1-(2,4-dimethylphenylazo)-2-naphthol

Endpoint summary

Description of key information

Acute toxicity: oral

LD50 was estimated to be 2998 mg/kg bw when rats were orally exposed with 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol. 

Acute toxicity: inhalation
the study need not be conducted because exposure of humans via inhalation is not likely taking into account the vapour pressure of the substance and/or the possibility of exposure to aerosols, particles or droplets of an inhalable size.

Acute toxicity: dermal

Acute dermal LD50 value of the test substance 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol is estimated to be 2332.617 mg/kg bw to rats.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification

Justification for type of information:

Data is predicted using OECD QSAR toolbox version 3.3 and the supporting QMRF report has been attached

Qualifier:

according to guideline

Guideline:

other: as below

Principles of method if other than guideline:

Prediction is done using QSAR Toolbox version 3.3

GLP compliance:

not specified

Test type:

other: No data

Limit test:

no

Specific details on test material used for the study:

- Name of test material (as cited in study report): C.I. Solvent orange 7
- Molecular formula (if other than submission substance): C18H16N2O
- Molecular weight (if other than submission substance): 276.337 g/mol
- Smiles notation (if other than submission substance): c12c(\N=N/c3c(cc(C)cc3)C)c(ccc1cccc2)O
- InChl (if other than submission substance): 1S/C18H16N2O/c1-12-7-9-16(13(2)11-12)19-20-18-15-6-4-3-5-14(15)8-10-17(18)21/h3-11,21H,1-2H3
- Structural formula attached as image file (if other than submission substance): No data available
- Substance type: Organic
- Physical state: Solid

Species:

rat

Strain:

not specified

Sex:

not specified

Details on test animals or test system and environmental conditions:

No data available

Route of administration:

oral: gavage

Vehicle:

not specified

Details on oral exposure:

not specified

Control animals:

not specified

Details on study design:

not specified

Statistics:

not specified

Preliminary study:

not specified

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

2 998 mg/kg bw

Based on:

test mat.

Remarks on result:

other: 50 % mortality observed

Mortality:

not specified

Clinical signs:

other: not specified

Gross pathology:

not specified

Other findings:

not specified

The prediction was based on dataset comprised from the following descriptors: LD50
Estimation method: Takes average value from the 6 nearest neighbours
Domain  logical expression:Result: In Domain

((((((((("a" or "b" or "c" or "d" or "e" or "f" )  and ("g" and ( not "h") )  )  and ("i" and ( not "j") )  )  and ("k" and ( not "l") )  )  and ("m" and ( not "n") )  )  and ("o" and ( not "p") )  )  and "q" )  and "r" )  and ("s" and "t" )  )

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as SN1 AND SN1 >> Nitrenium Ion formation AND SN1 >> Nitrenium Ion formation >> Aromatic azo by DNA binding by OECD

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Strong binder, OH group by Estrogen Receptor Binding

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Alkyl arenes AND Aryl AND Azo AND Fused carbocyclic aromatic AND Naphtalene AND Phenol by Organic Functional groups

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Alkyl arenes AND Aryl AND Azo AND Fused carbocyclic aromatic AND Naphtalene AND Overlapping groups AND Phenol by Organic Functional groups (nested)

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as Alcohol, olefinic attach [-OH] AND Aliphatic Carbon [CH] AND Aliphatic Carbon [-CH2-] AND Aliphatic Carbon [-CH3] AND Aliphatic Nitrogen, one aromatic attach [-N] AND Aromatic Carbon [C] AND Azo [-N=N-] AND Hydroxy, aromatic attach [-OH] AND Olefinic carbon [=CH- or =C<] AND Oxygen, one aromatic attach [-O-] by Organic functional groups (US EPA)

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as Aromatic compound AND Azo compound AND Hydroxy compound AND Phenol by Organic functional groups, Norbert Haider (checkmol)

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as No alert found by DNA binding by OASIS v.1.3

