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Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1974-05-08 to 1974-10-30
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Study was conducted in methods comparable to OECD guideline 408 " Repeated Dose 90-day Oral Toxicity Study in Rodents" with the following deviations: (1) hematology did not include an evaluate of platelet count or assess a measure of blood clotting; (2) An interim sacrifice of 5 animals/sex/dose was evaluated; however, the total number of animals was not increased accordingly as recommended in the guideline. Pre-GLP.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1974
Report Date:
1974

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
Deviations:
yes
Remarks:
See Rationale for Reliability above
Principles of method if other than guideline:
N/A
GLP compliance:
no
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): UDL-652 (dodecyl dimethyl amine oxide)
- Molecular formula (if other than submission substance): N/A
- Molecular weight (if other than submission substance): 235.7
- Smiles notation (if other than submission substance): N/A
- InChl (if other than submission substance): N/A
- Structural formula attached as image file (if other than submission substance): see Fig. N/A
- Substance type: active
- Physical state: a clear liquid, slightly viscous

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River
- Age at study initiation: 35 days old
- Weight at study initiation: Males (120-161 grams), Females (107-138 grams)
- Fasting period before study: N/A
- Housing: Individually in elevated wire mesh cages
- Diet (e.g. ad libitum): Purina Laboratory Rat Chow ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: N/A


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 72-78 deg. Fahrenheit
- Humidity (%): 45-50 percent
- Air changes (per hr): N/A
- Photoperiod (hrs dark / hrs light): 14 hrs. dark / 10 hrs. light


IN-LIFE DATES: From: 1974-05-08 To: 1974-08-04

Administration / exposure

Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on oral exposure:
PREPARATION OF DOSING SOLUTIONS: Test substance UDL-652 was incorporated into basal laboratory diet on a weight-per-weight basis and thoroughly mixed in a twin-shell Patterson-Kelley blender to achieve the desired concentration ot test substance for each dosage level. Doses were 740.7, 3703.7, and 18518.5 ppm UDL-652 in diet. UDL-652 = 26.8% C10-C16 alkyldimethyl N-oxide (DDAO), so diets were 0.02%, 0.1%, and 0.5% DDAO or 200, 1000, and 5000 mg DDAO/kg diet.


DIET PREPARATION
- Rate of preparation of diet (frequency): Weekly
- Mixing appropriate amounts with (Type of food): Purina Laboratory Rat Chow
- Storage temperature of food: Stored in a dark refrigerated area


VEHICLE
- Justification for use and choice of vehicle (if other than water): N/A
- Concentration in vehicle: N/A
- Amount of vehicle (if gavage): N/A
- Lot/batch no. (if required): N/A
- Purity: N/A
Analytical verification of doses or concentrations:
not specified
Details on analytical verification of doses or concentrations:
Test substance was assumed to be 100% pure for purpose of dosage calculation.
Duration of treatment / exposure:
13-14 weeks
Frequency of treatment:
Daily
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
0, 0.02, 0.1 and 0.5% AO in diet
Basis:
nominal in diet
Remarks:
Doses / Concentrations:
0, 17.6, 88, 440 mg AO/kg bw/day
Basis:
actual ingested
No. of animals per sex per dose:
20
Control animals:
yes, plain diet
Details on study design:
- Dose selection rationale: N/A
- Rationale for animal assignment (if not random): Stratified randomization by body weight was used for animal assignment to account for the difference in body weight, so that a homogenous distribution of weights was obtained between groups.
- Rationale for selecting satellite groups: N/A
- Post-exposure recovery period in satellite groups: N/A
- Section schedule rationale (if not random): N/A
Positive control:
N/A

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily
- Cage side observations included the following: animals were observed for mortality, morbidity, or other signs of systemic toxicity


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Weekly


BODY WEIGHT: Yes
- Time schedule for examinations: Weekly


FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes, on a weekly basis
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes


FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: Yes


WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): N/A
- Time schedule for examinations: N/A


OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: On all animals at pre-treatment, on animals sacrificed at 4 weeks (interim sacrifices), and on all surviving animals at 13 weeks
- Dose groups that were examined: all dose groups were examined


HAEMATOLOGY: Yes
- Time schedule for collection of blood: At 4 and 13 weeks
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: 5 rats/sex/dose group
- Parameters examined: hematocrit and hemoglobin determinations, erythrocyte count, total and differential leukocyte counts, mean corpuscular value, mean corpuscular hemoglobin concentration, and mean corpuscular hemoglobin determinations.


