Undecanal

Endpoint summary

Description of key information

In an OECD TG 422 study, undecanal did not cause systemic toxicity in male and female rats at doses (oral gavage) up to and including 1000 mg/kg bw and day. Local irritation in the stomach was noted at all dose levels starting at 100 mg/kg bw and day. 

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: oral

Remarks:

combined repeated dose and reproduction / developmental screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13 October 2009 - 30 November 2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

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

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: 2) The United States Environmental Protection Agency (EPA) Health Effects Test Guidelines OPPTS 870.3650, Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test, July 2000.

Deviations:

no

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

other: Crl:WI(Han)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany.
- Age at study initiation: Approximately 12 weeks.
At start treatment the animals were 12 weeks old instead of 10 weeks. A slight deviation in age does not affect the study integrity. Mating started shortly after the animals had attained full sexual maturity according to the OECD 422 guideline.
- Weight at study initiation: no data
- Fasting period before study: no
- Housing:
Pre-mating:Animals were housed in groups of 5 animals/sex/cage in Macrolon cages (MIV type, height 18 cm).
Mating:Females were caged together with males on a one-to-one-basis in Macrolon cages (MIII type, height 18 cm).
Post-mating:Males were housed in their home cage (Macrolon cages, MIV type, height 18 cm) with a maximum of 5 animals/cage. Females were individually housed in Macrolon cages (MIII type, height 18 cm).
General: Sterilised sawdust as bedding material (Litalabo, S.P.P.S., Argenteuil, France) and paper as cage-enrichment (Enviro-dri, Wm. Lillico & Son (Wonham Mill Ltd), Surrey, United Kingdom) were supplied. Certificates of analysis were examined and then retained in the NOTOX archives. During the motor activity test, males were caged individually and females were caged with their pups.No cage-enrichment was provided during activity monitoring.
- Health check F0: A health inspection was performed prior to commencement of treatment to ensure that the animals were in a good state of health.
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: At least 5 days prior to start of treatment.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19.6 – 21.6°C
- Humidity (%): 31 - 69%
Temporary deviations from the minimum level of relative humidity occurred in the animal room. Laboratory historical data do not indicate an effect of the deviations.

- Air changes (per hr): approximately 15 air changes per hour
- Photoperiod (hrs dark / hrs light): 12 hours artificial light and 12 hours darkness per day. Temporary fluctuations from the light/dark cycle (with a maximum of 1 hour) occurred due to performance of pupillary reflex tests in the room. Based on laboratory historical data, these fluctuations were considered not to have affected the study integrity.

IN-LIFE DATES: From: 13 October 2009 To: 30 November 2009

Route of administration:

oral: gavage

Vehicle:

propylene glycol

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
Formulations (w/w) were prepared daily within 6 hours prior to dosing and were homogenised to a visually acceptable level. Adjustment was made for density of the test substance (0.832 g/ml; i.e. the mean of the range indicated by the sponsor), and for specific gravity of the vehicle.

VEHICLE
- Justification for use and choice of vehicle (if other than water): Based on trial formulations performed at NOTOX.
- Concentration in vehicle: 20, 60 and 200 mg/ml
- Dose volume: 5 mL/kg body weight. Actual dose volumes were calculated according to the latest body weight.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses were conducted on a single occasion during the treatment phase, according to a validated method (NOTOX project 492005). Samples of formulations were analyzed for homogeneity (highest and lowest concentration) and accuracy of preparation (all concentrations). Stability in vehicle over 6 hours at room temperature was also determined (highest and lowest concentration).

The accuracy of preparation was considered acceptable if the mean measured concentrations were 90-110% of the target concentration. Homogeneity was demonstrated if the coefficient of variation was ≤ 10%. Formulations were considered stable if the relative difference before and after storage was maximally 10%.

Results:
The concentrations analysed in the formulations of Group 2, Group 3 and Group 4 were in agreement with target concentrations (i.e. mean accuracies between 90% and 110%).

