N-[3-(dimethoxymethylsilyl)propyl]ethylenediamine

Endpoint summary

Description of key information

The key study for acute oral toxicity, conducted according to OECD Test Guideline 423 and in compliance with GLP,  reported an LD₅₀ value of 200 - 2000 mg/kg bw for the registered substance, N-[3-(dimethoxymethylsilyl)propyl]ethylenediamine (CAS No. 3069-29-2, EC No. 221-336-6, Huntingdon Life Sciences, 1999). The result of this study is the most precautionary of the three available acute oral toxicity tests. Although the lower dose of 200 mg/kg bw, selected in the study, is below the recommended lower dose of 300 mg/kg bw by the current guideline, it was in line with the recommendations of the older version of OECD Test Guideline 423. Even though the lower dose of 200 mg/kg bw is below the threshold for Category 4 classification for acute oral toxicity, the supporting studies for the registered substance and other available information about the category suggest that classification Category 4 is appropriate.

The key study for acute inhalation toxicity, conducted according to OECD Test Guideline 403 and in compliance with GLP, reported an LC₅₀ value of >5.2 mg/l air for the registered substance, N-[3-(dimethoxymethylsilyl)propyl]ethylenediamine,

in response to the exposure to an aerosol in rat (Hoechst, 1992).

The key study for acute dermal toxicity for the registered substance, N-[3-(dimethoxymethylsilyl)propyl]ethylenediamine, conducted according to a protocol similar to OECD Test Guideline 402 and prior to GLP, reported an LD₅₀ value of 16 ml/kg (equivalent to 15520 mg/kg bw) for males and >16 ml/kg for female rabbits (BRRC, 1982).

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1999

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 423 (Acute Oral toxicity - Acute Toxic Class Method)

Deviations:

yes

Remarks:

Use of 200 mg/kg bw instead of 300 mg/kg bw

Principles of method if other than guideline:

Draft report, GLP etc not signed off. Doses of 2000 and 200 mg/kg bw, current guideline indicates 2000 and 300 mg/kg bw.

GLP compliance:

yes

Test type:

acute toxic class method

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan, UK
- Age at study initiation: 5 to 7 weeks
- Weight at study initiation: 97 to 135 g
- Fasting period before study: overnight
- Housing: metal cages with wire mesh floors
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: minimum 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21-25.5
- Humidity (%): 38-60
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Vehicle:

other: aqueous methylcellulose

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 2 or 20% w/v in 1% w/v aqueous methylcellulose


MAXIMUM DOSE VOLUME APPLIED: 10 ml/kg bw

Doses:

2000 mg/kg, 200 mg/kg

No. of animals per sex per dose:

3 females at 2000 and 200 mg/kg, 3 males at 200 mg/kg

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Animals were observed twice a day, and weighed on days 1, 8 and 15 or at death.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight,organ weights, histopathology, other: All animals were subjected to a macroscopic examination which consisted of opening the cranial thoracic and abdominal cavities. The macroscopic appearance of all examined organs was recorded.

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

200 - <= 2 000 mg/kg bw

Based on:

test mat.

Mortality:

All females dosed at 2000 mg/kg died within approximately 2 hours of dosing. Macroscopic examination of these animals revealed congestion in the subcutaneous tissue, brain, heart, liver, spleen and kidneys. Congestion with gaseous distension and fluid contents were also noted in the stomach and along the alimentary tract.

Clinical signs:

other: Piloerection was observed in all rats soon after dosing. This sign persisted and was accompanied during the study by hunched posture (all females at 200 mg/kg and one female at 2000 mg/kg) waddling/unsteady gait, lethargy, abnormal respiration (characteri

Gross pathology:

No macroscopic abnormalities were recorded for the animals killed and examined at study termination on day 15.

Other findings:

None reported.

A group of three fasted rats received a single oral gavage dose of the test substance, formulated in 1% w/v aqueous methylcellulose, at a dose level of 2000 mg/kg bodyweight. As a result of mortalities at this dosage indicating the acute lethal oral dose of the test material to be less than 2000 mg/kg bw, in compliance with the study guidelines a further group of three fasted females was dosed at 200 mg/kg. A group of three fasted males was then dosed at 200 mg/kg to confirm results at this dosage and complete the study.

