Sodium hydrogen-5-sulphoisophthalate

Endpoint summary

Description of key information

An in vitro study with reconstituted human epidermis indicated a low potential for skin irritation. A strong eye irritant and corrosive response was observed in rabbits following administration of the solid material.The effects were considered non-reversible.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

according to guideline

Guideline:

OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)

Version / remarks:

22 July 2010

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.46 (In Vitro Skin Irritation: Reconstructed Human Epidermis Model Test)

Version / remarks:

24 August 2009

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Test item is hygroscopic and was therefore stored in well-sealed container.
Test item is stability at higher temperatures (maximum temperature: >500°C).
No correction was made for the purity/composition of the test compound.

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Cell source:

skin obtained from plastic surgery from multiple donors

Justification for test system used:

The test is based on the experience that irritant chemicals show cytotoxic effects following short term exposure to the stratum corneum of the epidermis. The test is designed to predict and classify the skin irritation potential of a test substance by assessment of its effect on a three dimensional human epidermis model. The study procedures were based on a validated method according to OECD/EC guidelines.

Vehicle:

unchanged (no vehicle)

Details on test system:

The test system consisted of EPISKIN Small Model(TM) (EPISKIN-SM(TM), 0.38 cm^2, Batch no.: 12-EKIN-032).
Source: SkinEthic Laboratories, Lyon, France.

The test was performed on a total of 3 tissues per test substance together with negative and positive controls. The skin was moistened with 5 μl Milli-Q water to ensure close contact of the test substance to the tissue and the solid test substance (11.6 to 12.2 mg; with a small glass weight boat) was added into 12-well plates on top of the skin tissues. Three tissues were treated with 25 μl PBS (negative control) and 3 tissues with 25 μl 5% SDS (positive control), respectively. The positive control was re-spread after 7 minutes contact time. After the exposure period of 15 minutes at room temperature, the tissues were washed with PBS to remove residual test substance. After rinsing the cell culture inserts were each dried carefully and moved to a new well on 2 ml pre-warmed maintenance medium until all tissues were dosed and rinsed. Subsequently the skin tissues were incubated for 42 hours at 37°C.

After incubation, cell culture inserts were dried carefully to remove excess medium and were
transferred into a 12-wells plate prefilled with 2 ml MTT-medium (0.3 mg/ml). The tissues were
incubated for 3 h at 37°C. After incubation the tissues were placed on blotting paper to dry the tissues. Total biopsy was made by using a biopsy punch. Epidermis was separated from the collagen matrix and both parts were placed in prelabeled microtubes and extracted with 500 μl isopropanol. Tubes were stored refrigerated and protected from light for 70 hours. The amount of extracted formazan was determined spectrophotometrically at 570 nm in duplicate with the
Multiskan spectrum.
Cell viability was calculated for each tissue as a percentage of the mean of the negative control
tissues. Skin irritation potential of the test substance was classified according to remaining cell viability following exposure of the test substance.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

Negative control:
25 μl Phosphate buffered saline (PBS).

Positive control:
25 μl 5% (aq) Sodium dodecyl sulphate (SDS) in PBS.

Duration of treatment / exposure:

15 minutes

Duration of post-treatment incubation (if applicable):

42 hours

Number of replicates:

3

Irritation / corrosion parameter:

% tissue viability

Value:

96

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

5-(Sodiosulfo)isophthalic Acid was checked for possible direct MTT reduction by adding the test substance to MTT medium. Because no colour change was observed it was concluded that 5 - (Sodiosulfo)isophthalic Acid did not interact with MTT.

The positive control had a mean cell viability after 15 minutes exposure of 46% and did not meet the acceptability criteria. Approximately 1 hour after the performance of this test another in vitro skin irritation test was performed using the same batch of skin and the same batch of 5% (aq) SDS. The positive control had a mean cell viability of 5% and met the acceptability criteria. The absolute mean OD570 of the negative control tissues (in both in vitro skin irritation tests) were within the laboratory historical control data range (See APPENDIX 3). The standard deviation value of the percentage viability of three tissues treated identically was less than 11%, indicating that the test system functioned properly. It can be concluded that the deviation in the mean cell viability of the positive control in the first in vitro skin irritation test was caused by a technical error.

Mean tissue viability in the in vitro skin irritation test with 5 -(Sodiosulfo)isophthalic Acid (see table):

	Mean tissue viability(percentage of control)
Negative control	100
test substance	96
Positive control (note 1)	5

Note 1: Based on second in vitro skin irritation test

Interpretation of results:

GHS criteria not met

Conclusions:

Based on the results of an in vitro skin irritation test with 5-(Sodiosulfo)isophthalic Acid using a human skin model it is concluded that this test is valid and that 5-(Sodiosulfo)isophthalic Acid is non-irritant in the in vitro skin irritation test under the experimental conditions described in this report.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1981

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Although conducted prior to current protocol or GLP requirements, the study conformed to recognized protocols current at the time.

