2-(2-oxoimidazolidin-1-yl)ethyl methacrylate

Neurotoxicity

Description of key information

Combined repeated dose study in rats (OECD TG 422), gavage: NOEL parental toxicity: 100 mg/kg bw/day in males and 300 mg/kg bw/day in females (due to increased organ weights); NOAEL neurotoxicity >= 1000 mg/kg bw/day (no effects observed; GLP, Rohm & Haas 2002)

Key value for chemical safety assessment

Effect on neurotoxicity: via oral route

Link to relevant study records

Reference

Endpoint:

neurotoxicity: short-term oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2000-10-23 to 2000-12-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test) including FOB (Functional Observation Battery)

Deviations:

no

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

other: Crl:CD BR

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories (Raleigh Facility, Raleigh, NC)
- Age at study initiation: 11 weeks
- Weight at study initiation: males weighed 357.5 - 358.1 g; and females weighed 240.4 - 241.3 g
- Fasting period before study:
- Housing: Animals were individually housed in stainless steel cages (34 cm x 18 cm x 18 cm) with wire-mesh fronts and bottoms, suspended over pans containing absorbent liners. Cage liners were changed at least three times weekly. During mating, cage liners were changed daily. Clean cage banks were supplied approximately every two weeks. After mating, females were housed in polycarbonate shoe-box cages (53 cm x 29 cm x 20 cm) containing Alpha-Dri bedding (Shepherd Specialty Papers, Irre.) throughout gestation and lactation.
- Diet: During the acclimation and treatment periods, all animals had free access to PMI Certified Rodent Diet #5002M (Ralston Purina Co., St. Louis, MO).
- Water: Water purified by reverse osmosis was available ad libitum via an automatie watering system or water bottles.
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-22
- Humidity (%): 41-63
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Vehicle:

other: Reverse Osmosis (RO) Water

Details on exposure:

Dosage: 5 mL/kg bw
The appropriate amount of test substance was used to prepare sufficient quantities of gavage solutions at concentrations appropriate to deliver dose levels of 100, 300, and 1000 mg ai/kg/dayat a constant volume of 5 mL/kg. The dose levels were adjusted to represent percent active ingredient. The test substance was weighed in a hood and diluted in reverse osmosis (RG) water. Group 1 (control) received RO water only. Gavage solutions were prepared once a week and stored in the refrigerator. Prior to gavaging the animals each day, an aliquot of each concentration was placed in a small beaker and allowed to warm to approximate room temperature. Daily dosing solutions and any treated gavage solution unused at the end of a dosing period were discarded as hazardous waste.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Stability of the test substance in RO water, when stored refrigerated for 8 days, was determined from the first dose preparation. Homogeneity was
determined by analyzing top, middle and bottom sampIes from the first dose preparation. SampIes of dosing solutions prepared on days 34 and 52 were analyzed for active ingredient content to determine proximity to target concentrations.
The sampIes were diluted to 100 ppm with acetonitrile and analyzed by HPLC. Proximity to target for the sampIes analyzed ranged from 89.3% to 100.0%. Day 8 stability of the sampIes was confirmed. Homogeneity analysis was done by performing proximity to target far the top, middle, bottom sampIe and reporting the standard deviation. The standard deviation ranged from 1.19 to 3.39 (n = 3). There were no issues of homogeneity.

Duration of treatment / exposure:

8 weeks

Frequency of treatment:

daily

Remarks:

Doses / Concentrations:
0 (control), 100, 300 or 1000 mg a.i./kg body weight/day
Basis:
nominal conc.

No. of animals per sex per dose:

12

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: The test substance was administered daily via gavage at dose levels of 0 (control), 100, 300, or 1000 mg a.i./kg of body weight/day (Groups 1, 2, 3, and 4, respectively). The limit dose of 1000 mg a.i./kg bw/day was selected based on agavage range-finding study which induced minimal toxicity in the parameters measured. The low and middle doses were approximately logarithmically spaced from the high dose.
- Rationale for selecting satellite groups: no satellite groups

Observations and clinical examinations performed and frequency:

CLINICAL OBSERVATIONS AND FREQUENCY:
- Clinical signs: During the treatment period, each rat was observed twice daily for morbidity or mortality (except on weekends and holidays, when they were observed once). General clinical observations were made at least once daily,
- Mortality: Rats were euthanized for post-mortem examination if it is anticipated that they would not survive until the next observation period, or for human reasons.
- Body weight: Parental Animals: Body weight was determined weekly for males throughout this study. Females were weighed weekly until cohabitation, on Gestation Days (G) 0, 3, 6, 9, 12, 15, 18, and 20, and on Postnatal Days (PND) 0 and 4.
- Food consumption: Food consumption was determined weekly for male and female animals until cohabitation. Food consumption was not measured for either sex during cohabitation due to the inability to ascribe consumption to individual animals. Females feed consumption was measured from G0-7, G7-14, G14-21 and from PND 0-4 during lactation. The weekly feed consumption was resumed for males after the mating period and continued throughout the study.
- Haematology: Hematology and clinical chemistry measurements were performed on all animals at terminal necropsy. Animals were fasted overnight and blood samples were collected just prior to terminal necropsy. All samples were collected from the abdominal aorta of rats that had been anesthetized with an anesthetic mixture [ketamine HCL (100 mg/ml), xylazine (20 mg/ml), and acepromazine maleate (10 mg/ml) prepared at a 220:10:3 ratio] administered intraperitoneally at approximately 0.1 ml/150 g body weight to effect. Blood samples were collected in an order that rotated through treatment groups (i.e., one animal from each treatment group was bled before a second animal from the same group.) Once blood was collected, animals were exsanguinated via the abdominal aorta. Necropsy and blood sample collection were performed over two consecutive days (approximately 6 animals/sex/group were necropsied each day). The following hematology and clinical chemistry parameters were measured on each sample:
Hematology
a. Erythrocytes (RBC); b. Hematocrit (HCT); c. Hemoglobin (HGB); d. Mean Cell Hemoglobin (MCH); e. Mean Cell Hemoglobin Concentration (MCHC);
f. Mean Cell Volume (MCV); g. Platelets (PLT); h. Total White Blood Cell Count (WBC) and Differential (WBC DIFF)
Clinical Chemistry
a. Alanine aminotransferase (ALT); b. Albumin (ALB); c. Albumin/globulin ratio (A/G); d. Alkaline Phosphatase (ALP); e. Aspartate aminotransferase (AST); f. Blood Urea Nitrogen (BUN); g. Calcium (CA); h. Chloride (CL); i. Creatinine (CREA); j. Gamma Glutamyltransferase (GGT); k. Globulin (GLOB); l. Glucose (GLU); m. Inorganic Phosporus (PHOS); Clotting Potential; n. Potassium (K); o. Sodium (NA) Prothrombin time (PT); q. Total Cholesterol (CHOL);
r. Total Protein (TP); s. Triglycerides (TRIG)

Specific biochemical examinations:

no data

Neurobehavioural examinations performed and frequency:

A Functional Observational Battery (FOB) were performed on all surviving rats during the 5th week (males) or 7th week (females) of dosing. Also, the movement of each rat was monitored for 1.5 hours. Motor activity assessment was performed after all FOBs in a given day's replicate were completed. Each rat was placed individually in a stainless steel cage with a passive infrared motion sensor mounted to the cage front. The infrared sensors of each cage were connected to a computer. The computer recorded the number of movements and time spent in movement for each animal at 5-minute intervals.

Sacrifice and (histo)pathology:

ORGANS EXAMINED AT NECROPSY (MACROSCOPIC AND MICROSCOPIC):
- Organ weights: Organ weights (absolute and relative to body weight) obtained for all parental animals were: adrenals, brain, heart, kidneys, liver, spleen and thymus. For the males weights were obtained for testes and epididymides.

