Cyclohexapentylose

Endpoint summary

Description of key information

Since 20% .alpha.-CD induced no changes of any toxicological significance which were not also induced by 20% lactose, it appears that these test substance is as safe as lactose. Moreover, the observed changes appeared to be reversible. Because the findings produced by 20% lactose are not considered to represent toxic effects, it also appears that even 20% of the test substances cannot be considered a toxic effect level. Therefore it is concluded that under the conditions of the study, dietary levels of up to 20% .alpha.-CD are tolerated without obvious signs of toxicity.
Two chronic (52 weeks) feeding studies with dogs using the read-across substance .beta.-cyclodextrin have been performed; both result in a NOAEL of 50.000 ppm (highest dietary level tested). 

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:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

Rats were used, since this species is considered most suitable for this type of study and is usually required by regulatory agencies. Weanling (c. 4 weeks old) Wistar rats (Crl:WI(WU)BR) were obtained from Charles River Wiga GmbH, Sulzfeld, Germany. The animals for the study arrived on October 10, 1989 (males) and on October 17, 1989 (females). They were taken in their unopened shipping containers directly into their assigned animal room (males and females were housed in separate rooms in the main study, and in one room in the additional study). Upon arrival, the rats were checked for overt signs of ill health and anomalies. Then they were allocated to the various groups by a computer randomization program and identified with a temporary mark on their tail. They were acclimatized to the laboratory conditions for a period of 6 days before the treatment was started. During the acclimatization period, the health status of the rats was examined by the laboratory veterinarian. The rats were weighed in the acclimatization period (on day -3). On day 0, i.e. the day when treatment was started, they were weighed again and checked for adequate growth and correct body weight variation (< +/- 20% of the mean weight). Prior to the start of the treatment, a few rats were replaced for various reasons such as inadequate growth, abnormalities observed upon ophthalmoscopic examination, or in order to equalize the mean initial body weight. Subsequently, each rat was identified by a unique animal identification number that was tattooed in the ears. Then the treatment was started. The remaining rats were kept in reserve but none of these was used after the start of the study.

From their arrival until the end of the study, the rats were housed in groups of five, separated by sex, in suspended, stainless steel cages, fitted with wire mesh floor and front. The cages were randomly allocated to the various groups. Each cage was provided with a coloured card showing the animal identification number range, the cage number, the group letter and the study number.

Housing conditions were conventional. The temperature in the animal room was 20-24°C. The relative humidity fluctuated between 30 and 70%. Occasionally, the humidity exceeded the upper limit during a limited period, generally as a result of the wet cleaning of the room. Because of technical failure the humidity dropped below 30% at three occasions, lasting for one or a few hours. The above disturbances are not considered to have influenced the outcome of the study. The number of air changes was about 10 per hour. Lighting was artificial by fluorescent tubes, time switch controlled at a sequence of 12 hours light, 12 hours dark.

Diet and drinking water: Following the arrival of the rats till the initiation of the experimental period and also in the recovery period, the Institute's cereal based diet for rats, mice and hamsters were provided. During the study, the rats were fed a somewhat modified cereal based diet. The main modification consisted of the partial replacement of the cereals wheat and maize by 20% pregelatinized potato starch (Paselli WA-4), to enable the incorporation of 1.5%, 5% or 20% of the test substances at the expense of this starch. The test diets were prepared in two steps as follows: first a batch of 215 kg (main study) or 54 kg (additional study) pre-mixture containing all ingredients, except for pregelatinized potato starch and the appropriate test substance, was prepared by mixing for 2 minutes in a mechanical blender (Lödige mixer). Then each testor control diet was prepared by adding the appropriate amounts of test substance and pregelatinized potato starch to the pre-mixture. Homogeneity was achieved by mixing for 2 minutes in a Lödige mixer. Fresh batches of test and control diets were prepared monthly and stored in a refrigerator. Immediately after preparation of the diets, samples were taken to enable analysis for the content, homogeneity and stability of the test substances in the diets.

