Sulfuric acid, mono-C8-18-alkyl esters, magnesium salts, compds. with triethanolamine

Endpoint summary

Description of key information

skin irritation (OECD 431): corrosive 1B
eye irritation (worst case assumption): highly irritating/corrosive
SCLs according to GHS:
no scl possible based on corrosion result

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

July 2018 - Feb 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 431 (In Vitro Skin Corrosion: Reconstructed Human Epidermis (RHE) Test Method)

Version / remarks:

18 June 2019

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Solid / white

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Cell source:

other: MatTek In Vitro Life Science Laboratories, Bratislava, Slovakia

Vehicle:

unchanged (no vehicle)

Details on test system:

From the day of arrival in the laboratory, tissues were kept in the refrigerator. At least 1 hour, but not more than 1.5 hours before test substance application, tissues were transferred to 6-well plates with 0.9 mL assay medium and preconditioned in the incubator at 37°C. The pre-incubation medium was replaced with fresh medium immediately before application.
Two tissues per exposure time (3 minutes at room temperature or 1 hour in the incubator as a rule) and test group (test material, negative control and positive control; 12 tissues per test) were used. In addition, two killed control tissues per exposure time were treated with the test substance and the NC, respectively, to detect direct MTT reduction.

Due to the texture of the solid test substance the application with a sharp spoon was not
possible. Therefore, a metal pin (matched to the size of the tissue) was covered with
ca. 25 mg ground undiluted test substance and was applied with direct contact to the skin.
Before application the tissues were wetted with 25 μL deionized water

Control tissues were treated concurrently with 50 μL deionized water (NC, NC KC) or with 50 μL 8 N potassium hydroxide solution (PC) or test substance (KC).A nylon mesh was placed carefully onto the tissue surface of the NC afterwards (2nd test run).

The tissues were washed with PBS to remove residual test material 3 minutes or 1 hour after start of the application treatment.

Rinsed tissues were kept in 24-well plates (holding plates) at room temperature on assay medium until all tissues per application time were dosed and rinsed. The assay medium was then replaced with MTT solution, and the tissues were incubated for 3 hours.

After incubation, the tissues were washed with PBS to stop the MTT incubation. The formazan that was produced metabolically by the tissues was extracted by incubation of the tissues in isopropanol. The optical density at a wavelength of 570 nm (OD570) of the extracts was determined spectrophotometrically. Blank values were established of 4 microtiter wells filled with isopropanol for each microtiter plate.

Control samples:

yes, concurrent negative control

yes, concurrent MTT non-specific colour control

Amount/concentration applied:

TEST MATERIAL
(Skin irritation test, SIT)
- Amount(s) applied (volume or weight with unit):
25mg solid ground material per tissue

NEGATIVE CONTROL
- Amount(s) applied (volume or weight):
50 µL


POSITIVE CONTROL
(KOH)
- Amount(s) applied (volume or weight):
50 µL

Duration of treatment / exposure:

3 minutes and 1 h

Duration of post-treatment incubation (if applicable):

Rinsed tissues were kept in 24-well plates (holding plates) at room temperature on assay medium until all tissues per application time were dosed and rinsed.

Number of replicates:

2

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Tissue 2 (SCT 1h 2nd run)

Value:

25.3

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Tissue 1 (SCT 1h 2nd run)

Value:

25.4

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Tissue 2 (SCT 3 min 2nd run)

Value:

42.1

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Tissue 1 (SCT 3 min 2nd run)

Value:

31.4

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Tissue 1 (SCT, 3min)

Value:

27.7

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: 1st test run

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Tissue 2 (SCT, 3min)

Value:

26.7

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: 1st test run

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Tissue 1 (SCT, 1h)

Value:

38.6

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: 1st test run

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Tissue 2 (SCT, 1h)

Value:

34.9

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: 1st test run

Other effects / acceptance of results:

- OTHER EFFECTS:
- Visible damage on test system:
no
- Direct-MTT reduction:
no
- Colour interference with MTT:
no

DEMONSTRATION OF TECHNICAL PROFICIENCY:
yes

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control:
yes
- Acceptance criteria met for positive control: yes
- Acceptance criteria met for variability between replicate measurements: yes


Acceptance criteria for the positive control (PC) in Skin corrosion test:
8 N potassium hydroxide solution is used as positive reference.
A tissue viability of ≤ 30% is acceptable for the 3-minute exposure. Mean viability of the tissues exposed for 1 hour should be <15%.