A small response at the retention time of the test substance was observed in the chromatograms of the Group 1 formulation. It was not considered to derive from the formulation since a similar response was obtained in the analytical blanks.

The formulations of Group 2 and Group 4 were homogeneous (i.e. coefficient of variation ≤ 10%).

Formulations at the entire range were stable when stored at room temperature for at least 6 hours.

Duration of treatment / exposure:

Males were exposed for 28 days, i.e. 2 weeks prior to mating, during mating, and up to termination. Females were exposed for at 42-48 days, i.e. during 2 weeks prior to mating, during mating, during post-coitum, and during at least 4 days of lactation. Two females of Group 3 were not dosed during littering.

Frequency of treatment:

Once daily for 7 days per week, approximately the same time each day with a maximum of 6 hours difference between the earliest and latest dose. Animals were dosed up to the day prior to scheduled necropsy.

Dose / conc.:

0 mg/kg bw/day (actual dose received)

Dose / conc.:

100 mg/kg bw/day (actual dose received)

Dose / conc.:

300 mg/kg bw/day (actual dose received)

Dose / conc.:

1 000 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dose levels were based on results of a 14-day dose range finding study (NOTOX Project 492083). See Attachment.
- 5 animals/sex/group were randomly selected at allocation for functional observations, clinical pathology, macroscopic examination (full list), organ weights (full list) and histopathology:
Males: the first 5 males per group
Females: with live offspring only

Positive control:

no

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: At least twice daily (early morning/late afternoon).

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: At least once daily detailed clinical observations were made in all animals, at least between approximately 1 and 2 hours after dosing. Once prior to start of treatment and at weekly intervals this was also performed outside the home cage in a standard arena. Arena observations were not performed when the animals were mating, or housed individually.

BODY WEIGHT: Yes
- Time schedule for examinations: Males and females were weighed on the first day of exposure and weekly thereafter. Mated females were weighed on Days 0, 4, 7, 11, 14, 17 and 20 post-coitum and during lactation on Days 1 and 4.
- For one female of Group 1 no body weight was determined during the post-coitum period as mating of this female was overlooked. Body weights were determined during the mating period.

FOOD CONSUMPTION : Yes
- Weekly, for males and females. Food consumption was not recorded during the breeding period. Food consumption of mated females was measured on Days 0, 4, 7, 11, 14, 17 and 20 post-coitum and on Days 1 and 4 of lactation.
- For one female of Group 1 no food consumption was determined during the post-coitum period as mating of this female was overlooked. Sufficient food consumption data is available to make a good assessment.

FOOD EFFICIENCY: Yes
- (food consumption per animal per day/ average body weightper cage)*1000

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: immediately prior to scheduled post mortem examination, between 7.00 and 10.30 a.m.
- Anaesthetic used for blood collection: Yes (iso-flurane)
- Animals fasted: Yes, but water was provided
- How many animals: 5 animals/sex/group (females: with live offspring only)
- Parameters checked were: White blood cells, Differential leucocyte count (neutrophils, lymphocytes, monocytes, eosinophils, basophils) Red blood cells, Reticulocytes, Red blood cell distribution width, Haemoglobin, Haematocrit, Mean corpuscular volume, Mean corpuscular haemoglobin, Mean corpuscular haemoglobin concentration, Platelets, Prothrombin time, Activated Partial thromboplastin time

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: immediately prior to scheduled post mortem examination, between 7.00 and 10.30 a.m.
- Animals fasted: Yes, but water was provided
- How many animals: 5 animals/sex/group (females: with live offspring only)
- Parameters checked in table were: Alanine aminotransferase, Aspartate aminotransferase, Alkaline phosphatase, Total Protein, Albumin, Total Bilirubin, Urea, Creatinine, Glucose, Cholesterol, Sodium, Potassium, Chloride, Calcium, Inorganic Phosphate, Bile acids.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: The selected males were tested during Week 4 of treatment and the selected females (with live offspring) were tested during lactation (all before blood sampling).
- Dose groups that were examined: all
- Battery of functions tested: hearing ability, pupillary reflex, static righting reflex, grip strength and motor activity test

Sacrifice and pathology:

GROSS PATHOLOGY: Yes

All animals were subjected to macroscopic examination of the cranial, thoracic and abdominal tissues and organs, with special attention being paid to the reproductive organs. Descriptions of all macroscopic abnormalities were recorded. The number of former implantation sites and corpora lutea was recorded for all paired females.

