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EC number: 617-081-9
CAS number: 80473-92-3
A BCOP test showed that thioacid is not an eye irritant, having an in
vitro irritancy score of 0.9.
A skin corrosivity test showed that thioacid is not corrosive to skin.
The purpose of this test was to evaluate the corrosivity potential of
the test item using the SkinEthic in vitro Reconstructed Human Epidermal
(RHE, SkinEthic Laboratories, Lyon, France) model after treatment
periods of 3 and 60 minutes. Corrosive test items are able to penetrate
the stratum corneum and are sufficiently cytotoxic to cause cell death
in the underlying cell layers. Toxicity is determined by the metabolic
reduction of the yellow tetrazolium salt
(3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) to a
blue formazan dye by mitochondrial succinate dehydrogenase by viable
cells in the test item treated tissues relative to the negative control
Duplicate tissues were treated with the test item for exposure periods
of 3 and 60 minutes. At the end of the exposure period the test item was
rinsed from each tissue before each tissue was taken for MTT-loading.
After MTT loading each tissue was placed in 1.5 mL Isopropanol for MTT
extraction. At the end of the formazan extraction period the tissues
were mixed thoroughly and triplicate 200 μL samples were transferred to
the appropriate wells of a pre-labeled 96-well plate. The optical
density (OD) was measured at 562 nm (OD562). Data are presented in the
form of percentage viability (MTT reduction in the test item treated
tissues relative to negative control tissues).
The relative mean viabilities of the test item treated tissues were: 3
minutes exposure : 93.1% 60 minutes exposure : 98.3%
Quality criteria: The quality criteria required for acceptance of
results in the test were satisfied.
The test item was considered to be non-corrosive to the skin.
Tables with individual corneal results can be found in attached "BCOP
The purpose of this test was to identify test items that can induce
serious eye damage and to identify test items not requiring
classification for eye irritation or serious eye damage. The Bovine
Corneal Opacity and Permeability (BCOP) test method is an organotypic
model that provides short-term maintenance of normal physiological and
biochemical function of the bovine cornea in vitro. In this test method,
damage by the test item is assessed by quantitative measurements of
changes in corneal opacity and permeability. The test method can
correctly identify test items (both chemicals and mixtures) inducing
serious eye damage as well as those not requiring classification for eye
irritation or serious eye damage, as defined by the United Nations (UN)
Globally Harmonized System of Classification and Labelling of Items
(GHS) and EU Classification, Labelling and Packaging (CLP) of chemicals
(Regulation (EC) No 1272/2008), and it was therefore endorsed as
scientifically valid for both purposes. Test items inducing serious eye
damage are classified as UN GHS and EU CLP Category 1. Items not
classified for eye irritation or serious eye damage are defined as those
that do not meet the requirements for classification as UN GHS/ EU CLP
Category 1 or 2 (2A or 2B), i.e. they are referred to as UN GHS/EU CLP
The test item was applied at a concentration of 20% w/v in 0.9% w/v
sodium chloride solution for 240 minutes. Negative and positive control
items were tested concurrently. The two endpoints, decreased light
transmission through the cornea (opacity) and increased passage of
sodium fluorescein dye through the cornea (permeability) were combined
in an empirically derived formula to generate an In Vitro Irritancy
The test item is classified according to the prediction model below:
The in vitro irritancy scores are summarised as follows:
Based upon the negative results obtained in one in vitro study
performed in accordance with OECD guideline 431, Method B.40bis of
Commission Regulation 440/2008 and GLP, the substance does not fulfil
the criteria for classification as skin corrosive within the meaning of
Similarly, the results of the Bovine Corneal Opacity Study, conducted in
accordance with OECD guideline 437 and GLP, were also negative.
Therefore, the substance does not fulfil the criteria for classification
as eye irritant, according to CLP.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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