All females dosed at 2000 mg/kg died within ca. 2 hours of dosing. Macroscopic examination of decedents revealed a generalised congestion in the majority of organs and tissues. Clinical signs of reaction to treatment included piloerection, seen in all rats at both dosages. In addition, hunched posture, waddling/unsteady gait, lethargy, abnormal respiration, partially closed eyelids, pallid extremities, abnormal faeces, ungroomed appearance, prostration, blue/cold extremities and dark colouring to eyes were seen in one or more animals during the study. Recovery of surviving rats at 200 mg/kg dose, as judged by external behaviour, was complete by day 7. All surviving animals were considered to have achieved satisfactory bodyweight gains throughout the study. No macroscopic abnormalities were recorded for the animals killed and examined at study termination on day 15.

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

The LD50 value of 200 - 2000 mg/kg bw was reported in a reliable study carried out in accordance with OECD Test Guideline 423 and in compliance with GLP

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

200 mg/kg bw

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

not stated

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Hoechst AG, SPF-Zucht, GERMANY
- Age at study initiation: 8-10 weeks
- Weight at study initiation: males 208 g (199-222); females 194 g (184-200)
- Fasting period before study: not stated
- Housing: Makrolon cages
- Diet: standard diet ad libitum
- Water: drinking water ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/-2
- Humidity (%): 50 +/- 20
- Photoperiod (hrs dark / hrs light): 12 h/12 h

IN-LIFE DATES: not stated

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

other: 'head-nose' exposure (nose near to tube delivering test material)

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION

- Exposure apparatus: cylindrical plastic tubes
- Exposure chamber volume: 60 litres
- Method of holding animals in test chamber: not identified from report in German
- Source and rate of air: 800 l/h
- System of generating particulates/aerosols: not identified from report in German
- Method of particle size determination: Anderson-Kas-kadenimpaktor Mark III

TEST ATMOSPHERE
- Brief description of analytical method used: gravimetric
- Samples taken from breathing zone: unclear to this reviewer from report in German

TEST ATMOSPHERE (if not tabulated)
- particle size: see table 2
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): MMAD 1.0-1.1 micrometers. GSD 1.6-1.9

Analytical verification of test atmosphere concentrations:

yes

Remarks:

gravimetric

Duration of exposure:

4 h

Concentrations:

3.7, 5.2 mg/l

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days (3.7 mg/l males and females; 5.2 mg/l females); 28 days (5.2 mg/l males)
- Frequency of observations and weighing: observations 2/daily; weights weekly
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5.2 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: Study report states LC50 as ca. 5.2 mg/l.

Mortality:

See table 1, below.

Clinical signs:

other: See table 1, below.

Body weight:

Impaired development of body weight.

Gross pathology:

Abnormalities of the lungs were reported in 3 males and 1 female at 3.7 mg/l and in 4 males and 2 females at 5.2 mg/l. Lungs were discoloured or patchy or with emission of foam on dissection. All organs were examined macroscopically and there were no other remarkable findings.

Table 1: Concentrations, exposure conditions and mortality per animals treated

Analytical Conc. (mg/L)	MMAD µm	GSD	Mortality (dead/total)*			Evident toxicity
			Males	Females	Combined
3.7	0.98-1.12	1.81-1.76	1/5	0/5	1/10	Irregular breathing, breathlessnes or noisy breathing, uncoordinated or staggering gait, ataxia, prostration, narrowed eye, sneezing, blood-coloured nasal discharge, decreased spontaneous activity, aggressive or withdrawn behaviour, sunken flanks. Impaired bodyweight development.
5.2	0.99-1.08	1.92-1.64	0/5	2/5	2/10

* 14 days observation except for males exposed at 5.2 where observation was for 28 days.

Table 2: Particle size distribution

Particle size µm	Particle spectrum % (duplicate measurements at two concentrations)
	3.7 mg/l (1)	3.7 mg/l (2)	5.2 mg/l (1)	5.2 mg/l (2)
<0.6	15.68	12.11	17.8	9.98
0.6-0.8	28.97	20.33	28.80	26.10
0.8-1.5	30.63	33.03	24.61	31.86
1.5-3.0	22.69	31.39	28.80	30.33
3.0-4.8	1.48	2.54	0	1.73
4.8-7.0	0.55	0.60	0	0
7.0-10.3	0	0	0	0
>10.3	0	0	0	0

Interpretation of results:

GHS criteria not met

Conclusions:

A reliable study conducted according to OECD Test Guideline 403 and in compliance with GLP, reported deaths of 2 of 10 rats exposed for 4h to 5.2 mg/l (aerosol). The LC50 for males and females was therefore >5.2 mg/l.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LC50

Value:

5 200 mg/m³ air

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1982

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Species:

rabbit

Strain:

not specified

Sex:

male/female

Details on test animals or test system and environmental conditions:

No data.

Type of coverage:

not specified

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

No data.