Samples of the following tissues and organs were collected and fixed in 10% buffered formalin (neutral phosphate buffered 4% formaldehyde solution, Klinipath, Duiven, The Netherlands):

Selected 5 animals/sex/group (females: with live offspring only):

Identification marks (not processed), Adrenal glands, Aorta, Brain (cerebellum, mid-brain, cortex), Caecum, Cervix, Clitoral gland, Coagulation gland, Colon, Duodenum, Epididymides *, Eyes with optic nerve (if detectable) and Harderian gland *, Female mammary gland area, Femur including joint, Heart, Ileum, Jejunum, Kidneys, (Larynx), (Lacrimal gland, exorbital), Liver, Lung (infused with formalin), Lymph nodes (mandibular,mesenteric), (Nasopharynx), Oesophagus, Ovaries, Pancreas, Peyer's patches (jejunum, ileum) if detectable, Pituitary gland, Preputial gland, Prostate gland, Rectum, (Salivary glands - mandibular, sublingual), Sciatic nerve, Seminal vesicles, Skeletal muscle, (Skin), Spinal cord (cervical, midthoracic, lumbar), Spleen, Sternum with bone marrow, Stomach, Testes *, Thymus, Thyroid including parathyroid (if detectable), (Tongue), Trachea, Urinary bladder, Uterus, Vagina, All gross lesions

*Fixed in modified Davidson's solution (prepared at NOTOX using Formaldehyde 37-40%, Ethanol, Acetic acid (glacial)(all Merck, Darmstadt, Germany) and Milli-Ro water (Millipore Corporation, Bedford, USA)) and transferred to formalin after fixation for at least 24 hours.

Tissues/organs mentioned in parentheses were not examined by the pathologist, since no signs of toxicity were noted at macroscopic examination.

ORGAN WEIGHTS: Yes

The following organ weights and terminal body weight were recorded from the following animals on the scheduled day of necropsy:

Selected 5 animals/sex/group (females: with live offspring only): Adrenal glands, Spleen, Brain, Testes, Epididymides, Thymus, Heart, Uterus (including cervix), Kidneys, Prostate*, Liver, Seminal vesicles including coagulating glands*, Ovaries, Thyroid including parathyroid*
* weighed when fixed for at least 24 hours.

HISTOTECHNOLOGY: Yes
All organ and tissue samples, as defined under Histopathology (following), were processed, embedded and cut at a thickness of 2-4 micrometers and stained with haematoxylin and eosin (Klinipath, Duiven, The Netherlands).

HISTOPATHOLOGY: Yes
The following slides were examined by a pathologist:
- The preserved organs and tissues of the selected 5 animals/sex of Groups 1 and 4.
- All gross lesions of all animals (all dose groups).

Based on (possible) treatment-related changes in the stomach histological examination was extended to that particular organ of all selected animals of groups 2 and 3 (males and females).

Statistics:

The following statistical methods were used to analyse the data:
-If the variables could be assumed to follow a normal distribution, the Dunnett-test (Dunnett, 1955) (many-to-one t-test) based on a pooled variance estimate was applied for the comparison of the treated groups and the control groups for each sex.
-The Steel-test (Miller, 1981) (many-to-one rank test) was applied if the data could not be assumed to follow a normal distribution.
-The Fisher Exact-test (Fisher, 1950) was applied to frequency data.

