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Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records
Reference
Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)
GLP compliance:
yes
Specific details on test material used for the study:
HPbCD was obtained from Cargill, Inc. (Cedar Rapids, IA)
Species:
rat
Strain:
Sprague-Dawley
Details on species / strain selection:
Sprague-Dawley (Crl:CD[SD]VAF/Plus)
Details on test animals or test system and environmental conditions:
Sprague-Dawley (Crl:CD[SD]VAF/Plus) rats (10/sex/group) were obtained from Charles River Laboratories (Wilmington, MA). Rats were 6 ± 1 weeks old at initiation of dosing. Males were 220.7– 295.5 g and females 150.0–201.5 g at the initiation of dosing. All rats on study were individually housed in suspended, stainless steel cages, were maintained on a 12-h light cycle (temperature 72°F ± 4°F, 30–70% humidity), and were given water and certified rodent lab diet (PMI Nutrition International, Inc.) ad libitum.
Route of administration:
oral: gavage
Details on oral exposure:
5 ml/kg, calculated from most recent body weight
syringe and a ball-tipped gavage tube.
Analytical verification of doses or concentrations:
not specified
Duration of treatment / exposure:
92-93 days
Frequency of treatment:
daily
Dose / conc.:
500 mg/kg bw/day (nominal)
Dose / conc.:
1 000 mg/kg bw/day (nominal)
No. of animals per sex per dose:
10/sex/dose
Control animals:
other: historical control
Observations and examinations performed and frequency:
General observations: Body weight was measured weekly beginning 1 week prior to dosing, and a fasted terminal body weight was recorded prior to necropsy. Food consumption was measured weekly beginning 1 week prior to dosing. Rats were checked at least once daily for viability and clinical observations were recorded twice daily, at the time of dosing, and 1–3 h postdose.

Ophthalmologic examinations: Ophthalmologic examinations consisted of focal illumination and indirect ophthalmoscopy in a subdued light setting. Examinations were preformed 2 weeks prior to dosing and during weeks 5 and 11.

Hematology and serum chemistry evaluations: Blood for hematology and serum chemistry was collected during weeks 2 and 13. Total blood volume collected per interval for hematology and serum chemistry was 1 ml from mice, 1.5 ml from rats, and 3 ml from dogs and monkeys. Hematology analysis was performed using Cell- Dyn 3500 (Abbott Laboratories, Abbott Park, IL) and Sysmex R-3000 (Medical Electronics, Miami, FL) hematology analyzers. Serum chemistry parameters were assessed using a CX5CE/Delta (Beckman Instruments, Brea, CA).
Hematology parameters examined (measured and calculated): Erythrocyte count, Hemoglobin, Hematocrit, Mean corpuscular volume, Mean corpuscular hemoglobin, Mean corpuscular hemoglobin concentration, Reticulocyte count, Platelet count, Mean platelet volume, Total leukocyte count, Differential leukocyte, count Blood smear morphology. Serum chemistry parameters examined (measured and calculated) Hemolysis, Lipemia, Icterus, Glucose, Blood, urea, nitrogen, ALT, Aspartate aminotransferase, AP, Total bilirubin, Total protein, Albumin, Globulin, Albumin/globulin, ratio Creatinine GGT, Cholesterol, Triglycerides, Sodium, Potassium, Chloride, Calcium, Inorganic phosphorus.
Coagulation assessment: Blood for coagulation assessment was collected at necropsy. Prothrombin time and activated partial thromboplastin time were assessed using an STA Compact hemostasis analyzer (Diagnostica Stago, Inc., Parsippany, NJ).

