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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Study period:
2011-06-29 to 2012-01-23
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Scientifically well performed study.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2011

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Remarks:
8 animals per group
Qualifier:
according to
Guideline:
other: Commission Regulation (EC) No. 440/2008, L 142, Annex Part B, May 30, 2008
Deviations:
yes
Remarks:
8 animals per group
Principles of method if other than guideline:
The number of animals was 8 per group instead of 20.
GLP compliance:
no
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent

Test animals

Species:
rat
Strain:
Wistar
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River, 97633 Sulzfeld, Germany
- Age at study initiation: approx. 11-12 weeks old
- Housing: Full barrier in an air-conditioned room
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3°C
- Humidity (%): 55 ± 10%
- Air changes (per hr): 10 x / hour
- Photoperiod (hrs dark / hrs light): 12 hours light, 12 hours dark

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Analytical verification of doses or concentrations:
not specified
Details on mating procedure:
The animals were acclimatised for at least five days. After acclimatisation, females were paired with males as per the ratio of 1:2 (male to female). Females were paired for cohabitation in batches in order to regularize the number of animals for terminal sacrifice on particular day. The subsequent morning and the next morning onwards, the vaginal smear of female was checked to confirm the pregnancy. The day on which sperms were observed in the vaginal smear was considered as gestation day ‘0’. Mated females were assigned in an unbiased manner to the control and treatment groups ensuring that group mean body weights were comparable with each other.
Duration of treatment / exposure:
in females from the Gestation Day (GD) 5 to GD 19
Frequency of treatment:
daily
Duration of test:
On gestation day 20 caesarean section was performed
Doses / concentrations
Remarks:
Doses / Concentrations:
250, 500, 750 mg/kg bw
Basis:
actual ingested
No. of animals per sex per dose:
8 females per dose
Control animals:
yes

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: at least once a day
- morbidity and mortality

DETAILED CLINICAL OBSERVATIONS: Yes / No / No data
- Time schedule:at least once a day

BODY WEIGHT:
- The sperm positive females were weighed on GD 0, 5, 8, 11, 14, 17 and 20.
- Males were not weighed in this study.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption of sperm positive females was measured on GD 5, 8, 11, 14, 17 and 20. The food consumption was presented for period 0-5, 5-8, 8-11, 11-14, 14-17, and 17-20.
- The food consumption was measured neither for males during the entire study nor for both male and females during the mating period.

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 20
- structural abnormalities or pathological changes
- uteri, gravid uterus with cervix, corpora lutea
- Males were sacrificed at any time after completion of the mating of all females without any observations
Ovaries and uterine content:
The uterine contents were examined for embryonic or fetal deaths and the number of viable fetuses. The degree of resorption (late and early) was ascertained in order to help estimate the relative time of death of the conceptus.
The position /number of fetuses in each uterine horn were also be recorded.
Fetal examinations:
- External examinations: Yes
- Soft tissue examinations: Yes
- Skeletal examinations: Yes
- Head examinations: Yes

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
Mortality:
- no mortality

Clinical observation:
- salivation, moving the bedding, weight loss and piloerection at 500 and 750 mg/kg bw

Body weight development:
-significant body weight decrease between GD5 to 8 at 500 and 750 mg/kg bw
- significant body weight gain decrease from GD5 onwards at 500 and 750 mg/kg bw


Effect levels (maternal animals)

open allclose all
Dose descriptor:
NOAEL
Effect level:
250 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
other: developmental toxicity
Dose descriptor:
NOAEL
Effect level:
250 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
Prenatal data:
- inceased pre- and postimplantation loss at 500 and 750 mg/kg bw
- decreased number of live pubs at 500 and 750 mg/kg bw
- decreased mean litter weight at 750 mg/kg bw

Fetal external examination:
- no clear treatment related effect

Fetal visceral examination
- no clear treatment related effect.

