1-[1,3-bis(hydroxymethyl)-2,5-dioxoimidazolidin-4-yl]-1,3-bis(hydroxymethyl)urea

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Effect on fertility: via oral route

Endpoint conclusion:

no study available

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

Short description of key information:
In accordance with section 1 of REACH Annex XI, testing for reproductive toxicity in animals is not scientifically necessary and is therefore not required.
Several subchronic and subacute toxicity tests performed with the test substance have clearly demonstrated low systemic toxicity. In particular, no effects on weight or microstructure of rat testes or ovaries were found when rats were dosed orally for 90 days at dosages up to 200 and 300 mg/kg/day. The observed pattern of toxicity shows a direct contact effect in the stomach, but little indication of systemic toxicity. In one sub-chronic study (performed under GLP and following a standard test method) micropathology investigation of rats dosed at 300 mg/kg/day found: "The degree of spermatogenesis in the testes of the high dose males was similar to their counterpart vehicle controls. The ovarian activity of the high dose and vehicle controls was similar but varied depending on the stage of the estrus cycle. Dilatation of the uterine lumen and uterine glands occurred in individual rats in the vehicle control and high dose females and reflected the stages of the estrus cycle." Further, a clear absence of developmental toxicity has been demonstrated in rat studies using two different routes of administration.

These results show that there is no reason to require further investigation of reproductive performance in a 1- or 2-generation study, or performance of a reprotoxicity screening study: indeed low toxicity to reproduction can reasonably be predicted. Hence, there is sufficient weight of evidence, to claim that additional animal testing for assessment of effects on fertility is not justified according to article 13.1 of the REACH regulation, as well as not justified regarding reduction of testing on vertebrate animals in the spirit of Directive 2010/63/EU. In addition, the eventual cosmetic use of the substance argues against the performance of an extensive animal study (Directive 76/768/EEC).

Justification for selection of Effect on fertility via oral route:
Study not scientifically necessary and therefore waived in accordance with article 13.1 of the REACH regulation and Annex 11, section 1 (justification supplied).

Effects on developmental toxicity

Description of key information

No evidence of teratogenic or embryo-/foetotoxic activity has been observed in two well conducted test of developmental toxicity.

Link to relevant study records

Reference

Reference 1

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well reported study performed under GLP and using a standard test method.

Qualifier:

according to guideline

Guideline:

EPA OPP 83-3 (Prenatal Developmental Toxicity Study)

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

238-308g at study start. Individually caged in room designed to maintain 22+/-3C and 30-70% humidity, with a 12h light/dark cycle.

Route of administration:

oral: gavage

Vehicle:

water

Remarks:

deionised

Details on exposure:

Oral dosing with dose volume 10 ml/kg.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Colourimetric analysis (samples heated with reagent under acidic conditions, absorption measured at 520 nm). Measured concentrations of samples of formulated doses (1/per test dosage) confirmed to be within 10% of nominal values, and test substance absence in vehicle controls confirmed.

Details on mating procedure:

Females mated 1F:1M or 2F:1M until vaginal plug or sperm was seen (Day 0).

Duration of treatment / exposure:

10 days (gestation days 6-15).

Frequency of treatment:

Daily

Duration of test:

Treated females terminated on Day 20.

Remarks:

Doses / Concentrations:
125, 250, 500 mg/kg
Basis:
analytical conc.
administered dose

No. of animals per sex per dose:

27 females treated.

Control animals:

yes, concurrent vehicle

Maternal examinations:

Observed at least daily; bodyweights and food consumption measured during test period. Bodyweights and uterine weights recorded at necropsy.

Ovaries and uterine content:

Corpora lutea, early/late resorptions, viable/non-viable foetuses counted and recorded.

Fetal examinations:

Sexed, weighed, examined externally. Approximately half of each litter stained for skeletal abnormalities, remainder prepared and examined for soft tissue abnormalities.

Statistics:

Analysis of variance and non-parametric tests were applied to compare control and test group data.