Urinalysis: Freshly voided (4 h) and 24-h urine samples were collected from during weeks 2 and 13. Urine was collected within 24 h prior to blood collection for hematology and serum chemistry. Urinalysis parameters from the freshly voided (4 h) samples were evaluated using a CX5CE/Delta (Beckman Instruments), whereas urinalysis parameters from the 24-h samples were analyzed using a Bayer Clintek ATLAS (Bayer Diagnostics, Tarrytown, NY).
Parameters examined:
4-h Urinalysis/urine parameters examined—3-month: Color Clarity pH, Protein Glucose, Ketones, Bilirubin Blood Urobilinogen.
24-h Urinalysis/urine parameters examined—3-month: Volume, Sodium Chloride, Phosphorus, Osmolality, Potassium, Calcium (total), Creatinine clearance.
Sacrifice and pathology:
Macroscopic and histopathological evaluation: Rats were humanely euthanized by exsanguination under isoflorane anesthesia. All tissues were fixed in 10% neutral buffered formalin with the exception of the eyes (3% glutaraldehyde), harderian glands (3% glutaraldehyde), and testes (10% neutral buffered formalin in mice and rats; modified Davidson’s fixative in dogs and monkeys). Tissues were then trimmed, embedded in paraffin wax, and sectioned at 4–5 microns. All tissues were stained with hematoxylin and eosin, with the exception of the testes and epididymides, which were stained with periodic acid- Schiff stain. All tissues from all dose groups were examined by a boardcertified veterinary pathologist. Bone marrow smears were obtained from the sternum and were evaluated for cytology by a board-certified veterinary clinical pathologist.
Organweights measured: Ventral prostate gland, Liver, Spleen, Brain, Lungs, Thymus, Epididymides, Ovaries, Heart, Testes, Kidneys, Uterus (plus cervix).
Tissues collected and examined histopathologically: adrenal gland, Aorta—thoracic, Bone (Femur and sternum), Bone marrow (sternum), Brain, Epididymides,Esophagus, Eyes, Gall, bladder, Harderian glands, Heart, Kidneys, Large intestines (cecum and colon), Larynx/pharynx, Liver, Lungs, Lymph nodes (mandibular and mesenteric), Mammary gland, Ovaries, Pancreas, Parathyroid gland, Peripheral nerve (sciatic), Pituitary gland, Prostate gland, Salivary gland, Seminal vesicles, Skeletal muscle (biceps), Skin, Small intestines (duodenum, jejunum, ileum), Spinal cord (thoracolumbar), Spleen, Stomach, Testes, Thymus, Thyroid gland, Tongue, Trachea, Urinary bladder, Uterus (plus cervix),Vagina.
Statistics:
Statistics: Descriptive statistics (mean, index of variability, SEM, SD) were calculated for all parameters except ECGs. A student’s t-test was used to assess statistical significance of the serum transanimase values in mice and rats.
Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
no effects observed
Haematological findings:
no effects observed
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
In female rats, treatment with 500 or 1000 mg/kg HPbCD resulted in time- and dose-dependent increases in serum AST and ALT levels. After 3 weeks of treatment with 1000 mg/kg HPbCD, serum AST and ALT levels were elevated (þ 38.2% and þ 31.1%, respectively), whereas after 13 weeks of treatment, serum AST and ALT levels were elevated in animals treated with 500 and 1000 mg/kg HPbCD (AST: þ 49.3% and þ 11.5%, ALT: þ 64.8% and þ 195.2%, respectively). In the 1000 mg/kg dose group at week 13, increases in serum AST and ALT levels were significantly higher than those seen at week 2, suggesting a progression of hepatic toxicity in these animals. AP and GGT were unchanged, and male rats were unaffected.
Urinalysis findings:
no effects observed
Behaviour (functional findings):
no effects observed
Immunological findings:
no effects observed
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
no effects observed
Description (incidence and severity):
There was no hepatic histopathologic correlate for the elevated transaminase findings, and liver weight and macroscopic appearance were normal. AST and ALT levels in male rats were similar to controls are all time points examined.
Histopathological findings: neoplastic:
no effects observed
Key result
Dose descriptor:
NOAEL
Effect level:
>= 1 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Remarks on result:
not determinable due to absence of adverse toxic effects
Dose descriptor:
LOEL
Effect level:
500 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
female
Basis for effect level:
clinical biochemistry
Key result
Critical effects observed:
no
Conclusions:
In rats HP-beta-CD did not indcue adverse effects in rats when dosed orally for 90 days. The effect on liver enzymes is considered of an adaptive nature as neither liver weight nor histopathological examination showed a correlating effect. The NOAEL is considered >= 1000 mg/kg b.w.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records
Reference
Endpoint:
short-term repeated dose toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
1 (reliable without restriction)
Qualifier:
according to guideline
Guideline:
OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)
GLP compliance:
yes (incl. QA statement)
Limit test:
no
Species:
rat
Strain:
Wistar
Sex:
male
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany
- Age at study initiation: 8 weeks
- Weight at study initiation: 225g
- Housing: individually in restraining tubes (during exposure); suspended, stainless steel cages fitted with wire mesh floor and front (after exp.)
- Diet (e.g. ad libitum): powder/commercially available rodent diet; no access during exposure
- Water: ad libitum; no access during exposure
- Acclimation period: 14 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.0 - 22.0°
- Humidity (%): 47- 76
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light):12 hours light/12 hours dark
Route of administration:
inhalation: dust
Type of inhalation exposure:
nose only
Vehicle:
air
Remarks on MMAD:
MMAD / GSD: MMAD: 1.9, 2.3 and 2.8 µm
gsd: 2.3, 2.4 and 2.4
for the low, mid and high concentration test atmospheres
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: nose-only inhalation units
- Method of holding animals in test chamber: The rodent tube section had 20 ports fo28r animal exposure. Animals were secured in plastic animal holders (Battelle), positioned radially through the outer cylinder around the central column.
- Source and rate of air: humidified air
- Method of conditioning air: high concentration test atmosphere was generated by passing test material to an eductor using a dry material feeder
- System of generating particulates/aerosols: eductor (Fox Mini, type 060, Spraybest Europe BV, Zwanenburg, The Netherlands) using a dry material feeder (Gericke GMD 60, Gericke AG, Regensburg-Ziirich, Switzerland )
- Pressure in air chamber: 0.8-1.0 bar
- Air flow rate: 63, 15, 19 and 109 l/min (control, low, mid and high concentration test); 20-25 l/min (low and mid concentration test)
- Method of particle size determination: Every week, one particle size distribution measurement was carried out on each of the three test atmospheres using a 10-stage Andersen cascade impactor (Andersen, Atlanta, USA). The Mass Median Aerodynamic Diameter (MMAD) and the geometric standard deviation (gsd) were calculated (Lee, 1972).

TEST ATMOSPHERE
- Brief description of analytical method used: The filters were weighed before and immediately after sampling. The actual concentrations were calculated by dividing the amount of test material present on the filter by the volume of of the respective sample taken.
- Samples taken from breathing zone: yes
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
A-control goup: 0mg/m³ concentration in the air
B-Iow concentration group: 10mg/m³ concentration in the air
C-mid concentration group: 100mg/m³ concentration in the air
D-high concentration group: 1000mg/m³ concentration in the air

Gravimetric analysis
The concentration of the test material in the test atmosphere of each unit was determined by gravimetric analysis. Test atmosphere samples were obtained by passing measured amounts of test atmosphere at a sampling speed of approximately 5 l/min on fibre glass filters (Sartorius). The filters were weighed before and immediately after sampling. The actual concentrations were calculated by dividing the amount of test material present on the filter by the volume of of the respective sample taken. The volumes sampled were 10,50 and approximately 300 L, for exposure units D, C and B, respectively. Generally four samples per exposure day were taken from each exposure unit times (i.e. B, C and D).

