Sodium 4(or 5)-methyl-1H-benzotriazolide

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

For the substance Sodium Methyl-1H-Benzotriazole,
no studies on repeated dose toxicity are available.
As the substance will dissociate in aqueous media into Sodium ions
and Methyl-1H-Benzotriazolate ions, and the Methyl-1H-Benzotriazolate ions
are in equillibrium with the uncharged Methyl-1H-Benzotriazolate,
a read across from Methyl-1H-Benzotriazole is appropriate.

Link to relevant study records

Reference

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

HYPOTHESIS FOR THE ANALOGUE APPROACH
[Describe why the read-across can be performed (e.g. common functional group(s), common precursor(s)/breakdown product(s) or common mechanism(s) of action]
The source chemical Tolyltriazole (parent) and the target chemical Sodium tolyltriazolate (salt) have common breakdown products when present in aqueous solutions:
The salt and parent will be solved and a equilibrium, depending on pH between the uncharged parent and charged parent will be reached. Therefore, the active species will be the same in physiological surrounding. Due to the ubiquiteous presence of Sodium ions in biological and environmental surroundings, no effect from sodium is expected.



1. Source Chemical(s)


Benzotriazoles have two fused rings, one 1,2,3-triazole and one benzene ring. In Tolyltriazole, the benzene ring is substituted with one methyl group, while in Benzotriazole all substituents are hydrogen.

The Benzotriazoles can be deprotonated at the Nitrogen, leading to the conjugated base as sodium salt.

The differences in the chemical structure (from Benzotriazole to Tolyltriazole) are not expected to change the toxicological properties significantly.

The sodium salts are more basic than the neutral substances (Benzotriazole and Tolyltriazole) and present therefore irritant and corrosive properties, as seen in in vivo studies. Nevertheless, systemic effects are expected to be comparable between the salts and the neutral substances due to the fact that in physiological environment (pH 6-8) protonation of the slat occurs and the neutral species is yielded.


2. Purity/impurities


The impurities in the target substance do not indicate toxicological relevence to this endpoint. The impurities are all below 1 %.


The excess sodium hydroxide of sodium benzotriazolate and sodium tolyltriazolate increases the toxicological irritation/corrosion properties as seen in valid in vivo tests. Further on, it is assumed that no other influence then the basic reservoir is changed by this impurity


3. Analogue approach justification


According to Annex XI, 1.5 a read-across approach can be used to fill the data gap when certain criteria are fulfilled. The fulfillment of these criteria is discussed below. The information from the REACH technical guidance document R.6 are used for this assessment as well as ECHA's Practical guide 6 on category and read-across approaches (ECHA REACH TGD; ECHA, 2009).


Quality of the experimental data of the analogues


The source chemical has been tested in a well-conducted study (According to OECD TG 407). The study results receive reliability 1.


Toxicokinetics


The source and target chemicals indicate similarity in toxicokinetic behavior based on the molecular weight (< 200), physical form (all are solids), vapor pressure (< 10 Pa) and Log POW(0-2).


The difference between the neutral species and the salts in respect to log POWis in the range of 1 and expected to be of minimal relevance. The charge of the Benzotriazolate anion in the salts will decrease the bioavailability but in contact with water the neutral species will be formed in dependence of the pH.


Reactivity towards proteins and DNA


(Q)SAR modeling

The (Q)SAR modeling as such is not used for predictivity but it is used for showing that the Benzotriazoles have the same toxicological profile according to these models.

The OECD (Q)SAR toolbox program is used to obtain the toxicological profile for the source and target substances.

The benzotriazole structures result in two alerts with regard to toxicity:

- Toxic Hazard Classification by Cramer: High (Class III)

- In vivo mutagenicity (Micronucleus) alerts by ISS: H-Acceptor-path 3-H-acceptor for DNA-binding for in vivo mutagenicity.

No alerts were found for DNA or protein binding.


The Toxic Hazard Classification by Cramer: High (Class III) is verified by the observed oral toxicity of the different benzotriazoles (data matrix).


The “in vivo mutagenicity (Micronucleus) alert by ISS” is a false positive alert as the available in vivo genetic toxicity data is negative for this endpoint.


Similarities in results for toxicological endpoints between the target and the source chemical(s) to support read-across for acute dermal toxicity


As it is presented in the data matrix the acute oral toxicity is in the same range for the target and source chemical(s).


The neutral substances (Benzotriazole and Tolyltriazole) show no skin irritation, skin sensitization properties and only mild eye irritation, the salts (Sodium benzotriazolate and sodium tolyltriazolate) show severe skin irritation / corrosion which is caused by the high basicity and the pH of a solution of these substances.


