Urea, reaction products with formaldehyde, glyoxal and methanol

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Peer reviewed database.

Data source

Reference

Reference Type:

other: Secondary source

Title:

Unnamed

Year:

1983

Materials and methods

Principles of method if other than guideline:

Performed according to the NTP protocol

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Urea, reaction products with formaldehyde and glyoxal

EC Number:

296-664-6

EC Name:

Urea, reaction products with formaldehyde and glyoxal

Cas Number:

92908-35-5

IUPAC Name:

Urea, reaction products with formaldehyde and glyoxal

Test material form:

liquid: viscous

Test animals

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

Ninety three male and 96 female Fischer 344 rats were acclimated for a period of 15 days before treatment. Based on daily observations and a pre-initiation health verification conducted one week prior to study initiation, 90 males and 92 females were selected for possible use on study. A gross necropsy was performed on five males and 5 females one day prior to test initiation. All rats examined were found to be disease and parasite-free. Animals were randomly allocated to 4 groups of 10 animals/sex. They were 44-51 days old at study initiation. Males weighed 104-161 g and females weighed 96-115 g. Food and water were available ad libitum.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

Doses were given at a volume of 20 ml/kg.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Representative solutions were analyzed immediately after preparation at two labs. A sample taken from the 1000 mg/kg dosage level solution was analyzed to be 110% of the target concentration at one lab and 97% of the target concentration at the other lab.

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

5 days/week

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

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

Remarks:

(referring to 100 % substance)

Doses / concentrations 2

Dose / conc.:

3 000 mg/kg bw/day (actual dose received)

Remarks:

(referring to 100 % substance)

Doses / concentrations 3

Dose / conc.:

6 000 mg/kg bw/day (actual dose received)

Remarks:

(referring to 100 % substance)

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

Post-exposure period: no

Examinations

Observations and examinations performed and frequency:

Animals were weighed prior to dosing, at weekly intervals, and at termination. Animals were observed daily for mortality and clinical signs of toxicity.

Sacrifice and pathology:

All survivors were euthanized on day 91 and received complete post-mortem examinations. The brain, lung, heart, thymus, liver, right testis and right kidney were weighed and relative weights (to brain and body) were calculated. These tissues, plus the pituitary, eyes, nasal cavity and turbinates, oral cavity, larynx and pharynx, tongue, salivary gland, Zymbal's gland, trachea, thyroid, parathyroid, mandibular lymph node, esophagus, stomach, duodenum, jejunum, ileum, colon, cecum, rectum, sternum (with marrow), aorta, costochondral junction (rib), spinal cord, mammary gland, skin, mesenteric lymph node, pancreas, spleen, adrenal, urinary bladder, testes with epididymis, tunica of the testis and scrotal sac, seminal vesicles, prostate, ovary, uterus, preputial or clitoral gland, thigh muscle, blood smear, sciatic nerve, gross lesions, tissue masses or suspect tumors and regional lymph nodes were saved in neutral 10% formalin. Stained sections of all collected organs from the high dose and control animals (except the tongue, Zymbal's gland, costochondral junction (rib), skin, seminal vesicles, thigh muscle and sciatic nerve) were examined histologically. The eyes and pharynx were only examined if grossly abnormal. Histologic sections of heart and testis were examined for the low and mid-dose males.

Other examinations:

At study termination, serum samples from 5 rats/sex from the control groups were analyzed for the presence of antibodies to murine viruses designated by the NTP. Positive titers to both Sendai (all rats) and PVM virus (all females) were detected using a hemagglutination inhibition assay.

Statistics:

Body and organ weight data of treated animals were compared to controls using a one-way analysis of variance, Bartlett's test for homogeneity of variances and the appropriate t-test (for unequal and equal variances) as described by Steel and Torrie. Dunnett's multiple comparison tables were used to assess significant differences at p < 0.05.

Results and discussion

Results of examinations

Details on results:

Three males of the 6000 mg/kg/day dosage level were found dead on study day three. The cause of one of the deaths was aspiration pneumonia. The cause of death of the other animals was not determined. The males in the 6000 and 3000 mg/kg/day dosage level groups exhibited a lower mean body weight gain and had lower body weights at termination (314 +/- 18.1 g and 331 +/-27.1 g, respectively) than controls (358 +/- 31.1 g). The mean body weights of the males of the 1000 mg/kg/day dosage level and of the treated female rats were comparable to controls throughout the study.
Pharmacotoxic signs noted for male and female animals in the 3000 and 6000 mg/kg/day dosage level groups included primarily yellow discoloration of fur in the anogenital region and soft stool. In addition, male animals in the 6000 mg/kg/day dosage level group exhibited yellow discoloration of fur - abdominal region and soft stool. One male animal in the 6000 mg/kg/day dosage level group was noted for hypoactivity, decreased grasping reflex, extremities hypothermic to touch, and ataxia on study day 3. Other signs noted among rats of various dosage level groups, or controls, were considered incidental and unrelated to the test article.
No toxicologically significant organ weight changes occurred in this study. Macroscopically, one male from the 6000 mg/kg/day dosage level group was found at the post-mortem examination to have multiple yellowish linear macroscopic lesions in the right testis. Microscopically, the lesions were found to be moderate bilateral mineralization of testes. Microscopically, treatment related mild mineralization in the heart was seen in this male and another male in the 6000 mg/kg/day dosage level group. Mineralization in the testes and heart were considered to be test article-related lesions. No other macroscopic or microscopic findings were considered to be related to the test article.

Effect levels

1

Key result

Dose descriptor:

NOAEL

Effect level:

3 000 mg/kg bw/day (nominal)

Sex:

male

Basis for effect level:

body weight and weight gain

2

Key result

Dose descriptor:

NOAEL

Effect level:

6 000 mg/kg bw/day (nominal)

Sex:

female

Basis for effect level:

other: General toxicity

Target system / organ toxicity

Key result

Critical effects observed:

no

Applicant's summary and conclusion

Conclusions:

Effects on body weight of the 3000 mg/kg males were regarded as not adverse due to the relative low strength of effect (-7.5%) and the solitary appearance of this effect in this treatment.