alkaline distillation residues from epsilon-caprolactam

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted according to GLP and OECD Guideline 435

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 435 (In Vitro Membrane Barrier Test Method for Skin Corrosion)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

alkaline distillation residues from epsilon-caprolactam

EC Number:

938-820-4

Molecular formula:

Unspecified (UVCB substance)

IUPAC Name:

alkaline distillation residues from epsilon-caprolactam

Constituent 2

Reference substance name:

Lactamoil 70%

IUPAC Name:

Lactamoil 70%

Test material form:

liquid: viscous

Details on test material:

Physical state/color: solid viscous, brownish, turbid
pH: ca. 12 (undiluted test substance)
Storage conditions: room temperature
Homogeneity: The homogeneity of the test substance was provided by heating at ca. 95 °C for 24 hours.

Test animals

Species:

other: Corrositex® Biobarrier Membrane

Details on test animals or test system and environmental conditions:

The Corrositex® assay kit is commercially available from InVitro International. The Corrositex® Biobarrier Membrane is a test system consisting of a reconstituted collagen matrix. The assay is based on the time that is required for the test substance to penetrate through the Corrositex® Biobarrier Membrane and produce a change in the Chemical Detection System (CDS). The Corrositex® assay is used to determine the corrosive potential of test substances. The assay is limited to testing those materials which cause detectable pH changes in the CDS.

Test system

Duration of treatment / exposure:

The test substance was applied undiluted.

Observation period:

60 min

Details on study design:

The experimental design of this study consisted of a qualification screen with the CDS (to determine if a color change can be detected) and a categorization screen (to categorize weak acids/bases and strong acids/bases), which were performed as a pretest, and a definitive Corrositex® assay. The Corrositex® assay was evaluated on the basis of the color change of the CDS. The time that a color change was observed was recorded manually and the breakthrough times of the four replicates were used to determine the corrosive potential of the test substance.

TEST SUBSTANCE COMPATIBILITY WITH THE ASSAY (QUALITIFCATION SCREEN):
For the qualification screen, 150 µL of the test substance was added to the CDS screening tube. If the test substance failed to produce a color change in the CDS within one minute, the test substance could not be analyzed in this system, and no further testing was required.

CATEGORIZATION SCREEN:
The categorization screen was used to assess the appropriate scoring scale for the test substance. The categorization screen was performed by adding 150 µL of test substance to each tube A and B. Each tube was mixed and the resulting color observed. If required, 2 drops of the "confirm" reagent were added to tube B, the tube mixed, and the resulting color observed. The categorization kit and color chart provided by InVitro International were used to determine the category. The test substance was scored as category 1 (high acid/alkaline reserve) or category 2 (low acid/alkaline reserve).

BIOBARRIER PREPARATION:
The vial containing the biobarrier matrix powder was placed in a water bath at 64 – 68ºC. The entire contents of the biobarrier diluent vial was added slowly to the matrix powder. The stir bar rotated slowly enough to avoid foaming of the solution. Two hundred µL of the solubilized matrix was pipetted into each of the membrane discs. The membrane discs were then refrigerated for at least 2 hours at 2 – 8ºC. The biobarriers were wrapped and stored at 2 – 8ºC for a maximum of 7 days. Any remaining matrix solution was stored at 2 – 8ºC for up to 30 days in order to prepare additional biobarrier membrane discs.

CORROSITEX® ASSAY:
Following the acceptance of the positive control the Corrositex® assay was performed for the test substance. Four vials containing the CDS were used for the test substance. In addition, one vial was used for the PC, NC and for the color (blank) control, each. A membrane disc coated with the biobarrier matrix was placed into one vial containing the CDS and 500 µL of the undiluted test substance was added onto the membrane disc. An electronic time clock was started with the application. The vial was observed for three minutes for any change in the CDS. If no color change was observed within three minutes, the remaining membranes were treated with the test substance. An electronic time clock was started with each application. The vials were observed continuously for the first ten minutes. Thereafter the vials were observed for approximately ten minutes around the time points relevant for evaluation or until breakthrough of the test substance occurred. The elapsed time between test-substance application and the first change in the indicator solution (i.e. barrier penetration) was recorded. The positive control vial was prepared as described above and received one pellet of sodium hydroxide on top of the membrane disc. This vial was monitored continuously until breakthrough had occurred. The negative control vial was prepared as described above and received 500 µL of 10% citric acid. This vial was observed for 60 minutes and was evaluated as “non-corrosive” if no reaction had been observed.