The negative genotoxicity profile is also similar between the source and the target chemical.

For Benzotriazole the Ames test, the mammalian mutation test and the mouse micronucleus test are negative.

For Tolyltriazole the Ames test and the mouse micronucleus test are negative.


Systemic toxicity is seen for Benzotriazole in a two year study and for Tolyltriazole in a 28 days-repeated dose test. No target organ was identified.

A LOAELchronicof 325 mg/kg bw for Benzotriazole and a NOAELsub-acuteof 150 mg/kg bw for Tolyltriazole was established.

Toxicity to reproduction and fertility was tested in a Screening test according to OECD Guideline 421 for Benzotriazole. In this study, a NOAELReprotox-screeningof 200 mg/kg bw/day was found. Higher doses were not tested due to the systemic toxicity of the substance.


4. Data matrix (IUCLID: „Results and discussion“)


Separate document

Reason / purpose for cross-reference:

read-across source

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

only 4 strains used

Principles of method if other than guideline:

Study performed according to the Ames test protocol

GLP compliance:

no

Type of assay:

bacterial reverse mutation assay

Target gene:

his-

Species / strain:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

above 2000 µg/plate

Untreated negative controls validity:

valid

Positive controls validity:

valid

Conclusions:

The test item is cytotoxic to the used bacteria strains in doses above 2000 µg/plate.
Lower doses do not show this effect.
No mutagenic potential was observed in this study

Executive summary:

For Benzotriazole and Tolyltriazole well-conducted in vitro studies are available showing no genetic toxicity for gene mutation in bacteria. This means that a similar result for Sodium Tolyltriazolate can be anticipated.

 

Sodium Tolyltriazolate is not genetic toxic in respect to gene mutation in bacteria.

 

A DNEL for oral, dermal and/or inhalation route can be based on this information.

Classification and labelling are / are not needed for this endpoint.

A risk characterisation will be performed because the substance is classified for orale toxicity.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Description of key information

For the substance Sodium Methyl-1H-Benzotriazole,
no studies on repeated dose toxicity are available.
As the substance will dissociate in aqueous media into Sodium ions
and Methyl-1H-Benzotriazolate ions, and the Methyl-1H-Benzotriazolate ions
are in equillibrium with the uncharged Methyl-1H-Benzotriazolate,
a read across from Methyl-1H-Benzotriazole is appropriate.

Link to relevant study records

Reference

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

The source chemical Tolyltriazole (parent) and the target chemical Sodium tolyltriazolate (salt) have common breakdown products when present in aqueous solutions:
The salt and parent will be solved and a equilibrium, depending on pH between the uncharged parent and charged parent will be reached. Therefore, the active species will be the same in physiological surrounding. Due to the ubiquiteous presence of Sodium ions in biological and environmental surroundings, no effect from sodium is expected.




1. Source Chemical(s)


Benzotriazoles have two fused rings, one 1,2,3-triazole and one benzene ring. In Tolyltriazole, the benzene ring is substituted with one methyl group, while in Benzotriazole all substituents are hydrogen.

The Benzotriazoles can be deprotonated at the Nitrogen, leading to the conjugated base as sodium salt.

The differences in the chemical structure (from Benzotriazole to Tolyltriazole) are not expected to change the toxicological properties significantly.

The sodium salts are more basic than the neutral substances (Benzotriazole and Tolyltriazole) and present therefore irritant and corrosive properties, as seen in in vivo studies. Nevertheless, systemic effects are expected to be comparable between the salts and the neutral substances due to the fact that in physiological environment (pH 6-8) protonation of the slat occurs and the neutral species is yielded.


2. Purity/impurities


The impurities in the target substance do not indicate toxicological relevence to this endpoint. The impurities are all below 1 %.


The excess sodium hydroxide of sodium benzotriazolate and sodium tolyltriazolate increases the toxicological irritation/corrosion properties as seen in valid in vivo tests. Further on, it is assumed that no other influence then the basic reservoir is changed by this impurity


3. Analogue approach justification


According to Annex XI, 1.5 a read-across approach can be used to fill the data gap when certain criteria are fulfilled. The fulfillment of these criteria is discussed below. The information from the REACH technical guidance document R.6 are used for this assessment as well as ECHA's Practical guide 6 on category and read-across approaches (ECHA REACH TGD; ECHA, 2009).


Quality of the experimental data of the analogues


The source chemical has been tested in a well-conducted study (According to OECD TG 407). The study results receive reliability 1.


Toxicokinetics


The source and target chemicals indicate similarity in toxicokinetic behavior based on the molecular weight (< 200), physical form (all are solids), vapor pressure (< 10 Pa) and Log POW(0-2).