From the arrival of the rats until the end of the study, feed and water were provided ad libitum, unless precluded by the performance of certain laboratory investigations. Test diets and control diet were provided to the rats in stainless steel cans. The food was covered by a perforated stainless steel plate which prevented spillage. Twice a week fresh portions of the diets were provided to the rats. Tap-water was supplied in glass bottles which were cleaned once weekly. The water in the bottles was replenished if necessary. Routine analyses for contaminants in the cereal based stock diet and in drinking water are carried out twice a year.

Route of administration:

oral: feed

Vehicle:

other: food

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

1.5, 5 and 20% .alpha.-cyclodextrin

Duration of treatment / exposure:

90 d

Frequency of treatment:

daily

Remarks:

Doses / Concentrations:
0, 1.5, 5 or 20%
Basis:
nominal in diet

No. of animals per sex per dose:

20 per sex per dose

Control animals:

yes, plain diet

other: 20% lactose

Details on study design:

Main study:
Because of the great number of rats, the males and females were assigned to different (computer)assays which were separated by a one week interval. Males were assigned to assay no. 1170, which was started on October 16, 1989 and fema1es to assay no. 1171, which was started on October 23, 1989. Within these computer assays, the rats were divided into subgroups.
The 13-week toxicity study (treatment groups) was terminated on January 15-19 (males) and on January 22-26, 1990 (females). To investigate the reversibility of the effects found, satellite groups of 10 rats/ sex were attached to the highest dose and the control groups. The rats of the recovery groups were treated similarly to those of the treatment groups for 13 weeks (viz. males till January 15 and females till January 22, 1990). Then the treatment was stopped and the rats were continued on the Institute's cereal based stock diet for a period of one month. The males of the recovery groups were autopsied on February 12 and the females on February 19, 1990.

Positive control:

no data available

Observations and examinations performed and frequency:

Test substance analyses:
From the first batch of diets (prepared on 13-10-89 in the main study and on 15-02-90 in the additional study), 5 samples per test diet, taken at different locations in the feed container, were analysed in order to examine the homogeneity of the test substances in the diets.
In order to obtain information on the stability of the test substances in the diets, samples of the diets prepared on 13-10-89 were reanalysed after storage at room temperature for six weeks.
Further, the content of the test substances in the diets was checked in the batches prepared on 10-11-89 and 13-12-89 in the main study and in the batches prepared on 14-03-90 and 11-04-90 in the additional study.
In addition the purity of the test substances used in this study was reconfirmed.

Clinical signs:
The general condition and behaviour of all animals were checked daily in the morning hours. On working days, all cages were checked again late in the afternoon for dead or moribund animals, to minimise loss of animals from the study. In weekends only one check was carried out per day. All abnormalities, signs of ill health or reaction to treatment were recorded.

Ophthalmoscopic examination:
In the main study, eye observations were made in 20 rats/sex of the control group, the top-dose group and the lactose control group. The examinations were carried out prior to the start of the study (on day -4), and at the end of the treatment-period (day 86 for males, day 86 or 88 for females).
A hand slit lamp was used for the eye examination which was conducted after induction of mydriasis with a 1% solution of atropine sulphate.

Body weights:
The individual body weights of all rats were recorded initially, and at weekly intervals thereafter, throughout the main-and the additional study. In addition, rats were weighed on the day of autopsy in order to calculate their correct organ to body weight ratios.

Food consumption:
Food intake was measured per cage (5 rats/cage) weekly, by weighing the feeders, throughout the main- and the additional study. The efficiency of food utilization in the period of rapid growth was calculated and expressed as gram weight gain per gram food consumed.

Water intake:
The water consumption was measured on a cage basis (5 rats/cage) by daily weighing the water bottles, during the first seven days of the study and subsequently during four-day periods in week 4, 8, and 12 and, for the recovery study only, in week 16.

