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Description of key information

There are Klimisch 1 studies available on the Hydroxyethyl urea for acute oral, dermal and inhalation toxicity.  The oral and dermal studies showed LD50 values in excess of the 2000 mg/kg bodyweight limit dose.  The inhalation study did not reach the 20mg/l limit dose but at the maximum achievable dose of 4mg/l it showed no systemic toxic effect. 

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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study in accordance with OPPTS 870.1100 and OECD TG
Qualifier:
according to
Guideline:
OECD Guideline 401 (Acute Oral Toxicity)
Version / remarks:
version 1987
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 870.1100 (Acute Oral Toxicity)
Deviations:
no
GLP compliance:
yes
Test type:
standard acute method
Limit test:
yes
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Sprague Dawley Inc.
- Age at study initiation: males were about 10 to 11 weeks old; females were about 10 weeks old
- Weight at study initiation: males weighed 298-335 g; females weighed 187-226 g
- Fasting period before study: yes, overnight fasting
- Housing: individually in suspended stainless steel cages
- Diet (e.g. ad libitum): PMI Certified Rodent Chow #5002 (Purina Mills Inc) ad libitum
- Water (e.g. ad libitum): municipal tap water treated by reverse osmosis ad libitum
- Acclimation period: acclimated to the laboratory conditions for a minimum of five days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22-24
- Humidity (%): 30-45
- Air changes (per hr): 10 to 15
- Photoperiod (hrs dark / hrs light): 12 hours light/12 hours darkness
Route of administration:
oral: gavage
Vehicle:
unchanged (no vehicle)
Details on oral exposure:
MAXIMUM DOSE VOLUME APPLIED: 3.05 mL/kg
Doses:
3473 mg/kg corresponding to 2000 mg/kg active ingredient
No. of animals per sex per dose:
5 males, 5 females
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations: clinical observations were made two times on the day of administration and once per day thereafter
- Necropsy of survivors performed: yes
- Other examinations performed: bodyweight was determined on the day of administration, on day 7 and day 14
Statistics:
Not applicable
Sex:
male/female
Dose descriptor:
LD50
Effect level:
> 3 473 mg/kg bw
Based on:
test mat.
Remarks:
aqueous solution containing 57.58 % of the registration item
Sex:
male/female
Dose descriptor:
LD50
Effect level:
> 2 000 mg/kg bw
Based on:
act. ingr.
Mortality:
No mortality occurred during after oral administration or during the 14-day observation period.
Clinical signs:
Transient incidences of fecal stain, mucoid stools and dark material around the nose
Body weight:
Bodyweight gain was noted in all animals
Gross pathology:
No significant findings; one isolated incidence of foci on the thymus of one animal was observed that was considered to be not related to treatment
Interpretation of results:
not classified
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
The test material was not acutely toxic to rats after single oral administration and the LD50 was greater than 3473 mg/kg (> 2000 mg/kg for hydroxyethyl urea).
Executive summary:

The acute oral toxicity of the test substance EXP 3982 N-2-hydroxyethylurea containing 57.58% of the active ingredient hydroxyethyl urea was studied under GLP in a study according to OECD TG 401. After a preliminary study with doses ranging from 868 to 3473 mg/kg (corresponding to 500 to 2000 mg/kg active ingredient), a final limit test was conducted with a single dose of 3473 mg/kg corresponding to 2000 mg/kg active ingredient. Five male rats (10 to 11 weeks old, weighing 298 to 335 g) and five female rats (10 weeks old, weighing 187 to 226 g) of the Sprague-Dawley strain were fasted overnight and received a single oral dose of the test material by gavage at a volume of 3.05 mL/kg. Animals were housed individually in suspended cages and observed for a period of 14 days. Animals received food and drinking water ad libitum. At the end of the observation period the animals were sacrificed and a gross necropsy was performed on all animals. No mortality occurred after dosing or during the 14-day observational period. No significant clinical observations and findings at necropsy were made. Bodyweight development was normal. The LD50 value was greater than 3473 mg/kg for the formulation, which corresponds to >2000 mg/kg for the active ingredient.

Based of the lack of any significant toxicity at 2000mg/kg, hydroxyethyl urea is not classified for acute dermal toxicity according to GHS.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Quality of whole database:
The study is considered to be adequate for classification and labelling purposes.

