1,3-bis(hydroxymethyl)-5,5-dimethylimidazolidine-2,4-dione

Endpoint summary

Description of key information

DMDMH readily undergoes hydrolysis to DMH and therefore data is provided for both substances. In the case of long term testing, the data on DMH is considered more relevant. In a 90 day study with DMH the NOAEL was >1000 mg/kg and in 90 day dermal study the NOEL was 390 mg/kg (limited by solubility).

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:

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

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

EPA OPP 82-1 (90-Day Oral Toxicity)

Deviations:

yes

Remarks:

No measure of clotting potential, histopathology conducted on first 10 necropsied of the 15 animals/sex/dose group.

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Route of administration:

oral: gavage

Vehicle:

water

Duration of treatment / exposure:

90 days

Frequency of treatment:

5 days per week

Remarks:

Doses / Concentrations:
100 mg/kg
Basis:
actual ingested

Remarks:

Doses / Concentrations:
300 mg/kg
Basis:
actual ingested

Remarks:

Doses / Concentrations:
1000 mg/kg
Basis:
actual ingested

No. of animals per sex per dose:

15/ per sex/dose

Control animals:

yes, concurrent vehicle

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Detailed clinical examination made weekly, observation at least once per day.

BODY WEIGHT: Yes
- Time schedule for examinations: Weekly

FOOD CONSUMPTION: Yes
- Time schedule: Weekly

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Prior to study initiation and during final week of study

HAEMATOLOGY: Yes
- Time schedule for collection of blood: end of study
- Number of animals: First ten surviving animals/sex/group examined at necropsy
- Parameters: Haematocrit, haemoglobin concentration, erythrocyte count, total and differential leukocyte count, platelet count.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: end of study
- Number of animals: First ten surviving animals/sex/group examined at necropsy
- Parameters: sodium, potassium, chloride, glucose, calcium, globulin (calculated), blood urea nitrogen, total bilirubin, creatinine, total protein, albumin, alanine aminotransferase, aspartate aminotransferase, phosphorous, alkaline phosphatase, gamma glutamyl transferase, A/G ratio (calculated)

URINALYSIS: No

Sacrifice and pathology:

Organ Weights - Liver, kidneys, adrenals, testes, ovaries, brain with stem
Gross and histopathology - Gross necropsy performed on all animals surviving to termination. Hisptopathology performed on first 10 surviving animals/sex/dose level exmined at necropsy in high dose group and controls as well as animals that succumbed prior to termination: brain, spinal cord, pituitary, thyroid, parathyroid, thymus, oesophagus, salivary glands, stomach, sternum with marrow, small and large intestines, liver, pancreas, kidneys, adrenals, spleen, heart, trachea, lungs, aorta, uterus, mammary glands, prostate, urinary bladder, lymph nodes, skin, eyes. Histopathology performed on first 10 surviving animals/sex/dose level in mid and low dose groups: Gross lesions, tissue masses, liver, lungs and kidney.

Statistics:

Bartletts test was used to determine if dose groups had equal variance.
Parametric procedures used one way ANOVA using F distribution If significant differences were seen Dunnett’s test was used to determine which treatment groups differed significantly from the control.
For non parametric procedures test of equality of means was performed using Kruskal-Wallis test. If significant differences were seen Dunn’s Summed Rank test was used to determine which treatment groups differed significantly from the control.
In addition Jonckheere’s test for monotonic trend in the dose response was performed.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Sporadic occurrences of alopecia, missing/broken/maloccluded incisors and red/clear ocular discharge. One male in the control group was euthanized because of a broken snout. One female in the 300mg/kg dose group was found dead on due to mis dosing.

Mortality:

mortality observed, treatment-related

Description (incidence):

Sporadic occurrences of alopecia, missing/broken/maloccluded incisors and red/clear ocular discharge. One male in the control group was euthanized because of a broken snout. One female in the 300mg/kg dose group was found dead on due to mis dosing.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Decreased body weight gain in male rats in the high dose group. Increased body weight in females in all treatment groups.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Reduction in food consumption in the high dose male rats.