All tests were two-sided and in all cases p < 0.05 was accepted as the lowest level of significance.
Group means were calculated for continuous data and medians were calculated for discrete data (scores) in the summary tables. Test statistics were calculated on the basis of exact values for means and pooled variances. Individual values, means and standard deviations may have been rounded off before printing. Therefore, two groups may display the same printed means for a given parameter, yet display different test statistics values. No statistical analysis was performed on histopathology findings.

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:

no effects observed

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

for details see below

Urinalysis findings:

not examined

Behaviour (functional findings):

no effects observed

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

for details see below

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

for details see below

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Details on results:

ORGAN WEIGHTS:
A higher liver weight and liver to body weight ratio, and lower prostate and prostate to body weight ratio was noted for males at 1000 mg/kg/day (statistically significant for liver to body weight ratio only). These changes were only slightly outside the normal range for rats of this age and strain.

The higher prostate to body weight ratio of males at 100 mg/kg/day occurred in the absence of a dose-related trend, and the mean remained within the range considered normal for rats of this age and strain. No toxicological relevance was ascribed to this change. Other organ weights and organ to body weight ratios among the dose groups were similar to control levels.

GROSS PATHOLOGY:
The following necropsy findings were considered to be related to treatment with the test substance:
An irregular surface of the forestomach in all males at 300 and 1000 mg/kg/day, and in 6 females at 300 mg/kg/day and nine females at 1000 mg/kg/day.
Foci (black or red) in the forestomach in two males at 300 mg/kg/day.
Yellowish discolouration of the forestomach in one male at 300 mg/kg/day and one female at 1000 mg/kg/day.
Reddish discolouration/reddish foci in the glandular mucosa in two males at 1000 mg/kg/day.
Thickened glandular mucosa in three females at 1000 mg/kg/day.

Incidental findings among control and treated animals included reddish foci on the lungs, a nodule on the liver, epididymides or clitoral glands, agenesis of the testes and epididymides, reduced size of the seminal vesicles or preputial glands, tan foci on the preputial glands, a greenish/red-brown foci on the clitoral glands, a yellowish nodule on the uterine adipose tissue, scab formation on the skin, alopecia and exophthalmus. The incidence of these findings was within the background range of findings that are encountered among rats of this age and strain, and the incidence did not show a dose-related trend. These necropsy findings were therefore considered to be of no toxicological significance.

HISTOPATHOLOGY:
There were treatment-related microscopic findings in the stomach at 100 mg/kg/day and higher:
Lymphogranulocytic inflammation of the forestomach at 100 mg/kg/day in 4/5 males (minimal), at 300 mg/kg/day in 10/10 males (1: minimal, 9: slight) and 5/6 females (4: minimal, 1: slight), and at 1000 mg/kg/day in 10/10 males (3: minimal, 6: slight, 1: moderate) and 8/9 females (6: minimal, 2: slight).
Hyperplasia of the squamous epithelium of the forestomach at 100 mg/kg/day in 3/5 males and 4/5 females (minimal), at 300 mg/kg/day in 10/10 males (8: slight, 2: moderate) and 6/6 females (3: minimal, 3: slight) and at 1000 mg/kg/day in 10/10 males (4: slight, 6: moderate) and 9/9 females (2: minimal, 6: slight, 1: moderate).
Ulcer of the forestomach in 3/10 males at 300 mg/kg/day (2: minimal, 1: slight) and in 1/10 males of Group 4 (minimal). This was the microscopic correlate to the red/black foci in the forestomach recorded at necropsy.
Congestion of the glandular stomach in 2/10 males at 1000 mg/kg/day.

All remaining microscopic findings recorded were considered to be within the normal range of background pathology encountered in Wistar (Han) rats of this age and strain.

The assessment of the integrity of the spermatogenetic cycle did not provide any evidence of impaired spermatogenesis.

Key result

Dose descriptor:

NOAEL

Remarks:

systemic toxicity

Effect level:

1 000 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No signs of sytemic toxicity noted at any dose level. Histopathological changes resulting from local irritation were seen in the stomach of either sex at 100 mg/kg bw and day and higher.

