1,2-diethoxypropane

Endpoint summary

Description of key information

Repeated dose toxicity (oral, subacute): NOAEL = 100 mg/kg bw/day (equivalent or similar to OECD 407/GLP)

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: 7 day Dose Range Finding Study

Qualifier:

no guideline required

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Route of administration:

oral: gavage

Vehicle:

other: Distilled water containing the surfactant Tween 80

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

7 days

Frequency of treatment:

Daily

Dose / conc.:

0 mg/kg bw/day (nominal)

Dose / conc.:

10 mg/kg bw/day (nominal)

Dose / conc.:

50 mg/kg bw/day (nominal)

Dose / conc.:

250 mg/kg bw/day (nominal)

Dose / conc.:

1 000 mg/kg bw/day (nominal)

No. of animals per sex per dose:

5 males
5 females

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily

BODY WEIGHT: Yes
- Time schedule for examinations: Recorded twice weekly.

FOOD CONSUMPTION AND COMPOUND INTAKE: Recorded twice weekly.


WATER CONSUMPTION AND COMPOUND INTAKE : Yes
- Time schedule for examinations: Assessed visually throughout dosing period.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes; all animals were necropsied. Seven major organs were weighed and fixed in neutral buffered 10% formalin.
Female: Heart, kidneys, liver, lungs, ovaries, spleen
Male: Heart, kidneys, liver, lungs, testes, spleen


HISTOPATHOLOGY: No

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Clinical signs were evident on Days 1 and 2 only. Signs occurred post-dose and were present for part of the day. The severity of the signs recorded·was greater in the High dose group. On Day 1 clinical. signs including piloerection and subdued and lethargic behaviour were noted in 2/5 Intermediate I and 5/5 High dose males and 2/5 Intermediate I, 2/5 Intermediate II and 5/5 High dose females. Subdued behaviour only was also noted in 2/5 Low dose males on Day 1. However, the sign observed was graded as mild and not considered to be reproducible. On Day 2 subdued behaviour only was noted in 2/5 High dose males.

Mortality:

no mortality observed

Description (incidence):

There were no premature deaths.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

There were no notable intergroup differences.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

All groups receiving DEP performed similarly to Controls.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

no effects observed

Description (incidence and severity):

There.were no visual intergroup differences.

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Males: Liver weight was increased in the High dose group {18%, P<0.01) after covariance analysis.
Females: Liver weight was increased at 250 mg/kg bw/day (9%, P<0.05) and 1000 mg/kg bw/day (18%, P<0.001) after covariance analysis.

Gross pathological findings:

no effects observed

Description (incidence and severity):

There were no notable findings at necropsy.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Other effects:

not examined

Dose descriptor:

other: DRF study

Effect level:

0 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: DRF study

Critical effects observed:

not specified

Conclusions:

In a 7 day dose range finding study in rats, the doses 0, 10, 100 and 1000 mg/kg bw/day were selected for the 4 week oral toxicity study.

Executive summary:

In the 7 day dose range finding study, male and female Sprague Dawley rats (5/sex) were administered 1,2-Diethoxypropane (99.54%) in water/Tween 80 by gavage at doses of 0, 10, 50, 250 and 1000 mg/kg bw/day.

There were no mortalities. On Day 1 clinical signs including piloerection and subdued and lethargic behaviour were noted in 2/5 Intermediate I and 5/5 High dose males and 2/5 Intermediate I, 2/5 Intermediate II and 5/5 High dose females. On Day 2 subdued behaviour only was noted in 2/5 high dose males. There were no notable intergroup differences in body weight. There were no differences in food or water consumption. In males, liver weight was increased in the high dose group (18%, P<0.01) after covariance analysis. In females, liver weight was increased at 250 mg/kg bw/day (9%, P<0.05) and 1000 mg/kg bw/day (18%, P<0.001) after covariance analysis. There were no notable findings at necropsy. On the basis of these findings, it was agreed with the Sponsor to use dose levels of 0, 10, 100 and 1000 mg/kg bw/day in the subsequent 4 Week Oral Toxicity Study in Rats.