The difference between the neutral species and the salts in respect to log POWis in the range of 1 and expected to be of minimal relevance. The charge of the Benzotriazolate anion in the salts will decrease the bioavailability but in contact with water the neutral species will be formed in dependence of the pH.


Reactivity towards proteins and DNA


(Q)SAR modeling

The (Q)SAR modeling as such is not used for predictivity but it is used for showing that the Benzotriazoles have the same toxicological profile according to these models.

The OECD (Q)SAR toolbox program is used to obtain the toxicological profile for the source and target substances.

The benzotriazole structures result in two alerts with regard to toxicity:

- Toxic Hazard Classification by Cramer: High (Class III)

- In vivo mutagenicity (Micronucleus) alerts by ISS: H-Acceptor-path 3-H-acceptor for DNA-binding for in vivo mutagenicity.

No alerts were found for DNA or protein binding.


The Toxic Hazard Classification by Cramer: High (Class III) is verified by the observed oral toxicity of the different benzotriazoles (data matrix).


The “in vivo mutagenicity (Micronucleus) alert by ISS” is a false positive alert as the available in vivo genetic toxicity data is negative for this endpoint.


Similarities in results for toxicological endpoints between the target and the source chemical(s) to support read-across for acute dermal toxicity


As it is presented in the data matrix the acute oral toxicity is in the same range for the target and source chemical(s).


The neutral substances (Benzotriazole and Tolyltriazole) show no skin irritation, skin sensitization properties and only mild eye irritation, the salts (Sodium benzotriazolate and sodium tolyltriazolate) show severe skin irritation / corrosion which is caused by the high basicity and the pH of a solution of these substances.


The negative genotoxicity profile is also similar between the source and the target chemical.

For Benzotriazole the Ames test, the mammalian mutation test and the mouse micronucleus test are negative.

For Tolyltriazole the Ames test and the mouse micronucleus test are negative.


Systemic toxicity is seen for Benzotriazole in a two year study and for Tolyltriazole in a 28 days-repeated dose test. No target organ was identified.

A LOAELchronicof 325 mg/kg bw for Benzotriazole and a NOAELsub-acuteof 150 mg/kg bw for Tolyltriazole was established.

Toxicity to reproduction and fertility was tested in a Screening test according to OECD Guideline 421 for Benzotriazole. In this study, a NOAELReprotox-screeningof 200 mg/kg bw/day was found. Higher doses were not tested due to the systemic toxicity of the substance.

Reason / purpose for cross-reference:

read-across source

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

GLP compliance:

yes

Type of assay:

micronucleus assay

Sex:

male/female

Genotoxicity:

negative

Toxicity:

yes

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

RESULTS OF RANGE-FINDING STUDY
- Dose range: 500 - 1000 mg/kg bw
- Clinical signs of toxicity in test animals: apathy, horrent fur, narcotic state, prone position, spasm, breathlessness

RESULTS OF DEFINITIVE STUDY
- Induction of micronuclei (for Micronucleus assay): normal
- Ratio of NCE/PCE (for Micronucleus assay): 1000:1715

 

Group	evaluable polychromatic Erythrocytes	Ratio NCE/PCE	Micronuclei per 1000 NCE	Micronuclei per 1000 PCE
negative control	10000	1320	0.5	1.2
Tolyltriazole, 24 h	10000	1540	0.9	1.7
Tolyltriazole, 48 h	10000	1715	0.6	1.4
Tolyltriazole, 72 h	10000	994	0.5	1.0
positive control	10000	1393	0.8	14.7

 

 

Conclusions:

Tolyltriazole does not show genetic toxicity in this study.
Toxic effects were observed in a range finding study at 750 mg /kg bw

Executive summary:

Tolyltriazole is not genetic toxic in respect to micronucleus formation.

 

A DNEL for oral, dermal and/or inhalation route can be based on this information.

Classification and labeling are / are not needed for this endpoint.

A risk characterisation will be performed because the substance is classified for orale toxicity.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Justification for selection of genetic toxicity endpoint
Studies from analogues (Benzotriazole and Tolyltriazole) available.
The in vivo micronucleus test for Tolyl-Benzotriazole is selected as it is the most sensitive endpoint tested and the
analogue is most similar to the substance.

Short description of key information:
Sodium Tolyltriazolate is expected to be not genetic toxic because the analogues Tolyltriazolate and Benzotriazole have not shown genetic toxicity properties in well performed studies. These source chemicals are sufficiently similar to readacross towards sodium Tolyltriazolate.

Endpoint Conclusion: No adverse effect observed (negative)