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: At 4 and 13 weeks
- Animals fasted: Yes
- How many animals: 5 rats/sex/dose group
- Parameters examined: fasting blood sugar, blood urea nitrogen, total protein, total albumin, serum sodium, serum potassium, serum chloride, serum calcium, serum glutamic-pyruvic transaminase, serum glutamic-oxaloacetic transaminase, alkaline phosphatase, and bilirubin.


URINALYSIS: Yes
- Time schedule for collection of urine: At 11 and 13 weeks
- Metabolism cages used for collection of urine: Yes
- Animals fasted: No data
- Parameters examined: urea nitrogen, pH, specific gravity, 24-hour volume, glucose, protein determinations, and microscopic examination of the sediment.


NEUROBEHAVIOURAL EXAMINATION: No
- Time schedule for examinations: N/A
- Dose groups that were examined: N/A
- Battery of functions tested: sensory activity / grip strength / motor activity / other: N/A


OTHER: N/A
Sacrifice and pathology:
GROSS PATHOLOGY: Yes. After 4 weeks of treatment, 5 male and 5 female rats from each group (selected at random prior to initiation of treatment) were sacrificed and complete gross necropsies were performed. Following 13 weeks of treatment, an additional 10 male and 10 female animals were sacrificed and complete gross necropsies performed. The remaining 5 male and 5 female animals per group continued on treatment through 14 weeks, at which time they too were sacrificed and necropsied.
HISTOPATHOLOGY: Yes. Tissues examined for histopathology include: brain (with meninges), pituitary, thoracic spinal cord, thyroids, trachea, esophagus, salivary gland, eyes, tongue, lung, heart, liver, kidney, spleen, stomach, pancreas, lymph nodes, small intestine, large intestine, adrenal, urinary bladder, ureters, urethra, testes, ovaries, prostate, uterus, vagina, seminal vesicles, inguinal mammary gland, tibia, psoas muscle, skin, bone marrow, and any unusual lesions or tissue masses. Tissues examined microscopically include all preserved tissues from all control and high level animals sacrificed at 4 and 13 weeks. In addition, liver and kidney sections were examined from 5 male and 5 female animals of the low and intermediate dosage levels at 4 and 13 weeks.
Other examinations:
Organ weights were recorded for each animal for the following tissues: pituitary, heart, liver, adrenal, testes, ovaries, and kidney. Absolute and relative (to body weight) organ weights were determined.
Statistics:
Statistical evaluation was performed for the following criteria: growth rate, food consumption, terminal body weights, organ weights, and organ/body weight ratios. The statistical methods used included the following: analysis of variance, or F-test (5% probability level) and preliminary tests (where applicable) by methods of Rao, Bartlett, Scheffe, and Fisher-Behrens (t-test).

Results and discussion

Results of examinations

Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Food efficiency:
no effects observed
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
effects observed, treatment-related
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
Gross pathological findings:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Histopathological findings: neoplastic:
not examined
Details on results:
CLINICAL SIGNS AND MORTALITY: Survival was 100% in all groups. A slightly higher frequency of incidental clinical signs (i.e., hunched posture, rough fur coat, stains on fur coat, and soft feces) was observed in the high dose group when compared to the control and the low and intermediate dose groups.


