Registration Dossier

Diss Factsheets

Administrative data

Endpoint:
short-term repeated dose toxicity: oral
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
1996-09-24 to 1996-11-07
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1997
Report date:
1997

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)
Qualifier:
according to guideline
Guideline:
EU Method B.7 (Repeated Dose (28 Days) Toxicity (Oral))
GLP compliance:
yes
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Cyclododecanol
EC Number:
217-031-2
EC Name:
Cyclododecanol
Cas Number:
1724-39-6
Molecular formula:
C12H24O
IUPAC Name:
cyclododecanol
Details on test material:
TS: Cyclododecanol of Hüls AG, Sample from drum 1-358, ID 0637/81783, produced Jan/Feb 1996. Purity 99.3-99.4 % (2 GC analyses)

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ORGANISMS
- Strain: Wistar, Hsd/Win:WU
- Source: Harlan Winkelmann GmbH, D-33176 Borchen
- Age: approximately 6 to eight  weeks at beginning of treatment
- Weight at study initiation: Group means 137-142 g (females) / 205-219 g  (males)
- Number of animals: 5 per sex and dose group, total 60:   3 dose + 1 control + 2 recovery groups (high dose + control) = 6 groups
- Housing: five rats in MAKROLON cages
- Diet: ad libitum pelleted diet, Ssniff R 10
- Water: ad libitum, tab water
- Acclimation period: at least 5 days
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 °C +/- 3 °C
- Humidity (%): 30 % - 70%
- Air changes (per hr): 15 fold
- Photoperiod (hrs dark / hrs light): 12h/12h

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on oral exposure:
ADMINISTRATION / EXPOSURE 
- Vehicle: Corn oil. Formulations prepared weekly
- Concentration in vehicle: 30 / 100 / 200 mg/ml
- Total volume applied: 5 ml/kg bw/day
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The concentration (weight-%) was determined by gas-liqiud chromatography. The density was determined by a density meter or a density bottle
and used to calculate concentration in weight/volume. Details see below under: other informations on results
Duration of treatment / exposure:
28 days
Frequency of treatment:
daily (i.e. 28 administrations)
Doses / concentrations
Remarks:
Doses / Concentrations:
150; 500; 1000 mg/kg bw/day
Basis:

No. of animals per sex per dose:
5 per sex and dose group, total 60:   
3 dose + 1 control + 2 recovery groups (high dose + control) = 6 groups
Control animals:
yes, concurrent vehicle
Details on study design:
Post-exposure period: 2 weeks (recovery groups only)
Positive control:
no positive control

Examinations

Observations and examinations performed and frequency:
CLINICAL OBSERVATIONS AND FREQUENCY: 
- Clinical signs: Twice daily (weekends: once daily); detailed  examination once a week
- Mortality: Twice daily (weekends: once daily)
- Body weight: Before first dose and at 7 day intervals thereafter
- Food consumption: In each cage (i.e. for 5 animals) in weekly intervals
- Water consumption: Once daily for each cage group
- Ophthalmoscopic examination: During 5 day acclimatization and prior to  terminal sacrifice, using an opthalmoscope and treating one eye with  
Mydriaticum Stulln(R) prior to investigation.
- Hematology: End of treatment / recovery period: red blood cell count,  total white blood cell count, platelet count, hemoglobin, hematocrit,  
erythrocyte indices (mean corpuscular volume, mean corpuscular  hemoglobin, mean corpuscular hemoglobin concentration), differential  white 
blood cell count.
- Biochemistry: End of treatment / recovery period: sodium, potassium,  calcium, aspartate aminotransferase, alanine aminotransferase, alkaline  
phosphatase, glucose, triglycerides, cholesterol, total bilirubin, blood  urea nitrogen, creatinine, total protein, albumin.
- Urinalysis: End of treatment / recovery period: volume, specific  gravity, pH, color. Semiquantitative: protein, glucose, keton,  urobilinogen, blood 
ingredients. Microscopic urine sediment analysis:  Leucocytes, erythrocytes, bacteria, epithelial cells (squamous), oxalate  crystals, triple phosphate  crystals, urate crystals.
Sacrifice and pathology:
ORGANS EXAMINED AT NECROPSY (MACROSCOPIC AND MICROSCOPIC): 
- Macroscopic: Complete autopsy including macropathological examination.  Weights of adrenals, kidneys, liver, spleen, testes.
- Microscopic: Selection of organs depended on macroscopic findings.  Histopathological examination was performed for epididymis, kidney,  liver, 
lung, mandibular lymph node, ovary, testis and uterus of control  and high-dose groups. It was extended to other groups in case of  substance 
related findings (liver: all; lung: 7 selected individuals;  uterus: 1 female).
Other examinations:
no other examinations
Statistics:
STATISTICAL METHODS:
- Kruskal Wallis non parametric analysis of variance; in case of  significance pairwise comparison using a Wilcoxon, Mann, and Whitney  U-Test: 
Absolute body weights, body weight changes, absolute and relative  organ weights, differential blood count and urine analysis data.
- One way analysis of variance (ANOVA) incorporating a Bartlett's test  for homogeneity of variance; in case of heterogenous variances Kruskal  Wallis  test; in case of significant ANOVA Scheffe Test: Hematological  data (except differential blood count) and serum clinical chemistry data.
- Group means with standard deviation, medians, ranges, or geometric  means where appropriate.