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:
from 2006-11-03 to 2008-08-25
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP and guideline complient study
Qualifier:
according to
Guideline:
EPA OPPTS 870.1300 (Acute inhalation toxicity)
Deviations:
yes
Remarks:
seven types of deviations were identified, however there were no effects on the study
GLP compliance:
yes
Test type:
standard acute method
Limit test:
yes
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories (Wilmington, MA)
- Age at study initiation:
50 days old for the Exposure 1
49 to 56 days old for the Exposure 2
54 days old for the Exposure 3
- Weight at study initiation:
183 to 190 g (males) and 154 to 177 g (females) for the Exposure 1
204 to 223 g (males) and 172 to 190 g (females) for the Exposure 2
209 to 220 g (males) and 198 to 209 g (females) for the Exposure 3
- Fasting period before study: no
- Housing: two per cage in metal cages in a housing chamber
- Diet (e.g. ad libitum): Certified Purina Rodent Chow 5002 (PMI Nutrition International, LLC, Brentwood, MO) ad libitum, except during the exposure period
- Water (e.g. ad libitum): City ofChicago tap water, via automatic water system, ad libitum, except during the exposure period
- Acclimation period: 2 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C):
from 19.3 to 23.9 (for the Exposure 1)
from 19.8 to 24.4 (for the Exposure 2)
from 19.0 to 22.2 (for the Exposure 3)
- Humidity (%):
from 15.2 to 60.0 (for the Exposure 1)
from 25.1 to 51.7 (for the Exposure 2)
from 38.0 to 67.9 (for the Exposure 3)
- Air changes (per hr): 12 to 15
- Photoperiod (hrs dark / hrs light): 12/12
Route of administration:
inhalation: aerosol
Type of inhalation exposure:
nose only
Vehicle:
other: ASTM Type 1 water (1:1 dilution) only for the Exposure 2
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus:
Exposure 1 and Exposure 2: 64-port nose only systems
Exposure 3: Cannon stainless sreel 52-port nose-only inhalation cliamber (Lab Products Inc, Seaford, DE)
- Method of holding animals in test chamber: nos-only inhalation holders
- System of generating particulates/aerosols:
Exposure 1: one-jet Laskin nebulizer (IITRI built)
Exposure 2: one-jet Laskin nebulizer and one Aerogen (Aeroneb) nebulizer (Aerogen Ireland Ltd, Galway, Ireland)
Exposure 3: compressed air-operated Laskin nebulizer positioned in a three-neck round bottom flask
- Method of particle size determination: Quartz Crystal Microbalance cascade impactor (Model PC-2, California Measurements Inc, Sierra Madre, CA)
- Treatment of exhaust air: by HEPA filtration prior to being discharged into the outside atmosphere

TEST ATMOSPHERE
- Brief description of analytical method used: Samples from the first and third exposures were collected on pre-weighed filters. After sampling, the filters were weighed again to determine the weight oftest substance collected. A dry gas meter connected to the vacuum punlp was used to measure the corresponding total volume of chamber air sampled and the weight to volume ratio was determined in order calculated the aerosol mass concentration.
Samples from the second exposure were collected on filters that were first desiccated on a plastic Petri dish in a bell jar. In order to calculate the actual test substance concentration in the second exposure, the dried filters were weighed (pre-sampling weight); the samlple collected, and the wet filters were again weighed (wet value) before being desiccated again in the Petri dishes to obtain the dry weight. The Hydrovance® concentration was the total desiccated dry weight of the filter minus the pre-sampling weight multiplied by four.
- Samples taken from breathing zone: yes

TEST ATMOSPHERE (if not tabulated)
Exposure 1:
- Particle size distribution: 0.83-1.28 µm
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): 1.06 µm / 1.80

Exposure 2:
- Particle size distribution: 0.66-3.10 µm
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): 1.63 µm / 2.33

Exposure 3:
- Particle size distribution: 1.30-2.75 µm
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): 1.90 µm / 2.87

