Urea, reaction products with formaldehyde, glyoxal and methanol

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

In a reliable repeated dose study with reproduction/developmental screening test there were no changes in any parameters examined that were considered to be an effect of treatment, thus revealing a No Observed Adverse Effect Level (NOAEL) for parental and reproduction toxicity for the test item of 1000 mg/kg/day.

Additionally, there is sufficient information from subchronic studies with the structural analogue Urea, reaction products with formaldehyde and glyoxal (CAS 92908-35-5/1854-26-8) in rats and mice to conclude that the test substance is very unlikely to impair reproductive capacity (Read-across). In these studies microscopic inspection of sex organs (including testis, epididymis, prostate, preputial gland/uterus, ovaries, clitoral gland) gave no indication to morphological abnormalities in two subchronic studies with oral administration. No histopathological changes were observed up to 3000 mg/(kg*d) in male rats and up to 6000 mg/(kg*d) (referring to 100 % substance) in female rats and both genders of mice.

Link to relevant study records

Reference

Reference 1

Endpoint:

reproductive toxicity, other

Remarks:

90-d repeated dose study

Type of information:

experimental study

Adequacy of study:

other information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Basic data are given

Principles of method if other than guideline:

Performed according to the NTP protocol

GLP compliance:

not specified

Species:

mouse

Strain:

B6C3F1

Route of administration:

oral: gavage

Duration of treatment / exposure:

Exposure period: 90 d

Frequency of treatment:

5x/wk

Reproductive effects observed:

not specified

Microscopic inspection of sex organs (including testis, epididymis, prostate, preputial gland/uterus, ovaries, clitoral gland) gave no indication to morphological abnormalities. No histopathological changes up to 6000 mg/(kg*d) (referring to 100 % substance) in both genders of mice.

Reference 2

Endpoint:

reproductive toxicity, other

Remarks:

90-d repeated dose study

Type of information:

experimental study

Adequacy of study:

other information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Basic data are given

Principles of method if other than guideline:

Performed according to the NTP protocol

GLP compliance:

not specified

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Route of administration:

oral: gavage

Duration of treatment / exposure:

Exposure period: 90 d

Frequency of treatment:

5x/wk.

Key result

Reproductive effects observed:

no

Microscopic inspection of sex organs (including testis, epididymis, prostate, preputial gland/uterus, ovaries, clitoral gland) gave no indication to morphological abnormalities. No histopathological changes up to 3000 mg/kg/d in male rats and up to 6000 mg/kg/d (referring to 100 % substance) in female rats.

Reference 3

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

From 5 AUG 2010 to 24 APR 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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: EPA OPPTS 870.3650

Deviations:

not applicable

GLP compliance:

yes

Remarks:

according to Swiss Ordinance [SR 813.115.1]

Limit test:

no

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Batch No.of test material: OP1
- Expiration date of the lot/batch: 16 October, 2014

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature (20 +/- 5 °C)

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- strain: RccHan:Wistar
- Source: Harlan Laboratories, B.V., Horst, The Netherlands
- Age at study initiation: 11 weeks
- Weight at study initiation: group means males: 291-319 g; group means females: 185-218 g
- Fasting period before study: no
- Housing:
During the pairing period, females were housed with sexually mature males (1:1) until evidence of copulation was observed.
Afterwards animals were housed individually in Macrolon cages (Type III).
- Diet: pelleted standard Kliba Nafag 3433 rodent maintenance diet (Provimi Kliba SA, Kaiserazgst, Switzerland, batch no. 22/10), ad libitum
- Water: community tap water, ad libitum
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 3
- Humidity (%): 30-75.8
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Vehicle:

water

Remarks:

(highly purified)

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
- formulations (w/v) were prepared weekly
- storage at room temperature (20 +/-5 °C)
- homogeneity of the test item in the vehicle was maintained during daily administration period using a magnetic stirrer