Acceptance criteria for the variability of the tissues in Skin corrosion test:
For every treatment, two tissues are treated in parallel. In the range of 20% and 100% viability, variability between the tissues is considered to be acceptable if the coefficient of variation (CV) of % viability is ≤ 30%.

Acceptance criteria for the killed controls (KC)
The OD570 of the tissues for the KC of the NC should be ≤ 0.35. The OD570 value for direct MTT reduction of a test substance should be ≤ 30% of the OD570 of the NC.

Interpretation of results:

Category 1B (corrosive) based on GHS criteria

Conclusions:

Based on the results observed and by applying the evaluation criteria described, it was concluded the test item has an intermediate or a weak corrosive potential and may be assigned to UN GHS skin corrosivity subcategories 1B or 1C as cited in current OECD TG 431

Executive summary:

The potential of the test substance to cause dermal corrosion/irritation was assessed by a single topical application of ca. 25 mg ground undiluted test substance to a reconstructed threedimensional human epidermis model (EpiDerm™) according to OECD 431 (BASF 2019).

Due to the texture of the solid test substance the application with a sharp spoon was not possible. Therefore, a metal pin (matched to the size of the tissue) was covered with ca. 25 mg ground undiluted test substance and was applied with direct contact to the skin. Before application the tissues were wetted with 25 μL deionized water or PBS. For the corrosion test, two EpiDerm™ tissues were incubated with the test substance for 3 minutes and 1 hour, each.

Tissue destruction was determined by measuring the metabolic activity of the tissue after exposure/post-incubation by using a colorimetric test. The reduction of mitochondrial dehydrogenase activity measured by reduced formazan production after incubation with a tetrazolium salt (MTT) was chosen as endpoint. The formazan production of the epidermal tissues treated with the test substance is compared to that of negative control tissues. The quotient of the values indicates the relative tissue viability.

In addition to the test substance, 50 μL per tissue of a negative control (deionized water) and of a positive control (8 N KOH) were applied to two tissues each per exposure period.

The test substance is not able to reduce MTT directly.

Two test runs of the Skin Corrosion Test were performed.
Results of the 1st test run:
The relative mean viability of the tissues treated with the test substance determined after an exposure period of 3 minutes was 27.2%, and it was 36.8% after an exposure period of 1 hour. The results indicated a corrosive potential of the test substance at the 3-minutes exposure period. However, the result of the 1-hour exposure lies above the cutoff for skin corrosion. To clarify the inconclusive result the study was repeated.

Results of the 2nd test run:
The relative mean viability of the tissues treated with the test substance determined after an exposure period of 3 minutes was 36.8%, and it was 25.4% after an exposure period of 1 hour. Thus, the 2nd test run verified the results of the 1st test run.

The acceptance criteria for the variability of the tissues are met.

Overall, the results of the skin corrosion test indicate a corrosive potential of the test substance. The results after the 3-minutes exposure period indicates that the test substance has an intermediate or a weak corrosive potential and may be assigned to UN GHS skin corrosivity subcategories 1B or 1C as cited in current OECD TG 431

Based on the results observed it was concluded that the test item shows a skin corrosion potential in the EpiDerm™ in vitro skin irritation and corrosion test strategy under the test conditions chosen.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (corrosive)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irreversible damage)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

There are reliable study in vitro studies on skin irritation of C8-18AS TEA&Mg (CAS 85586-38-5) available.

Skin irritation

in vitro SCT:

The potential of the test substance to cause dermal corrosion/irritation was assessed by a single topical application of ca. 25 mg ground undiluted test substance to a reconstructed threedimensional human epidermis model (EpiDerm™) according to OECD 431 (BASF 2019).

Due to the texture of the solid test substance the application with a sharp spoon was not possible. Therefore, a metal pin (matched to the size of the tissue) was covered with ca. 25 mg ground undiluted test substance and was applied with direct contact to the skin. Before application the tissues were wetted with 25 μL deionized water or PBS. For the corrosion test, two EpiDerm™ tissues were incubated with the test substance for 3 minutes and 1 hour, each.

Tissue destruction was determined by measuring the metabolic activity of the tissue after exposure/post-incubation by using a colorimetric test. The reduction of mitochondrial dehydrogenase activity measured by reduced formazan production after incubation with a tetrazolium salt (MTT) was chosen as endpoint. The formazan production of the epidermal tissues treated with the test substance is compared to that of negative control tissues. The quotient of the values indicates the relative tissue viability.