Fetal skeletal examination:
- increased incidences of abnormality at 500 and 750 mg/kg bw

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

Maternal toxicity: Table 1 - 3

Table 1: Summary of Clinical Observation (Number of animals affected) 

Clinical Findings

Control

n=8

250 mg/kg bw

n=8

500 mg/kg bw

n=8

750 mg/kg bw

n=11

Reduced spontaneous acticity

0

0

1

3

Piloerection

0

0

2

6

Prone position

0

0

1

1

Ataxia

0

0

1

1

Moving the bedding

0

0

2

9

Salivation

0

0

0

3

Table 2: Summary of Gestation Body Weight [g]

Gestation Day

Control

 

n=7

250 mg/kg bw

n=6

500 mg/kg bw

n=6

750 mg/kg bw

n=8

0

200 ± 7

203 ± 9

208 ± 14

220 ± 12

5

215 ± 6

221 ± 10

220 ± 12

228 ± 13

8

222 ± 10

227 ± 9

223 ± 13

227 ± 13

11

230 ± 11

239 ± 9

229 ± 17

237 ± 13

14

247 ± 11

250 ± 8

238 ± 21

249 ± 13

17

268 ± 12

275 ± 14

255 ± 27

267 ± 14

20

296 ± 18

317 ± 30

279 ± 39

296 ± 17

Table 3: Summary of Gestation Body Weight Gain [g]

Gestation Day

Control

 

n=8

250 mg/kg bw

n=8

500 mg/kg bw

n=6

750 mg/kg bw

n=10

0 to 20

96 ± 18

114 ± 33

71 ± 33

77 ± 12

0 to 5

16 ± 5

18 ± 6

12 ± 3

10 ± 7

5 to 8

7 ± 5

6 ± 4

3 ± 2

-1 ± 3

8 to 11

7 ± 9

12 ± 3

6 ± 8

9 ± 3

11 to 14

17 ± 9

11 ± 3

9 ± 5

12 ± 2

14 to 17

21 ± 6

26 ± 8

16 ± 7

18 ± 5

17 to 20

28 ± 7

42 ± 23

24 ± 12

29 ± 8

Prenatal Data: Table 4

Table 4: Summary of Prenatal Data

Control 

n=7

250 mg/kg bw

n=6

500 mg/kg bw

n=6

750 mg/kg bw

n=8

Terminal Body Weight [g]

296 ± 17

317 ± 29

279 ± 39

296 ± 16

Uterus Weight[g]

54 ± 17

65 ± 8

47 ± 30

53 ± 12

Adjusted Weight [g]

242 ± 9

252 ± 27

232 ± 14

243 ± 13

Corpora Lutea

12.57 ± 1.13

12.33 ± 1.03

11.17 ± 4.45

12.00 ± 1.41

Implantations

10.14 ± 3.39

12.00 ± 1.41

8.83 ± 6.01

10.13 ± 2.36

Live Fetuses

10.00 ± 3.37

11.50 ±1.38

8.50 ± 6.02

9.50 ± 2.33

Dead Fetuse

0

0

0

0

Total Resorption

0.14 ± 0.38

0.50 ± 0.55

0.33 ± 0.52

0.63 ± 0.92

Pre Implantation Loss [%]

19.85 ± 24.66

2.78 ± 6.80

29.57 ± 35.18

15.51 ± 5.90

Post Implantation Loss [%]

1.30 ± 3.44

4.09 ± 4.53

9.38 ± 20.06

18.53 ± 8.96

Litter Data: Table 5

Table 5: Summary of Litter Weight Data

Control 

n=8

250 mg/kg bw

n=8

500 mg/kg bw

n=6

750 mg/kg bw

n=10

Litter Mean Weight [g]

3.33 ± 0.19

3.31 ± 0.32

3.51 ± 0.31

3.29 ± 0.21

Total Litter Weight[g]

33.00 ± 10.93

38.00 ± 5.35

28.40 ± 19.52

31.29 ± 8.04

Category approach justification:

The developmental toxicity of DEGDBE is to be assessed by read-across consideration. Three structurally related glycol ethers are identified as suitable surrogates. Together with DEGDBE, a category building is proposed to increase the robustness of the read-across consideration.