Haematology:
Haematology in the treatment period:
The following haematological variables were determined in blood collected from the tip of the tail of 10 rats/sex/treatment group on day 85.
The following analyses were conducted:
- haemoglobin concentration
- packed cell volume
- red blood cell count
- red blood cell distribution width (ROW-SO)
- total white blood cell count
- differential white blood cell count
- prothrombin time
- thrombocyte count
- mean platelet volume (MPV)
- platelet distribution width (POW)
- mean corpuscular volume (MCV)
- mean corpuscular haemoglobin (MCH)
- mean corpuscular haemoglobin concentration (MCHC)

Haematology in the recovery period:
In the recovery period of the study, blood was collected from the tip of the tail of all rats of the recovery groups on day 113. The above parameters were determined except for differential white blood cell count.

Clinical chemistry:
Clinical chemistry in the treatment period:
On day 88, blood was collected from the tip of the tail of 10 rats/ sex/ treatment group, after deprivation of water for 24 hours and of food during the last 16 hours of this period. In the blood samples glucose was determined.
Blood was collected from 10 rats/ sex/ treatment group whilst under ether anaesthesia at autopsy. The sampling was done on day 91-93, in such a sequence that the average time of sampling was about the same for each treatment group. The blood samples were collected from the abdominal aorta in heparinized plastic tubes. The samples were centrifuged at 1250 x g for about 15 minutes, using Sure-sep II dispensers from General Diagnostics for good separation of the plasma. The following measurements were made in the plasma:
- alkaline phosphatase activity (ALP)
- aspartate aminotransferase activity (ASAT)
- alanine aminotransferase activity (ALAT)
- gamma glutamyl transferase activity (GGT)
- total protein
- albumin
- ratio albumin to globulin
- urea
- total bilirubin
- creatinine
- inorganic phosphate
- sodium (Na)
- potassium (K)
- calcium (Ca)
- chloride (Cl)
- triglycerides
- phosholipids
- total cholesterol

Urine analysis:
Urine analysis in the treatment period:
Determinations in fasting urine samples.:
Shortly before the end of the treatment period (on day 87-88), 10 rats/ sex/ treatment group were deprived of water for 24 hours and of food during the last 16 hours of this period.
During the last 16 hours of the deprivation period, urine was collected from individual animals while kept in metabolism cages for separate collection of urine and faeces. The following determinations were carried out on day 88:
In individual urine samples;
- volume
- density
In pooled urine samples [2 –samples (of 5 rats each)/sex/treatment group];
- appearance
- glucose
- occult blood
- ketones
- protein
- bilirubin
- urobilinogen
- microscopy of the sediment.

Determinations in non-fasting urine samples:
Shortly before the end of the treatment period (on day 87), freshly voided urine samples were collected from 10 rats/ sex/ treatment group during 2-3 hours early in the morning. The following examinations were conducted in individual samples:
- pH
- calcium concentration
- calcium excretion (expressed normalized according to creatinine).

Urine analysis in the recovery period:
Shortly before the end of the recovery period (on day 115), non-fasting urine samples were collected from all rats of the recovery groups as described above. The following examinations were conducted in individual samples:
- pH
- calcium concentration
- calcium excretion (expressed normalized according to creatinine)

Faeces analysis
Faeces analysis in the treatment period:
Shortly before the end of the treatment period (on day 73), fresh faeces samples of as much rats of the treatment groups as possible were collected and pooled per cage. The samples were homogenized with a standard amount of distilled water and the pH was recorded by means of Philips P.W. 9410 pH meter.
Subsequently (day 74), all faeces produced during a 24-hour period was collected per cage in all treatment groups. The samples were dried in an oven (at 80°C, during 24 hours), the dry weight of the faeces produced during 24-hour was recorded and the nitrogen content of the faeces was determined by Kjeldahl. The nitrogen excretion per 24 hours was calculated (nitrogen content of (dried) faeces x total weight of (dried) faeces produced in 24-h).

Faeces analysis in the recovery period:
The faeces analyses described above were repeated in the recovery period. The pH of the faeces was determined on day 112, and the total dry faeces weight, faecal nitrogen content and nitrogen excretion were determined for faeces collected on day 113.