Results and discussion

Results of examinations

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 examined
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
no effects observed
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
Higher relative liver weights were noted in the female high and medium dose groups when compared with controls.
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
The livers of 4 females and 3 males of the high-dose group showed mild  to moderate centrolobular hypertrophy. 
Histopathological findings: neoplastic:
no effects observed
Details on results:
TOXIC RESPONSE/EFFECTS BY DOSE LEVEL: 
- Mortality and time to death: There were no mortalities.
- Clinical signs: One high dose male animal showed at the end of the  first treatment week for a duration of two days aggravated breath and  salivation  No other clinical signs were observed during treatment and  recovery period.
- Body weight gain: No findings of toxicological importance were found.
- Food/water consumption: Mean food consumption was similar in all  groups. The highest differences between treated and control were observed  
for low-dose females (5-7 % below control, not statistically  significant). The food conversion rate was insignificantly increased in  all dosed groups  when compared with control, which was considered to be substance-related. Evidence of reversibility was found at the end of the  recovery period.    There were no overt intergroup differences in water consumption.
- Ophthalmoscopic examination: No signs of test substance related effects  on lenses or cornea were observed in either dose group.
- Clinical chemistry: Findings at the end of the treatment or recovery  period were considered to be of no toxicological importance. In females,  
statistically significant differences between treated and control were  confined to the mid-dose group. In high-dose males, aspartate  
aminotransferase (-43 %) and alkaline phosphatase (-32 %) were  significantly reduced and also slightly outside the range of historical  background  data, however evidence of reversibility was found in the  recovery animals. 
Blood urea nitrogen was increased in mid- (+18 %) and  high-dose males (+30 %), and triglycerides were decreased in low- (-19 %)  and high-dose 
(-41 %) males. Although statistically significant, these  differences were minor and within the normal range of historical  background data. Evidence  of reversibility was found in the recovery  groups.
- Hematology: No relevant findings were noted in treated animals.  
Statistically significant differences between treated and control were  confined to recovery males, low, and within the range of historical  control data-  Urinalysis: No findings of toxicological importance were noted.  Statistically significant differences between treated and control were  confined to mi d-dose males, low, and within the range of historical  control data.
- Organ weights: Statistically significantly higher relative (not  absolute) liver weights were noted in the female high (+19 %) and medium  
(+16 %) dose groups when compared with controls. These differences were  considered to be treatment-related. Evidence of reversibility was found   at the end of the recovery period (treated 4.8 % above control). No other  statistically significant differences between treated and control were 
observed at the end of the treatment period. At the end of the recovery  period, dosed males showed statistically significantly higher absolute  
(+13 %) and relative (+13 %) kidney weights when compared with the  recovery control group. This was mainly due to a severe increase in one  
animal and was not associated with any relevant finding. Thus it was  considered to be of minor toxicological importance.
- Gross pathology: No macroscopical lesions were considered to be related  to treatment with the test substance.
- Histopathology: The histopathological findings in the high dose and  control groups consisted of spontaneous lesions such as hydrometriosis of  
the uterus, focal cortical calcification of the kidney, focal hemopoiesis  in the liver and mild to moderate pneumonia characterized by multifocal  
interstitial lymphocyte infiltrates. The lesions in the lung were most  likely caused as part of a virus infection. The other changes were  considered 
part of the normal background.   
The livers of 4 females and 3 males of the high-dose group showed mild  to moderate centrolobular hypertrophy. Therefore the livers of all other  
groups including the recovery groups were examined. Mild to moderate  centrolobular hypertrophy was also found in 4 mid-dose and 1 low-dose   males and in 5 mid-dose and 3 low-dose females but not in treated or  control recovery rats. None of the livers examined showed nuclear or 
cytoplasmic degenerative or necrotic changes of hepatocytes. The  hepatocellular hypertrophy was correlated with higher relative liver  weights in 
medium- and high-dose females. These findings were considered  to be substance-related. Evidence of reversibility was found at the end  of the 
recovery period. It is suggested that the reversible liver changes  observed are an expression of an adaptive response of the liver to the  test 
substance. As such, it is generally not considered as an adverse  effect.