CLASS METHOD (if applicable)
- Rationale for the selection of the starting concentration: ≥2mg/L, or the highest attainable concentration if less than 2 mg/L, for 4 hours + T (90), the time required to reach 90 % of the target concentration (as determined during the test atmosphere development phase)
Analytical verification of test atmosphere concentrations:
yes
Remarks:
Air containing aerosols collected on pre-weighed filters; collected amount of substance related to volume of air streaming into exposure chamber during sampling period to determine aerosol mass concentration in test air
Duration of exposure:
4.05 h
Remarks on duration:
The rats were exposed four 4 hours plus three minutes (time to reach 90 % concentration, T90)
Concentrations:
Exposure 1: 0.59 mg/L
Exposure 2: 5.152 mg/L
Exposure 3: 0.125 mg/L
No. of animals per sex per dose:
5
Control animals:
no
Details on study design:
- Duration of observation period following administration: 15 days
- Frequency of observations and weighing: the animals were observed for signs of toxicity during exposure (to the extent possible), immediately after the first exposure (within eight minutes), second exposure (within three minutes) and third exposure (within one to six minutes), and at least once daily during a 15-day observation period (including the exposure day). Body weights were determined on the day after animal receipt, prior to randomisation, on Day 1 (prior to exposure), and weekly thereafter. All animals were weighed on the day of necropsy prior to euthanasia.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight, histopathology.
Statistics:
Descriptive statistics (mean and standard deviation) were calculated for the inhalation exposure data and body weights.
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 5.152 mg/L air (analytical)
Based on:
act. ingr.
Exp. duration:
4.05 h
Mortality:
No rats died during the study.
Clinical signs:
Eight minutes following the first exposure, five male and four female animals had wet inguinal fur and two females had redness around nose. At approximately four hours post exposure, all animals were normal and remained so until necropsy.
Three minutes following the second exposure, all animals had wet inguinal fur, one male and two females had salivation and two females had redness around the nose. At approximately two and a half hours post exposure, all animals were normal and remained so until necropsy, except one female who displayed red material (crust) around the left eye from day 7 until necropsy.
One to six minutes after the third exposure all animals had wet inguinal fur, one male and one female had red material around eye(s), and three males and four females had red material around the nose. At approximately three hours post exposure, all male animals and three females were normal and two females displayed red material around nose. One male displayed alopecia from day 2 until necropsy.
The clinical sign of wet inguinal fur was considered to have resulted from being in the nose-only exposure tubes, rather than an indication of toxicity. The clinical observation of redness around nose (red material around nose third exposure) was considered to be the result of exposure to the test substance. The observation of red material around the eye was considered to be due to all injury the animal sustained.
Body weight:
All exposed rats gained weight during the study.
Gross pathology:
After the first exposure, gross lesions noted at necropsy included lungs with foci in three females. Gross lesions noted at necropsy after the second exposure included foci on the lungs of four males and one female, a white lesion on the small intestine in one male, and a white opaque lesion on the left kidney in one female. After the third exposure, gross lesions noted at necropsy included lungs with foci in two males. Histopathologic evaluation of the lungs from two animals from the third exposure having lung foci showed no hemosiderophages in the lymph node of either animal. This supports a Iack of subacute to chronic hemorrhage in the pulmonary parenchyma of both animals. Since small foci of peracute hemorrhage in the lungs are not rare in rodents, the lung foci found in animals from this study were not considered related to treatment with the test substance.
Interpretation of results:
not classified
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
Based on the results of this study, the acute inhalation median lethal concentration (LC50) of the solid fraction of Hydrovance® Moisturing Agent in male and female rats is greater than 5.152 mg/L, the highest test atmosphere concentration attainable for this test substance.
Executive summary:

The test substance, Hydrovance® Moisturizing Agent, was tested as aerosols for acute inhalation toxicity in rats and observing its effects on five male and five female rats following nose-only inhalation exposure. The rats were exposed for four hours plus three minutes (time to reach 90% concentration, T90). The test atmosphere was generated by aerosolising the neat or diluted test substance with a one jet Laskin nebulizer. Following exposure, the rats were observed daily for adverse clinical signs and weighed weekly. All rats were euthanised and subjected to a gross necropsy following the 15-day (including exposure day) observation period. Three exposures were conducted: Exposures 1 and 3 used the Hydrovance® Moisturizing Agent as supplied, and Exposure 2 used Hydrovance® diluted (1:1) with ASTM type 1 water. The nominal concentration of non-volatiles in the test substance is 50%. The test concentrations which were measured gravimetrically using filter-collected aerosol samples during the exposure are indicative of the non-volatile portion of the test substance only. The test substance concentrations were calculated using the appropriate non-volatile fraction present in the formulation (50% for Exposures 1 and 3, and 25% for Exposure 2). For Exposure 1, the mean aerosol mass concentration was 0.59 mg/L. No animals died during the exposure or observation period. All animals gained weight. Gross lesions noted at necropsy included lungs with foci in three females. For Exposure 2, the mean aerosol mass concentration was 5.152 mg/L. No mortality occurred during the exposure or observation periods. Salivation was observed in two females and one male after exposure to the test substance. All animals gained weight during the observation period. Gross lesions noted at necropsy included lungs with foci on four males and one female, one male with a lesion on the small intestine, and one female with a white opaque lesion on the left kidney. Exposure 3 had a mean aerosol mass concentration of 0.125 mg/L. No animals died during the exposure or observation period. All animals gained weight. The clinical observations included red material around the nose (three males and four females), red material around the eyes (one male and one female) and alopecia (one male). Gross lesions noted at necropsy included lungs with foci in two males. Histopathologic evaluation of the lungs from two animals from the third exposure group having lung foci showed no hemosiderophages in the lymph node of either animal. This supports a lack of subacute to chronic hemorrhage in the pulmonary parenchyma of both animals. Since small foci of peracute hemorrhage in the lung are not rare in rodents, the lung foci found in animals from this study were not considered related to treatment with the test substance. Based on the results of this study, the acute inhalation median lethal concentration (LC50) of the solid fraction of Hydrovance in male and female rats is greater than 5.152 mg/L, the maximum concentration attained in this study. Based on the typical composition of Hydrovance which is 80% of the solids is hydroxyethyl urea, this correspods to ca. >4 mg/l of hydroxyethyl urea. Based on this and the lack of adverse effects hydroxyethyl urea is not classified for GHS.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Quality of whole database:
The study is considered to be adequate for classification and labelling purposes.

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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study in accordance with OECD TG 402
Qualifier:
according to
Guideline:
OECD Guideline 402 (Acute Dermal Toxicity)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 870.1200 (Acute Dermal Toxicity)
Deviations:
no
GLP compliance:
yes
Test type:
standard acute method
Limit test:
yes
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Spargue Dawley Inc.
- Age at study initiation: 11 weeks
- Weight at study initiation: males: 330-365 g, females: 211 - 243 g
- Fasting period before study: No
- Housing: individually in suspended stainless steel cages
- Diet (e.g. ad libitum): PMI Certified Rodent Chow #5002 (Purina Mills Inc) ad libitum
- Water (e.g. ad libitum): municipal tap water treated by reverse osmosis ad libitum
- Acclimation period: acclimated to the laboratory conditions for a minimum of five days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22-24
- Humidity (%): 36 -45
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12/12
Type of coverage:
occlusive
Vehicle:
unchanged (no vehicle)
Details on dermal exposure:
TEST SITE
- Area of exposure:
- % coverage: 10% of body surface area
- Type of wrap if used: gauze dressing backed with a plastic wrap, elastic wrap over trunk and test area

REMOVAL OF TEST SUBSTANCE
- Washing (if done): residual test article removes using gauze moistened with deionized waster followed by dry gauze
- Time after start of exposure: 24 h

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 3473 mg/kg (corresponding to 2000 mg/kg active ingredient)
- Constant volume or concentration used: yes
Duration of exposure:
24 h
Doses:
3473 mg/kg corresponding to 2000 mg/kg active ingredient
No. of animals per sex per dose:
5 males, 5 females
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: daily examinations for erythema and edema, daily clinical observations, twice daily mortality check, weighing on day 0, 7 and 14
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight,organ weights
Sex:
male/female
Dose descriptor:
LD50
Effect level:
> 3 473 mg/kg bw
Based on:
test mat.
Remarks:
aqueous solution containing 57.58 % of the registration item
Sex:
male/female
Dose descriptor:
LD50
Effect level:
> 2 000 mg/kg bw
Based on:
act. ingr.
Mortality:
No mortality occurred during the limit test.
Clinical signs:
Few faeces, dark material around the facial area, dermal irritation at site of test material application
Body weight:
Slight body weight loss in one male and one female during day 0 to 7 body weight interval. Body weight gain noted for all other animals during test period.
Gross pathology:
No significant gross internal findings at necropsy
Interpretation of results:
not classified
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
Under the conditions of this test, the acute dermal LD50 was estimated to be greater than 3473 mg for the aqueous solution EXP 3982 N-2-hydroxyethylurea per kg in the rat. This corresponds to a LD50 of > 2000 mg/kg for hydroxyethyl urea.
Executive summary:

The single-dose dermal toxicity of the test substance EXP 3982 N-2-hydroxyethylurea containing 57.58% of the active ingredient hydroxyethyl urea was evaluated in rats in accordance with OECD TG 402. The study was performed under GLP.