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

other: other: breakthrough time of test substance through biobarrier

Remarks on result:

other:

Remarks:

Basis: mean. Remarks: The mean breakthrough time through the biobarrier in 3 vials was 50:28 min.. (migrated information)

Any other information on results incl. tables

Table 2. Breakthrough times of the test substance and the PC (positive control) and NC (negative control).

	Breakthrough Time [min:s]
Test substance	Vial 1*	Vial 2	Vial 3	Vial 4	Mean
Lactamoil 70%	65:00	54:18	49:12	47:54	50:28
PC (sodium hydroxide, solid)	12:34	-	-	-	-
NC (10% citric acid)	NB	-	-	-	-

*Breakthrough time of vial 1 exceeds the border of 60 min, therefore it was not used for calculation of the mean.

NB = no breakthrough within maximum observation period (60 min)

Applicant's summary and conclusion

Interpretation of results:

corrosive

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Based on the observed results and applying the evaluation criteria it was concluded, that Lactamoil 70 % shows a corrosive potential in the Corrositex® - Skin Corrosion Test under the test conditions chosen. The mean breakthrough time determined in the in vitro membrane barrier test was 50 minutes and 28 seconds. The breakthrough time indicates that the test substance has a weak corrosive potential and should be assigned to UN GHS skin corrosivity subcategories 1C or UN Transport Packing Group III as specified in OECD TG 435 (adopted 19 July 2006).

Executive summary:

The potential ofLactamoil 70 % to cause dermal corrosion was assessed by a single topical application of 500 µL of the test substance to the Corrositex^®Biobarrier Membrane (Corrositex^®assay).

The Corrositex^®Biobarrier Membrane is the test system consisting of a reconstituted collagen matrix. The assay is based on the time that is required for the test substance to penetrate through the Corrositex^®Biobarrier Membrane and produce a change in the Chemical Detection System (CDS).

The qualification screen demonstrated that the test substance is able to react with the CDS and produce a visible color change. Therefore the membrane barrier test method was determined to be suitable for the evaluation of the corrosive potential of the test substance. 

A timescale category test was carried out to distinguish between weak and strong acids or bases. The test substance was assigned to timescale category 2 (having a low acid/alkaline reserve). In the main test four Corrositex^®Biobarrier Membranes were treated with the undiluted test substance.

The mean breakthrough time of three membranes of the test substance, determined in the actual Corrositex^®assay, was 50 minutes and 28 seconds. One of the four membranes treated with the test substance showed a longer breakthrough time (65 minutes) than the other three membranes. However, as the reaction times of 3 membranes were below the border of 60 minutes after application, it was concluded, that the test substance shows a weak corrosive potential and had to be assigned to PG III.

Sodium hydroxide (solid), applied as positive control showed a reaction time of 12 minutes and 34 seconds after application. The negative control did not produce any reactions within 60 minutes after application. Thus, the controls fulfill the acceptance criteria and demonstrate the validity of the assay.

Based on the observed results it was concluded, thatLactamoil 70 %shows a corrosive potential in the Corrositex^®- Skin Corrosion Test under the test conditions chosen. The mean breakthrough time determined in the in vitro membrane barrier test was 50 minutes and 28 seconds. The breakthrough time indicates that the test substance has a weak corrosive potential and should be assigned to UN GHS skin corrosivity subcategories 1C or UN Transport Packing Group III as specified in OECD TG 435 (adopted 19 July 2006).

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