Sacrifice and pathology:

Autopsy at the end of the treatment period:
In week 14, all rats of the treatment groups were killed on a number of successive working days by exsanguination from the abdominal aorta under ether anaesthesia. Autopsy was performed on day 91-95, in such a sequence that the average time of killing was approximately the same for each treatment group. All animals were examined macroscopically for pathological changes, and the following organs of all animals were weighed:
Adrenals, brain, caecum (full and empty), heart, kidneys, liver, ovaries, spleen, testes, thyroid and parathyroids, thymus (if present). Samples of the following tissues and organs of all animals were preserved in a neutral, aqueous, phosphate-buffered, 4 per cent solution of formaldehyde:
Adrenals, aorta, axillary lymph nodes, brain (brain stem, cerebrum and cerebellum), caecum, pancreas, parotid salivary glands, pituitary, prostate, rectum, sciatic nerve, colon, seminal vesicles, duodenum, epididymides, eyes, exorbital lachrimal glands, femur with joint, heart, ileum, jejunum, kidneys, liver, lungs (with mainstem bronchi), mammary glands (males and females), mandibular (cervical) lymph nodes, mesenteric lymph nodes, oesophagus, ovaries, skeletal muscle (thigh), skin (flank), spinal cord (three revels), spleen, sternum (with bone marrow), stomach (cardia, fundus and pylorus), sublingual salivary glands, submaxillary salivary glands, testes, thymus, thyroid (with parathyroids), trachea, urinary bladder, uterus (with cervix), all gross lesions.

Autopsy at the end of the recovery period:
On day 119, all rats of the recovery groups were killed by exsanguination from the abdominal aorta under ether anaesthesia. Autopsy was performed in such a sequence that the average time of killing was approximately the same for each recovery group. All animals were examined macroscopically for pathological changes, and the organs or tissues were weighed and preserved.

Other examinations:

Microscopic examination:
Microscopic examination at the end of the treatment period:
The tissues required for microscopic examination were processed and embedded in paraffin wax. Sections were cut at 5 µm and stained with haematoxylin and eosin, and then examined microscopically.
Histopathological examination was conducted on rats killed at the end of the treatment period. All tissues and organs listed above were examined in all animals of the control group and the top-dose group. In addition, the kidneys, liver, lungs and gross lesions were examined microscopically in all rats of the low- and mid-dose groups.

Microscopic examination at the end of the recovery period:
Histopathological examination was not conducted in rats of the recovery groups, because treatment-related histopathological changes were not observed at the end of the treatment-period.

Statistics:

Body weight data were analysed by one-way analysis of covariance using pre-exposure (day 0) weights as the covariate. When group means were significantly different (p<0.05), individual pairwise comparisons were made using Dunnett's multiple comparison method. During the recovery period, body weight data were analysed by two sample t-tests. Food intake, water intake and food conversion efficiency data were analysed by one-way analysis of variance. If significant differences (p<0.05) among the means occurred, LSD tests were performed to determine which groups differed significantly from the controls. During the recovery period, food- and water intake data were analysed by two sample t-tests. Haematology, clinical chemistry, urinary volume, density and calcium levels, and organ weight data were analysed by ANOVA and Dunnett's tests. During the recovery period, two sample t-tests or Mann-Whitney U tests (for urinary calcium data and faeces data) were applied. White blood cell counts and urine pH values were analysed by Kruskal-Wallis one-way analysis of variance. In case of a significant difference, pairwise comparisons between the control- and treatment groups were made by means of Mann-Whitney U tests. Data on body weight, food/water intake, food conversion, haematology, clinical chemistry, urinary volume/density and organ weight, were analysed by two sample t-tests both in the main- and recovery period. White blood cell counts, urine pH, urinary calcium and faeces data were analysed by Mann-Whitney U tests both in the main- and recovery period. Incidences of hist.pat. changes were analysed by Fisher's exact probability test. All pairwise comparisons were two tailed. Group mean differences with an associated probability of less than 0.05 were considered to be statistically significant.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

soft stool

Mortality:

mortality observed, treatment-related

Description (incidence):

soft stool

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

slightly decreased (males)