Nominal concentration:
The nominal concentration of the high concentration test atmosphere was calculated each day by dividing the weight of the test material used that day by the total amount of air passed on that day through the high concentration exposure unit. Since the test atmospheres of the mid and low concentration were derived from the high concentration test atmosphere, their nominal concentrations could not be derived.
Duration of treatment / exposure:
6 hours a day, 5 days a week for a period of 28 days
Frequency of treatment:
daily apart from weekends
Dose / conc.:
10 mg/m³ air (nominal)
Dose / conc.:
100 mg/m³ air (nominal)
Dose / conc.:
1 000 mg/m³ air (nominal)
No. of animals per sex per dose:
12 per dose (6x12 males)
Control animals:
yes
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily in the morning hours and in the afternoon (shortly after exposure); weekenddays once daily

BODY WEIGHT: Yes
- Time schedule for examinations:4 days before start of 1st exposure; just prior befor start of 1st exposure; once/week thereafter

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/animal/day: Yes

FOOD EFFICIENCY:
- Body weight gain in g/food consumption in g and body weight gain data: Yes

WATER CONSUMPTION: No data

OPHTHALMOSCOPIC EXAMINATION: No data

HAEMATOLOGY: Yes
- Time schedule for collection of blood: end of their exposure period (day 28)
- Anaesthetic used for blood collection: Yes (identity)
- Animals fasted: No data
- How many animals: 6 rats/group
- Parameters checked in table were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: no data
- Animals fasted: No data
- How many animals: 6/group (same as at HAEMATOLOGY)
- Parameters checked in table were examined.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes
Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
decreased on day 7 in the animals of the high concentration group
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
effects observed, treatment-related
Description (incidence and severity):
significantly decreased in 1st exp. week in high exp. group, sig. increased in last exp. week in all exp. groups compared to control group
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not specified
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
not specified
Behaviour (functional findings):
not specified
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
lung weights increased in mid+high concentration group; weights of testes+liver increased in high concentration group
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
olfactory mucosa of the epithelium and lamina proria, squamous epithel in the nasal cavity and trachea
Histopathological findings: neoplastic:
no effects observed
Details on results:
Clinical signs and survival:
The group-wise observation carried out about halfway through each day's exposure did not reveal abnormalities.
Individual observations in the mornings, i.e. before the start of each day's exposure did neither reveal treatment-related abnormalities. The changes observed, sparsely haired skin, microphtalmia and, dermal encrustations, were seen at a low incidence and only in the control group. They were therefore not considered to be related to the exposure. All rats survived until their scheduled necropsy.

Body weights:
Body weight was significantly decreased on day 7 in the animals of the high concentration group. Although body weight was numerically less in the latter group compared to the control during the exposure period, the differences were slight and were not necessarily considered to be related to exposure.
No differences in body weight gain were observed during the recovery period

Food consumption and food conversion efficiency:
Differences in food intake were not observed during exposure, except for a slight, statistically insignificant, lower overall intake in animals of the high concentration group. In the second week of the recovery period food intake was significantly increased in animals of the high exposure recovery group.
Food conversion efficiency was significantly decreased in the first exposure week in animals of the high exposure group and significantly increased in the last exposure week in all exposure groups compared to the control group. Most probably, food conversion efficiency was low in control animals during the last week of exposure rather than that it was increased due to the exposure.
Food conversion efficiency was increased during the first week after exposure, both in the control and the high exposure group. The increase, however, was significantly larger in the high exposure (recovery) group (p<0.00l).
Haematology: At the end of the exposure period, changes in red blood cell parameters were limited to a decrease in thrombocytes in the animals of the mid concentration group. Because it was not concentration-related, it was considered a fortuitous finding unrelated to treatment.
Statistically significant changes in the absolute or relative numbers- of white blood cells were not seen at the end of the exposure period.

Clinical chemistry: At the end of the exposure period, significant changes in clinical chemistry parameters were not seen.

Organ weights:
At the end of the exposure period, absolute and relative lung weights were increased in a concentration-related fashion in animals of the mid and high concentration groups. In addition, the absolute and relative weight of the testes and the relative weight of the liver were increased in animals of the high concentration group. In the other organs significant weight differences between control and exposed animals could not be detected.
An increase in absolute and relative lung weight was still present in animals of the high concentration group at the end of the recovery period but to a clearly lower extent. No changes were observed in the weight of the other organs.

Pathology:
Macroscopic examination: Gross examination at necropsy at the end of the exposure period did not reveal exposure-related changes. One low-concentration male exhibited red appearance of the thymus; one mid-concentration male showed uni-lateral red patches on the thymus. Both changes are quite common for rats of this strain and age.
Gross examination at necropsy after the recovery period did not reveal exposure related changes. Several changes were observed in control males and one change was found in a high-concentration male. These changes were considered to be common for rats of this strain and age.

Microscopic examination: Histopathological examination was performed on the complete respiratory tract of all animals of all groups (including the animals of the recovery groups). Liver, kidneys and testes were examined in animals of the main control (group A) and the high concentration group (group D) only.
Inhalation of hydroxypropylated .beta.-cyclodextrin induced histopathological changes in the nasal tissues, the trachea and the lungs of exposed animals. In the larynx the relationship between the observed changes and exposure to the test compound was questionable.