Reference 2

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

7 February 1992 - 11 November 1992

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

GLP compliance:

yes

Limit test:

no

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Synthetic Chemicals Limited, PO Box 8, Common lane, Knottingley, West Yorkshire, WF11 8BW; 370101
- Purity: 99.54%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: in the dark at ambient temperature

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River (UK) Limited, Margate, Kent, England
- Females (if applicable) nulliparous and non-pregnant: [yes/no]
- Age at study initiation: 4 weeks
- Weight at study initiation: 60 g (female); 85 g (male)
- Housing: Rats were housed 2 or one per cage by sex and dose group in suspended polypropylene cages (overall dimensions ca 420 x 270 x 200 mm) with stainless steel wire grid tops and bottoms. Beneath each cage was suspended a polypropylene tray containing absorbent paper. Tray paper was changed twice each week during the study. Each cage had a polypropylene water bottle (total capacity 300 ml) with rubber washer and melamine cap. Water bottles were changed once each week during the course of the study
- Diet (e.g. ad libitum): SQC Expanded Rat and Mouse No. 1 Maintenance Diet, supplied by Special Diets Services Limited, Stepfield, Witham, Essex, CMB 3AD ad libitum.
- Water: tap water ad libitum
- Acclimation period: 9 days

DETAILS OF FOOD AND WATER QUALITY: Analysis of the batch of diet used for the majority of the study and analysis of water sampled during the course of the study are presented in Appendices 2 and 3.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20°C ± 2°C
- Humidity (%):50% ± 15%
- Air changes (per hr): 15-20 air changes per hour
- Photoperiod (hrs dark / hrs light): 12 h light/dark cycle

Route of administration:

oral: gavage

Vehicle:

other: Distilled water containing the surfactant Tween 80 (2%)

Details on oral exposure:

- PREPARATION OF DOSING SOLUTIONS:
DEP was administered once each day for 28 consecutive days orally via a steel cannula at a constant dose volume of 10 ml dosing suspension/kg of bodyweight. To achieve this animals were weighed each day and this weight used to derive the correct volume of dosing suspension to be administered. Control rats received the vehicle at the same dose volume.
Dosing suspensions of 1 (low), 10 (Intermediate) and 100 (High) mg/ml were prepared fresh daily be serial dilution of the highest concentration. The highest concentration of dosing suspension was prepared by direct admixture, using distilled water containing the surfactant Tween 80 (2%) as vehicle. Dosing suspensions for Control animals were also prepared fresh daily, using distilled water containing Tween 80.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses of dosing suspensions were undertaken on samples prepared during the first and fourth weeks of dosing, a summary of results is included in Appendix 5. Analyses of dosing suspensions prepared for one day during Weeks 1 and 4 of dosing showed all values to be acceptable for accuracy of preparation (-7.6% to -2.1%).

Duration of treatment / exposure:

28 days

Frequency of treatment:

Daily

Dose / conc.:

0 mg/kg bw/day (nominal)

Dose / conc.:

10 mg/kg bw/day (nominal)

Dose / conc.:

100 mg/kg bw/day (nominal)

Dose / conc.:

1 000 mg/kg bw/day (nominal)

No. of animals per sex per dose:

5 males
5 females

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: The doses for the study were selected based on the results of the 7 day DRF study (Supporting, RL2, rat (DRF)/Shell, 1992/Repeated dose toxicity: oral.001).

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: All animals were examined for reaction to treatment during each day. The onset, intensity and duration of these signs were recorded.
All animals received a detailed clinical examination once each week, including appearance, movement, and behaviour patterns, skin and hair condition, eyes and mucous membranes, respiration and excreta.

BODY WEIGHT: Yes
- Time schedule for examinations: The weight of each animal was recorded twice each week commencing one week before the start of treatment up until the end of the study.

FOOD CONSUMPTION AND COMPOUND INTAKE:
The quantity of food consumed by each cage of animals was recorded twice each week, commencing one week before the start of treatment up until the end of the study.

WATER CONSUMPTION AND COMPOUND INTAKE: Yes
- Time schedule for examinations: Water consumption was monitored by visual inspection on a weekly basis throughout the study.

HAEMATOLOGY: Yes
Samples were taken from all rats from each group during Week 4 of dosing without overnight deprivation of food. Blood samples were collected from the orbital sinus under light ether anaesthesia except for the Hepato Quick test (a measure of clotting time) which was sampled by tailsnip without anaesthesia. Haematology parameters were measured on 0.5 ml of whole blood taken into tubes containing EDTA.