VEHICLE
- vehicle: highly purified water
- dose volume: 10 mL/kg bw

Details on mating procedure:

- M/F ratio per cage: 1/1
- Length of cohabitation: up to 14 days
- Proof of pregnancy: copulation plug observed or daily vaginal smear was sperm positive
- After 14 days of unsuccessful pairing replacement of first male by another male with proven fertility.
- Further matings after two unsuccessful attempts: no
- After successful mating each pregnant female was caged: individually
- Any other deviations from standard protocol: no

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analytical study was performed to check accuracy of preparation and to determine stability and homogeneity of test substance preparation (HPLC coupled to an ELSD detector).

Duration of treatment / exposure:

F0-males:
- at least 28 days (14 days pre-pairing, 14 days maximum during mating, until the day before sacrifice)
F0-females:
- approx. 7 weeks (2 weeks prior to mating, throughout mating (14 days maximum), and approx. 21 days gestation and at least up to day 4 post partum, and including the day before sacrifice)

Frequency of treatment:

once daily

Details on study schedule:

- Age at mating of the mated animals in the study: 14 weeks

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: based on the results of a dose range finding study with the test item (in Han Wistar rats, Harlan Laboratories Study, using dose levels of 100, 300 and 1000 mg/kg/day).

Positive control:

none

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- clinical signs time schedule: daily cage-side observation (during acclimatisation up to necropsy), females were observed for signs of difficult or prolonged parturition, and behavioral abnormalities in nesting and nursing.
-detailed clinical signs time schedule: Once prior to the first administration of the test item and weekly thereafter, observations were performed outside the home cage.

BODY WEIGHT: Yes
- Time schedule for examinations:
F0-generation (parental animals): daily from treatment start to day of necropsy
F1-generation (pups): weighed on day 0 (if possible), day 1 and 4 post partum

FOOD CONSUMPTION: Yes
- Time schedule for examinations: weekly, but not during the mating period
(in detail: Males: Weekly during pre-pairing and after pairing periods
Females: Pre-pairing period days 1 - 8 and 8 - 14; gestation days 0 - 7, 7 - 14 and 14 - 21 post coitum, and days 1 - 4 post partum.)

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

OTHER:
Observations on haematology, clinical chemistry and neurobehavioural examination are reported in section 7.5.

Sperm parameters (parental animals):

Parameters examined in males: Epididymides, Prostate Glands, Seminal Vesicles and Coagulating Glands, microscopic examination of the integrity of the spermatogenietic cycle

Litter observations:

STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: no

PARAMETERS EXAMINED
The litters were examined for
- litter size,
- live births,
- still births and
- any gross anomalies.
- The sex ratio of the pups was recorded.
- Pups were weighed individually (without identification) on days 0 (if possible), 1 and 4 post partum.

Postmortem examinations (parental animals):

SACRIFICE
- Male animals: at least until the minimum total dosing period of 28 days
- Maternal animals: On day 5 post partum. If birth did not occur on the expected date (day 21 post coitum), the dam was sacrificed on day 25 post coitum.

GROSS PATHOLOGY: Yes (with special attention to the reproductive organs; The number of implantation sites and corpora lutea was recorded for all dams with litters. The uteri of non-pregnant females were placed in a solution of ammonium sulfide to visualize possible hemorrhagic areas of implantation sites)

HISTOPATHOLOGY: Yes
- from all males: prostate, testes, seminal vesicles with coagulating gland, epididymides
- from all females: ovaries
- from 5 animals/sex/group: any gross lesions, adrenal glands, brain, heart, kidneys, liver, spleen, thymus, spinal chord, small and large intestines, stomach, thyroids, trachea and lungs (inflation and immersion), uterus with vagina, urinary bladder, lymph nodes (mandibular, mesenterical), peripheral nerv (sciatic), bone marrow

Other examinations
ORGAN WEIGHTS
- from all males: testes, epididymides
- from 5 animals/sex/group: adrenal glands, brain, heart, kidneys, liver, spleen, thymus

Postmortem examinations (offspring):

SACRIFICE
- The F1 offspring were sacrificed at 4 days of age.
- These animals were subjected to postmortem examinations (macroscopic).