Histopathological findings in animals of the main groups:
High-concentration group animals
The nasal lesions occurred in the nasal squamous epithelium (SE), transitional (non-ciliated) epithelium (TE) and olfactory epithelium (OE). The SE changes consisted of hyperplasia of the septal squamous epithelium in the vestibulum of the nose (cross level 1), and of polymorphonuclear inflammatory cells infiltrating the SE of the ventral meatus at cross levels 1, 2, 3 and/or 4. The TE changes consisted of hyperplasia of the septal transitional epithelium at level 1, and occurred in association with the hyperplasia of the SE. Degeneration was observed in the entire OE lining, at cross levels 3, 4, 5 and 6. It was manifested by a decrease in nuclear density of the sensory cell layer rather than by a thinning of the epithelium. The loss of nuclei was especially prominent towards the topical site of the epithelium. As a result, the intact nuclei of the sustentacular cells were very conspicuous. There was some nuclear debris and mitotic figures were seen occasionally. The nerves in the underlying lamina propria appeared slightly affected, i.e. a decrease in diameter, a coarse aspect which suggested vacuolation of the axons, and/or an increase in nuclei in the larger nerves. These changes were collectively reported as 'neural change'.
The epithelium of the trachea was slightly thickened, due to hypertrophy of the lining epithelial cells and hyperplasia. It is highly conceivable that the increase in cells consisted mainly of mononuclear inflammatory cells which infiltrated the epithelium.
Accumulation of inflammatory cells in the alveolar lumina was the most prominent treatment-related observation in the lungs and could very well explain the increase in lung weight. The inflammatory cells consisted of a mixture of large macrophages with foamy cytoplasm and granulocytes. The respiratory epithelium lining the bronchi and• larger bronchioli was• slightly hypertrophic and hyperplastic.
Minimal respiratory cell hypertrophy/hyperplasia was also observed in the larynx of half of the top-concentration animals, and in the larynx of one control. In addition, a small intraepithelial cyst and a mixed inflammatory cell infiltrate were observed in a single top-concentration animal. The relationship between these changes and exposure to the test compound is questionable because either the incidence and degree of these changes did not differ distinctly between the test animals and controls or they occurred in a single animal and were not of a remarkable nature.
The remaining changes observed in the aforementioned organs and tissues were not considered to be treatment-related. In the other organs examined (liver, kidneys and testes) no exposure-related changes were observed.

Mid-concentration animals
The nasal lesions occurred in the OE and consisted of very slight to slight degeneration.
Accumulation of inflammatory cells in the alveolar lumina occurred in the lungs of all mid-concentration animals. The infiltrate was mixed in only one animal, in all others it consisted almost exclusively of alveolar macrophages. Respiratory epithelial hypertrophy/hyperplasia was found in one mid-concentration animal only.
No exposure-related changes were observed in the trachea and larynx.

Low-concentration animals
Accumulation of alveolar macrophages was focal instead of diffuse as observed in the high- and mid-concentration animals.
No exposure-related changes were observed in the nasal cavity, trachea and larynx.

Histopathological findings in animals of the recovery groups:
Microscopic examination of animals at the end of the recovery period revealed exposure-related histopathological changes in the nasal tissues and the lungs only. The nasal lesions occurred in the nasal transitional/ciliated epithelium (TE/CE) and the olfactory epithelium (OE). The TE/CE lesion consisted of squamous metaplasia on the septum at cross level 2, and was observed in 2 out of 6 high concentration animals. The OE of all high-concentration animals showed areas of degeneration at cross levels 3, 4, 5 and 6. The degeneration was of a somewhat lesser degree than observed at the end of the exposure period. One high concentration animal exhibited cytoplasmic eosinophilic inclusions in the OE. This change is sometimes found in the OE of old rats. Because of this and the occurrence in a single animal, the relationship with the exposure is not clear. Accumulation of alveolar macrophages was observed in the lungs of all high concentration animals. The majority of macrophages was smaller than those of the high-concentration animals in the main study. Also, the accumulation of macrophages was more focal. These focal accumulations were associated with increased septal cellularity. Interstitial mononuclear inflammatory cell infiltrations, an increase in type 11 pneumocytes and alveolar macrophages between or adjacent to the epithelial cells were the major contributors to the increased septal cellularity. Bronchial/bronchiolar respiratory epithelial hypertrophy/hyperplasia was not observed.
No exposure-related changes were found in the larynx and trachea.
Key result
Dose descriptor:
NOAEC
Remarks:
systemic effects
Effect level:
>= 1 000 mg/m³ air
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: overall effects
Dose descriptor:
NOAEC
Remarks:
local effects
Effect level:
10 mg/m³ air
Based on:
test mat.
Sex:
male/female
Basis for effect level:
histopathology: non-neoplastic
Dose descriptor:
LOAEC
Remarks:
local effects
Effect level:
100 mg/m³ air
Based on:
test mat.
Sex:
male/female
Basis for effect level:
histopathology: non-neoplastic

Further, additional numbers of animals were included in the present study. These were exposed to the test atmospheres as described above, and part of these were also kept for a post-treatment period of 14 days. At necropsy, the lungs of these animals were lavaged and the bronchoalveolar lavage fluid obtained was examined for total and differential white blood cell numbers, viability and cell differentials, and for a few biochemical parameters.

Conclusions:
From the results of this part of the study it was concluded that inhalation exposure to hydroxypropylated .beta.-cyclodextrin for four weeks resulted in local toxicity at levels of 100 and 1000 mg/m³, consisting of histopathological changes of the respiratory tract and a concentration-related increase in lung weight. Although changes were less severe at a concentration of 1000 mg/m³ after a recovery period of 14 days, reversibility of these effects was not complete. At a level of 10 mg/m3 no such effects were observed, which was therefore considered a No-Observed-Effect Concentration (NOAEC) for local toxicity. Based on the severity of effects on the olefactory epithelium at 100 mg/m3 (2 with very slight and 4 slight degeneration out of 6 animals) and the tendency to recover at 1000 mg/m3, 10mg/m3 is in the absence of a other concentration groups a very conservative NOAEC for local effects.
Very slight growth retardation and reduced food intake and food conversion efficiency were observed at a level of 1000 mg/m³. These changes were considered to be indirect effects due to a lack in well-being (respiratory tract lesions). Since no systemic toxicity was observed at any of the concentrations tested, the NOAEL for systemic toxicity was >=1000 mg/m³.
Executive summary:

The inhalation toxicity of hydroxypropylated .beta.-cyclodextrin was studied in a sub-acute (28-day) study in Wistar rats according to OECD Guideline Study 412. Groups of 6 male rats were exposed to target concentrations of 0 (control), 10, 100 or 1000 mg/m³ hydroxypropylated .beta.-cyclodextrin for six hours a day, 5 days a week during a period of 28 days, with a total of 20 exposure days. The rats were necropsied the day after the last exposure. Two additional groups of 6 rats were exposed to either 0 (control) or 1000 mg/m³ hydroxypropylated .beta.-cyclodextrin as described above and were kept for a post-treatment period of 14 days to examine reversibility of toxic effects. To examine the toxicity of the test material clinical signs, body weights, food consumption, food conversion efficiency, haematology, and clinical chemistry were used. In addition, a full necropsy was performed and a selection of organs including the respiratory tract was examined microscopically.