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as AN2 OR AN2 >> Shiff base formation after aldehyde release OR AN2 >> Shiff base formation after aldehyde release >> Specific Acetate Esters OR Non-covalent interaction OR Non-covalent interaction >> DNA intercalation OR Non-covalent interaction >> DNA intercalation >> DNA Intercalators with Carboxamide Side Chain OR Non-covalent interaction >> DNA intercalation >> Fused-Ring Primary Aromatic Amines OR Radical OR Radical >> Radical mechanism via ROS formation (indirect) OR Radical >> Radical mechanism via ROS formation (indirect) >> Fused-Ring Primary Aromatic Amines OR Radical >> Radical mechanism via ROS formation (indirect) >> Nitro Azoarenes OR Radical >> Radical mechanism via ROS formation (indirect) >> Nitroaniline Derivatives OR Radical >> Radical mechanism via ROS formation (indirect) >> Nitroarenes with Other Active Groups OR Radical >> Radical mechanism via ROS formation (indirect) >> Nitrophenols, Nitrophenyl Ethers and Nitrobenzoic Acids OR SN1 OR SN1 >> Alkylation after metabolically formed carbenium ion species OR SN1 >> Alkylation after metabolically formed carbenium ion species >> Polycyclic Aromatic Hydrocarbon Derivatives OR SN1 >> Nucleophilic attack after carbenium ion formation OR SN1 >> Nucleophilic attack after carbenium ion formation >> Specific Acetate Esters OR SN1 >> Nucleophilic attack after diazonium or carbenium ion formation OR SN1 >> Nucleophilic attack after diazonium or carbenium ion formation >> Nitroarenes with Other Active Groups OR SN1 >> Nucleophilic attack after metabolic nitrenium ion formation OR SN1 >> Nucleophilic attack after metabolic nitrenium ion formation >> Fused-Ring Primary Aromatic Amines OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation >> Nitro Azoarenes OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation >> Nitroaniline Derivatives OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation >> Nitroarenes with Other Active Groups OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation >> Nitrophenols, Nitrophenyl Ethers and Nitrobenzoic Acids OR SN2 OR SN2 >> Acylation OR SN2 >> Acylation >> Specific Acetate Esters OR SN2 >> Alkylation, direct acting epoxides and related after P450-mediated metabolic activation OR SN2 >> Alkylation, direct acting epoxides and related after P450-mediated metabolic activation >> Polycyclic Aromatic Hydrocarbon Derivatives OR SN2 >> Nucleophilic substitution at sp3 Carbon atom OR SN2 >> Nucleophilic substitution at sp3 Carbon atom >> Specific Acetate Esters OR SN2 >> SN2 attack on activated carbon Csp3 or Csp2 OR SN2 >> SN2 attack on activated carbon Csp3 or Csp2 >> Nitroarenes with Other Active Groups by DNA binding by OASIS v.1.3

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as Not possible to classify according to these rules by DPRA Cysteine peptide depletion

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as High reactive OR High reactive >> alpha,beta-carbonyl compounds with polarized multiple bonds OR Moderate reactive OR Moderate reactive >> Activated 1,3,5-triazine derivatives OR Moderate reactive >> Mono-methacrylic acid esters by DPRA Cysteine peptide depletion

Domain logical expression index: "k"

Referential boundary: The target chemical should be classified as Strong binder, OH group by Estrogen Receptor Binding

Domain logical expression index: "l"

Referential boundary: The target chemical should be classified as Non binder, impaired OH or NH2 group OR Non binder, MW>500 OR Non binder, non cyclic structure OR Non binder, without OH or NH2 group OR Very strong binder, OH group by Estrogen Receptor Binding

Domain logical expression index: "m"

Referential boundary: The target chemical should be classified as No alert found by Protein binding by OASIS v1.3

Domain logical expression index: "n"

Referential boundary: The target chemical should be classified as Acylation OR Acylation >> Ester aminolysis OR Acylation >> Ester aminolysis >> Amides OR Michael Addition OR Michael Addition >> Michael addition on conjugated systems with electron withdrawing group OR Michael Addition >> Michael addition on conjugated systems with electron withdrawing group >> alpha,beta-Carbonyl compounds with polarized double bonds  OR Nucleophilic addition OR Nucleophilic addition >> Addition to carbon-hetero double bonds OR Nucleophilic addition >> Addition to carbon-hetero double bonds >> Ketones by Protein binding by OASIS v1.3

Domain logical expression index: "o"

Referential boundary: The target chemical should be classified as No alert found by Protein binding by OECD

Domain logical expression index: "p"

Referential boundary: The target chemical should be classified as Acylation OR Acylation >> Direct Acylation Involving a Leaving group OR Acylation >> Direct Acylation Involving a Leaving group >> Acetates by Protein binding by OECD