-Category members and chemical structures: the similarity in their structure is given by presence of butoxylated ethylene glycol at terminal position (Butyl-O-CH2-OH-).

Ethylene glycol butyl ether (EGBE)*

CAS 111-76-2

Butyl-O-CH2-OH

Diethylene glycol butyl ether (DEGBE)*

CAS 112-34-5

Butyl-O-CH2-O-CH2-OH

Diethylene glycol dibutyl ether (DEGDBE)**

CAS 112-73-2

Butyl-O- CH2-O-CH2-O-Butyl

Polyethylene glycol dibutyl ether (PolyEGDBE)***

CAS 31885-97-9

Butyl-O- CH2-O-CH2-O-CH2-O-Butyl

* EGBE and DEGBE are extensively investigated substances and reviews on their toxicity profiles are available in public domain (i.e. EU Risk Assessment Report, 2-Butoxyethanol (EGBE), CAS 111 -76 -2, 2008; Opinion on Diethylene Glycol Monobutyl Ether (DEGBE), SCCP/1043/06, 2006).**target chemical. ***Clariant own data, details provides in corresponding endpoint study record.

 

-The proposed grouping is justified by the common mode of action, namely systemic exposure to 2-butoxyacetic acid (2-BAA) and/or butoxyethoxyacetic acid (BEAA):

- EGBE: 2-BAA is the major urinary metabolite (summarized in EU risk assessment, 2008)

- DEGBE: BEAA is the major urinary metabolite (Deisinger et al. 1989)

- DEGDBE: in 28-day study (Clariant own data) the urinary 2-BAA determination was incorporated; 750 mg/kg bw external dose level corresponded to 1400 mg/L 2-BAA in urine.

- PolyEGDBE: no experimental data on metabolism is available; BEAA and/or 2-BAA as metabolite can be reasonably assumed.

 

- The proposed grouping is justified by the comparable toxicity profiles, which reflects the toxicity action of 2-BAA and/or BEAA. Both metabolites are known to induce hemolysis (Udden 2002; Udden 2005).

- EGBE: hemolytic action demonstrated in acute and repeated dose toxicity studies (summarized in EU risk assessment, 2008)

- DEGBE: i.e. in 2 and 13 week oral toxicity studies (Johnson et al. 2005)

- DEGDBE: in 28-day study (Clariant own data) RBC reduction and hematuria was evident.

- PolyEGDBE: in dose-range finding study for OECD 422 (Clariant own data), minimal RBC reduction was found in females in absence of any other significant toxicity indication.

Applicant's summary and conclusion

Conclusions:
The developmental toxicity of PolyEGDBE was investigated according to OECD 414 with deviations of using limited number of animals. PolyEGDBE induced at 500 mg/kg bw and above reduced body weight gain and increased pre and post implantation loss, reduced number of live pubs. At 250 mg/kg bw no maternal toxicity and no fetal toxicity was found.
Executive summary:

The developmental toxicity of DEGDBE was assessed based on the use of read-across. PolyEGDBE is considered to be one of the appropriate source chemical.

The developmental toxicity of PolyEGDBE was investigated according to OECD 414 with deviations of using limited number of animals. Eight pregnant rats each were treated with PolyEGDBE per gavage at doses of 0. 250, 500 or 750 mg/kg bw.

PolyEGDBE at 500 and 750 mg/kg bw induced transient body weight loss (gestation day 5 -8, ), reduced body weight gain, increased pre- and post-implantation loss, reduced live fetuses, reduced litter mean weight. No maternal and fetal toxicity was found at 250 mg/kg bw.

The infindings in this study is in line with the OECD 414 study on DEGDBE, whereas maternal toxicity at 500 and 750 mg/kg bw was more evident for DEGDBE.