Duration of exposure:

24 hours

Doses:

1, 2, 4, 8, 16 ml/kg (males), 16 ml/kg females.

No. of animals per sex per dose:

4

Control animals:

other: solvent control, methanol

Details on study design:

- Duration of observation period following administration: 14 days

- Necropsy of survivors performed: yes

Key result

Sex:

male

Dose descriptor:

LD50

Effect level:

16 mL/kg bw

Based on:

test mat.

Remarks on result:

other: Equivalent to 15520 mg/kg (calculated with specific gravity of 0.97 g/m3)

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

> 16 mL/kg bw

Based on:

test mat.

Remarks on result:

other: Equivalent to >15520 mg/kg (calculated with specific gravity of 0.97 g/m3)

Mortality:

At 16 ml/kg 2/4 males died within 3.3 days. At 8 ml/kg 1/4 males died on day 3. At all other doses, in all other animals, there were no deaths.

Clinical signs:

other: Clinical signs in males were swollen testes at day 1; convulsions in 1 at day 1. Recovery of survivors occurred within 2 days. Erythema was present at all doses in all animals. In females, no clinical signs. The results indicated that scrotal edema accou

Gross pathology:

Dark red lungs, liver with tan patches in one victim. Lungs of one male survivor mottled red. In male survivors, trachea with red patches and lungs discoloured. Gross pathological exady revealed scrotal swelling on 4 of 4 rabbits dosed with the test material, and 2 of 4 rabbits dosed with methanol. The scrotal tissue had a gelatinous appearance on the cut surface. Many of the histopathologic findings were common to both treatment groups. The presence of spermatozoa in the epididymides was more prevalent in the methanol dosed rabbits. Scrotal edema and the lymphangiectasis of the scrotal skin were somewhat more common to the silane dosed animals. Epidermal serofibrinious exudate, epidermal bacterial colonies and increased dermal acidophilis were observed among rabbits treated with the test substance but not in those receiving methanol.
In females, no remarkable findings at necropsy.

Interpretation of results:

GHS criteria not met

Conclusions:

The LD50 value for acute dermal toxicity is reported to be 16 ml/kg for males and >16 ml/kg (equivalent to 15520 mg/kg) for female rabbits in a reliable study conducted according to a protocol similar to OECD Test Guideline 402 but which is not compliant with GLP.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

15 520 mg/kg bw

Additional information

The key study for acute oral toxicity, conducted according to OECD Test Guideline 423 and in compliance with GLP, reports an LD50 value in the range 200 - 2000 mg/kg bw (Huntingdon Life Sciences, 1999). A group of three fasted rats received a single oral gavage dose of the test substance, N-[3-(dimethoxymethylsilyl)propyl]ethylenediamine (CAS No. 3069-29-2, EC No. 221-336-6), formulated in 1% w/v aqueous methylcellulose, at a dose level of 2000 mg/kg bw. All females dosed at 2000 mg/kg bw died within approximately 2 hours of dosing. As a result of mortalities at the higher dosage the results indicate the acute lethal oral dose of the test material to be less than 2000 mg/kg bw, and in compliance with the study guideline, a further group of three fasted females was dosed at 200 mg/kg bw. A group of three fasted males was then dosed at 200 mg/kg bw to confirm results at this dosage and complete the study. There were no deaths at 200 mg/kg bw. Macroscopic examination of the 2000 mg/kg bw decedents revealed a generalised congestion in the majority of organs and tissues. Piloerection was observed in all rats soon after dosing. This sign persisted and was accompanied during the study by hunched posture (all females at 200 mg/kg and one female at 2000 mg/kg) waddling/unsteady gait (all females at 2000 mg/kg bw), lethargy (all females at 2000 mg/kg bw), abnormal respiration (characterised by increased respiration) (all females at 2000 mg/kg bw), partially closed eyelids (all females at 2000 mg/kg bw), pallid extremities (all females at 2000 mg/kg bw), prostration (collapsed state) (all females at 2000 mg/kg bw), blue/cold extremities and dark colouring to eyes (all females at 2000 mg/kg), abnormal faeces (characterised by soft liquid faeces) (one male at 200 mg/kg) and ungroomed appearance (characterised by soiled/stained fur around the ano/genital region) (one female at 2000 mg/kg). Recovery of surviving rats, as judged by external appearance and behaviour, was complete by either day 5 (females at 200 mg/kg) or day 7 (males at 200 mg/kg). All surviving animals were considered to have achieved satisfactory bodyweight gains throughout the study. No macroscopic abnormalities were recorded for the 200 mg/kg bw group of animals, which were killed and examined at study termination on day 15.