Indices:

Maternal bodyweights and food consumption.
Dams with resorptions only, dams with viable foetuses.
Viable foetuses/dam
Total implants/dam
Total implant losses/dam
Pre-implantation loss (corpora lutea - implants/corpora lutea), % by dam
Post-implantation loss (implants - viable foetuses/implants), % by dam.

Foetal sex distribution
Foetuses with soft tissue malformations
Foetuses with skeletal malformations
Foetuses with soft tissue and/or skeletal malformations.

Litters with with soft tissue malformations
Litters with skeletal malformations
Litters with soft tissue and/or skeletal malformations.

Details on maternal toxic effects:

Maternal toxic effects:no effects. Remark: post-dose salivation (seen at 250 mg/kg/day and in all but one animal at 500 mg/kg/day) was the only significant clinical sign

Details on maternal toxic effects:
There were no treatment-related effects on bodyweights and food consumption; no dams aborted or showed late delivery. Deaths of 1 low-dose and 2 high-dose test dams during the dosing period were attributed to maldosing.

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
No treatment-related effects on any reproductive indices (for embryo/foetal toxicity).

Malformations:
- no soft tissue malformations were seen
- two cases of skeletal malformation were seen (1 foetus with a short tail in the 250 mg/kg/day group, 1 case of fused ribs in the 500 mg/kg/day group) but these were deemed spontaneous and not treatement-related.

The types and incidences of observed skeletal variations (mainly of the sternebrae, ribs, skull and vertebrae) did not differ significantly between controls and test groups.

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Basis for effect level:

other: teratogenicity

Abnormalities:

not specified

Developmental effects observed:

not specified

Females pregnant at termination were 25 (controls) and 26, 27, 23 in low-, mid- and high-dose test groups respectively: all had viable foetuses at termination.

Group mean data.

Embryo/foetal index	Vehicle controls	Test substance 125 mg/kg/day	Test substance 250 mg/kg/day	Test substance 500 mg/kg/day
Viable foetuses/dam	14.2 +/- 2.28	14.9 +/- 2.04	14.1 +/- 3.41	14.7 +/- 1.89
% Post-implantation loss	9.4	7.4	8.1	6.8
% Pre-implantation loss	9.4	10.0	10.2	8.1
Foetal sex distribution: % male	52.8	50.4	49.6	49.0
Foetal bodyweight	3.8 +/- 0.36	3.7 +/- 0.35	3.7 +/- 0.51	3.7 +/- 0.56

Conclusions:

In this study repeated oral application of the test substance to pregnant rats at dosages up to 500 mg/kg/day produced no significant maternal toxicity and no evidence of teratogenicity or embryo/foetal toxicity.

Reference 2

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Fully reported study performed under GLP and following a standard test method.

Qualifier:

according to guideline

Guideline:

EPA OPP 83-3 (Prenatal Developmental Toxicity Study)

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

80-120 days old at study start. Individually caged, in room designed to maintain 22+/-3C, 30-70% humidity, with a 12h light/dark cycle.

Route of administration:

dermal

Vehicle:

water

Remarks:

deionised

Details on exposure:

Applications sites shaved prior to first treatment and as necessary thereafter. Daily topical administration of a 30% solution onto mid-dorsal skin (4 x 4 cm site), without occlusion; rats collared during the treatment period to prevent ingestion.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Colourimetric analysis (samples heated with reagent under acidic conditions, absorption measured at 520 nm). Measured concentrations of two formulated dose samples (nominally 300 mg/ml) confirmed to be within 10% of nominal values, and test substance absence in vehicle controls confirmed.

Details on mating procedure:

Females mated 1F:1M or 2F:1M until vaginal plug or sperm was seen (Day 0).

Duration of treatment / exposure:

10 days (gestation days 6-15).

Frequency of treatment:

Daily

Duration of test:

Treated females terminated on day 20.

Remarks:

Doses / Concentrations:
30, 95 and 300 mg/kg/day
Basis:
analytical conc.

