Reaction product of Phenol, Sulphuric acid and Sodium hydroxide

Endpoint summary

Description of key information

Skin: irritant
Eye: irritant

Key value for chemical safety assessment

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin

Different results of skin irritation studies on BPS CAS 80-09-1 available have limited details, but one of the tests with negative results was performed for both irritation and corrosion potentials on a reconstructed, three dimensional human epidermis model EpiDermTM (OECD 431).

This allows the discrimination between irritants of GHS category 2 and non-irritants based on results on human skin.

Different results define no corrosion or irritation potential on rabbit skin (OECD 404) while only in one case, a slight skin irritation was observed on the guinea pig skin.^{1 2 3}

2,4'-sulfonyldiphenol CAS 5397-34-2 is considered corrosive (C&L ECHA Inventory), but no data is available.

Also, data on benzenesulfonic acid, 4-hydroxy-, sodium salt (1:1), CAS 825-90-1 is not available.

The substance is the salified form of phenol sulfonic acid, which is a very acidic substance (comparable to sulphuric acid) and is almost completely ionised in watery environments, even at low pH.⁴

The product is neutralized, therefore, data on salified sulphonated phenols (similar substances called hydrotropes), can be considered.

A category approach evaluation is available for sodium xylenesulphonate. The estimated irritant property of this substance can be helpful (in read across as well) to understand the irritant property of sodium sulphonated phenols, part of the intermediate DCB.

The sodium xylenesulphonate is considered a non skin irritant.⁵

Phenol is corrosive to the skin and is listed in the Annex VI of the CLP Regulation as a corrosive substance (H314; Cat. 1). However, it has a specific limit that will be considered in the classification section. ⁶

Eye

Different results from eye irritation studies on BPS are available, that permits estimation of the hazard of the intermediate DCB in read across.

Some of these studies (with limited details) indicate a slight/mild irritation potential on rabbit eyes with recovery, but other OECD 405 studies on the same substance define no irritation potential.^{1 2 3}

2,4'-sulfonyldiphenol CAS 5397-34-2 is considered corrosive (C&L ECHA Inventory), but no data is available.

Also data on benzenesulfonic acid, 4-hydroxy-, sodium salt (1:1), CAS 825-90-1 is not available.

The substance is the salified form phenol sulfonic acid, which is a very acidic substance (comparable to sulphuric acid) and is almost completely ionised in watery environments, even at low pH.⁴

The product is neutralised, thus, more realistic data on salified similar substances called hydrotropes, can be considered.

The specific cation is not expected to have an appreciable effect on fate, ecotoxicity or mammalian toxicity and therefore, the dataset for the entire hydrotropes category can be applied broadly. 

A category approach evaluation has been done for the evaluation of sodium xylenesulphonate. The estimated irritant property of this substance can be helpful (in read across as well) to understand the irritant property of sodium sulphonated phenols, part of the intermediate DCB.

Sodium xylenesulphonate is considered an eye irritant.⁵

Phenol is causes high damage to the eye and it is listed in the Annex VI of the CLP Regulation as a corrosive substance (H314; Cat. 1).

However, it has a specific limit that will be considered in the classification section. ⁶

References:

¹ECHA Registration Dossier CAS 80-09-1;

²SIDS INITIAL ASSESSMENT PROFILE, CAS 80-09-1, CoCAM 4, 16-18 April 2013;

³EPA, U.S. Environmental Protection Agency, Bisphenol A alternatives in thermal paper, Final Report, January 2014.

⁴HPV Assessment Report On Hydroxybenzenesulphonic acid CAS No. 1333-39-7, 2004, NOTOX.

⁵ECHA Registration Dossier, Sodium xylenesulphonate, CAS 1300-72-7;

⁶Toxicological review of phenol. EPA, IRIS, 2002, EPA/635/R-02/006.

Justification for selection of skin irritation / corrosion endpoint:
Conclusion defined from literature data.

