Registration Dossier

Administrative data

Endpoint:
in vivo mammalian germ cell study: cytogenicity / chromosome aberration
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
The study was conducted similar to an appropriate OECD TG, but without GLP

Data source

Reference
Reference Type:
publication
Title:
2-ISOCYANATOETHYL METHACRYLATE - AN INHALATION DOMINANT LETHAL STUDY IN THE MALE SPRAGUE DAWLEY RAT
Author:
Murray J. S. et al.
Year:
1980
Bibliographic source:
Drug and Chemical Toxicology 3(4): 381-392

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 478 (Genetic Toxicology: Rodent Dominant Lethal Test)
Version / remarks:
(1984)
Deviations:
no
GLP compliance:
no
Type of assay:
rodent dominant lethal assay

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
rat
Strain:
other: Sprague-Dawley (Spartan substrain)
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS- Source: Spartan Research Animals, Haslett, Michigan- Age at study initiation: 10-12 weeks- Housing: 2 per cage in wire-bottom cages- Diet: Purina laboratory chow, ad libitum (during the non-exposure period)- Water: ad libitum (during the non-exposure period)

Administration / exposure

Route of administration:
inhalation: vapour
Vehicle:
- Vehicle used: air
Details on exposure:
TYPE OF INHALATION EXPOSURE: no dataGENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION- Exposure apparatus: 4.3 m³ Rochester-type chamber at dynamic airflow conditions- System of generating vopour: Vapour was generated by counter-current exchange between air and liquid test material in a 15-plate perforated plate distillation column. To increase the stability of the system, the distillation was water jacketed and thermostated to a few degrees below ambient room temperature. The generating system was arranged so that air was continuously pumped through a closed loop containing the distillation column and a 5 liter plenum flask. The apparatus was designed to hold the concentration of the test material in the plenum flask at a level of approximately 100 ppm. The chambers were supplied by pumping air from the plenum flask via positive displacement piston pumps, and diluting the stream 400 - 4000 fold to achieve the target concentrations. - Temperature and humidity in air chamber: approximately 72 °F (22.2 °C) and 50% humidity - Air flow rate: 700 l/minTEST ATMOSPHERE- Brief description of analytical method used: To ensure stable operation, the test material concentration in the plenum flask was monitored periodically by a semiautomated gas chromatographic method. Primary analysis of chamber air was made via a liquid chromatographic procedure. 20 l of the chamber air was bubbleed through an impinger at a rate of 2 l/min into a solution containing p-nitrobenzyl propyl amine. The test item reacts quantitatively with this material to form the urea derivate of the isocyanato group. An aliquot of this solution containing the urea derivate of the test material and the unreacted p-nitrobenzyl propyl amine, was analysed by HPLC with an UV detector at 250 nm. This method was used to precisely measure test material concentrations in the chamber, whereas a second on-line analytical method was employed to detect fluctuations in chamber concentrations. Therefore an MDA paper tape detector (MDA Scientific Inc., Park Ridge, Illinois), specific for isocyanates, was connected to each chamber to provide a continous record of the test material concentration. - Samples taken from breathing zone: yes
Duration of treatment / exposure:
6 h
Frequency of treatment:
10 weeks: 4 days for the first week, and 5 days/week for the subsequent 9 consecutive weeks
Post exposure period:
week 1 post exposure: each male rat was mated with 2 adult (at least 10-12 weeks old) untreated virgin femalesweek 2 post exposure: each male rat was mated with 2 other females
Doses / concentrationsopen allclose all
Dose / conc.:
25 other: ppb (nominal)
Remarks:
24.1±2.3 ppb (analytical conc.)
Dose / conc.:
80 other: ppb (nominal)
Remarks:
79.1±3.6 ppb (analytical conc.)
Dose / conc.:
250 other: ppb (nominal)
Remarks:
245±12 ppb (analytical conc.)
No. of animals per sex per dose:
20 male rats
Control animals:
yes, concurrent no treatment

Examinations

Tissues and cell types examined:
Number of corpora lutea and live and dead implantations were counted.
Statistics:
Body weight, number of implantations, and number of corpora lutea were evaluated by a one-way analysis of variance; differences between experimental groups and the controls were analysed using Dunnett's test. The fertility index was analysed by the Fisher's exact propability test. The pre-implantation loss and resorption rate data were analysed using the Wilcoxon test as modified by Haseman and Hoel.