GROSS NECROPSY
- Gross necropsy and external examinations were performed

HISTOPATHOLOGY / ORGAN WEIGTHS: No

Statistics:

- means and standard deviations were calculated
- Dunnett-test
- Steel-test
- exact Fisher-test

Reproductive indices:

Percentage mating = (Females mated / Females paired) * 100
Fertility index = (Females achieving a pregnancy / Females paired) * 100
Conception rate = (Females achieving a pregnancy / Females mated) * 100
Gestation index = (Number of females with living pups / Number of females pregnant) * 100

Offspring viability indices:

Birth index = (number of pups born alive / number of implantations) * 100
Viability index = (number of alive pups on day 4 p.p. / number of pups born alive) * 100
- percentage live males at first litter check: (number of live male pups)/(number of live pups) * 100
- percentage live females at first litter check: (number of live female pups)/(number of live pups) * 100

Clinical signs:

no effects observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Other effects:

not specified

Description (incidence and severity):

Test substance intake: not applicable for a gavage study

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

no effects observed

Reproductive performance:

no effects observed

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
No treatment related clinical signs were observed (see section 7.5.1).

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
Body weights and body weight gain of treated animals remained in the same range as controls (see section 7.5.1).

TEST SUBSTANCE INTAKE (PARENTAL ANIMALS)
There were no differences in food consumption (absolute and relative) between treated and control animals (see section 7.5.1).

REPRODUCTIVE FUNCTION: ESTROUS CYCLE (PARENTAL ANIMALS)
not examined

REPRODUCTIVE FUNCTION: SPERM MEASURES (PARENTAL ANIMALS)
All findings recorded were within the range of normal background lesions which may be recorded in animals of this strain and age.
The histopathological evaluation of the reproductive organs did not reveal any test-item related changes in animals of the high-dose group, even in the evaluation with special emphasis on stages of spermatogenesis and histopathology of interstitial cell morphology.
Higher degree of oligospermia in epididymides was recorded in animal nos. 6 and 8, which was considered to be associated with the tubular atrophy of testes. Nothing special related to the infertility was observed in prostate glands, seminal vesicles and coagulating glands of these infertile animals.
Nothing special related to the infertility was observed in the other infertile animals (nos. 1 and 4 of group 1, no. 16 of group 2, and no. 36 of group 4).
Overall the assessment of the integrity of the spermatogenesis in testes did not provide any evidence of impairment related to the treatment of test item.

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
Six females (4 females on vehicle control group and one in each of group 2 and 4 (los and high dose)) were non-pregnant.

One female in group 2 (no. 52) mated during the second additional pairing period. All the other females mated during the first pairing period. In groups 1, 2, 3 and 4, mean precoital time was 4.4, 1.7, 1.9 and 2.2 days and median precoital time was 3, 2, 2 and 2 days, respectively. For the
female which mated during the second period the precoital time was 4 days.
Four females in group 1, one female each in groups 2 and 4 were not pregnant. All the pregnant females delivered pups. Therefore, the gestation index was 100% in all groups.

The mean duration of gestation was unaffected by the treatment with the test item. Mean duration of gestation was 21.2, 21.3, 21.4 and 21.2 days, in order of ascending dose level.

Mean number of corpora lutea per dam (determined at necropsy) was 14.7, 15.9, 14.7 and 14.1 in order of ascending dose level and gave no indication of a test item-related effect.