Effect level: empty Endpoint conclusion: Adverse effect observed

Effect level: empty Endpoint conclusion: Adverse effect observed

Justification for classification or non-classification

Skin corrosion/irritation

In order to classify the whole mixture for skin corrosion/irritation, the available classification and the results of the reported studies of every known component has been taken into account.

4,4'-sulfonyldiphenol (BPS): non classified

Benzenesulfonic acid, 4-hydroxy-, sodium salt (1:1)- hydrotropes, sodium xylenesulphonate (category approach): non classified

2,4'-sulfonyldiphenol: H314 (C&L ECHA Inventory).

Phenol: H314

Approximately 48% of the organic part of the intermediate under registration is composed of BPS.

Approximately 14% of the organic part of the mixture is the salified form of the phenol sulfonic acid, benzenesulfonic acid, 4-hydroxy-, sodium salt (1:1).

Actually, this substance is completely salified, and therefore, a category approach based on the hydrotropes should be taken into account for a more realistic classification of the whole intermediate mixture DCB, which is in the neutralized form.

2,4'-sulfonyldiphenol is present at 6 %, and it is classified in the C&L inventory as corrosive. However, no data on its corrosivity are available.

Phenol is a skin corrosive and it is listed in the Annex VI of the CLP Regulation.

According to the CLP Regulation 1272/2008/EC, 3.2 section, point 3.2.3.3, Table 3.2.3, the generic concentration limits shall be used to determine if the mixture is considered to be an irritant or a corrosive to the skin (concentration limits >=1 % - < 3 %).

Due to the likely corrosivity properties of 2,4'-sulfonyldiphenol, the product could have corrosive effects on the skin.

However, according to the point 3.2.3.3.4.2, the pH shall be used as a classification criterion.

The measured pH of the salified final mixture is almost neutral 7-8, therefore the intermediate DCB 58% can be considered only irritant for the skin.

Based on the information available, it can be concluded that the intermediate DCB 58 % is classified as a skin irritant, Category 2, H315 due to its neutralized form.

Eye corrosion/irritation

In order to classify the whole mixture for the eye corrosion/irritation, the available classification and the results of the reported studies of every known component has been taken into account.

4,4'-sulfonyldiphenol (BPS): non classified.

Benzenesulfonic acid, 4-hydroxy-, sodium salt (1:1)- hydrotropes, sodium xylenesulphonate (category approach): H319

2,4'-sulfonyldiphenol: H314 (C&L ECHA Inventory).

Phenol: H314. According to the specific limits (>= 1- <3 %), H319

Approximately 48% of the organic part of the intermediate under registration is composed of BPS.

Approximately 14% of the organic part of the mixture is the salified form of the phenol sulfonic acid, benzenesulfonic acid, 4-hydroxy-, sodium salt (1:1).

Actually, this substance is completely salified, and therefore, a category approach based on the hydrotropes should be taken into account for a more realistic classification of the whole intermediate mixture DCB, that it is in the neutralized form.

2,4'-sulfonyldiphenol is present at 6 %, and it is classified in the C&L inventory as corrosive. However, no data on its corrosivity is available.

Phenol is an eye irritant according to the specific limits of the Annex VI of CLP ( >=1 % - < 3 %).

According to the CLP Regulation 1272/2008/EC, 3.3 section, point 3.3.3.3, Table 3.3.3, generic concentration limits shall be used to determine if the mixture is considered to be an irritant or a corrosive to the eye.

Due to the likely corrosivity properties of 2,4'-sulfonyldiphenol, the product could have corrosive effects on the eyes.

However, according to the point 3.2.3.3.4.2, the pH shall be used as a classification criterion.

The measured pH of the salified final mixture is almost neutral 7 -8, therefore the intermediate DCB 58 % can be considered only irritant for the eye.

Phenol is present at concentration of 1.8 %, above its specific concentration limits ( >=1 % - < 3 %), it contributes for the classification as irritant for the eye of the final product.

Based on the information available, the intermediate DCB 58% is classified H319: Causes eye irritation, Category 2, due to its neutralized form.