No. of animals per sex per dose:

27 females/group treated.

Control animals:

yes, concurrent vehicle

Maternal examinations:

Observed at least daily; bodyweights and food consumption measured during test period. Bodyweights and uterine weights recorded at necropsy.

Ovaries and uterine content:

Corpora lutea, early/late resorptions, viable/non-viable foetuses counted and recorded.

Fetal examinations:

Sexed, weighed, examined externally. One third of each litter stained for skeletal abnormalities, remainder prepared and examined for soft tissue abnormalities.

Statistics:

Analysis of variance (Dunnett's test); non-parametric test where variances differed significantly.

Indices:

Maternal bodyweights and food consumption.
Dams with resorptions only, dams with viable foetuses.
Viable foetuses/dam
Total implants/dam
Total implant losses/dam
Pre-implantation loss (corpora lutea - implants/corpora lutea), % by dam
Post-implantation loss (implants - viable foetuses/implants), % by dam.

Foetal sex distribution
Foetuses with soft tissue malformations
Foetuses with skeletal malformations
Foetuses with soft tissue and/or skeletal malformations.

Litters with with soft tissue malformations
Litters with skeletal malformations
Litters with soft tissue and/or skeletal malformations.

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
Local skin reactions: yellowing, scabs and erythema (incidence dose-dependent).
No deaths, abortions or late deliveries.
No bodyweight or food consumption effects of treatment.
No treatment-related effects on any reproductive indices.

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Basis for effect level:

other: other:

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
No treatment-related effects on any reproductive indices (for embryo/foetal toxicity).

Malformations:
- one vehicle control group foetus with unilateral testes
- one high-dose group foetus with acaudia (which also had absent sacral and lumbar vertebrae).

Skeletal variations:
- mainly of the sternebrae, skull, hyoid arch but without significant difference between groups or dose-relationship.

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Basis for effect level:

other: teratogenicity

Abnormalities:

not specified

Developmental effects observed:

not specified

26 females were pregnant at termination in all groups except at 30 mg/kg/day where all 27 were pregnant: all had viable foetuses.

Group mean data.

Embryo/foetal index	Vehicle controls	Test substance 30 mg/kg/day	Test substance 95 mg/kg/day	Test substance 300 mg/kg/day
Viable foetuses/dam	13.8 +/- 2.78	13.3 +/- 2.44	14.1 +/- 1.88	13.2 +/- 3.35
% Post-implantation loss	7.2	10.6	6.4	13.8
% Pre-implantation loss	6.8	6.4	6.1	4.4
Foetal sex distribution: % male	49.4	56.1	47.8	52.6
Foetal bodyweight   (by dam)	4.1 +/- 0.26	4.1 +/- 0.28	4.2 +/- 0.28	4.1 +/- 0.30

Conclusions:

In this study repeated dermal application of the test substance to rats produced local skin reactions in dams but no evidence of teratogenicity or embryo/foetal toxicity.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

500 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

Reliable (Klimisch 1) key study performed under GLP and using a standard test method (also supported by a rat dermal study and a (smaller scale) oral dose rangefinding test).

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

300 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

Reliable (Klimisch 1) study performed under GLP and using a standard test method (also supported by a rat oral study).

Additional information

In the dermal rat study, repeated application of test substance at a level causing evident local skin reaction produced no evidence of teratogenic, embryotoxic or foetotoxic activity.

In the oral rat study, repeated administration at 2.5x the NOAEL for subchronic oral toxicity produced no evident developmental toxicity.

Justification for selection of Effect on developmental toxicity: via oral route:
No adverse effects seen in the key rat developmental toxicity study using oral administration at dosages up to 500 mg/kg/day.

Justification for selection of Effect on developmental toxicity: via dermal route:
No adverse effects seen in the key rat developmental toxicity study using dermal administration at dosages up to 300 mg/kg/day.

Justification for classification or non-classification

Reliable studies of developmental toxicity in the rat by the oral and dermal routes found no evidence of developmental toxicity.