Key result

Dose descriptor:

LOAEL

Remarks:

local effects

Effect level:

100 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

histopathology: non-neoplastic

Remarks on result:

other:

Remarks:

local effects observed in the stomach

Key result

Critical effects observed:

yes

Lowest effective dose / conc.:

100 mg/kg bw/day (actual dose received)

System:

gastrointestinal tract

Organ:

other: forestomach

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

no

Local effects in forestomach are not regarded as relevant to humans, as anatomical situation in humans is different from rats and because the substance is not ingested by humans.

Conclusions:

n-Undecanal was administered by daily oral gavage to male and female Wistar Han rats at dose levels of 100, 300 and 1000 mg/kg/day. Males were exposed for 2 weeks prior to mating, during mating, and up to termination (for 28 days). The females were exposed for 2 weeks prior to mating, during mating, during post-coitum, and at least 4 days of lactation (for 42-48 days).

Formulation analysis showed that the formulations were prepared accurately and homogenously, and were stable for at least 6 hours at room temperature.

No toxicologically relevant changes were noted during clinical or functional observations or in body weight and food intake during treatment up to 1000 mg/kg/day.

Based on these results, the following No Observed Adverse Effect Levels (NOAEL) were derived:
Parental NOAEL: Systemic toxicity: 1000 mg/kg/day
Local toxicity: no NOAEL

Executive summary:

N-Undecanal was administered by daily oral gavage to male and female Wistar Han rats (10 rats per sex and dose) at dose levels of 100, 300 and 1000 mg/kg bw and day. Males were exposed for 2 weeks prior to mating, during mating, and up to termination (for 28 days). The females were exposed for 2 weeks prior to mating, during mating, during post-coitum, and at least 4 days of lactation (for 42-48 days). Formulation analysis showed that the formulations were prepared accurately and homogenously, and were stable for at least 6 hours at room temperature.

No toxicologically relevant changes were noted during clinical or functional observations or in body weight and food intake during treatment up to 1000 mg/kg bw and day day. Histopathological changes resulting from local irritation were seen in the stomach of either sex at 100, 300, and 1000 mg/kg bw and day (NOTOX, 2010).

Based on these results, the following No Observed Adverse Effect Levels (NOAEL) were derived:

Parental NOAEL: Systemic toxicity: 1000 mg/kg bw and day; Local toxicity: no NOAEL (<100 mg/kg bw and day)

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subacute

Species:

rat

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Quality of whole database:

sufficient for evaluation

Mode of Action Analysis / Human Relevance Framework

In the absence of information on a species specific mode of action the absence of systemic effects in rats are considered as relevant for humans. However, due to differences in stomach anatomy (no forestomach in humans) and the fact that the substance is not ingested by humans the local effects observed in rats are not regarded as relevant for humans.

Additional information

N-Undecanal was administered by daily oral gavage to male and female Wistar Han rats (10 rats per sex and dose) at dose levels of 100, 300 and 1000 mg/kg bw and day. Males were exposed for 2 weeks prior to mating, during mating, and up to termination (for 28 days). The females were exposed for 2 weeks prior to mating, during mating, during post-coitum, and at least 4 days of lactation (for 42-48 days). Formulation analysis showed that the formulations were prepared accurately and homogenously, and were stable for at least 6 hours at room temperature.

No toxicologically relevant changes were noted during clinical or functional observations or in body weight and food intake during treatment up to 1000 mg/kg bw and day day. Histopathological changes resulting from local irritation were seen in the stomach of either sex at 100, 300, and 1000 mg/kg bw and day (NOTOX, 2010).

Based on these results, the following No Observed Adverse Effect Levels (NOAEL) were derived:

Parental NOAEL: Systemic toxicity: 1000 mg/kg bw and day; Local toxicity: no NOAEL (<100 mg/kg bw and day)

Justification for classification or non-classification

No classification required according to Regulation (EC) No 1272/2008.