sodium 4,4-dimethyl-2,5-dioxoimidazolidin-1-ide

Repeated dose toxicity: dermal

Administrative data

Endpoint:

sub-chronic toxicity: dermal

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

in year 1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study performed to GLP and guideline

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Report date:

1994

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EPA OPP 82-3 (Subchronic Dermal Toxicity 90 Days)

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

5,5-dimethylhydantoin

EC Number:

201-051-3

EC Name:

5,5-dimethylhydantoin

Cas Number:

77-71-4

IUPAC Name:

5,5-dimethylimidazolidine-2,4-dione

Constituent 2

Reference substance name:

Dimethylhydantoin

IUPAC Name:

Dimethylhydantoin

Details on test material:

- Name of test material (as cited in study report): 5,5-dimethylhydantoin (DMH)
- Structural formula attached as image file (if other than submission substance): see Data Matrix attachment in Section 13 for DMH structural formula
-Physical state: white crystalline powder
-Stability under test conditions: Stability analysis indicated that DMH remained stable in water for at least 14 days when stored at room temperature.

Test animals

Species:

rat

Strain:

other: CD

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Testing lab
- Age at study initiation: 32 days old
- Weight at study initiation: Males: 236-313 g - Females: 159-215 g
- Housing: stainless steel cages (1 animal per cage during study)
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 3 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 66-77 °F
- Humidity (%): 40-70%
- Air changes (per hr): 10 room air changes per hour.
- Photoperiod: 12 hours per day of fluorescent light.

Administration / exposure

Type of coverage:

occlusive

Vehicle:

water

Details on exposure:

TEST SITE
- Area of exposure: Dosing solution was applied directly to the back
- Type of wrap if used: Wrapped with VETRAP® Bandaging Tape (3M Personal Care Products) and secured with Elastikon®
- Time intervals for shavings or clipplings: Ten days prior to initiation of study


REMOVAL OF TEST SUBSTANCE
- Washing (if done): Rinsed with water
- Time after start of exposure: After 6 hours


TEST MATERIAL
- Amount applied: 0, 39,130 and 390 mg/kg/day corresponding to a dose volume 3.0, 0.3, 1.0 and 3.0 mL/kg/day.
- Constant volume or concentration used: yes - a constant concentration of 13% (w/w) DMH was used.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Concentration verification analyses on solutions used for dosing showed analytical values ranging from 99.2% to 106.3% of nominal for the 6 periods of analysis.

Duration of treatment / exposure:

90 days

Frequency of treatment:

6 hours/day; 5 days per week

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
39
Basis:
nominal per unit body weight

Doses / concentrations 2

Remarks:

Doses / Concentrations:
130
Basis:
nominal per unit body weight

Doses / concentrations 3

Remarks:

Doses / Concentrations:
390
Basis:
nominal per unit body weight

No. of animals per sex per dose:

15/sex/group

Control animals:

yes

Details on study design:

- Dose selection rationale: Previously a 5-day repeated dermal toxicity study was conducted with DMH to generate information to aid in the selection of dose levels for the 90 day study. Male rats were treated dermally 6 hours/day (occluded) for 5 days with 2 mL/kg of 5 or 10% aqueous solutions of DMH or 25 or 50% aqueous mixtures of DMH. These treatments corresponded to dose levels ranging from 100 to 1000 mg/kg/day. No toxicity or skin irritation was observed. Results of the dose solution preparation indicated that even mixtures of DMH in water could not be prepared above saturating DMH concentrations (~13%).

DMH dose levels for the 90 day study were selected based on the results of the preliminary 5 day study, the maximum aqueous solubility of DMH (13%) and the maximum dose volume which could be adminsitered in the test system (3.0 mL/kg/day).

Examinations

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice daily

DERMAL IRRITATION (if dermal study): Yes

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION: Yes
- Time schedule for examinations: weekly

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: prior to first exposure and following sixty-third treatment

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at end of study
- How many animals: all animals
- Parameters: Haematocrit, haemoglobin, erythrocyte count, total and differential leukocyte count, platelet count, reticulcyte count, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC).

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at end of study
- How many animals: all animals
- Parameters examined: sodium, potassium, chloride, calcium, phosphorus, glucose, cholesterol, urea nitrogen, total bilirubin, direct bilirubin, indirect bilirubin, creatinine, total protein, albumin, globulin, A/G ratio, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, gamma glutamyl transpeptidase.

URINALYSIS: No

Sacrifice and pathology:

GROSS PATHOLOGY AND HISTOPATHOLOGY: Yes
High dose group and controls
organs: brain, spinal cord, pituitary, thyroid, parathyroid, thymic region, oesophagus, salivary glands, stomach, small and large intestines, liver, pancreas, kidneys, adrenals, spleen, heart, trachea, lungs, aorta, uterus, vagina, female mammary gland, prostate, testes, seminal vesicles, urinary bladder, lymph nodes sciatic nerve, femur, sternum (including marrow), eyes, exorbital lacrimal gland, thigh musculature, skin (treated and untreated)
* Lungs, liver, kidneys, treated and untreated skin were examined from the low and mid-dose groups. In addition, submandibular lymph nodes were examined from all low and mid dose male rats

Other examinations:

Not specified

Statistics:

Data for quantitative continuous variables were compared for the 3 treatment groups and control group by use of Levene’s test for equality of variances, analysis of variance (ANOVA), and t-tests. The t-tests were used when the F value from the ANOVA was significant. When Levene’s test indicated homogenous variances, and the ANOVA was significant, a pooled t-test was used for pairwise comparisons. When Levene’s test indicated heterogenous variances all groups were compared by an ANOVA for unequal variances followed, when necessary, by a separate variance t-test for pairwise comparisons. Nonparametric data were statistically evaluated using the Kruskal-Wallis test followed by the Mann-Whitney U test when appropriate. Incidence data were compared using Fishers exact test. For all statistical tests, the probability value of <0.05 (two-tailed) was used as the critical level of significance.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Dermal irritation:

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):

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

not examined

Details on results:

CLINICAL SIGNS
No treatment effects.

MORTALITY One male from the control group was found dead on day 17 and one male from the low dose group was sacrificed moribund on day 39.

BODY WEIGHT GAIN
No treatment related effects.

FOOD CONSUMPTION
No treatment related effects.

OPHTHALMOSCOPIC EXAMINATION
No adverse effects.

HAEMATOLOGY
No treatment related effects.

CLINICAL CHEMISTRY
No treatment related effects

ORGAN WEIGHTS
No treatment related effects

GROSS PATHOLOGY
No treatment related effects.

HISTOPATHOLOGY: NON-NEOPLASTIC
No treatment related effects.

Effect levels

Dose descriptor:

NOEL

Effect level:

390 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: Based upon the observation of no clinical signs of toxicity or effects on any study parameters.

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

No clinical signs of toxicity or effects on any of these parameters were found. Based on the results of this study, repeated dermal exposure to saturated aqueous solutions of DMH does not result in systemic toxicity or skin irritation in the rat. NOEL = 390 mg/kg bw/d.

Executive summary:

This study has been performed on DMH (Dimethyl Hydantoin) and has been used for read-across purposes.

No clinical signs of toxicity or effects on any of these parameters were found. Based on the results of this study, repeated dermal exposure to saturated aqueous solutions of DMH does not result in systemic toxicity or skin irritation in the rat. NOEL = 390 mg/kg bw/d.