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

slightly increased (males+females 20% .alpha.-CD), slightly decreased (males+females in other groups)

Food efficiency:

effects observed, treatment-related

Description (incidence and severity):

decreased (males)

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

effects observed, treatment-related

Description (incidence and severity):

slightly increased (males+females), slightly decreased (males+females; other group), clearly increased (males, lactose control group)

Ophthalmological findings:

no effects observed

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

see details on results

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

see details on results

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

see details on results

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

see details on results

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

caecal enlargement

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

Clinical signs and survival:
In the first few weeks of the study, soft stools were observed underneath most of the cages of the 20% .alpha.-CD group and the lactose control group. The finding, which was most evident in males, disappeared in the course of the study. Otherwise, no signs of reaction to the treatment with .alpha.-CD were observed. There were no treatment-related deaths during the study. One rat of the 5% .alpha.-CD group had to be killed on day 49 of the study because of a prolapse of the vagina.

Ophthalmoscopic examination:
Ophthalmoscopic examinations, carried out prior to the start of the study and at the end of the treatment period, did not reveal treatment related differences between the control group, the 20% lactose group or the 20% .alpha-CD group. All ocular changes observed are common findings in rats of this strain and age.

Body weights:
Mean body weights were slightly decreased in males fed 20% .alpha.-CD in the last few weeks of the treatment period. Body weights were also decreased in males of the lactose-control group throughout the treatment period. In males of the other groups and in females of all groups no consistent growth reduction was observed during the treatment period. In the recovery period, no statistically significant changes in mean body weights occurred in the 20% .alpha.-CD group or the lactose control group.

Food intake and food efficiency:
Mean food intake was slightly increased in males and females fed 20% .alpha.-CD at various stages throughout the treatment period. In the other groups, food intake was generally comparable to the controls, except for the first week of the study in which food intake was slightly decreased in males and females in the lactose group. In the recovery period, no consistent changes in food intake were observed. Food conversion efficiency was decreased in males of the 20% .alpha.-CD group and the lactose control group.

Water intake:
In the first week of the study water intake was slightly increased in males and females of the 5% or 20% .alpha.-CD group on several days. In males of the 20% .alpha.-CD group, a tendency towards increased water intake was also observed in wk 8 and wk 12. Otherwise, the feeding of .alpha.-CD did not induce consistent changes in water intake. Water intake was clearly increased in males of the lactose-control group in the first week of the study. At the subsequent stages, the males of this group showed a tendency towards increased water intake. In the recovery period, there were no distinct differences in water intake between the test groups and the controls.

Haematology:
Values obtained for red blood cell parameters did not reveal any effects that could be related to the feeding of .alpha.-cyclodextrin or lactose. Although some small differences in values obtained for treated rats attained the level of statistical significance when compared to controls, such differences did never occur in both sexes and were not accompanied by other changes in related red blood cell- or platelet variables. Therefore, they were not considered to be of toxicological significance. These change were:
- increases in haemoglobin concentration in females of the lactose control group, at the end of both the treatment period and the recovery period, and in females of the 20% .alpha.-CD group at the end of the recovery period
In males, total white blood cell count was increased in the 20% .alpha.-CD group and in the 20% lactose group. Differential counts did not reveal a shift in the percentages of white blood cells but, as a result of the increases in total white blood cells, the absolute values of both lymphocytes and neutrophils in these groups were higher than in controls. No other changes were observed in total and differential white blood cell counts at the end of the treatment period or the recovery period.