CLINICAL CHEMISTRY: Yes
Samples were taken from all rats from each group during Week 4 of dosing without overnight deprivation of food. Blood samples were collected from the orbital sinus under light ether anaesthesia except for the Hepato Quick test (a measure of clotting time) which was sampled by tailsnip without anaesthesia. Clinical chemistry parameters were measured on plasma from 1.5 ml of whole blood taken into tubes containing heparin.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes

HISTOPATHOLOGY: Yes

Weights and histology: Liver, Heart, Kidney, Spleen, Adrenals, Testes & epididymides. The tissues examined histologically were from all animals in the Control and High dose groups.
Fixed: Liver, Heart, Kidney, Spleen, Adrenals, Testes, Ovaries, Abnormal Tissue.

Statistics:

Haematology, clinical chemistry, organ weight and body weight data were statistically analysed for homogeneity of variance using the 'F-max' test. If the group variances appeared homogeneous a parametric ANOVA was used and pairwise comparisons made via Student's t-test using Fisher's F-protected LSD. If the variances were heterogeneous log or square root transformations were used in an attempt to stabilise the variances. If the variances remained heterogeneous, then a non-parametric test such as Kruskal-Wallis ANOVA was used.

Organ weights were also analysed conditional on body weight (i.e. analysis of covariance).

Histology data were analysed by Fisher's Exact Probability test.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Notable clinical signs (piloerection and sleepy and/or subdued behaviour) were seen in 5/5 High dose males and 5/5 High dose females from Day 1 to Day 9 of the study. These signs were evident post dose and generally lasted for only part of the day. Clinical signs (piloerection and subdued behaviour) were also seen in 4/5 Intermediate dose females on Day 3 only. These signs were graded as mild and as with those seen in the High dose group were evident post dose for only part of the day.

Mortality:

no mortality observed

Description (incidence):

There were no premature deaths.

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

Males: The Low dose group showed a slight (12%) reduction in body weight gain. Due to the lack of effect in the Intermediate or High dose groups this reduction is considered to be due to chance.
Females: There were no notable intergroup differences.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

There were no notable intergroup differences.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

no effects observed

Description (incidence and severity):

Visual assessment of water bottles revealed no notable intergroup differences.

Ophthalmological findings:

not examined

Haematological findings:

effects observed, non-treatment-related

Description (incidence and severity):

In males, there were no notable intergroup differences. In females, Hepato Quick (pro-thrombin time) was slightly increased in the Low (10%, P<0.05) and Intermediate (14%, P<0.01) dose groups. Due to the lack of effect in the High dose group, these changes are considered to be due to chance.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

In males, there were no notable intergroup differences. In females, ALT was reduced in the Intermediate dose group (18%, P<0.01). Due to the lack of effect in the High dose group this reduction is considered to be due to chance.

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

In males, liver and kidney weight were increased in the High dose group after covariance analysis (18%, P<0.01 and 10%, P<0.01) respectively). Kidney weight was also slightly decreased in the Intermediate dose group after covariance analysis (6%, P

Gross pathological findings:

no effects observed

Description (incidence and severity):

There were no notable findings.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Centrilobular hepatocyte hypertrophy, graded as very mild was seen in 5/5 High dose males and 2/5 Control males. This finding was not seen in any females.

Histopathological findings: neoplastic:

not examined

Other effects:

not examined

Dose descriptor:

NOAEL

Effect level:

100 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

histopathology: non-neoplastic

organ weights and organ / body weight ratios

Critical effects observed:

no

Conclusions:

In a 28 day repeated dose toxicity study in rats, the NOAEL (male/female) was 100 mg/kg bw/day based on changes in the liver.

Executive summary:

In a sub-acute toxicity study (7804), 1,2-Diethoxypropane (99.54%) was administered by gavage to Sprague-Dawley rats (5/sex/group) in distilled water with 2% Tween 80 at 0, 10, 100 or 1000 mg/kg bw/day for 28 days.

Analyses of dosing suspensions prepared for one day during Weeks 1 and 4 of dosing showed all values to be acceptable for accuracy of preparation (-7.6% to -2.1% difference from nominal concentrations).