The mean number of implantations per dam did not give any indication of a test item-related effect.
The higher incidence of post-implantation loss which occurred in groups 2 and 3 (10.4% and 6.3% compared to 3.7% in the control group) was considered to be incidental since it did not follow a dose-dependent pattern. The mean numbers of implantations per dam were 13.7, 13.9, 12.8 and 12.4 in order of ascending dose level.
The mean incidence of post-implantation loss as a percentage of total implantations was 3.7%, 10.4%, 6.3% and 4.5%, in order of ascending dose level.

ORGAN WEIGHTS (PARENTAL ANIMALS)
Organ weights and organ:body weight of treated animals were considered to be similar to those of control animals (see section 7.5.1).

GROSS PATHOLOGY (PARENTAL ANIMALS)
Macroscopic observations of the remaining animals at necropsy did not reveal any alterations that were considered to have arisen as a result of treatment (see section 7.5.1).

HISTOPATHOLOGY (PARENTAL ANIMALS)
There were no microscopic findings recorded which could be attributed to treatment with the test substance (see section 7.5.1).

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: see 'Remark'

Key result

Critical effects observed:

no

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

VIABILITY (OFFSPRING)
Litter size at first litter check: In group 4, one female (no. 78) had only one female pup. Taking this into consideration, birth index and litter size were not considered to be affected.
In order of ascending dose level, birth index was 96.3, 89.6, 93.8 and 95.5. and mean litter size at first litter check was 13.2, 12.4, 12.0 and 11.9.

Postnatal Loss Days 0 - 4 Post Partum: In group 4, one female (no. 78) lost the only one pup on day 2 post partum. The other postnatal losses were: one male pup in another female (no. 79) in group 4 and one male pup in one female (no. 62) in group 3. Excluding the female which lost the only pup on day 2 post partum, the viability index (number of living pups on day 4 p.partum / number of pups born alive) was 100.0%, 100.0%, 99.2% and 99.1%, in groups 1, 2, 3, and 4, respectively.

CLINICAL SIGNS (OFFSPRING)
No test item-related abnormal findings were observed at first litter check or during the lactation until day 4 post partum. The only clinical signs noted were wound on lower jaw in one female pup in group 2 and wound on snout in one female pup in group 4.

BODY WEIGHT (OFFSPRING)
Mean pup weights on day 1 post partum were unaffected by treatment with the test item. On day 1 post partum mean pup weights were 5.9, 6.0, 6.0 and 5.9 g in order of ascending dose level. During the lactation period (to day 4 post partum), no test item-related effects were observed in body weight development. Mean pup weights on day 4 post partum were 8.7, 9.2, 9.3 and 9.0 g in order of ascending dose level.

GROSS PATHOLOGY (OFFSPRING)
No abnormal macroscopical findings were observed at macroscopic examination of F1 pups.

OTHER FINDINGS (OFFSPRING)
Sex ratios at first litter check and on day 4 post partum were unaffected by exposure to the test item.
The proportion of males on day 4 post partum was 41%, 53%, 42% and 48%, in order of ascending dose level.

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no changes in litter observations that were considered to be an effect of treatmemt

Key result

Critical effects observed:

no

Key result

Reproductive effects observed:

no

Conclusions:

There were no changes in clinical appearance, functional observations, body weights, food consumption, clinical laboratory investigations, reproduction, litter observation, macroscopic examination, organ weights and microscopic examination that were considered to be an effect of treatment.
From the results presented in this report a No Observed Adverse Effect Level (NOAEL) for parental and reproduction/developmental toxicity for the test item of 1000 mg/kg/day was established.