A supporting study for acute oral toxicity reported an LD₅₀ value of >2000 mg/kg bw in rats (SafePharm, 1987). Hunched posture, lethargy, piloerection, decreased respiratory rate or ptosis were noted in all survivors at the 1 or 4 h observation. There were no abnormal clinical observations two days after dosing. Animals that died showed abnormally red lungs, dark liver, haemorrhage of the rugae (folds) of the glandular region of the stomach and congestion of the small intestine. No abnormalities were reported in survivors. There were no effects on body weight. A second supporting study for acute oral toxicity reported an LD₅₀ value of 4.29 ml/kg (equivalent to 4161 mg/kg bw) for males and 3.08 ml/kg (equivalent to 2987 mg/kg bw) for females in a reliable study not compliant with GLP. Clinical signs included sluggishness, prostration, unsteady gait, difficulty in breathing, cyanosis death within 20 - 40 min (highest dose). At necropsy, many victims had red stomachs; several survivors had lung discolouration.

The key study for acute inhalation toxicity, conducted according to OECD Test Guideline 403 and in compliance with GLP, reported an LC₅₀ value of >5.2 mg/l air in response to the exposure to an aerosol of N-[3-(dimethoxymethylsilyl)propyl]ethylenediamine in rat (Hoechst, 1992). Decreased body weight gain was observed. Clinical signs at both test concentrations included irregular breathing, breathlessness or noisy breathing, uncoordinated or staggering gait, ataxia, prostration, narrowed eye, sneezing, blood-coloured nasal discharge, decreased spontaneous activity, aggressive or withdrawn behaviour, sunken flanks. Abnormalities of the lungs were reported in 3 males and 1 female at 3.7 mg/l and in 4 males and 2 females at 5.2 mg/l. Lungs were discoloured or patchy or with emission of foam on dissection. There were no other remarkable findings.

A supporting study for inhalation (TNO, 1984) exposed rats to an aerosol of the test substance at the concentration of 3 mg/l air, with no subsequent deaths. The study was compliant with GLP and conducted according to an appropriate protocol. Because of the density of the aerosol during the exposure, the animals could not be observed during the exposure. No abnormalities were found during gross pathology at autopsy. A second, reliability 4 supporting study was also available, in which the death of 2/5 female and 0/5 males is reported after a 6 hour inhalation study in which test concentrations were not verified analytically (BRRC, 1982). Clinical signs included lacrimation, wet noses, hypoactivity and ataxia, loss of coordination, corneal opacity and depression of reflex responses.

The key study for acute dermal toxicity for N-[3-(dimethoxymethylsilyl)propyl]ethylenediamine, conducted according to a protocol similar to OECD Test Guideline 402 but prior to GLP, reported an LD₅₀ value of 16 ml/kg (equivalent to 15520 mg/kg bw) for males and >16 ml/kg for female rabbits (BRRC, 1982). Clinical signs in males were swollen testes and convulsions. Recovery of survivors occurred within 2 days. Erythema was present at all doses in all animals. In females, no clinical signs were evident. The results indicated that scrotal edema accounted for the apparent testicular enlargement and that methanol solvent produced similar but less marked effects. Gross pathology reports dark red lungs and a liver with tan patches in one victim. In male survivors, the trachea had red patches and lungs were discoloured. Gross pathological examination revealed scrotal swelling on 4 out of 4 rabbits dosed with the test material, and 2 of 4 rabbits dosed with methanol. The scrotal tissue had a gelatinous appearance on the cut surface. Many of the histopathologic findings were common to both treatment groups. The presence of spermatozoa in the epididymides was more prevalent in the methanol dosed rabbits. Scrotal edema and the lymphangiectasis of the scrotal skin were somewhat more common to the silane dosed animals. Epidermal serofibrinous exudate, epidermal bacterial colonies and increased dermal acidophilis were observed among rabbits treated with the test substance but not in those receiving methanol. In females, no remarkable findings were recorded at necropsy.

Supporting acute oral, inhalation and dermal tests for the analogue substance N-(3-(trimethoxysilyl)propyl)ethylenediamine (CAS No. 1760-24-3, EC No. 217-164-6) are included only to support the read-across justification for the genetic toxicity endpoint currently using this analogue substance.

Justification for classification or non-classification

Based on the available information, N-[3-(dimethoxymethylsilyl)propyl]ethylenediamine is classified for acute oral toxicity Category 4, H302: "Harmful if swallowed" but is not classified for acute inhalation or dermal toxicity according to Regulation (EC) No. 1272/2008.