Clinical chemistry:
In males of the 20% .alpha.-CD group, gamma glutamyl transferase activity, triglycerides, phospholipids and total protein concentration were decreased, and the albumin/globulin ratio was increased at the end of the treatment period. In males of the lactose control group phospholipids and total protein concentration were also decreased and triglycerides concentration was relatively low. At the end of the recovery period, no changes were observed that could be related to the feeding of .alpha.-CD. In females of the lactose control group, phospolipids and cholesterol concentration were increased at the end of the recovery period. However, since such changes were not observed at the end of the treatment period, they are very likely fortuitous findings.

Urinalysis:
Urinary volume and density were not unfavourably affected by the treatment with .alpha.-CD, indicating unaffected concentrating ability of the kidneys. Urinary density was decreased in males of the lactose control group, but the change was only slight and, therefore, probably of no toxicological significance. No changes were found in semi-quantitative observations of the urine or microscopy of the urinary sediment that could be ascribed to the feeding of .alpha.-cyclodextrin.
The urinary pH was decreased in males and females of the lactose control group at the end of the treatment period. In rats of the .alpha.-CD groups no statistically significant changes in urinary pH occurred, although relatively low values were found in males of the 20% .alpha.-CD group in the treatment period. The urinary calcium concentration was increased in the lactose control group and the 20% .alpha.-CD group in both sexes. In order to assess changes in urinary calcium excretion, the calcium concentration was related to the creatinine level (calcium could not be related to the urinary volume, because urine was collected over only two hours). The calcium/creatinine ratio was increased in the lactose control group in both sexes and in females of the 20% .alpha.-CD group. At the end of the recovery period, no noticeable changes in urinary pH or calcium concentration were observed.
Faeces analysis:
At the end of the treatment-period, the pH of the faeces showed dose related decreases in males of all .alpha.-CD groups and in females of the top dose (20% .alpha.-CD) group. The dry weight of the faeces and the faecal nitrogen excretion were increased in the 20% .alpha.-CD group in both sexes. In the lactose control group, faecal pH was decreased in males, and the faecal weight and nitrogen excretion were increased in both sexes, but the changes were less pronounced than with 20% .alpha.-CD. At the end of the recovery period, no changes in faecal pH, weight or nitrogen excretion were observed that could be related to the feeding of .alpha.-CD or lactose.

Organ weights:
At the end of the treatment period, the absolute and the relative weights of both the full and empty caecum were clearly increased in males and females of the 5% and 20% .alpha.-CD groups and the lactose control group.At the end of the recovery period, increases in full and/or empty caecal weight were still present in males and females of the 20% .alpha.-CD group and the lactose control group, but these changes were only slight in comparison with those at the end of the treatment period.
In males, the relative adrenal weight was increased in the 20% .alpha.-CD group and in the lactose control group, at the end of the treatment period. The relative weight of the spleen was increased in males of the 20% .alpha.-CD group and in females of the lactose control group. The relative weight of the liver was slightly increased in females o£ the lactose control group. Other changes in organ weights which were observed at the end of the treatment period were not considered to be of toxicological significance for the following reasons: Increases in the relative weights of brain and testicles in males of the lactose control group are ascribed to the growth retardation in these groups and the well known inverse correlation between body weight and relative weight of the testes and brain. Decreases in the absolute weights of the liver, kidneys, thyroid and heart in males of the lactose control group, and in the absolute weight of the thyroid in males of the 5% .alpha.-CD group were not reflected in alterations in the relative weight of these organs. At the end of the recovery period, no treatment-related changes in organ weights were observed apart from the caecal enlargement mentioned above [a decreased thymus weight in males of the 20% .alpha.-CD group and the lactose control group, a decreased absolute adrenal weight in males of the 20% .alpha.-CD group were considered to be fortuitous findings since they were not observed at the end of the treatment period].

Pathology:
Gross examination:
Gross examination at autopsy revealed caecal enlargement in 4 males and 6 females of the 20% .alpha.-CD group and in 4 males and 1 female of the lactose control group. All other gross changes are common findings in rats of this strain and age, and occurred in one or a few animals only.

