Bottom residues resulting from the synthesis of propylene oxide and styrene from epoxidation of propylene with ethylbenzene hydroperoxide

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation / corrosion

Remarks:

in vitro

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: IN VITRO SKIN CORROSION HUMAN SKIN MODEL TEST according to OECD 431 under GLP conditions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2011

Report date:

2011

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EU Method B.40 (In Vitro Skin Corrosion: Transcutaneous Electrical Resistance Test (TER))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Bottom product of propylene oxide and styrene production

IUPAC Name:

Bottom product of propylene oxide and styrene production

Details on test material:

- Name of test material (as cited in study report): KORE grade V
- Substance type: UVCB
- Physical state: Brown viscous liquid
- Stability under test conditions: months
- Storage condition of test material: room temperature

Test animals

Species:

human

Test system

Type of coverage:

open

Vehicle:

unchanged (no vehicle)

Controls:

not required

Duration of treatment / exposure:

Duplicate EST-1000™ tissues were exposed to the test item, positive control or negative control for each of two different exposure periods: 3 minutes and 1 hour.
After the pre-incubation of the EST-1000™ tissues was completed (2 hours for the 1 hour exposure and 2 hours 20 minutes for the 3 minutes exposure) the medium in each well was replaced by 1.0 mL fresh medium per well. The negative control (50 µL deionised water) was added to the surface of duplicate EST-1000™ tissues. Subsequently, the remaining tissues were exposed to the test item and the positive control in the same manner. The 6-well plates were then placed into an incubator (37 ± 1.5 °C, 5 ± 0.5% CO2).
At the end of the exposure period the tissues were removed from the 6-well plate and gently rinsed using a wash bottle containing PBS to remove any residual test material. Excess PBS was removed by gently shaking the tissue insert and blotting the lower surface with blotting paper. The tissues were placed in the prepared holding plate until all tissues were rinsed.

Observation period:

3 minutes after exposure on the skin model.
1 hour after exposure on the skin model.

Number of animals:

Duplicate EST-1000™ tissues were exposed to the test item, positive control or negative control for each of two different exposure periods: 3 minutes and 1 hour.

Results and discussion

Any other information on results incl. tables

Table 1: Results after treatment with Bottom product of propylene oxide and styrene production

 

Dose group	Ex-posure Interval	Absorbance 570 nm Tissue 1*	Absorbance 570 nm Tissue 2*	Mean Absorbance of 2 Tissues	Rel. Absorbance  [% of Negative Control]**
Negative Control	3 min	0.792	0.811	0.801	100.0
Positive Control	3 min	0.328	0.280	0.304	38.0***
Bottom product of propylene oxide and styrene production	3 min	0.501	0.566	0.533	66.5
Negative Control	1 hour	0.774	0.837	0.806	100.0
Positive Control	1 hour	0.008	0.004	0.006	0.7
Bottom product of propylene oxide and styrene production	1 hour	0.128	0.157	0.143	17.7

*       Mean of three replicate wells after blank correction
**      relative absorbance [rounded values]:

***     Although, the relative absorbance value of the positive control for the 3 minutes exposure was above the validity criteria (30%), the test is considered to be valid, since the positive control proved to be distinctive corrosive to the skin model (threshold for corrosivity for the 3 minutes treatment is 50%), and since the relative absorbance value of the positive control for the 1 hour exposure met the validity acceptance criteria clearly.

The optical evaluation of the MTT-reducing capacity of the test item after one hour incubation with MTT-reagent did not show evidence of a blue colour and thereby was not considered to be an MTT reducer.

The test item Bottom product of propylene oxide and styrene production is considered to be non-corrosive to skin:

·        since the viability after 3 minutes exposure is greater than 50% and

·        the viability after 1 hour exposure is greater than 15%.

 

Due to the high volatility of the test item, and due to the nearly borderline result, the test item could possibly be corrosive to skin, if covered after application.

Applicant's summary and conclusion

Interpretation of results:

other: Non corrosive, but the nearly borderline result shows that the test item could possibly be corrosive to skin, if covered after application.

Remarks:

Criteria used for interpretation of results: OECD GHS

Conclusions:

In conclusion, it can be stated that in this study and under the reported experimental conditions, the test item Bottom product of propylene oxide and styrene production was non corrosive to skin according to UN GHS / EU CLP Cat.1 / DSD (67/548/EEC). Due to the high volatility of the test item, and due to the nearly borderline result, the test item could possibly be corrosive to skin, if covered after application.

Executive summary:

This in vitro study was performed to assess the corrosive potential of Bottom product of propylene oxide and styrene production by means of the Human Skin Model Test.

Independent duplicate tissues of the human skin model EST-1000™ were exposed to the test item, the negative control or the positive control for 3 minutes and 1 hour, respectively.

The liquid test item (50 µL) was applied to each tissue and spread evenly over the surface of the tissue.

A volume of 50 µL of either the negative control (deionised water) or the positive control (8.0 N KOH) was applied to each tissue.

After exposure to the negative control the absorbance values exceeded the required acceptability criterion of mean OD₅₇₀≥ 0.8 for both treatment intervals thereby confirming the acceptable quality of the tissues.

Exposure to the positive control induced a decrease in the relative absorbance compared to the negative control, both for the 3 minutes exposure period and for the 1 hour exposure.

After exposure to the test item Bottom product of propylene oxide and styrene production the relative absorbance values decreased to 66.5% after 3 minutes. After the 1 hour exposure relative absorbance values were reduced to 17.7%. Both values did not exceed the threshold for corrosivity of 50% for the 3 minutes exposure and above 15% for the 1 hour exposure. Therefore, the test item was not considered to be corrosive.

In conclusion, it can be stated that in this study and under the reported experimental conditions, the test item Bottom product of propylene oxide and styrene production was non corrosive to skin according to UN GHS / EU CLP Cat.1 / DSD (67/548/EEC). Due to the high volatility of the test item, and due to the nearly borderline result, the test item could possibly be corrosive to skin, if covered after application.