Domain logical expression index: "q"

Referential boundary: The target chemical should be classified as Not bioavailable by Lipinski Rule Oasis ONLY

Domain logical expression index: "r"

Similarity boundary:Target: Cc1ccc(N=Nc2c3ccccc3ccc2O)c(C)c1
Threshold=60%,
Dice(Atom centered fragments)
Atom type; Count H attached; Hybridization

Domain logical expression index: "s"

Parametric boundary:The target chemical should have a value of log Kow which is >= 6.2

Domain logical expression index: "t"

Parametric boundary:The target chemical should have a value of log Kow which is <= 6.96

Interpretation of results:

Category 5 based on GHS criteria

Conclusions:

LD50 was estimated to be 2998 mg/kg bw when rats were orally exposed with 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol.

Executive summary:

In a prediction done by SSS (2017) using the OECD QSAR toolbox with log kow as the primary descriptor, the acute oral toxicity was estimated for 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol. The LD50 was estimated to be 2998 mg/kg bw when rats were orally exposed with 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol. 

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 998 mg/kg bw

Quality of whole database:

Data is Klimisch 2 and from OECD QSAR toolbox

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Data waiving:

other justification

Justification for data waiving:

the study does not need to be conducted because exposure of humans via inhalation is not likely taking into account the vapour pressure of the substance and/or the possibility of exposure to aerosols, particles or droplets of an inhalable size

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification

Justification for type of information:

Data is predicted by OECD QSAR Toolbox version 3.3. The supporting QMRF report has been attached

Qualifier:

according to guideline

Guideline:

other: as mentioned below

Principles of method if other than guideline:

Data is predicted by OECD QSAR Toolbox version 3.3.

GLP compliance:

not specified

Species:

rabbit

Strain:

not specified

Sex:

not specified

Type of coverage:

not specified

Vehicle:

not specified

Details on dermal exposure:

Not specified

Duration of exposure:

Not specified

Doses:

Not specified

No. of animals per sex per dose:

Not specified

Control animals:

not specified

Details on study design:

Not specified

Key result

Sex:

not specified

Dose descriptor:

LD50

Effect level:

2 332.617 mg/kg bw

Based on:

test mat.

Mortality:

Not specified

Clinical signs:

other: Not specified

Gross pathology:

Not specified

Other findings:

Not specified

The prediction was based on dataset comprised from the following descriptors: LD50
Estimation method: Takes average value from the 5 nearest neighbours
Domain  logical expression:Result: In Domain

((((((("a" or "b" or "c" )  and ("d" and ( not "e") )  )  and ("f" and ( not "g") )  )  and ("h" and ( not "i") )  )  and ("j" and ( not "k") )  )  and "l" )  and ("m" and "n" )  )

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as SN1 AND SN1 >> Nitrenium Ion formation AND SN1 >> Nitrenium Ion formation >> Aromatic azo by DNA binding by OECD

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Strong binder, OH group by Estrogen Receptor Binding

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Phenols by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as No alert found by DNA binding by OASIS v.1.3

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as Non-covalent interaction OR Non-covalent interaction >> DNA intercalation OR Non-covalent interaction >> DNA intercalation >> DNA Intercalators with Carboxamide Side Chain OR Radical OR Radical >> Radical mechanism by ROS formation OR Radical >> Radical mechanism by ROS formation >> Polynitroarenes OR Radical >> Radical mechanism via ROS formation (indirect) OR Radical >> Radical mechanism via ROS formation (indirect) >> Nitrophenols, Nitrophenyl Ethers and Nitrobenzoic Acids OR SN1 OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation >> Nitrophenols, Nitrophenyl Ethers and Nitrobenzoic Acids OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation >> Polynitroarenes by DNA binding by OASIS v.1.3

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as Non-Metals by Groups of elements

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as Alkali Earth OR Halogens by Groups of elements

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as Phenols by Skin irritation/corrosion Inclusion rules by BfR

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as Aromatic amines OR Ketones by Skin irritation/corrosion Inclusion rules by BfR

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as No alert found by Protein binding alerts for Chromosomal aberration by OASIS v1.1

Domain logical expression index: "k"

Referential boundary: The target chemical should be classified as AN2 OR AN2 >> Michael-type addition to quinoid structures OR AN2 >> Michael-type addition to quinoid structures >> Phenols by Protein binding alerts for Chromosomal aberration by OASIS v1.1

Domain logical expression index: "l"

Referential boundary: The target chemical should be classified as High (Class III) by Toxic hazard classification by Cramer (original) ONLY

Domain logical expression index: "m"

Parametric boundary:The target chemical should have a value of log Kow which is >= 4.23

Domain logical expression index: "n"

Parametric boundary:The target chemical should have a value of log Kow which is <= 13.4

Interpretation of results:

other: not irritating

Conclusions:

Acute dermal LD50 value of the test substance 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol is estimated to be 2332.617 mg/kg bw to rbbits.