Further, additional groups of animals (6 male rats/ group) were included in the present study. The animals were exposed to the test atmospheres as described above during a period of 29 days (21 exposure days), and part of them were also kept for a post-treatment period of 14 days. Clinical signs, body weights, food consumption and food conversion efficiency were recorded. At necropsy, the lungs of these animals were lavaged and the bronchoalveolar lavage fluid obtained was examined for total and differential white blood cell numbers, viability and cell differentials, and for a few biochemical parameters.

These results are described in part 2 of this report. The mean actual concentrations (± standard deviation) of hydroxypropylated .beta.-cyclodextrin in the test atmospheres were 10.4 ± 0.8, 102 ± 9 and 1006 ± 74 mg/m³ for the low, mid and high concentration test atmospheres, respectively. The Mass Median Aerodynamic Diameter (MMAD)was 1.9, 2.3 and 2.8 µm, and the geometric standard deviation (gsd) was 2.3, 2.4 and 2.4 for the low, mid and high concentration test atmospheres, respectively.

No treatment-related abnormalities in clinical signs or behavior were seen during the exposure and recovery -period.

Minimal reductions in body weight gain, food intake and food conversion efficiency were observed in animals of the high concentration group during the exposure period.

No treatment-related changes in haematology or clinical chemistry were observed.

A concentration-related increase in absolute and relative lung weights was observed in animals of the mid and high concentration group. In addition, the absolute and relative weight of the testes and the relative weight of the liver were increased in animals of the high concentration group. At the end of the recovery period, increased absolute and relative lung weights were still observed. No changes were observed in weights of other organs.

Inhalation of hydroxypropylated .beta.-cyclodextrin induced histopathological changes in the respiratory tract, i.e nasal cavity, trachea and lungs. Concentration-related changes were seen in the olfactory mucosa of the epithelium and underlying associated lamina propria of animals of the mid and high concentration. Histopathological changes of the transitional (non-ciliated) and squamous epithelium in the nasal cavity, consisting of epithelial hyperplasia and/or presence of polymorphonuclear inflammatory cells were seen in animals of the high concentration group only. Tracheal changes, consisting of epithelial hyperthrophy and hyperplasia, were also observed in animals of the high concentration group only. A concentration-related increase in accumulation of alveolar macrophages was seen in animals of the mid and high concentration group. Granulocytes were also present in all animals of the high concentration group, and in one animal of the mid concentration group. This change was accompanied by hypertrophy and hyperplasia of the respiratory epithelium lining the.bronchi and larger bronchioli. Although macrophage accumulations were also seen in animals of the low concentration group, no granulocytes were observed.

Moreover, these changes were focal rather than diffuse and were not accompanied by epithelial changes.

At the end of the recovery period, changes of the olfactory epithelium were still present but less severe. In lout of 6 high concentration animals, squamous metaplasia of the transitional/ciliated epithelium was observed on the nasal septum. Histopathological lung changes consisted of focal accumulations of alveolar macrophages which were associated with increased septal cellularity but not with bronchial/bronchiolar respiratory epithelial hypertrophy/hyperplasia. As overall changes were less severe at the end of the recovery period, reversibility of the effects occurred but was not completed during the 14-day recovery period.

No treatment-related histopathological changes were observed in the larynx, liver, kidneys and testes.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed

Repeated dose toxicity: inhalation - local effects

Link to relevant study records
Reference
Endpoint:
short-term repeated dose toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
1 (reliable without restriction)
Qualifier:
according to guideline
Guideline:
OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)
GLP compliance:
yes (incl. QA statement)
Limit test:
no
Species:
rat
Strain:
Wistar
Sex:
male
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany
- Age at study initiation: 8 weeks
- Weight at study initiation: 225g
- Housing: individually in restraining tubes (during exposure); suspended, stainless steel cages fitted with wire mesh floor and front (after exp.)
- Diet (e.g. ad libitum): powder/commercially available rodent diet; no access during exposure
- Water: ad libitum; no access during exposure
- Acclimation period: 14 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.0 - 22.0°
- Humidity (%): 47- 76
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light):12 hours light/12 hours dark
Route of administration:
inhalation: dust
Type of inhalation exposure:
nose only
Vehicle:
air
Remarks on MMAD:
MMAD / GSD: MMAD: 1.9, 2.3 and 2.8 µm
gsd: 2.3, 2.4 and 2.4
for the low, mid and high concentration test atmospheres
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: nose-only inhalation units
- Method of holding animals in test chamber: The rodent tube section had 20 ports fo28r animal exposure. Animals were secured in plastic animal holders (Battelle), positioned radially through the outer cylinder around the central column.
- Source and rate of air: humidified air
- Method of conditioning air: high concentration test atmosphere was generated by passing test material to an eductor using a dry material feeder
- System of generating particulates/aerosols: eductor (Fox Mini, type 060, Spraybest Europe BV, Zwanenburg, The Netherlands) using a dry material feeder (Gericke GMD 60, Gericke AG, Regensburg-Ziirich, Switzerland )
- Pressure in air chamber: 0.8-1.0 bar
- Air flow rate: 63, 15, 19 and 109 l/min (control, low, mid and high concentration test); 20-25 l/min (low and mid concentration test)
- Method of particle size determination: Every week, one particle size distribution measurement was carried out on each of the three test atmospheres using a 10-stage Andersen cascade impactor (Andersen, Atlanta, USA). The Mass Median Aerodynamic Diameter (MMAD) and the geometric standard deviation (gsd) were calculated (Lee, 1972).