Microscopic examination:
The incidence of rats with corticomedullary mineralisation in the kidneys was relatively high in females of the 1.5% .alpha.-CD group. In the 1.5% .alpha.-CD group, the difference with the controls attained the level of statistical significance. These changes are not considered to be treatment-related because they were not confirmed at higher dose level(s) and because a large variation in incidence of this renal change is not uncommon in female rats. Moreover, the changes were about equally distributed among the control group and the top-dose groups or they occurred in a single animal only. Therefore, they were not ascribed to the feeding of .alpha.-cyclodextrin.

Dose descriptor:

NOAEL

Effect level:

> 20 other: % in the diet

Based on:

test mat.

Sex:

male

Basis for effect level:

other: overall effects

Dose descriptor:

NOAEL

Effect level:

12 764 mg/kg bw/day (nominal)

Based on:

test mat.

Critical effects observed:

not specified

Conclusions:

In conclusion, since 20% .alpha.-CD induced changes of any toxicological significance which were not induced by 20% lactose, it appears that these test substance is as safe as lactose. Moreover, the observed changes appeared to be reversible.
Because the findings produced by 20% lactose are not considered to represent toxic effects, it also appears that even 20% of the test substances cannot be considered a toxic effect level. Therefore it is concluded that under the conditions of the study, dietary levels of up to 20% .alpha.-CD are tolerated without obvious signs of toxicity.

Executive summary:

The oral toxicity of .alpha.-cyclodextrin (.alpha.-CD) was examined in a sub-chronic (13-week) study with groups of 20 male and 20 female wistar rats. The test substance was incorporated in the diet at levels of 0 (control), 1.5%, 5% and 20%. For comparison, one extra control group was fed a diet containing 20% lactose.

In addition, the recovery of the changes induced was examined with groups of 10 rats/sex which were fed control diet or diet containing 20% .alpha.-CD or 20% lactose during the same 13-week period, followed by a one-month non-treatment period.

There were no treatment-related deaths during the study. Ophthalmoscopic examination did not reveal any effects attributable to the feeding of .alpha.-CD or lactose. In the first few weeks of the study, soft stools were observed in rats of the 20% .alpha.-CD group and the lactose control group.

Slight growth retardation was observed in males of the 20% .alpha.-CD group and the lactose control group. This finding was ascribed to less efficient utilization of the top-dose diets, and was accompanied by decreased food efficiency figures in the 20% .alpha.-CD group and the lactose control group, and by increased food intake in the 20% .alpha.-CD group.

In the first week of the study, water intake was increased in the 5% and 20% .alpha.-CD groups and in the lactose control group.

Total white blood cell count was increased in males of the 20% .alpha.-CD group and the lactose control group.

In males of the 20% .alpha.-CD group, plasma y-glutamyltransferase activity, phospholipids, triglycerides and total protein concentration were decreased. Phospholipids and total protein concentration were also decreased in males of the lactose control group.

Increases in urinary calcium concentration were observed in the 20% .alpha.-CD group and the lactose control group.

Faecal dry weight and excretion of faecal nitrogen were increased, and faecal pH was decreased in the 20% .alpha.-CD group and in the lactose control group. Faecal pH was also decreased in males of the 1.5% and 5% .alpha.-CD group.

The weights of the filled and empty caecum were increased in the 5% and 20% .alpha.-CD groups and the lactose control group.

The relative weight of the adrenals was increased in males of the 20% .alpha.-CD group and the lactose control group. The relative weight of the spleen was increased in males of the 20% .alpha.-CD group and in females of the lactose control group. The relative weight of the liver was slightly increased in females of the lactose control group.

Microscopic examination did not reveal any treatment-related differences between the controls and the rats of the 20% .alpha.-CD group.

At the end of the recovery period, the above changes had disappeared, except for a slight increase in caecum weight which was still observed in the 20% .alpha.-CD group and the lactose control group.