BODY WEIGHT AND WEIGHT GAIN: Analysis of growth rate (body weight gain) data for the high dose group animals revealed a statistically significant suppression of this parameter when compared to the control group and the remaining test groups. The suppressed body weight gains coincided with decreased food consumption, noted as early as week 1, and persisted throughout the study.


FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Analysis of food consumption data for the high dose group animals revealed a statistically significant suppression of this parameter when compared to the control group and the remaining test groups. Animals in the high dose group displayed a reluctance to consume the diet mixture, due to its palatability, as early as week 1. This sign continued throughout the 14 weeks with growth rates, food consumption, and terminal body weights for these animals being significantly affected.


FOOD EFFICIENCY: There were occasional slight decreases in food efficiency noted among the high dose group animals. However, the finding of statistically decreased food consumption among the high dose group animals accounted for this occasional decrease in food efficiency.


WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): N/A


OPHTHALMOSCOPIC EXAMINATION: Examination of the 15 male and 15 female animals of the high dose group at week 13 revealed moderate to severe bilateral cataracts in four rats (two males and two females). The etiology of this finding was difficult to determine due to the marked growth retardation displayed by these animals; however, the possibility that ocular changes in these animals were effected by nutritional deficiencies was not substantiated by ophthalmoscopic findings normally associated with the onset of nutritional cataracts. Further, other studies in the testing laboratory wherein test substances produced severe reductions in food consumption and body weight gains for up to 52 weeks failed to reveal an effect of this nature. The relatively high incidence of these findings, when compared to the control group, as well as their appearance in animals of this age suggested a possible effect of administration of C10-C16 alkyldimethyl, N-oxide.


HAEMATOLOGY: Evaluation of the hematology data revealed no distinct test substance-related effects upon test animals at any dosage level.


CLINICAL CHEMISTRY: Blood chemistry data revealed no meaningful alterations in any of the parameters examined.


URINALYSIS: Results of urine analysis revealed no significant alterations in the parameters examined attributable to the treatment program.


NEUROBEHAVIOUR: N/A


ORGAN WEIGHTS: Statistically significant findings in the low and intermediate dose groups include: lower pituitary weights were observed in low dose males at week 4, elevated pituitary weights were observed in intermediate dose group males at week 4, and elevated pituitary/body weight ratios were observed in low dose females at week 13. These findings were considered not biologically relevant due to the lack of a dose-response relationship. Results of analysis of the high dose group animals revealed statistically significant alterations in a number of absolute and relative organ weights for these animals at all intervals. Terminal body weight values for these animals were also significantly lower than corresponding values for male and female control animals. Therefore, the relative lower mean weights for a number of organs probably were a reflection of the growth retardation experienced by animals in this group.


GROSS PATHOLOGY: Gross necropsy findings for the high dose group at 13 and 14 weeks were indicative of suppressed growth (described in the results for "body weight/weight gain") and ocular changes (described in the results for the ophthalmoscopic examination). In addition, animals in the high dose group had darker liver color due to decreased fatty tissue content.


HISTOPATHOLOGY: NON-NEOPLASTIC: There were no tissue alterations attributable to the test substance following 4 weeks of treatment. At the 13-week sacrifice, the only possible test substance-related histomorphologic alterations were observed in the high dose group animals, and consisted of bilateral lenticular cataracts in two males and two females.


HISTOPATHOLOGY: NEOPLASTIC (if applicable): N/A


HISTORICAL CONTROL DATA (if applicable): N/A


OTHER FINDINGS: N/A

Effect levels

open allclose all
Dose descriptor:
NOAEL
Effect level:
0.1 mg/kg diet
Based on:
act. ingr.
Sex:
male/female
Basis for effect level:
other: m & f at 0.5%: consumed less diet and a depression in the average body weight gain was observed by the end of the first week. Two m & 2 f in the 0.5% group developed moderate to severe bilateral cataracts.
Dose descriptor:
NOAEL
Effect level:
88 mg/kg bw/day (nominal)
Based on:
act. ingr.
Sex:
male/female
Basis for effect level:
other: m & f at 0.5%: consumed less diet and a depression in the average body weight gain was observed by the end of the first week. Two m & 2 f in the 0.5% group developed moderate to severe bilateral cataracts.