Other examinations:

none

Positive control:

not required

Statistics:

The litter (i.e., proportion of pups/litter, or litter mean) was used, where appropriate, as the experimental unit for the purpose of statistical evaluation. The level of statistical significance selected was p<0.05, unless otherwise noted. The statistical tests that were used to analyze the parameters studied are listed below:
- Analysis of Variance (ANOVA)
- 2xN Chi-square test
- 2xN Kruskal-Wallis nonparametric ANOVA
- Dunnett's test
- Fisher's exact test

Details on results:

Statistically significant increases in the number of rears in males at 300 mg a.i./kg (week 1) and at 1000 mg a.i./kg (weeks 1-3) were not considered treatment-related since there was no clear dose response, females were not affected, and this parameter was not significant in the Functional Observation Battery evaluation. A statistically significant difference in homecage behavior was noted in males at 100 ppm during week 4. This change was considered incidental since similar effects were not noted at higher doses.
No further data regarding FOB results. See IUCLID chapter 7.5.1 (repeated dose toxicity) for observations of systemic toxicity.

Dose descriptor:

NOEL

Remarks:

systemic toxicity

Effect level:

100 mg/kg bw/day

Based on:

test mat.

Sex:

male

Basis for effect level:

other: increased liver weights

Remarks on result:

other: Generation: maternal (migrated information)

Dose descriptor:

NOEL

Remarks:

systemic toxicity

Effect level:

300 mg/kg bw/day

Based on:

test mat.

Sex:

female

Basis for effect level:

other: increased liver and kidney weights

Remarks on result:

other: Generation: maternal (migrated information)

Dose descriptor:

NOAEL

Remarks:

neurotoxicity

Effect level:

>= 1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no effects observed

Remarks on result:

other: Generation: maternal (migrated information)

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:

GLP and guideline study.

Effect on neurotoxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Effect on neurotoxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

The neurotoxicity of ureido methacrylate was assessed regarding results of a FOB and motor activity evaluation during a subacute oral study in rats.

 

oral

The neurotoxic potential of the test substance, ureido methacrylate (purity unknown), was evaluated in a GLP conform combined repeated dose study in rats following OECD test guideline 407 including a functional observation battery and a motor activity evaluation (Rohm & Haas 2002). The test substance was administered orally by gavage to four groups of 12 male and 12 female Crl:CD BR rats once daily for eight weeks. Dose levels were 0, 100, 300, and 1000 mg a.i./kg/day, administered at a dosage volume of 5 ml/kg. The control group received the vehicle, double-distilled water, on a comparable regimen at a dosage volume of 5 ml/kg. Males and females of the same treatment group were mated 1:1 two weeks after the beginning of the treatment.

During the treatment period, each rat was observed twice daily for morbidity or mortality. General clinical observations were made at least once daily. Body weight was determined at least weekly throughout this study. Functional Observational Battery (FOB) and motor activity evaluations were performed on week 5 (males) and week 7 (females). After eight weeks, overnight fasted animals were euthanized and necropsied. Hematology and clinical chemistry measurements were performed on all animals at terminal necropsy. Animals were fasted overnight and blood samples were collected just prior to terminal necropsy. Microscopic examinations of the studied organs were performed for 5 (randomly selected) parental animals/sex in the high dose group and control group. All tissues exhibiting gross pathological changes were examined microscopically.

Treatment-related decreases in hemoglobin (6%), hematocrit (7%), and mean cell volume (4%) were noted in males at 1000 mg a.i./kg bw/day. In addition, platelet counts were increased (14%) at this level. Treatment-related increases in absolute and relative kidney weights (10-11%) and in absolute and relative liver weights (20%) were noted in both sexes at 1000 mg a.i./kg. Absolute and relative liver weights were also increased (12-16%) in males at 300 mg a.i./kg. Other effects were considered as incidental and not treatment-related. Microscopic examinations in the relevant organs revealed no complementary effects seen in liver and kidney weights, these observations are considered as not adverse.

No treatment related effects were observed in both the functional Observational Battery (FOB) and motor activity evaluations.

Based on the results of this study, the NOEL (no-observed-effect level) for systemic toxicity of ureido methacrylate administered orally is 100 mg a.i./ kg bw/day in males and 300 mg a.i./ kg bw/day in females. The NOAEL for neurotoxicity is assessed to be >= 1000 mg a.i. /kg bw/ day.

Justification for selection of effect on neurotoxicity via oral route endpoint:
Only one GLP and guideline study available.

Justification for classification or non-classification

There is no indication given for a relevant neurotoxic potential of ureido methacrylate and in conlusion the substance has not to be classified according to 67/548/EEC and Regulation (EC) No 1272/2008 (GHS, CLP), respectively.