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

ORGAN WEIGHTS - The mean absolute and relative liver weights for male rats in the high dose group were decreased. The mean absolute and relative liver weigh values for females were increased in the high dose group. The mean absolute kidney weights were also increased in the high dose females but was considered to be a reflection of the increased body weight.

GROSS AND HISTOPATHOLOGY - Abnormalities noted at very low incidences included entire GI tract distended with gas, emaciation, smaller than normal seminal vesicles, clear yellow liquid in stomach, distended uterus, larger than normal ovaries, liver mass, liver thickening, lung discoloration and distended cecum. None of these appeared to be related to the treatment.

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Critical effects observed:

not specified

Conclusions:

The NOAEL for DMH is >1000 mg/kg

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

Sufficient to meet data requirements. The study is Klimisch 1.

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Quality of whole database:

A repeated dose inhalation toxicity study is scientifically unjustified and is not in the interests of animal welfare.

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Quality of whole database:

A repeated dose inhalation toxicity study is scientifically unjustified and is not in the interests of animal welfare.

Repeated dose toxicity: dermal - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: dermal

Type of information:

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

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 411 (Subchronic Dermal Toxicity: 90-Day Study)

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

other: CD

Sex:

male/female

Type of coverage:

occlusive

Vehicle:

water

Details on exposure:

TEST SITE
- Area of exposure: Entire application area in the high dose group and over proportionately smaller areas in the mid and low dose groups.

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

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 3.0, 0.3, 1.0 and 3.0ml/kg/day
- Concentration (if solution): A constant concentration of 13% (w/w) in water was used for animals in DMH treatment groups.

Duration of treatment / exposure:

90 days

Frequency of treatment:

6 hours/day, 5 days per week

Remarks:

Doses / Concentrations:
39 mg/kg
Basis:
analytical per unit body weight

Remarks:

Doses / Concentrations:
130 mg/kg
Basis:
analytical per unit body weight

Remarks:

Doses / Concentrations:
390 mg/kg
Basis:
analytical per unit body weight

No. of animals per sex per dose:

15/sex/group

Control animals:

yes, concurrent vehicle

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Twice daily

BODY WEIGHT: Yes
- Time schedule for examinations: Weekly

FOOD CONSUMPTION: Yes
- Time schedule: 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: All animals at end of study
- Parameters: Haematocrit, haemoglobin, erythrocyte count, total and differential leukocyte count, platelet count, reticulocyte count, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH),mean corpuscular haemoglobin concentration (MCHC)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: All animals at end of study
- Parameters: 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:

Organ Weights: liver, kidneys, adrenals, testes, ovaries, spleen, brain, heart

Gross and histopathology: 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

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.

Clinical signs:

no effects observed

Description (incidence and severity):

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.

Mortality:

no mortality observed

Description (incidence):

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 and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Details on results:

The death of the male rat in the low dose group was not considered to be treatment related due to a lack of dose-response relationship.

Dose descriptor:

NOEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Critical effects observed:

not specified

Conclusions:

The NOEL for DMH is 390 mg/kg. The highest dose tested was limited by solubility.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

390 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

Sufficient to meet data requirements. The study is Klimisch 1. The top dose level was limited by solubility.

Repeated dose toxicity: dermal - local effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: dermal

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Qualifier:

no guideline followed

GLP compliance:

no

Remarks:

GLP was not compulsory at the time the study was performed

Limit test:

no

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Type of coverage:

semiocclusive

Vehicle:

water

Details on exposure:

TEST SITE
- % coverage: Approximately 20 % of body surface
- Type of wrap if used: semiocclusive or other

REMOVAL OF TEST SUBSTANCE
- Washing (if done): Not stated
- Time after start of exposure: 24 h or other

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 2.0 ml/kg
- Concentration (if solution): Dose levels of 8 and 800 mg/kg in the form of 0.4 and 40% (w/v) aqueous solutions

Duration of treatment / exposure:

28 days

Frequency of treatment:

5 days per week for 4 weeks for a total of 20 applications

Remarks:

Doses / Concentrations:
8 mg/kg (as 0.4% w/v solution)
Basis:
nominal per unit body weight

Remarks:

Doses / Concentrations:
800 mg/kg (as 40% w/v solution)
Basis:
nominal per unit body weight

No. of animals per sex per dose:

3/sex/group

Control animals:

yes, concurrent vehicle

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily

BODY WEIGHT: Yes
- Time schedule for examinations: Weighed on days -21, -14, -7, 0 ,7, 14, 21 and 28

FOOD CONSUMPTION: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: all animals prior to start and at end of study
- Parameters: Haematocrit, haemoglobin concentration, erythrocyte count, total and differential leukocyte count

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: all animals prior to start and at end of study
- Parameters: fasting glucose concentration, blood urea nitrogen (BUN), serum alkaline phosphatise activity (SAP), serum glutamic pyruvic transaminase activity (SGPT), serum glutamic oxalcetic transaminase activity (SGOT)

URINALYSIS: Yes
- Time schedule for collection of urine: 4 rabbits from control (2 male and 2 female) and 4 rabbits (2 male and 2 female) from 800 mg/kg dose group prior to and at end of study
- Parameters: specific gravity, pH, n, glucose, albumin , microscopic elements (RBC, WBC, crystals and casts)

Sacrifice and pathology:

Organ Weights: liver, kidneys, adrenal gland, thyroid glands, gonads spleen, brain, heart

Gross and histopathology: all dose groups/ high dose group and controls, other dose groups only if effects
organs: brain, spinal cord, pituitary, thyroid glands, parathyroid glands, thymus gland, lymph nodes oesophagus, salivary glands, stomach, small and large intestines, liver, pancreas, digestive system kidneys, spleen, heart, trachea, lungs, aorta,, prostate, urinary bladder, gall bladder, testes, epididymides, seminal vesicle, uterus, ovaries, peripheral nerve, sternum and sternal barrow, skeletal muscle (thigh), skin from the control and application sites

Statistics:

Organ weights and their corresponding ratios to the weight of the body were subjected to a statistical analysis, viz. an Analaysis of Variance followedby the Kruskal-Wallis test

Clinical signs:

no effects observed

Dermal irritation:

effects observed, treatment-related

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Dose descriptor:

NOAEL

Effect level:

> 800 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Critical effects observed:

not specified

Conclusions:

The NOAEL systemic for Dantoin DMDMH-55 is > 800 mg/kg equivalent to > 440 mg DMDMH/kg.
The NOAEL local for Dantoin DMDMH-55 is 8 mg/kg equivalent to 4.4 mg DMDMH/kg.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Study duration:

subacute

Species:

rabbit

Quality of whole database:

Sufficient to meet data requirements. The study is Klimisch 2. The LOAEL was 440 mg/kg.

Additional information

DMDMH readily undergoes hydrolysis to DMH and therefore data is provided for both substances. In the case of long term testing the data on DMH is considered more relevant.

Following 90 days oral dosing of DMH at up to 1000 mg/kg for 90 days, no significant toxicity was observed (NOAEL >1000 mg/kg). Following 90 days dermal dosing of DMH at up to 390 mg/kg (top dose limited by solubility), no significant systemic or local toxicity was observed (NOAEL = 390 mg/kg).

Following 28 days dermal dosing of DMDMH at up to 440 mg/kg, no significant systemic toxicity was observed (NOAEL > 440 mg/kg) however skin effects at the application site were observed.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
One study available on DMDMH and two studies on the hydrolysis product DMH. It is most appropriate to select a longer term study on DMH and there is a larger toxicology database available in the rat.

Justification for selection of repeated dose toxicity dermal - systemic effects endpoint:
Two studies are available on DMDMH and one study on the hydrolysis product DMH. It is most appropriate to select a longer term study on DMH and this study is a reliable, GLP, guideline, sub-chronic study.

Justification for selection of repeated dose toxicity dermal - local effects endpoint:
Two studies available on DMDMH and one study on the hydrolysis product DMH. Both of the DMDMH studies demonstrated skin effects at the application site. This study demonstrated an effect at a lower dose level.

Justification for classification or non-classification

The results from the various repeat dose studies on both DMDMH and DMH do not meet the criteria for classification.