TEST ATMOSPHERE
- Brief description of analytical method used: The filters were weighed before and immediately after sampling. The actual concentrations were calculated by dividing the amount of test material present on the filter by the volume of of the respective sample taken.
- Samples taken from breathing zone: yes
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
A-control goup: 0mg/m³ concentration in the air
B-Iow concentration group: 10mg/m³ concentration in the air
C-mid concentration group: 100mg/m³ concentration in the air
D-high concentration group: 1000mg/m³ concentration in the air

Gravimetric analysis
The concentration of the test material in the test atmosphere of each unit was determined by gravimetric analysis. Test atmosphere samples were obtained by passing measured amounts of test atmosphere at a sampling speed of approximately 5 l/min on fibre glass filters (Sartorius). The filters were weighed before and immediately after sampling. The actual concentrations were calculated by dividing the amount of test material present on the filter by the volume of of the respective sample taken. The volumes sampled were 10,50 and approximately 300 L, for exposure units D, C and B, respectively. Generally four samples per exposure day were taken from each exposure unit times (i.e. B, C and D).

Nominal concentration:
The nominal concentration of the high concentration test atmosphere was calculated each day by dividing the weight of the test material used that day by the total amount of air passed on that day through the high concentration exposure unit. Since the test atmospheres of the mid and low concentration were derived from the high concentration test atmosphere, their nominal concentrations could not be derived.
Duration of treatment / exposure:
6 hours a day, 5 days a week for a period of 28 days
Frequency of treatment:
daily apart from weekends
Dose / conc.:
10 mg/m³ air (nominal)
Dose / conc.:
100 mg/m³ air (nominal)
Dose / conc.:
1 000 mg/m³ air (nominal)
No. of animals per sex per dose:
12 per dose (6x12 males)
Control animals:
yes
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily in the morning hours and in the afternoon (shortly after exposure); weekenddays once daily

BODY WEIGHT: Yes
- Time schedule for examinations:4 days before start of 1st exposure; just prior befor start of 1st exposure; once/week thereafter

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/animal/day: Yes

FOOD EFFICIENCY:
- Body weight gain in g/food consumption in g and body weight gain data: Yes

WATER CONSUMPTION: No data

OPHTHALMOSCOPIC EXAMINATION: No data

HAEMATOLOGY: Yes
- Time schedule for collection of blood: end of their exposure period (day 28)
- Anaesthetic used for blood collection: Yes (identity)
- Animals fasted: No data
- How many animals: 6 rats/group
- Parameters checked in table were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: no data
- Animals fasted: No data
- How many animals: 6/group (same as at HAEMATOLOGY)
- Parameters checked in table were examined.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes
Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
decreased on day 7 in the animals of the high concentration group
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
effects observed, treatment-related
Description (incidence and severity):
significantly decreased in 1st exp. week in high exp. group, sig. increased in last exp. week in all exp. groups compared to control group
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not specified
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
not specified
Behaviour (functional findings):
not specified
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
lung weights increased in mid+high concentration group; weights of testes+liver increased in high concentration group
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
olfactory mucosa of the epithelium and lamina proria, squamous epithel in the nasal cavity and trachea
Histopathological findings: neoplastic:
no effects observed
Details on results:
Clinical signs and survival:
The group-wise observation carried out about halfway through each day's exposure did not reveal abnormalities.
Individual observations in the mornings, i.e. before the start of each day's exposure did neither reveal treatment-related abnormalities. The changes observed, sparsely haired skin, microphtalmia and, dermal encrustations, were seen at a low incidence and only in the control group. They were therefore not considered to be related to the exposure. All rats survived until their scheduled necropsy.

Body weights:
Body weight was significantly decreased on day 7 in the animals of the high concentration group. Although body weight was numerically less in the latter group compared to the control during the exposure period, the differences were slight and were not necessarily considered to be related to exposure.
No differences in body weight gain were observed during the recovery period

Food consumption and food conversion efficiency:
Differences in food intake were not observed during exposure, except for a slight, statistically insignificant, lower overall intake in animals of the high concentration group. In the second week of the recovery period food intake was significantly increased in animals of the high exposure recovery group.
Food conversion efficiency was significantly decreased in the first exposure week in animals of the high exposure group and significantly increased in the last exposure week in all exposure groups compared to the control group. Most probably, food conversion efficiency was low in control animals during the last week of exposure rather than that it was increased due to the exposure.
Food conversion efficiency was increased during the first week after exposure, both in the control and the high exposure group. The increase, however, was significantly larger in the high exposure (recovery) group (p<0.00l).
Haematology: At the end of the exposure period, changes in red blood cell parameters were limited to a decrease in thrombocytes in the animals of the mid concentration group. Because it was not concentration-related, it was considered a fortuitous finding unrelated to treatment.
Statistically significant changes in the absolute or relative numbers- of white blood cells were not seen at the end of the exposure period.

Clinical chemistry: At the end of the exposure period, significant changes in clinical chemistry parameters were not seen.

Organ weights:
At the end of the exposure period, absolute and relative lung weights were increased in a concentration-related fashion in animals of the mid and high concentration groups. In addition, the absolute and relative weight of the testes and the relative weight of the liver were increased in animals of the high concentration group. In the other organs significant weight differences between control and exposed animals could not be detected.
An increase in absolute and relative lung weight was still present in animals of the high concentration group at the end of the recovery period but to a clearly lower extent. No changes were observed in the weight of the other organs.