Executive summary:

In a prediction done by SSS (2017) using the OECD QSAR toolbox with log kow as the primary descriptor, the acute oral toxicity was estimated for 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol. The acute dermal LD50 value of the test substance 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol is estimated to be 2332.617 mg/kg bw to rabbits.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 332.617 mg/kg bw

Quality of whole database:

Data is Klimisch 2 and from OECD QSAR toolbox

Additional information

Acute oral toxicity:

In different studies, 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol (CAS no 3118-97-6) has been investigated for acute oral toxicity to a greater or lesser extent. Often are the studies based on in vivo experimental and estimations in rodents, i.e. most commonly in mice and rats for 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol along with on structurally similar read across substance1-[(2-methoxyphenyl)diazenyl]-2-naphthol (CAS no 1229-55-6)and Sudan orange R (CAS 842-07-9).The predicted data using the OECD QSAR toolbox has also been compared with the experimental data.

In a prediction done by SSS (2017) using the OECD QSAR toolbox with log kow as the primary descriptor, the acute oral toxicity was estimated for 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol. The LD50 was estimated to be 2998 mg/kg bw when rats were orally exposed with 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol. 

In another experimental study summarized by Commission of The European Communities (Directorate-General Telecommunications, Information Industries and Innovation; Batiment Jean Monnet, LUXEMBOURG, 1988), mice were treated with 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol orally. 50 % Mortality was observed in treated mice at 20,000 mg/kg bw. Therefore, LD50 was considered to be 20,000 mg/kg bw. When mice were treated with 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol orally.

Also it is further supported by experimental study conducted by Mayhewet al(American College of Toxicology, Part B.15 (Suppl 1),S43,1996) and given by NTRL (U.S. Army Medical Bioengineering Research and development Laboratory, 1986)on structurally similar read across substance 1-[(2-methoxyphenyl)diazenyl]-2-naphthol (CAS no 1229-55-6), Fischer 344 male and female rats were treated Solvent Red 1 (1-[(2-methoxyphenyl)diazenyl]-2-naphthol) in the concentration of 5000 mg/kg bw in corn oil orally by gavage. No mortality was observed in treated rat at 5000 mg/kg bw. Red colored urine and stool; loose stool; red stained fur in the perianal region, on the head and ventral portion of the body, on the muzzle and red colored stain on the tail of treated rat. Overall body weight gain was observed in treated rat. No gross pathological abnormal findings were observed in treated rat. Therefore, LD50 was considered to be > 5000 mg/kg bw when Fischer 344 male and female rats were treated Solvent Red 1 (1-[(2-methoxyphenyl)diazenyl]-2-naphthol) orally.

Further supported by experimental study conducted by BSF Company (1977) on structurally similar read across substance Sudan orange R (RA CAS 842-07-9), acute oral toxicity was evaluated in rats by using Sudan orange R in the concentration of 10000 mg/kg bwas a 5-35% suspension in 0.5% aqueous CMC preparation orally by gavage and observed for 14 days. No mortality was observed in treated rat at 10000 mg/kg bw and orange discolored of skin, feces and urine were observed in treated rats. Therefore, LD50 was considered to be > 10000 mg/kg bw when rats were treated with Sudan orange R as a 5-35% suspension in 0.5% aqueous CMC preparation orally by gavage. 

This further supported by experimental study conducted by National Toxicology Program (1982) and National Technical Information Service (1981) on structurally similar read across substance Sudan orange R (RA CAS 842-07-9), acute oral toxicity was evaluated in F344 male and female rats and B6C3F1 male and female mice were treated with C. I. Solvent Yellow 14 in the concentration of 0, 600, 1250, 2500, 5000 and 10000 mg/kg/day and 0, 1200, 2500, 5000, 1000 and 20000 mg/kg/day orally in feed and observed for 14 days. No effect on survival and signs of toxicity were observed in treated mice and rat. Therefore, LD50 was considered to be > 10000 mg/kg bw for rats and > 20000 ma/kg bw for mice when F344 male and female rats and B6C3F1 male and female mice were treated with C. I. Solvent Yellow 14 orally by feed.