Results and discussion

Test results
Sex:
male
Genotoxicity:
negative
Toxicity:
no effects
Vehicle controls validity:
not examined
Negative controls validity:
valid
Positive controls validity:
not examined

Any other information on results incl. tables

During the third week of exposure, all animals at every dose level and the control group exhibited signs of consistent sialodacryoadentitis (swelling in the neck area and the appearance of a red crusty material around the eyes and nasal area). After approx. ten days, these signs subsided. Beginning with the seventh week of exposure and lasting throughout the rest of the treatment period, five animals at the 250 ppb level exhibited swelling and ulcerated abscesses in the throat region. Control animals appeared normal in appearance and behaviour, and did not show these signs.

Two rats at 250 ppb (high dose group) died during the study. One animal showed signs of a distended and hard abdomen after the first 6 - hour exposure period and died after eleven exposures to 250 ppb of the test material. The second animal died after ten weeks of exposure to 250 ppb of the test item and upon gross examination this animal exhibited a distended and hard abdomen. Gross pathology on both high dose males revealed that death was caused by a large abscessed mass and an infection in the abdominal cavity. Hence, the deaths are considered to be not related to the test material treatment, but attributed to an incidental infection.

Throughout the study, mean body weights of male rats at all dose levels were comparable to those in the control group. Weight losses occurred in some rats during 3rd and 4th weeks of exposure when the signs of sialodacryoadentitis were evident; however, no statistical differences were observed between the rats exposed to the test item and the control animals.

Vaginal plugs were observed with equal frequency beneath the cages of control and of treated rats suggesting that mating occurred in all groups. The fertility indices of male rats exposed to the test item were comparable to the control group. All groups had 95% or higher fertility rate for both weeks of mating. The average number of implantations, corpora lutea, and resorptions in the unexposed female rats bred to the male rats exposed to the test material are given in Tab.1. All exposure levels had values for these parameters which were comparable to the control group. For the first week of breeding the average pre- implantation loss for all dose groups was not significantly different from the control data. For the second week of breeding the average pre- implantation loss at the 80 ppb level was significantly lower than the control mean (Tab. 2). This was not a detrimental effect and was not considered to be of toxicological importance. The average resorption rates in the treatment levels for the first and second week of breeding were comparable to the respective control group resorption rate (Tab. 2).

Tab. 1: Reproductive parameters – average number of implantations, corpora lutea, and resorptions in unexposed female rats bred to male rats exposed to the test item by inhalation

 

Post exposure breeding

Exposure level [ppb]

control

25

80

250

Week 1

Average corpora lutea

13 ± 1

14 ± 1

13 ± 1

14 ± 1

Average implantations

13 ± 2

13 ± 1

13 ± 2

13 ± 1

Average resorptions

1 ± 1

1 ± 1

1 ± 1

1 ± 1

Week 2

Average corpora lutea

14 ± 2

14 ± 2

14 ± 2

14 ± 2

Average implantations

13 ± 2

13 ± 1

13 ± 1

13 ± 2

Average resorptions

1 ± 1

1 ± 1

1 ± 1

1 ± 1

Mean ± SD. The average number of implantations, corpora lutea, or resorptions for the two females bred to each male was calculated. Group means were then calculated from the averaged values.

No values were significantly different from control values by an analysis of variance and Dunnett’s Test or by a modified Wilcoxon Test, p < 0.05.

 

Tab. 2: Reproductive parameters – average pre- implantations loss and average resorption rate in unexposed female rats bred to male rats exposed to the test item by inhalation Average pre- implantation loss [%]

 

Post exposure breeding

Exposure level [ppb]

control

25

80

250

Average pre- implantation loss [%]

Week 1

6± 7

8 ± 8

6 ± 8

5 ± 5

Week 2

9 ± 10

7 ± 5

5 ± 6*

9 ± 9

Average resorption rate [%]

Week 1

5 ± 6

3 ± 5

6 ± 7

5 ± 4

Week 2

6 ± 4

4 ± 5

5 ± 6

6 ± 7

* Significantly different from the control mean by a modified Wilcoxon Test, p < 0.05

Applicant's summary and conclusion

Conclusions:
Interpretation of results: negative