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

The following gonadal tissues were examined for all control and high dose group animals at 4 and 13 weeks: testes, ovaries, prostate, uterus, vagina, seminal vesicles, inguinal mammary gland. No test substance-related microscopic or macroscopic changes were seen in any of these tissues at any dose level.

Additionally, organ weights were performed for each animal for the testes and ovaries; absolute and relative (to body) organ weights were determined. Absolute and relative organ weights for the high dose animals sacrificed at 4, 13, and 14 weeks were significantly altered when compared to control animals. These findings likely reflect the effect of suppressed body weight gain in the high dose group, as a result of the animals' reluctance to consume the diet mixture.

Applicant's summary and conclusion

Conclusions:
In conclusion, dietary administration of C10-C16 alkyldimethyl, N-oxide at levels of 0.02, 0.1 and 0.5% in diet produced moderate suppression of food consumption among the high level animals (related to the palatability of the diet mixture), and the possibility of treatment-related cataractogenesis at the high dose level. The NOAEL was deemed to be 0.1% active amine oxide in the diet or 1000 mg/kg DDAO. Using a food consumption factor of 0.088kg food/kg BW/day for rats, this translates into a delivered dose of 88 mg/kg BW/day.
Executive summary:

A 13-week repeated dose toxicity study was conducted where C10-C16 alkyldimethyl, N-oxide was administered by oral administration in the diet daily to three groups of 20 male and 20 female Charles River CD Sprague-Dawley rats at dosage levels of 0.02, 0.1, and 0.5%. A fourth group of 20 male and 20 female rats received the basal diet only and served as the control. Five males and five females from each treatment group (including untreated control group) were sacrificed at 4 weeks, 10 males and 10 females were sacrificed after 13 weeks, and the remaining animals, after review of the previous necropsy findings, were sacrificed at the end of week 14.

The effect of C10-C16 alkyldimethyl, N-oxide on the rats was evaluated according to physical appearance, behavior, growth (weekly), food consumption (weekly), survival, clinical laboratory studies (blood and urine), microscopic eye examinations, organ weights, and gross and microscopic pathology. No adverse effects were observed in rats consuming diets containing 0.02 or 0.1% C10-C16 alkyldimethyl, N-oxide. Male and female rats receiving diets containing 0.5% test substance generally consumed less diet (grams of diet/kg body weight), and a depression in the average body weight gain was observable by the end of the first week. This sign continued throughout the 14 weeks with growth rates, food consumption, and terminal body weights for these animals being significantly affected. The alterations observed in the absolute and relative organ weights (including the testes and ovaries) in the 0.5% treatment group probably were secondary to body weight effects. Clinical laboratory findings for the high dose group animals generally remained within acceptable limits; however, slight electrolyte imbalance and slight elevation of alkaline phosphatase and blood urea nitrogen values were evident in some animals. Subsequent histopathology failed to confirm an indication of alterations in organ morphology and these findings may be related to the decrease in food consumption. Gonadal tissues were examined for both gross pathology and histopathology and no treatment-related effects were detected.

Significantly, 2/20 males and 2/20 females in the 0.5% treatment group developed moderate to severe bilateral cataracts. The incidence and early appearance of these cataracts in only the high dose group suggests that these ocular changes may be an effect of test substance treatment. This effect could be a direct effect of C10-C16 alkyldimethyl, N-oxide or an indirect effect caused by the effect of the test substance on food consumption and nutrient absorption or utilization. Based on these results, the NOAEL for the C10 -C16 alkyldimethyl, N-oxide was 0.1% (in the diet) or 1000 mg DDAO/kg diet. Using a food consumption factor of 0.088 kg food/kg bw/day for rats of this strain and age, this translates into a delivered dose of 88 mg AO/kg bw/day.