Executive summary:

A combined repeated dose toxicity study with reproduction/developmental toxicity screening test with the test item administered by oral gavage in Wistar rats (10/sex/dose) was performed according to OECD guideline 422. The dose levels for this study were 0, 100, 300 and 1000 mg/kg/day. Oral dosing of male and female Wistar rats with the test item for at least 28 days (males; females were treated up to approx. 7 weeks), revealed no treatment-related findings on parental animals, on fertility, on embryo-foetal development, or on pup development.From the results presented (absence of adverse effects) in this report a No Observed Adverse Effect Level (NOAEL) for parental and reproduction/developmental toxicity for the test item of 1000 mg/kg/day was established.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Species:

rat

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

A combined repeated dose toxicity study with reproduction/developmental toxicity screening test with the test item administered by oral gavage in Wistar rats (10/sex/dose) was performed according to OECD guideline 422 (Clariant, C92401, 2001). The dose levels for this study were 0, 100, 300 and 1000 mg/kg/day. Oral dosing of male and female Wistar rats with the test item for at least 28 days (males; females were treated up to approx. 7 weeks), revealed no treatment-related findings on parental animals, on fertility, on embryo-foetal development, or on pup development.  
Parameters examined were clinical appearance, functional observations, body weights, food consumption, clinical laboratory investigations, reproduction, litter observation, macroscopic examination, organ weights and microscopic examination.
From the results presented (absence of adverse effects) in this report a No Observed Adverse Effect Level (NOAEL) for parental and reproduction/developmental toxicity for the test item of 1000 mg/kg/day was established.  

Additionally, study data with the structural analogue Urea, reaction products with formaldehyde and glyoxal (CAS 92908-35-5/1854-26-8) is available: There is sufficient information from subchronic studies to conclude that the test substance is very unlikely to impair reproductive capacity in both sexes (IRDC, 5701 -303 and 5701 -307, 1983): Within the scope of a comprehensive subchronic investigation in rats and mice, microscopic inspection of sex organs (testis, epididymis, prostate, preputial gland/uterus, ovaries, clitoral gland) gave no indication to morphological abnormalities. No histopathological changes were found up to 3000 mg/kg bw/d in male rats and up to 6000 mg/kg bw/d (100% substance) in both genders of mice and female rats.

Effects on developmental toxicity

Description of key information

Oral administration of the test item (DMDHEU, a surrogate substance to submission substance) to the rat at doses of 250, 500 or 1000 mg/kg body weight (i.e. 160, 320 or 640 mg surrogate substance/kg bw/day) from day 7 - 16 of pregnancy did not cause any maternal toxicity or embryotoxicity. With regard to the present study the No Observed Adverse Effect Level (NOAEL) is 640 mg/kg/day.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

640 mg/kg bw/day

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

Groups of 23 mated female Wistar rats received the test item (DMDHEU, a surrogate substance to submission substance) by oral gavage once daily at the dose levels of 0, 250, 500 or 1000 mg/kg body weight (i.e. 160, 320 or 640 mg surrogate substance/kg bw/day) from day 7 to 16 of pregnancy (day 0 = day of mating; day 1 = day of sperm detection) and were sacrificed an day 21 of pregnancy.
There were no deaths during the study and no clinical signs were observed in any of the animals. Body weights and food consumption were not affected by the administration of the test compound. No compound-related effects were observed at necropsy of the animals.
Gravid uterus weights, crown-rump lengths, litter size, sex ratios, foetal and placental weights remained unaffected by the administration of the test compound. There was no increase in the number of early or late conceptuses undergoing resorption. Morphological examination of the foetuses did not reveal any compound-related effect.

Justification for classification or non-classification

In a reliable repeated dose study with reproduction/developmental screening test there were no changes in any parameters examined related to fertility/reproduction or developmental toxicity, thus revealing a NOAEL for parental and reproduction toxicity for the test item of 1000 mg/kg/day.

In a teratogenicity study conducted with DMDHEU (a surrogate substance to submission substance) no adverse effects on the test animals could be determined (i.e. highest tested dose = NOAEL = 640 mg test substance/kg bw/day).

Based on the negative findings of the teratogenicity study and negative results from the screening study the submission substance has not to be classified for toxicity to reproduction according to Regulation (EC) No. 1272/2008 (CLP), as amended for the tenth time in Regulation (EU) No 2017/776.