Pathology:
Macroscopic examination: Gross examination at necropsy at the end of the exposure period did not reveal exposure-related changes. One low-concentration male exhibited red appearance of the thymus; one mid-concentration male showed uni-lateral red patches on the thymus. Both changes are quite common for rats of this strain and age.
Gross examination at necropsy after the recovery period did not reveal exposure related changes. Several changes were observed in control males and one change was found in a high-concentration male. These changes were considered to be common for rats of this strain and age.

Microscopic examination: Histopathological examination was performed on the complete respiratory tract of all animals of all groups (including the animals of the recovery groups). Liver, kidneys and testes were examined in animals of the main control (group A) and the high concentration group (group D) only.
Inhalation of hydroxypropylated .beta.-cyclodextrin induced histopathological changes in the nasal tissues, the trachea and the lungs of exposed animals. In the larynx the relationship between the observed changes and exposure to the test compound was questionable.

Histopathological findings in animals of the main groups:
High-concentration group animals
The nasal lesions occurred in the nasal squamous epithelium (SE), transitional (non-ciliated) epithelium (TE) and olfactory epithelium (OE). The SE changes consisted of hyperplasia of the septal squamous epithelium in the vestibulum of the nose (cross level 1), and of polymorphonuclear inflammatory cells infiltrating the SE of the ventral meatus at cross levels 1, 2, 3 and/or 4. The TE changes consisted of hyperplasia of the septal transitional epithelium at level 1, and occurred in association with the hyperplasia of the SE. Degeneration was observed in the entire OE lining, at cross levels 3, 4, 5 and 6. It was manifested by a decrease in nuclear density of the sensory cell layer rather than by a thinning of the epithelium. The loss of nuclei was especially prominent towards the topical site of the epithelium. As a result, the intact nuclei of the sustentacular cells were very conspicuous. There was some nuclear debris and mitotic figures were seen occasionally. The nerves in the underlying lamina propria appeared slightly affected, i.e. a decrease in diameter, a coarse aspect which suggested vacuolation of the axons, and/or an increase in nuclei in the larger nerves. These changes were collectively reported as 'neural change'.
The epithelium of the trachea was slightly thickened, due to hypertrophy of the lining epithelial cells and hyperplasia. It is highly conceivable that the increase in cells consisted mainly of mononuclear inflammatory cells which infiltrated the epithelium.
Accumulation of inflammatory cells in the alveolar lumina was the most prominent treatment-related observation in the lungs and could very well explain the increase in lung weight. The inflammatory cells consisted of a mixture of large macrophages with foamy cytoplasm and granulocytes. The respiratory epithelium lining the bronchi and• larger bronchioli was• slightly hypertrophic and hyperplastic.
Minimal respiratory cell hypertrophy/hyperplasia was also observed in the larynx of half of the top-concentration animals, and in the larynx of one control. In addition, a small intraepithelial cyst and a mixed inflammatory cell infiltrate were observed in a single top-concentration animal. The relationship between these changes and exposure to the test compound is questionable because either the incidence and degree of these changes did not differ distinctly between the test animals and controls or they occurred in a single animal and were not of a remarkable nature.
The remaining changes observed in the aforementioned organs and tissues were not considered to be treatment-related. In the other organs examined (liver, kidneys and testes) no exposure-related changes were observed.

Mid-concentration animals
The nasal lesions occurred in the OE and consisted of very slight to slight degeneration.
Accumulation of inflammatory cells in the alveolar lumina occurred in the lungs of all mid-concentration animals. The infiltrate was mixed in only one animal, in all others it consisted almost exclusively of alveolar macrophages. Respiratory epithelial hypertrophy/hyperplasia was found in one mid-concentration animal only.
No exposure-related changes were observed in the trachea and larynx.

Low-concentration animals
Accumulation of alveolar macrophages was focal instead of diffuse as observed in the high- and mid-concentration animals.
No exposure-related changes were observed in the nasal cavity, trachea and larynx.

Histopathological findings in animals of the recovery groups:
Microscopic examination of animals at the end of the recovery period revealed exposure-related histopathological changes in the nasal tissues and the lungs only. The nasal lesions occurred in the nasal transitional/ciliated epithelium (TE/CE) and the olfactory epithelium (OE). The TE/CE lesion consisted of squamous metaplasia on the septum at cross level 2, and was observed in 2 out of 6 high concentration animals. The OE of all high-concentration animals showed areas of degeneration at cross levels 3, 4, 5 and 6. The degeneration was of a somewhat lesser degree than observed at the end of the exposure period. One high concentration animal exhibited cytoplasmic eosinophilic inclusions in the OE. This change is sometimes found in the OE of old rats. Because of this and the occurrence in a single animal, the relationship with the exposure is not clear. Accumulation of alveolar macrophages was observed in the lungs of all high concentration animals. The majority of macrophages was smaller than those of the high-concentration animals in the main study. Also, the accumulation of macrophages was more focal. These focal accumulations were associated with increased septal cellularity. Interstitial mononuclear inflammatory cell infiltrations, an increase in type 11 pneumocytes and alveolar macrophages between or adjacent to the epithelial cells were the major contributors to the increased septal cellularity. Bronchial/bronchiolar respiratory epithelial hypertrophy/hyperplasia was not observed.
No exposure-related changes were found in the larynx and trachea.
Key result
Dose descriptor:
NOAEC
Remarks:
systemic effects
Effect level:
>= 1 000 mg/m³ air
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: overall effects
Dose descriptor:
NOAEC
Remarks:
local effects
Effect level:
10 mg/m³ air
Based on:
test mat.
Sex:
male/female
Basis for effect level:
histopathology: non-neoplastic
Dose descriptor:
LOAEC
Remarks:
local effects
Effect level:
100 mg/m³ air
Based on:
test mat.
Sex:
male/female
Basis for effect level:
histopathology: non-neoplastic

Further, additional numbers of animals were included in the present study. These were exposed to the test atmospheres as described above, and part of these were also kept for a post-treatment period of 14 days. At necropsy, the lungs of these animals were lavaged and the bronchoalveolar lavage fluid obtained was examined for total and differential white blood cell numbers, viability and cell differentials, and for a few biochemical parameters.