Thus, based on the above studies and predictions on 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol and by applying weight of evidance, it can be concluded that LD50 value is greater than 2000 mg/kg bw. Thus comparing this value with the criteria of CLP regulation, 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol can be “Not Classified” for acute oral toxicity.

Acute toxicity: inhalation
The study need not be conducted because exposure of humans via inhalation is not likely taking into account the vapour pressure of the substance and/or the possibility of exposure to aerosols, particles or droplets of an inhalable size.

Acute toxicity: dermal
In below summary, 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol (CAS No.- 3118-97-6) has been reviewed for acute dermal toxicity to a greater or lesser extent. The studies are based on prediction for 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol along with the study available on structurally similar read across substances 2-Naphthalenol, 1-[[4-(phenylazo)phenyl]azo]-, ar',ar''-Me derivs (CAS No. – 70879-65-1) and Solvent Red 1 (1-[(2-methoxyphenyl)diazenyl]-2-naphthol) (CAS: 1229-55-6).

In a prediction done by SSS (2017) using the OECD QSAR toolbox with log kow as the primary descriptor, the acute oral toxicity was estimated for 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol. The acute dermal LD50 value of the test substance 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol is estimated to be 2332.617 mg/kg bw to rabbits. 

This is supported by the acute dermal toxicity study of structurally similar read across substance 2-Naphthalenol, 1-[[4-(phenylazo)phenyl]azo]-, ar',ar''-Me derivs conducted by Sustainability Support Services (Europe) AB, at IIRT (2012), Wistar male and female rats were treated with 2-Naphthalenol, 1-[[4-(phenylazo)phenyl]azo]-, ar',ar''-Me derivs in the concentration of 2000 mg/kg bw by dermal application. No mortality and any clinical signs of toxicity were observed throughout the observation period of 14 days in treated rats. The body weight of each animal recorded on day 0, 7th and 14th showed normal increase and there was no significant increase or decrease in weight was recorded. Therefore, LD50 was considered to be > 2000 mg/kg bw when Wistar male and female rats were treated with 2-Naphthalenol, 1-[[4-(phenylazo)phenyl]azo]-, ar',ar''-Me derivs by dermal application.

Moreover, in the study conducted byGunda Reddy et al.,( International Journal of Toxicology Vol 15, Issue 1_suppl, pp. S43 - S44, 1996), New Zealand White male and female rabbits were treated with Solvent Red 1 (1-[(2-methoxyphenyl)diazenyl]-2-naphthol) in the concentration of 5000 mg/kg bw in physiological saline applied on dorsal and lateral trunk (approximately 10% of the body surface area) of each animal was clipped free of hair with Oster electric clippers equipped with a number 40 (surgical) blade for 24 hours. No mortality was observed in treated rabbits. Red stain on teat site, feet and head discolored red in treated male and female rabbits. Few stools and loose stool were observed in treated male rabbits. Overall body weight increased was observed in treated male and female rabbits. Red discoloration of treated skin, red discoloration of fur, a liver with a dark red discoloration, and 2 lungs with red discoloration was observed in treated male and female rabbits. Therefore, LD50 was considered to be > 2000 mg/kg bw when New Zealand White male and female rabbits were treated with Solvent Red 1 (1-[(2-methoxyphenyl)diazenyl]-2-naphthol) by dermal application for 24 hours.

Thus, based on the above studies and predictions on 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol (Sudan II) and its read across substances, it can be concluded that LD50 value is > 2000 mg/kg bw. Thus comparing this value with the criteria of CLP regulation, it infers that 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol (CAS No. 3118-97-6) does not classify as an acute dermal toxicant i.e it is acutely non toxic to animals.

Justification for classification or non-classification

Based on the above studies and predictions on 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol, it can be concluded that LD50 value is greater than 2000 mg/kg bw. Thus comparing this value with the criteria of CLP regulation, 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol can be “Not Classified” for acute oral as well as dermal toxicity.