The changes seen even at the highest dietary level (20%) of .alpha.-CD were common to those observed with lactose, and consisted of nonspecific findings which represent adaptations to the ingestion of low digestibility carbohydrates, rather than toxic effects of cyclodextrins. Therefore it was concluded that, under the conditions of the study, dietary levels of up to 20% .alpha.-CD are tolerated without obvious signs of toxicity.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

12 764 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

Klimisch 1

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

repeated dose toxicity: inhalation

Data waiving:

other justification

Justification for data waiving:

other:

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Link to relevant study records

Reference

Endpoint:

repeated dose toxicity: inhalation

Data waiving:

other justification

Justification for data waiving:

other:

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Link to relevant study records

Reference

Endpoint:

repeated dose toxicity: dermal

Data waiving:

other justification

Justification for data waiving:

other:

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Link to relevant study records

Reference

Endpoint:

repeated dose toxicity: dermal

Data waiving:

other justification

Justification for data waiving:

other:

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

The oral toxicity of .alpha.-cyclodextrin (.alpha.-CD) was examined in a sub-chronic (13-week) study with groups of 20 male and 20 female wistar rats. The test substance was incorporated in the diet at levels of 0 (control), 1.5%, 5% and 20%. For comparison, one extra control group was fed a diet containing 20% lactose. In addition, the recovery of the changes induced was examined with groups of 10 rats/sex which were fed control diet or diet containing 20% .alpha.-CD or 20% lactose during the same 13-week period, followed by a one-month non-treatment period. There were no treatment-related deaths during the study. Ophthalmoscopic examination did not reveal any effects attributable to the feeding of .alpha.-CD or lactose. In the first few weeks of the study, soft stools were observed in rats of the 20% .alpha.-CD group and the lactose control group. Slight growth retardation was observed in males of the 20% .alpha.-CD group and the lactose control group. This finding was ascribed to less efficient utilization of the top-dose diets, and was accompanied by decreased food efficiency figures in the 20% .alpha.-CD group and the lactose control group, and by increased food intake in the 20% .alpha.-CD group. In the first week of the study, water intake was increased in the 5% and 20% .alpha.-CD groups and in the lactose control group. Total white blood cell count was increased in males of the 20% .alpha.-CD group and the lactose control group. In males of the 20% .alpha.-CD group, plasma y-glutamyltransferase activity, phospholipids, triglycerides and total protein concentration were decreased. Phospholipids and total protein concentration were also decreased in males of the lactose control group. Increases in urinary calcium concentration were observed in the 20% .alpha.-CD group and the lactose control group. Faecal dry weight and excretion of faecal nitrogen were increased, and faecal pH was decreased in the 20% .alpha.-CD group and in the lactose control group. Faecal pH was also decreased in males of the 1.5% and 5% .alpha.-CD group. The weights of the filled and empty caecum were increased in the 5% and 20% .alpha.-CD groups and the lactose control group. The relative weight of the adrenals was increased in males of the 20% .alpha.-CD group and the lactose control group. The relative weight of the spleen was increased in males of the 20% .alpha.-CD group and in females of the lactose control group. The relative weight of the liver was slightly increased in females of the lactose control group. Microscopic examination did not reveal any treatment-related differences between the controls and the rats of the 20% .alpha.-CD group. At the end of the recovery period, the above changes had disappeared, except for a slight increase in caecum weight which was still observed in the 20% .alpha.-CD group and the lactose control group. The changes seen even at the highest dietary level (20%) of .alpha.-CD were common to those observed with lactose, and consisted of nonspecific findings which represent adaptations to the ingestion of low digestibility carbohydrates, rather than toxic effects of cyclodextrins. Therefore it was concluded that, under the conditions of the study, dietary levels of up to 20% .alpha.-CD are tolerated without obvious signs of toxicity.

Justification for classification or non-classification

The subchronic oral treatment with .alpha.-cyclodextrin did not induce signs of adverse effects in dogs up to dietary levels of 20%.alpha.-cyclodextrin. The read-across substance .beta.-cyclodextrin showed no adverse effects or signs of toxicity in a chronic study in dogs up to 50.000 ppm. The data are conclusive but not sufficient for classification.