In addition to the test substance, 50 μL per tissue of a negative control (deionized water) and of a positive control (8 N KOH) were applied to two tissues each per exposure period.

The test substance is not able to reduce MTT directly.

Two test runs of the Skin Corrosion Test were performed.
Results of the 1st test run:
The relative mean viability of the tissues treated with the test substance determined after an exposure period of 3 minutes was 27.2%, and it was 36.8% after an exposure period of 1 hour. The results indicated a corrosive potential of the test substance at the 3-minutes exposure period. However, the result of the 1-hour exposure lies above the cutoff for skin corrosion. To clarify the inconclusive result the study was repeated.

Results of the 2nd test run:
The relative mean viability of the tissues treated with the test substance determined after an exposure period of 3 minutes was 36.8%, and it was 25.4% after an exposure period of 1 hour. Thus, the 2nd test run verified the results of the 1st test run.

The acceptance criteria for the variability of the tissues are met.

Overall, the results of the skin corrosion test indicate a corrosive potential of the test substance. The results after the 3-minutes exposure period indicates that the test substance has an intermediate or a weak corrosive potential and may be assigned to UN GHS skin corrosivity subcategories 1B or 1C as cited in current OECD TG 431

in vitro SIT:

The potential of the test substance to cause dermal irritation was assessed by a topical application of 25mg ground undiluted test substance to a reconstructed three-dimensional human epidermis model (EpiDerm™) according to OECD 439 (BASF 2019).

Due to the texture of the solid test substance the application with a sharp spoon was not possible. Therefore, a metal pin (matched to the size of the tissue) was covered with ca. 25 mg ground undiluted test substance and was applied with direct contact to the skin. Before application the tissues were wetted with 25 μL deionized water or PBS.

Three EpiDerm™ tissues were incubated with the test substance for 1 hour followed by a 42-hour post-incubation period. In addition to the test substance, 30 µL per tissue of a negative control (PBS) and of a positive control (5% SDS) were applied to three tissues each.

Tissue destruction was determined by measuring the metabolic activity of the tissue after exposure/post-incubation by using a colorimetric test. The reduction of mitochondrial dehydrogenase activity measured by reduced formazan production after incubation with a tetrazolium salt (MTT) was chosen as endpoint. The formazan production of the epidermal tissues treated with the test substance is compared to that of negative control tissues. The quotient of both values indicates the relative tissue viability.  

The following results were obtained in the EpiDerm skin irritation test:

The test substance is not able to reduce MTT directly

The relative mean viability of the tissues treated with the test substance determined after an exposure period of 1 hour with an about 42-hour post-incubation was 2.4%. The acceptance criteria for the variability of the tissues are met.

The mean OD570 of the negative control (PBS) fulfills the acceptance criteria and demonstrates the validity of the assay.

The tissues treated with the positive control (5% SDS) showed a relative mean viability of 2.7% reflecting the expected sensitivity of the tissues.

 

Based on the kombined results observed it was concluded that the test item shows a skin corrosion potential in the EpiDerm™ in vitro skin irritation and corrosion test strategy under the test conditions chosen.

As the neat substance has to be classified as skin corrosive the substance will also be classified as may cause respiratory irritation (STOT SE3, H335 and R37, respectively) in case the substance is available as neat powder.

 

Eye irritation

There are several studies investigating the eye irritating potential of alkyl sulfates (AS) which have shown that AS concentrations of 10% and higher are moderately to strongly irritating to rabbit eyes and that formulations containing more than 20% AS can cause serious eye damage.

Nevertheless the substance registred here show skin corrosion potenial in in vitro skin corrosion test and as it stays unclear if the corrosion depends on the higher concentration or variation due to surfactant specific characteritics the tested substance (UVCB) is assumed to be corrosive also to the eye and therefore classified as Eye Dam. 1, H318 according to Regulation (EC) 1272/2008. Further no SCLs like set up for other Alkylsulfates are suggested here as further information might be missing about the concentration behavior on this effect. 

 

Justification for selection of skin irritation / corrosion endpoint:
Reliable skin irritation/corrosion in vitro test

Justification for selection of eye irritation endpoint:
Worst case assumption

Effects on skin irritation/corrosion: corrosive

Effects on eye irritation: corrosive

Justification for classification or non-classification

 

According to the classification criteria of Regulation (EC) No 1272/2008 the test substance needs to be classified with Skin Corr. 1B, H314 and related on this worst case Eye Dam.1, H318.

Due to skin corrosive character of the substance and further missing information on eye irritation no Specific Concentration Limits (SCLs) can be set.