Effect levels

Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw/day (nominal)
Sex:
male/female
Basis for effect level:
clinical biochemistry

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

ACTUAL DOSE RECEIVED BY DOSE LEVEL BY SEX
  Two formulations per dose level were analyzed at two different times 

 separated by one week, leading to four analytical values per dose level:
  ---------------------------------------------------------
  Nominal   first analysis   repeat analysis       mean
    30       28.5 /  29.4      29.5 /  29.9     29.3 mg/cm3
   100       92.5 /  92.1      92.5 /  94.7     92.9 mg/cm3
   200      137.6 / 185.1     143.7 / 187.3    163.4 mg/cm3
  ---------------------------------------------------------
  The analytical values are slightly reduced by measuring the density in  

a pycnometer at 100 °C. The repeat analyses confirm the stability of the  

formulations. Only for one high concentration formulation the analytical  

result was clearly below the nominal concentration. The mean analytical  

concentrations correspond to dose levels of 147; 465; 817 mg/kg bw/day.

Applicant's summary and conclusion

Conclusions:
The increased food conversion rate noticed in treated males and females during the treatment period was reversible and therefore not regarded as an adverse effect. The reversible liver changes are regarded as a transient adaptive response of the liver to the test substance. As such they are generally not considered as an adverse effect. Therefore the NOAEL is 1000 mg/kg bw/day.
Executive summary:

In this 28-day repeated dose oral toxicity study three groups of male and female rats were dosed with 150, 500, and 1000 mg Cyclododecanol /kg bw daily for 4 weeks by oral gavage. A concurrrent control group received corn oil only. A control and a high dose recovery group each consisting of five males and 5 females, were observed for a perios of 14 days after the end of the dosing period. There were no mortalities during the study. Apart from one male which showed during the treatment period for a duration of 2 days aggravated breath and salivation, no clinical signs were observed. For Ophthalmological examination, bodyweight, water consumption, Serum clinical chemistry, haematology, urine analysis and necroscopy no findings of toxiclogical importance were noted. The increased food conversion rate noticed in treated males and females during treatment period was reversible and therefore not regarded as adverse effect. Centrolobular hypertrophy was observed predominantly in the liver of male and female animals in the high and medium dose group, but was also found to a certain extent in male and female animals of the low dose group. The hepatocellular hypertrophy was correlated with statistically significant higher relative liver weights in medium and high dose females. These findings were considered to be substance-related. Evidence of reversibility was found at the end of the recovery period. The reversible liver changes are regarded as a transient adaptive response of the liver to the test substance. As such, it is gerenerally not considered as adverse effect.

Therefore, in our experimental conditions, the no-observed-adverse-effect level (NOAEL is 1000 mg/kg/day.