeated dose toxicity study was conducted with C12-14-alkylmorpholine according to OECD/EC guidelines and GLP principles. Male and female rats were exposed to 0, 30, 100 and 300 mg/kg bw/day via oral gavage (10 animals/sex/dose). Chemical analysis of the formulations confirmed correct concentrations and stability.

No mortality occurred during the study. Clinical signs included salivation, which was expected to be related to irritant properties of the test substance and hunched posture and slight piloerection at 300 mg/kg bw/day during the study. No treatment related effects were seen on functional behaviour.

Males treated at 300 mg/kg bw/day gained less body weight than controls from initiation of treatment (final body weight -16% compared to controls), although relative food consumption was higher in males treated at 300 mg/kg bw/day than in controls from week 2 onwards. The males treated at 100 mg/kg bw/day also showed a lower final body weight (-6.4%) compared to control. No effects on body weight were seen in treated females although higher food consumption values (before and after correction for body weight) were noted at 300 mg/kg bw/day from week 2 onwards.

Absolute and relative neutrophil counts were slightly increased in males and females at 100 and 300 mg/kg bw/day (See graphs). Relative kidney weights were statistically significantly increased at 300 mg/kg bw/day in males conform lower BW. In females, absolute and relative liver and kidney weights were statistically significantly increased at 300 mg/kg bw/day.

Macroscopy revealed local effects in the forestomach in 4/10 males and 3/10 females treated at 100 mg/kg bw/day and in 9/10 males and 9/10 females treated at 300 mg/kg bw/day. This observation was confirmed at histopathology, where squamous cell hyperplasia/hyperkeratosis, erosion/ulceration and/or lymphogranulocytic inflammation were present in the (fore)stomach of females treated at all dose groups and males from 100 mg/kg bw/day onwards. Furthermore increased basophilia of the proliferation zone (adjacent to limiting ridge) of the glandular mucosa and increased macrophage foci in the mesenteric lymph node of both sexes at 300 mg/kg bw/day were seen. These foci were without necrosis or additional inflammatory response and expected to be related to the (local) forestomach changes.

Taken all data together, the local NOAEL of C12-14-alkylmorpholine was determined to be <30 mg/kg bw/day based on adverse, local effects in the stomach (mainly in the forestomach) at 30 mg/kg bw/day observed in one female (forestomach lesions consisting of slight inflammation, slight hyperplasia/hyperkeratosis and minimal erosion/ulceration of the squamous epithelium).

The systemic NOAEL was found to be 30 mg/kg bw/day, based on lower body weight (males only), slight changes in absolute and relative neutrophil counts indicative of inflammation, and slight increased kidney weights and liver weight at 100 mg/kg bw/day, that are more pronounced at 300 mg/kg bw in females.