2,4,6-trichloro-1,3,5-triazine

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions (e.g. purity of test substance not reported)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1983

Report date:

1983

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

yes

Remarks:

: food consumption and uterus weights not determined, treatment from day 6 to day 19 of gestation

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2,4,6-trichloro-1,3,5-triazine

EC Number:

203-614-9

EC Name:

2,4,6-trichloro-1,3,5-triazine

Cas Number:

108-77-0

Molecular formula:

C3Cl3N3

IUPAC Name:

trichloro-1,3,5-triazine

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Test animals

Species:

rat

Strain:

other: Charles River CD

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc. , Portage, Michigan
- Age at study initiation: approximately 70 days
- Weight at study initiation: not reported
- Fasting period before study: none
- Housing: individually in suspended wire mesh cages (except during mating)
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 51 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23 - 24 °C
- Humidity (%): 31 - 51 %
- Air changes (per hr): not reported
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: mineral oil;

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
- Concentrations in vehicle: 5, 25 and 50 mg/mL
- weighing and suspending of test substance in vehicle (mineral oil) with a tissue homogenizer with pestel
- transfer of the mixture to a graduated mixing cylinder and addition of the respective amount of vehicle and homogenization by manual shaking of cylinder

VEHICLE
- Justification for use and choice of vehicle: none stated, but the test item is known to decompose in water
- Amount of vehicle: 1 mL/kg bw
- Purity: not reported

Analytical verification of doses or concentrations:

no

Details on mating procedure:

- Impregnation procedure: cohoused
- M/F ratio per cage: 1 male and 1 female
- Length of cohabitation: until copulation (determined by appearance of copulatory plug in females)
- Further matings after two unsuccessful attempts: not reported
- Verification of same strain and source of both sexes: yes
- Proof of pregnancy: vaginal plug referred to as day 0 of pregnancy
- After mating females were returned to individual cages and identified by ear tag

Duration of treatment / exposure:

day 6 to day 19 of gestation

Frequency of treatment:

daily

Duration of test:

day 0 to day 20 of gestation

No. of animals per sex per dose:

25

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: doses based on range finding study (83-0092-FKR):
block design:
The assignment to groups was based on the time point of notification of the appearance of the copulatory plug (gestation day 0).
The first mated animal was assigned to group 1 (control group), the second animal to group 2 (low dose) and so on.
Animals were assigned in this manner until the required number of females had been placed into each group

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily from day 0 to day 5 of gestation, once daily from day 6 to day 20 of gestation
- Cage side observations checked in table 2 were included.
- No difference was made in the report between cage side observations and clinical observations


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice daily from day 0 to day 5 of gestation, once daily from day 6 to day 20 of gestation
- Cage side observations checked in table 2 were included.
- No difference was made in the report between cage side observations and clinical observations


BODY WEIGHT: Yes
- Time schedule for examinations: day 0, 6, 9, 12, 16 and day 20 ( day 19 values as discribed in the results section were determined on day 20)


POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 20
- Organs examined:
uterus
ovaries
gross examination for evident morphological changes of organs in the thoratic and the abdominal cavities

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight:No
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: Uteri that appear non-gravid were further examined by ammonium sulphide (10 %) staining to confirm the non-pregnant status (Kopf, R., Lorenz, D., Salewski, E.(1964). "THE EFFECT OF THALIDOMIDE ON THE FERTILITY OF RATS IN REPRODUCTION EXPERIMENTS OVER 2 GENERATIONS". Naunyn Schmiedebergs Arch Exp Pathol Pharmakol, Vol. 247, p. 121-35)

Fetal examinations:

- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: approximately half per litter
- Skeletal examinations: Yes: approximately half per litter
- Head examinations: Yes: all per litter (palate and eyes)
- Weighted: Yes: all per litter
- Sex determination: Yes: all per litter

Statistics:

- male to female sex rations and proportions of litters with malformations: Chi-square test criterion with Yates' correction for 2 x 2 contigency tables and/or Fisher's exact probability test as described by Sigel (see remark (III)) to judge significance of difference
- proportions of resorbed and dead fetuses and postimplantational losses : Mann Whitney U-test as described by Siegel (Siegel, S. (1956). "Nonparametric Statistics for the Behavioral Sciences. McGraw-Hill, New York, N. Y., U.S.A) to judge significance of difference
- mean number of corpora lutea, total implantations, live fetuses and mean body weights: one way ANOVA, Bartlett's test for homogeneity of variances and the appropriate t-test(for equal or unequal variances) as described by Steel and Torrie (Steel, R. G. D. and Torrie, J. H. (1960). "Priciples and Procedures of Statistics". McGraw-Hill, New York, N. Y., U.S.A) using Dunnett's multiple comparison tables (see remark (Dunnett, C. W. (1964). New tables for multiple comparisons with a control. Biometrics, Vol. 20, p. 482-491) to judge significance of difference

Indices:

- Group mean preimplantational loss = ((Total No. Corpora Lutea – Total No. Implantations)/ Total No. Corpora Lutea) x 100
- Group mean postimplantational loss = ((Total No. Implantations – Total No. Viable Fetusses)/ Total No. Implantations) x 100

Historical control data:

Historical data comprises data from 1579 litters, complete statistic data on:
Preimplantational loss (and complete data to calculated this value)
Postimplantational loss (and complete data to calculated this value)
Fetal sex ration
Fetal body weight
Nature and frequency of observed malformations in fetuses
Nature and frequency of observed variations in fetuses

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
- clinical signs: in the high dose group: dry brown , red or black matter around eyes, nose, mouth, face, forelimbs or anogenital area; exess salivation; matted haircoat; respiratory rales
- body weight: slightly reduced body weight gain in the high dose group, see table 3

Effect levels (maternal animals)

Key result

Dose descriptor:

NOAEL

Effect level:

25 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:yes. Remark: Embryotoxic effects, no teratogenic effects

Details on embryotoxic / teratogenic effects:
- slight increase in mean total postimplantation loss in all treated groups compared to the control group that was considered treatment related in the high dose group and resulted in fewer viable fetuses/dam only in this group (see table 4)
- reassessment of the data revealed, that in the control group postimplatational losses ranged from 0 - 3 (mean 0.8). In the low dose group all of the gravid animals except two (no. of postimplantational losses 4 and 5) are within this range. In the mid dose group all of the gravid animals except two (no. of postimplantational losses 4 and 7) are within this range. In the high dose group all of the gravid animals except one (no. of postimplantational losses 10) are within this range. In all treatment groups only these one or two outliers per treatment group of 25 animals cause the differences.
- mean fetal body weights of the treated groups were equal or slightly higher than in the control group (see table 4)
- No meaningful differences in the incidence of fetal malformations (table 5) and developmental variations between control and treated groups

Effect levels (fetuses)

Key result

Dose descriptor:

NOAEL

Effect level:

25 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

reduction in number of live offspring

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

The study presents a NOAEL for maternal toxicity (oral) of 25 mg/kg bw/day based on clinical signs and body weight gain and a NOAEL for embryotoxic effects (oral application to the parent) of 25 mg/kg bw/day based on fewer viable fetuses/dam in the high dose group.