Cyclododeca-1,5,9-triene

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1999

Reference 2

Reference Type:

publication

Title:

Evaluation of the potential developental toxicity of cyclodedecatriene (CDDT).

Author:

Munley SM, Kelly DP and Kennedy GL jr.

Year:

2003

Bibliographic source:

Drug Chem. Toxicol. 26 (3), 199-212.

Reference 3

Reference Type:

publication

Title:

Robust summary for 1,5,9-cyclododecatriene (revised).

Author:

DuPont Safety, Health & Environmental Excellence Center, Wilmington (Del., USA)

Year:

2003

Bibliographic source:

U.S. EPA, 46 pp

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

1,5,9-cyclododecatriene

IUPAC Name:

1,5,9-cyclododecatriene

Constituent 2

Reference substance name:

Cyclododeca-1,5,9-triene

EC Number:

225-533-8

EC Name:

Cyclododeca-1,5,9-triene

Cas Number:

4904-61-4

Molecular formula:

C12H18

IUPAC Name:

cyclododeca-1,5,9-triene

Details on test material:

1,5,9-cyclododecatriene of DuPont Nylon, purity 99.83%

Test animals

Species:

rat

Strain:

other: Crl:CD (SD)BR

Details on test animals or test system and environmental conditions:

TEST ORGANISMS
- Source: Charles River Breeding Laboratories, Raleigh (North Carolina,  USA)
- females; age: 51-70 days when received (at 1, 2, or 3 days of gestation); 5, 4,  or 3 days acclimation
- Number of animals: 22 per exposure concentration

Administration / exposure

Route of administration:

inhalation

Type of inhalation exposure (if applicable):

whole body

Vehicle:

air

Details on exposure:

ADMINISTRATION / EXPOSURE
- Type of exposure: whole-body
- Concentrations: 10 / 25 / 75 ppm (target)
- Type or preparation of particles: Controlled flows of high-pressure air  and liquid test substance through heated mixing flask (approx. 240 °C),  dilution with additional air, total airflow 60 l/min (target; measured:  59 - 62 l/min).
- Exposure chamber temperature: target 22 +/- 2 °C; measured 22 - 27 °C

The time-mated female rats were exposed whole-body to generated atmospheres of the test substance in 300 L stainless steel and glass exposure chambers. Atmospheres of 1,5,9-cyclododecatriene were generated, such that the high concentration (67 ppm) chamber contained a mixture of aerosol and vapor components, while the low (10 ppm) and intermediate (25 ppm) concentration chambers contained primarily vapor, with little or no aerosol component. Exposure atmospheres were generated by metering the liquid test substance into a heated, glass, 3- neck mixing flask with an infusion pump. High pressure air was passed through the mixing flask and carried the test atmospheres to the exposure chamber. Dilution air was added between the flask and the chamber inlet for a total airflow of 60 L/min. Desired atmospheric concentrations of 1,5,9-cyclododecatriene were controlled by varying the test substance feed rate delivered to the mixing flask. The control group was exposed to air only. The atmospheric concentration of 1,5,9-cyclododecatriene was determined at approximate 60-minute intervals during each exposure by gas chromatography and gravimetric analyses for the vapor and aerosol components, respectively. Samples to determine particle size distribution were taken 3 times during the study from the 67 ppm chamber. Chamber temperature, humidity, oxygen concentration, and airflow were recorded.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

- Concentration monitoring:   known volume samples from breathing zone at 60 minute intervals;   passage through glass fiber filter followed by glass impinger with  hexane as collection medium;   weighing of filter before and after sampling;   GC / FID analysis of hexane solution, quantification with standard  curve.
- Particle size (high test concentration, 3 measurements): MMAD 5.4 / 1.5  / 0.76 µm, mean 2.6 µm, with 13-56% of the particles < 1 µm; 35-89% < 3  µm; 66-99% < 10 µm.
-further details: see references

Details on mating procedure:

-mated by supplier

Duration of treatment / exposure:

days 6-20 of gestation

Frequency of treatment:

6 hours/day

Duration of test:

16 days

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
10; 25; 67 ppm = 67.5; 169; 452 mg/m3
Basis:
nominal conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
10 +/- 0.27 ppm; 25 +/- 0.33 ppm; 67 +/- 1.9 ppm
Basis:
analytical conc.