Conclusions:
From the results of this part of the study it was concluded that inhalation exposure to hydroxypropylated .beta.-cyclodextrin for four weeks resulted in local toxicity at levels of 100 and 1000 mg/m³, consisting of histopathological changes of the respiratory tract and a concentration-related increase in lung weight. Although changes were less severe at a concentration of 1000 mg/m³ after a recovery period of 14 days, reversibility of these effects was not complete. At a level of 10 mg/m3 no such effects were observed, which was therefore considered a No-Observed-Effect Concentration (NOAEC) for local toxicity. Based on the severity of effects on the olefactory epithelium at 100 mg/m3 (2 with very slight and 4 slight degeneration out of 6 animals) and the tendency to recover at 1000 mg/m3, 10mg/m3 is in the absence of a other concentration groups a very conservative NOAEC for local effects.
Very slight growth retardation and reduced food intake and food conversion efficiency were observed at a level of 1000 mg/m³. These changes were considered to be indirect effects due to a lack in well-being (respiratory tract lesions). Since no systemic toxicity was observed at any of the concentrations tested, the NOAEL for systemic toxicity was >=1000 mg/m³.
Executive summary:

The inhalation toxicity of hydroxypropylated .beta.-cyclodextrin was studied in a sub-acute (28-day) study in Wistar rats according to OECD Guideline Study 412. Groups of 6 male rats were exposed to target concentrations of 0 (control), 10, 100 or 1000 mg/m³ hydroxypropylated .beta.-cyclodextrin for six hours a day, 5 days a week during a period of 28 days, with a total of 20 exposure days. The rats were necropsied the day after the last exposure. Two additional groups of 6 rats were exposed to either 0 (control) or 1000 mg/m³ hydroxypropylated .beta.-cyclodextrin as described above and were kept for a post-treatment period of 14 days to examine reversibility of toxic effects. To examine the toxicity of the test material clinical signs, body weights, food consumption, food conversion efficiency, haematology, and clinical chemistry were used. In addition, a full necropsy was performed and a selection of organs including the respiratory tract was examined microscopically.

Further, additional groups of animals (6 male rats/ group) were included in the present study. The animals were exposed to the test atmospheres as described above during a period of 29 days (21 exposure days), and part of them were also kept for a post-treatment period of 14 days. Clinical signs, body weights, food consumption and food conversion efficiency were recorded. At necropsy, the lungs of these animals were lavaged and the bronchoalveolar lavage fluid obtained was examined for total and differential white blood cell numbers, viability and cell differentials, and for a few biochemical parameters.

These results are described in part 2 of this report. The mean actual concentrations (± standard deviation) of hydroxypropylated .beta.-cyclodextrin in the test atmospheres were 10.4 ± 0.8, 102 ± 9 and 1006 ± 74 mg/m³ for the low, mid and high concentration test atmospheres, respectively. The Mass Median Aerodynamic Diameter (MMAD)was 1.9, 2.3 and 2.8 µm, and the geometric standard deviation (gsd) was 2.3, 2.4 and 2.4 for the low, mid and high concentration test atmospheres, respectively.

No treatment-related abnormalities in clinical signs or behavior were seen during the exposure and recovery -period.

Minimal reductions in body weight gain, food intake and food conversion efficiency were observed in animals of the high concentration group during the exposure period.

No treatment-related changes in haematology or clinical chemistry were observed.

A concentration-related increase in absolute and relative lung weights was observed in animals of the mid and high concentration group. In addition, the absolute and relative weight of the testes and the relative weight of the liver were increased in animals of the high concentration group. At the end of the recovery period, increased absolute and relative lung weights were still observed. No changes were observed in weights of other organs.

Inhalation of hydroxypropylated .beta.-cyclodextrin induced histopathological changes in the respiratory tract, i.e nasal cavity, trachea and lungs. Concentration-related changes were seen in the olfactory mucosa of the epithelium and underlying associated lamina propria of animals of the mid and high concentration. Histopathological changes of the transitional (non-ciliated) and squamous epithelium in the nasal cavity, consisting of epithelial hyperplasia and/or presence of polymorphonuclear inflammatory cells were seen in animals of the high concentration group only. Tracheal changes, consisting of epithelial hyperthrophy and hyperplasia, were also observed in animals of the high concentration group only. A concentration-related increase in accumulation of alveolar macrophages was seen in animals of the mid and high concentration group. Granulocytes were also present in all animals of the high concentration group, and in one animal of the mid concentration group. This change was accompanied by hypertrophy and hyperplasia of the respiratory epithelium lining the.bronchi and larger bronchioli. Although macrophage accumulations were also seen in animals of the low concentration group, no granulocytes were observed.

Moreover, these changes were focal rather than diffuse and were not accompanied by epithelial changes.

At the end of the recovery period, changes of the olfactory epithelium were still present but less severe. In lout of 6 high concentration animals, squamous metaplasia of the transitional/ciliated epithelium was observed on the nasal septum. Histopathological lung changes consisted of focal accumulations of alveolar macrophages which were associated with increased septal cellularity but not with bronchial/bronchiolar respiratory epithelial hypertrophy/hyperplasia. As overall changes were less severe at the end of the recovery period, reversibility of the effects occurred but was not completed during the 14-day recovery period.

No treatment-related histopathological changes were observed in the larynx, liver, kidneys and testes.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
LOAEC
100 mg/m³
Study duration:
subacute
Species:
rat

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Justification for classification or non-classification