Registration Dossier

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Diss Factsheets

Toxicological information

Acute Toxicity: dermal

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Administrative data

Endpoint:
acute toxicity: dermal
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The source substance is used to supplement old but reliable data on the registered substance itself. The source substance is a structural isomer of the target substance differing in branching of the propyl end group of the molecule. (The target substance is isopropyl whereas the source substance is n-propyl.) The source and target substance therefore have common functional groups, identical molecular weights and similar physicochemical properties and common breakdown pathways. (The latter are discussed in more detail in read across justification documents appended to other end points in this dossier. For the relatively simple toxicological end point of acute dermal toxicity, a detailed read across justification does not seem warranted, especially when there is actually a reliable study that could stand alone on the target substance

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Target substance: Isopropoxyethanol (subject of this dossier)
Source subtance: 2-n-propoxy ethanol (SMILES CCCOCCO, CAS 2807-30-9)
Purity: Both substances as tested are >99% pure and do not contain impurities that could impact the validity of the read across.

3. ANALOGUE APPROACH JUSTIFICATION
Both substances have similar acute oral LD50 values and similar dermal penetration rates.

4. DATA MATRIX
Rat oral LD50 values, EGiPE (target substance): >2mg/kgbw, 5.1g/kgbw. EGnPE (source substance): 3.1g/kgbw (fasted), 6.2g/kgbw (not fasted)
Percutaneous absorption rate, human skin: EGiPE (target substance) 0.2 - 0.3mg/cm2/hr. EGnPE (source substance): 0.2 - 1.0 mg/cm2/hr.
Cross-reference
Reason / purpose for cross-reference:
read-across source
Reference
Endpoint:
acute toxicity: dermal
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1981
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Full study report available with detailed information on study. Not to GLP. Rationale for using a read across substance is included in overall remarks section.
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 402 (Acute Dermal Toxicity)
Deviations:
no
Remarks:
, no significant deviations noted from the information available.
GLP compliance:
no
Test type:
standard acute method
Limit test:
no
Species:
rabbit
Strain:
New Zealand White
Sex:
male
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Dutchland Laboratory animals Inc, Denver, PA
- Age and weight at study initiation: no data
- Housing: metal cages
- Diet (e.g. ad libitum): Purina lab chow, ad libitum
- Water: ad libitum
- Acclimation period: 3 weeks


ENVIRONMENTAL CONDITIONS
- no data
Type of coverage:
occlusive
Vehicle:
unchanged (no vehicle)
Details on dermal exposure:
TEST SITE
- Area of exposure: dorsal
- % coverage: 3.5x4 inch area.
- Type of wrap if used: Pad in close contact with skin occluded with dental dam wrap. Substance injected under dam into pad then dam edges sealed with adhesive tape.


REMOVAL OF TEST SUBSTANCE
- Washing (if done): Wiped with cotton wool. No washing.
- Time after start of exposure: 24 hours
Duration of exposure:
24 hours
Doses:
541, 1092, 2184, 4368 mg/kg (based on 5.2, 10.5, 21, 42 mmol/kg)
No. of animals per sex per dose:
5
Control animals:
other: no but other substances tested in same study acted as reference 'controls'
Details on study design:
- Duration of observation period following administration: 14 days.
- Frequency of observations and weighing: Twice per day for mortality, once per day for abnormal signs. Body weights recorded before treatment and on days 7 & 14 (end of study).
- Necropsy of survivors performed: yes as well as animals that died.
- Other examinations performed: clinical signs, body weight,organ weights, gross pathology
Statistics:
LD50 calculated using the method of Thompson and Weil (Biometrics 8, 51-4 (1952))
Sex:
male
Dose descriptor:
LD50
Effect level:
1 337 mg/kg bw
95% CL:
> 1 009 - < 1 768
Mortality:
no details reported.
Clinical signs:
other: At lower doses: anorexia, slight depression, cyanosis, ataxia, soft faeces. At higher doses: salivation, nasal discharge, iritis, significant depression, llaboured breathing, prostration.
Gross pathology:
Redish colour fluid was observed in the urinary bladder. Also see table below
Other findings:
- Potential target organs: see table below

Summary of gross pathology:

Dose (mmol/kg)  5.2  10.5 21 42  
Number of rabbits examined/with pathology  5/2  5/5  5/5  5/5

 Thymus - red spots on surface

 1

   

 
 Spleen - enlarged    

 1

   
Liver - pale        
 Liver - margin discoloured (tan)    1    
Kidney - cortex and medulla wide zone between        3    
 Kidney - corex and medulla poor differentiation between  1  4    
 Kidney - enlarged  3  

   
 Kidney - dark red    1

 5

 

   
Stomach - lining red or dark red    1 5    
Stomach - dark red     4

 Intestines, large and small - red discoloration     1 5  3    
Interpretation of results:
harmful
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
The LD50 dose response is quite sudden with no deaths or adverse pathology noted at a dose of 307mg/kg.
Executive summary:

In a single 24 hour exposure dermal toxicity study, male NZ white rabbits were exposed to 2 -n-propoxyethanol. The LD50 value is shown below. Sub-lethal effects included at lower doses anorexia, slight depression, cyanosis, ataxia, soft faeces, and at higher doses salivation, nasal discharge, iritis, significant depression, laboured breathing, and prostration.. The only significant pathology was to the kidney and GI tract.

Results synopsis

LD50: 1337mg/kg

Data source

Materials and methods

Test material

Constituent 1
Reference substance name:
2807-3-9
IUPAC Name:
2807-3-9
Constituent 2
Chemical structure
Reference substance name:
2-(propyloxy)ethanol
EC Number:
220-548-6
EC Name:
2-(propyloxy)ethanol
Cas Number:
2807-30-9
Molecular formula:
C5H12O2
IUPAC Name:
2-propoxy-1-ethanol
Details on test material:
- Name of test material (as cited in study report): 2-Propoxyethanol
- Molecular formula (if other than submission substance): C3H7)CH2CH20H
- Molecular weight (if other than submission substance): 104.15
- Source: Tennessee Eastman Company (Kingsport, TN)
- Analytical purity: 99.5%
- Impurities (identity and concentrations): 2-n-butoxyethanol, triethylene glycol n-butyl ether, isopropyl ethanol

Results and discussion

Effect levels
Sex:
male
Dose descriptor:
LD50
Remarks:
rat
Effect level:
ca. 1 300 mg/kg bw
Based on:
test mat.

Applicant's summary and conclusion