There were no premature deaths. Clinical reaction to treatment which included piloerection and sleepy and/or subdued behaviour was seen in High dose males and females post dose from Day I to Day 9 of the study. Piloerection and subdued behaviour were also noted in Intermediate dose females post dose on one day only. Since the reactions recorded in this 'group were graded as mild and were evident for only a short period of time they are not considered to be of toxicological significance and their reproducibility is doubtful. There were no notable intergroup differences in either sex in body weights, food consumption, haematological or clinical chemistry parameters. A slight, equivocal increase in kidney weight was seen in High dose males and females; there were no related histological changes. Centrilobular hepatocyte hypertrophy in the liver was increased in incidence but not severity in High dose males, this change may relate to the slight, equivocal increase in liver weight seen in High dose males and females. Since the centrilobular hepatocyte hypertrophy was graded as very mild and seen in males only its reproducibility is considered to be doubtful.

The changes noted in the male livers are more than likely adaptive but as the dosing interval was 10-fold, a NOAEL of 100 mg/kg bw/day was selected, as a conservative approach.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

100 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

There is one DRF study and one 28 day repeated dose toxicity study available. The key study has a Klimisch score of 2.

System:

hepatobiliary

Organ:

liver

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

There is one 7 day dose range finding study in rats and one 28 day repeated dose toxicity study in rats available.

In the 7 day dose range finding study, male and female Sprague Dawley rats were administered 1,2-Diethoxypropane (99.54%) in water/Tween 80 by gavage at doses of 0, 10, 50, 250 and 1000 mg/kg bw/day. There were no mortalities. On Day 1 clinical signs including piloerection and subdued and lethargic behaviour were noted in 2/5 Intermediate I and 5/5 High dose males and 2/5 Intermediate I, 2/5 Intermediate II and 5/5 High dose females. On Day 2 subdued behaviour only was noted in 2/5 high dose males. There were no notable intergroup differences in body weight. There were no differences in food or water consumption. In males, liver weight was increased in the high dose group (18%, P<0.01) after covariance analysis. In females, liver weight was increased at 250 mg/kg bw/day (9%, P<0.05) and 1000 mg/kg bw/day (18%, P<0.001) after covariance analysis. There were no notable findings at necropsy. On the basis of these findings, it was agreed with the Sponsor to use dose levels of 0, 10, 100 and 1000 mg/kg bw/day in the subsequent 4 Week Oral Toxicity Study in Rats.

In a sub-acute toxicity study (equivalent or similar to OECD 407/GLP), 1,2-Diethoxypropane (99.54%) was administered by gavage to Sprague-Dawley rats (5/sex/group) in distilled water with 2% Tween 80 at 0, 10, 100 or 1000 mg/kg bw/day for 28 days. Analyses of dosing suspensions prepared for one day during Weeks 1 and 4 of dosing showed all values to be acceptable for accuracy of preparation (-7.6% to -2.1% difference from nominal concentrations). There were no premature deaths. Clinical reaction to treatment which included piloerection and sleepy and/or subdued behaviour was seen in High dose males and females post dose from Day I to Day 9 of the study. Piloerection and subdued behaviour were also noted in Intermediate dose females post dose on one day only. Since the reactions recorded in this 'group were graded as mild and were evident for only a short period of time they are not considered to be of toxicological significance and their reproducibility is doubtful. There were no notable intergroup differences in either sex in body weights, food consumption, haematological or clinical chemistry parameters. A slight, equivocal increase in kidney weight was seen in High dose males and females; there were no related histological changes. Centrilobular hepatocyte hypertrophy in the liver was increased in incidence but not severity in High dose males, this change may relate to the slight, equivocal increase in liver weight seen in High dose males and females. Since the centrilobular hepatocyte hypertrophy was graded as very mild and seen in males only its reproducibility is considered to be doubtful. The changes noted in the male livers are more than likely adaptive but as the dosing interval was 10-fold, a NOAEL of 100 mg/kg bw/day was selected, as a conservative approach.

Justification for classification or non-classification

Based on available information in the dossier, the substance 1,2 Diethoxypropane (CAS No. 10221-57-5) does not need to be classified for specific target organ toxicity (repeated) when considering the criteria outlined in Annex I of 1272/2008/EC.