A limit test was performed in which one group of five male and five female rats received a single dermal administration of the test substance at a dose of 3573 mg/kg formulation (2000 mg/kg active ingredient). Following dosing, the test animals were observed daily and weighed weekly. A gross necropsy examination was performed on all animals at the time of scheduled euthanasia (day 14).

No mortality occurred during the limit test. Clinical abnormalities observed during the study included few faeces and dark material around the facial area. Dermal irritation was noted at the site of test article application. A slight body weight loss was noted for one male and one female during the day 0 to 7 body weight interval. Body weight gain was noted for all other animals during the test period. No significant gross internal findings were observed at necropsy on study day 14.

Under the conditions of this test, the acute dermal LD50 of EXP 3982 N-2-hydroxyethylurea was estimated to be greater than 3473 mg/kg in the rat. This corresponds to a LD50 of > 2000 mg/kg for hydroxyethyl urea. Based of the lack of any significant toxicity at 2000mg/kg, hydroxyethyl urea is not classified for acute dermal toxicity according to GHS.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Quality of whole database:
The study is considered to be adequate for classification and labelling purposes.

Additional information

There are Klimisch 1 studies available on the Hydroxyethyl urea for acute oral and dermal acute toxicity which showed no adverse effects indicating any systemic toxicity, both indicating LD50 values in excess of the 2000 mg/kg upper limit dose. The Klimisch 1 acute inhalation data is from testing of a product Hydrovance ca. 40% hydroxyethyl urea, this study showed no systemic toxicity at the maximum dose used of ca. 4mg/l of hydroxyethyl urea. Taken together these three studies show that hydroxyl ethyl urea is of very low acute toxicity.


Justification for selection of acute toxicity – oral endpoint
There is Klimisch validity 1, GLP compliant oral LD50 study available for hydroxyethyl urea CAS No 1320-51-0 carried out to OECD401. The oral LD50 was greater than the highest dose level which was 3473mg/kg bodyweight of the 57.58% solution of hydroxyethyl urea (EXP 3982) which is >2000mg/kg bodyweight of the hydroxyethyl urea. There were no mortalities or other signs of acute toxic effects. Therefore Hydroxyethyl urea is not classified for acute oral toxicity by the criteria of EU CLP or global GHS criteria.

Justification for selection of acute toxicity – inhalation endpoint
There is Klimisch validity 1, GLP compliant acute inhalation toxicity study carried out to a protocol compliant with US EPA OPPTS 870.1300. Testing was of the product Hydrovance which is a ca. 50 % solids of which 80% was hydroxyethyl urea. In addition unlike EXP 3982 the product is neutralized with lactic acid to reduce the pH from ca. pH9 to pH7, and this produces ca. 1.5% ammonium lactate in the solution.
This study was done in a number of stages; the highest achieved concentrate was an aerosol of 5.151 mg/l solids which required the hydrovance to be diluted to 50% solids. This was equivalent to 4 mg/l of hydroxyethyl urea. At this level there were no mortalities or signs of toxicity, however four of five males and I of 5 females had some small red foci on their lungs. These were examined in a third phase of the study, where they were confirmed not to be associated with haemorrhage, and such foci are relatively common it was concluded they were not considered to be related to treatment. Based on the lack of any toxic effects at this dose of 4mg/l of hydroxyethyl urea, the LC50 was expected to be significantly higher. There was therefore no evidence to support classification for acute inhalation toxicity based on EU CLP criteria

Justification for selection of acute toxicity – dermal endpoint
There is Klimisch validity 1, GLP compliant dermal LD50 study available for hydroxyethyl urea CAS No 1320-51-0 carried out to OECD402. The dermal LD50 was greater than the highest dose level which was 3473mg/kg bodyweight of the 57.58% solution of hydroxyethyl urea (EXP 3982) which is >2000mg/kg bodyweight of the hydroxyethyl urea. There were no mortalities or other signs of acute systemic toxic effects. Therefore Hydroxyethyl urea is not classified for acute dermal toxicity by the criteria of EU CLP or global GHS criteria.

Justification for classification or non-classification

The acute oral and dermal toxicity studies indicate very low acute toxicity with LD50 values greater than 2000 mg/kg. The more limited data on acute inhalation toxicity was consistent with this low acute toxicity with no adverse systemic effects at the highest dose used 4 mg/l. Therefore there is no requirement for hydroxyethyl urea to be classified for acute toxicity by the criteria of the EU CLP or global GHS criteria.