Justification for type of information:

The study was performed before non-animal test methods were available.

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method B.5 (Acute Toxicity: Eye Irritation / Corrosion)

Principles of method if other than guideline:

Conducted prior to current protocol and GLP requirements but by a method acceptable at the time. Based on the standard Draize test in common use.

GLP compliance:

no

Species:

rabbit

Strain:

not specified

Vehicle:

unchanged (no vehicle)

Amount / concentration applied:

A few dry crystals

Observation period (in vivo):

14 days

Number of animals or in vitro replicates:

6

Details on study design:

A few dry crystals were placed into one eye from each of six rabbits. The eyes of three rabbits were immediately washed with distilled water.

Irritation parameter:

cornea opacity score

Basis:

other:

Time point:

other: 1 hour

Remarks on result:

probability of severe irritation

Remarks:

The experiment was terminated based on severe effects

Irritation parameter:

conjunctivae score

Basis:

other: All three animals with unwashed eyes

Time point:

other: 1 hour

Remarks on result:

probability of severe irritation

Remarks:

The experiment was terminated based on severe effects

Irritant / corrosive response data:

The experiment in rabbits with unwashed eyes was terminated based on severe effects observed after one hour.

The washed eyes exhibited slight to moderate erythema and edema after 1 hour; all three eyes appeared normal by 48 hours. In 2/3 washed eyes, fluorescein staining of the adnexa was observed.

Overall irritation score after 14 days (animals with unwashed eyes):

fluorescein staining of cornea/adnexa - 3/3 animals; scar tissue on eyelids (2/3); purulent discharge (1/3); bloody discharge (1/3); and moderate to severe corneal opacity (2/3). These observations indicate that the effect of the test item was non-reversible.

Interpretation of results:

Category 1 (irreversible effects on the eye) based on GHS criteria

Conclusions:

The test material was a strong eye irritant. The effects were considered non-reversible.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin Irritation

Following OECD guideline 439 (In Vitro Skin Irritation), the subject material was applied for a 15 min period unchanged to reconstituted human epidermis. Cell viability, as measured by reduction of MTT, indicated a 96% viability of the test substance treated epidermis versus the control (untreated) and was not rated as an irritant. In vivo supporting studies confirmed this result. Application of the subject material as a moistened solid to the skin of 3 guinea pigs under occlusive wrap for 24 h produced spotty erythema (3/5 animals) in 24 h with residual minute eschars and vesiculation present after 7 to 10 days. The subject material was deemed a slight skin irritant under these conditions. Application of a 50% solution of the subject material applied to the clipped backs of 5 guinea pigs for 10 applications produced an irritative response that was slightly exacerbated by repeated exposures. The subject material in water was administered to the skin of 3 guinea pigs under occlusion (cuff) at doses of 0.25 to 1.0 g/kg bw. Slight edema and erythema with minute eschar formed by 24 h; at 1 week, slight desquamation and alopecia; and at 2 weeks, slight alopecia. In the latter study, the subject material was rated a slight skin irritant.

Eye Irritation

In a reliable study in rabbits, the solid subject material was administered to the eyes of 6 rabbits with immediate washing with distilled water in 3 rabbits. In unwashed eyes, a severe response (erythema and edema) was present by 1 h. Fluorescein staining of the cornea and adnexa was present. At 14 days, effects included: scar tissue, 2/3; purulent discharge, 1/3; bloody discharge, 1/3; and moderate to severe corneal opacity, 2/3. In wased eyes effects were greatly reduced with eyes in 2/3 rabbits appearing normal by 48 h. Fluorescein staining of the adnexa was observed in washed eyes.

Justification for selection of skin irritation / corrosion endpoint:
The subject material was not considered an irritant under the conditions of an in vitro skin irritation study using reconstituted human epidermis.

Justification for selection of eye irritation endpoint:
The subject material was considered a strong eye irritant in rabbits with effects that were not reversed in a 14-day observation period.

Effects on eye irritation: corrosive

Justification for classification or non-classification

The results of in vitro and in vivo skin irritation testing indicate a low potential for skin irritation. Thus, no classification is warranted.

The subject material is classified as an R41 (Risk of serious damage to eyes) under EU Directive 67/548/EEC.

The subject material is classified as a Category 1 for eye effects (Serious eye damage/eye irritation) under the EU Regulation 1272/2008.