No. of animals per sex per dose:

22 per exposure concentration

Control animals:

yes, concurrent vehicle

Examinations

Maternal examinations:

PARAMETERS ASSESSED DURING STUDY:
- Body weight gain: days 0, 6, 8, 10, 12, 14, 16, 18, 20, 21
- Food consumption: days 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 21
- Clinical observations: once daily (before onset of exposure; including  day 21), on exposure days also 1 h after exposure

ORGANS EXAMINED AT NECROPSY (MACROSCOPIC AND MICROSCOPIC): Study  terminated on day 21
- Macroscopic: Organs of the thoracic and abdominal cavities were examined for gross pathologic changes. The intact and empty uterine weights were recorded to calculate maternal body weight adjusted to exclude the products of conception.
The corpora lutea count for each ovary of dams with viable fetuses was recorded. For each female with visible implants, the type (live and dead fetuses, and resorptions) and their relative positions were recorded. The uterus of each apparently “nonpregnant” rat was stained to detect very early
resorptions.

Ovaries and uterine content:

- Examination of uterine content: type (live and dead fetuses, and  resorptions) and relative positions 

Fetal examinations:

The body weight, sex, and external alterations for each fetus were recorded. For each litter, the first live fetus and every other live fetus thereafter were examined for visceral alterations. The heads of decapitated fetuses were fixed, examined, and alterations were recorded. The remaining fetuses were euthanized. Skeletal alterations were recorded for all live fetuses, excluding the fetal heads examined above.

Statistics:

STATISTICAL METHODS: 
- Maternal weight, weight change, food consumption: parametric linear  contrast of means
- Incidence data (pregnancy, clinical observations): Cochran-Armitage test
- Reproductive outcome data and fetal alteration data: Jonckheere's test;  at > 75 % ties: permutation methodology
- Mean fetal weight, sex ratio: Analysis of variance (ANOVA), applying a  parametric linear contrast of least square means

Indices:

no

Historical control data:

no

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
MATERNAL TOXIC EFFECTS BY DOSE LEVEL:
- Mortality and day of death: no deaths
- Description, severity, time of onset and duration of clinical signs:    10 ppm: no effect; 25 ppm: increase in facial staining;   67 ppm: diminished response to alerting stimulus; stained and/or wet  fur, staining was considered to be the result of increased lacrimation  and salivation and decreased grooming.
- Body weight: statistically significant decrease at mid and high dose  beginning on day 8; data for day 21:   25 ppm:  -5.3% absolute,  -5.6% corrected for uterine content   67 ppm: -14.8% absolute, -15.0% corrected for uterine content   increase day 6-21 (also statistically significant):   25 ppm: -14.5% absolute, -30.8% corrected for uterine content   67 ppm: -36.0% absolute, -69.6% corrected for uterine content   At 10 ppm, statistically significant but minimal (3-4 %) and transient  differences to control in weight increase were observed during the first  week.
- Food/water consumption:   The maternal weight data corresponded to food consumption values, which  were reduced at 25 (-9%) and 67 (-28%) ppm but unaffected at 10 ppm.
- Number pregnant per dose level = number of litters:   0 ppm: 21;  10 ppm: 20;  25 ppm: 22;  67 ppm: 20. ==> no effect
- Number aborting: none - Number of resorptions (mean):   0 ppm: 1.0; 10 ppm: 0.7; 25 ppm: 0.4; 67 ppm: 0.7 ==> no effect
- Number of implantations (mean):   0 ppm: 14.1; 10 ppm: 14.1; 25 ppm: 13.3; 67 ppm: 13.8 ==> no effect
- Pre and post implantation loss: none - Number of corpora lutea (mean):   0 ppm: 15.6; 10 ppm: 15.4; 25 ppm: 14.8; 67 ppm: 15.0 ==> no effect

Effect levels (maternal animals)

1

Dose descriptor:

NOEL

Effect level:

10 ppm

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

2

Dose descriptor:

NOEL

Effect level:

25 ppm

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
FETAL DATA: 
- Litter size and weights (mean):    0 ppm: 13.1 fetuses (6.9 males + 6.2 females) with 5.68 g mean weight   10 ppm: 13.4 fetuses (7.1 males + 6.4 females) with 5.63 g mean weight   25 ppm: 13.0 fetuses (6.6 males + 6.4 females) with 5.55 g mean weight   67 ppm: 13.1 fetuses (6.5 males + 6.7 females) with 4.93 g mean weight   ==> statistically significant effect on weight (-13.2%) at 67 ppm
- Number viable: all live
- Sex ratio: male/total = 0.53 / 0.52 / 0.50 / 0.49 ==> no effect
- Grossly visible abnormalities: no effect observed
- External abnormalities: no effect observed
- Skeletal abnormalities:    Compound related, statistically significant increase in incidence of  delayed skeletal ossification:   
- sternebrae: 0 ppm: -; 10 ppm: 1 fetus; 25 ppm: 2 fetuses (2 litters);  67 ppm: 8 fetuses (5 litters): considered compound-related and consistent  with reduced fetal weight.   
- vertebrae: 0 ppm: 113 fetuses (21 litters) 10 ppm: 123 (20); 25 ppm:  134 (22); 67 ppm: 136 (20): not considered toxicologically relevant based  on high background incidence; well within the control range of four  studies from the same time: 128-161 fetuses in 23-25 litters.

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Any other information on results incl. tables

The analytically determined mean concentrations of 1,5,9-cyclododecatriene were 10 ± 0.27, 25 ± 0.33, and 67 ± 1.9 ppm for the 10, 25, and 67 ppm exposure levels, respectively. The 1,5,9-cyclododecatriene aerosol generated in the 67 ppm chamber was considered to be respirable in rats. The mass median aerodynamic diameter (MMAD) measurement was 2.6 μm, with 13-56% of the particles less than 1 μm, 35-89% of the particles less than 3 μm, and 66-99% of the particles less than 10 μm. Chamber airflow, oxygen concentration, temperature, and humidity were 59-62 L/min, 21%, 22-27ºC, and 27-67% respectively.

Applicant's summary and conclusion

Conclusions:

The NOAEL for maternal toxicity was 10 ppm (67.5 mg/m3), based on decrease of bodyweight and food consumption at 25 ppm. Developmental toxicity was observed at 67 ppm, the NOAEL for developmental toxicity was 25 ppm (169 mg/m3). Therefore, the results of this study indicate that
1,5,9-cyclododecatriene is not likely to be uniquely toxic to the rat conceptus.

Executive summary:

Female rats were exposed to 1,5,9 -cyclododecatriene aerosol at 10, 25 and 67 ppm (corresponding to 67.5, 169 and 452 mg/m3 respectively) from gestation day 6 to day 20. Observations for morbidity and mortality were made daily. Body weights, food consumption, and individual clinical signs were recorded. Females were euthanized on GD 21 and the organs of the thoracic and abdominal cavities were examined for gross pathologic changes. The intact and empty uterine weights were recorded to calculate maternal body weight adjusted to exclude the products of conception. The corpora lutea count for each ovary of dams with viable

fetuses was recorded. For each female with visible implants, the type (live and dead fetuses, and resorptions) and their relative positions were recorded. The uterus of each apparently “nonpregnant” rat was stained to detect very early resorptions. The body weight, sex, and external alterations for each fetus were recorded. For each litter, the first live fetus and every other live fetus thereafter were examined for visceral alterations. The heads of decapitated fetuses were fixed, examined, and alterations were recorded. The remaining fetuses were euthanized. Skeletal alterations were recorded for all live fetuses.

Maternal toxicity was observed in this study, clinical observations, a decreased of bodyweight gain and food consumption were observed at 25 and 67 ppm.

There were no mortalities or early deliveries observed at any dose level. There were no compound-related effects on mean number of

corpora lutea, implantations, resorptions, live fetuses, or fetal sex ratio at any exposure level. There was no evidence of compound-related embryolethality at any exposure level tested.

No evidence of developmental toxicity was observed at 10 and 25 ppm. The only evidence of developmental toxicity was a significant reduction in mean fetal weight, and a concomitant increase in the incidence of delayed skeletal ossification at 67 ppm.

The NOAEL for maternal toxicity was 10 ppm (67.5 mg/m3), based on decrease of bodyweight and food consumption at 25 ppm. Developmental toxicity was observed at 67 ppm, the NOAEL for developmental toxicity was 25 ppm (169 mg/m3). Therefore, the results of this study indicate that 1,5,9-cyclododecatriene is not likely to be uniquely toxic to the rat conceptus.