Sodium 4-[4-[[2-methyl-4-[[(p-tolyl)sulphonyl]oxy]phenyl]azo]anilino]-3-nitrobenzenesulphonate

Endpoint summary

Description of key information

Oral LD50 > 2000 mg/kg bw (males and females)

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

December from 05th to 28th, 2000

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Remarks:

The complete study report is not available, thus some details about test conditions are missing.

Qualifier:

according to guideline

Guideline:

OECD Guideline 423 (Acute Oral toxicity - Acute Toxic Class Method)

Version / remarks:

adopted 22 March 1996

Qualifier:

according to guideline

Guideline:

EU Method B.1 tris (Acute Oral Toxicity - Acute Toxic Class Method)

GLP compliance:

yes

Test type:

acute toxic class method

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Fasting period before study: fasted animals.

Route of administration:

oral: unspecified

Vehicle:

arachis oil

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

Three females and three males.

Details on study design:

Clinical signs and bodyweight development were monitored during the study.
All animals were subjected to gross necropsy.
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: clinical signs and bodyweight development were monitored during the study.
- Necropsy of survivors performed: yes, all animals were subjected to gross necropsy.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Remarks on result:

not determinable due to absence of adverse toxic effects

Mortality:

No deaths occurred.

Clinical signs:

other: No signs of systemic toxicity were noted during the study. The faeces of the females were stained orange on day 1.

Gross pathology:

No abnormalities detected.

Individual bodyweight and weekly bodyweight changes

Dose level (mg/kg bw)	Animal N. and sex	Bodyweight (g) at day			Bodyweight gain (g) during week
		0	7	14	1	2
2000	1-0 female	217	262	286	45	24
	1-1 female	214	255	277	41	22
	1-2 female	211	258	276	47	18
	2-0 male	285	338	377	53	39
	2-1 male	299	376	420	77	44
	2-2 male	273	332	366	59	34

Interpretation of results:

other: not classified, according to the CLP Regulation (EC) No 1272/2008

Conclusions:

LD50 > 2000 mg/kg bw (males and females)

Executive summary:

The study was performed to assess the acute oral toxicity of the test material following a single oral administration in the Sprague-Dawley rat. The method followed the OECD Guideline 423 (adopted 22 March 1996), EU Commission Directive 96/54/EEC method B1. A group of three fasted females was treated with 2000 mg/kg bodyweight; this was followed by a group of three fasted animals of the other sex at the same dose level. The test material was administered orally as a suspension in arachis oil BP.

No deaths occurred and no signs of systemic toxicity were noted during the study. The faeces of the females were stained orange on day 1. Necropsy did not revealed abnormalities.

Conclusion

LD50 > 2000 mg/kg bw (males and females)

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

ACUTE ORAL TOXICITY

The key study was performed following a single oral administration in the Sprague-Dawley rat. The method followed the OECD Guideline 423. A group of three fasted females was treated with 2000 mg/kg bodyweight; this was followed by a group of three fasted animals of the other sex at the same dose level. The test material was administered orally as a suspension in arachis oil BP. No deaths occurred and no signs of systemic toxicity were noted during the study. The faeces of the females were stained orange on day 1. Necropsy did not revealed abnormalities.

Further two reliable studies are available, in which 10 rats were treated at a dosage level of 5000 mg/kg bw. In one case the substance was prepared as a 40 % suspension in aqueous gum tragacanth (0.5 %) and administered by oral intubation; in the other one, a 25 % w/w solution of the compound in deionised water was administered as a single dose by gavage, at a dose rate of 20 mg/kg.

In the first experiment, signs of reaction to treatment, observed shortly after dosing, consisted of lethargy and piloerection only. Two rats died within 18 hours of treatment. Autopsy revealed the test material in the lungs. Recovery of survivors, as judged by external appearance and behaviour, was apparently complete within five days of treatment. This observation was substantiated by normal bodyweight gains, compared with controls and normal autopsy findings.

In the other test, no clinical symptoms were recorded and no deaths occurred during the 14 day observation period; at autopsy no changes in organs or tissues caused by the administration of the test compound were seen.

In both cases, the LD50 value was established to be higher than 5000 mg/kg bw (males and females).

In addition, an old experiment of low reliability is available; however, due to the fact that details on testing procedures and results are lacking, a reliability cannot be assigned. Groups of three male and three female rats were dosed at 4000, 2000 and 1000 mg/kg of test material. The animals excreted orange faeces, but otherwise there were no toxic signs during seven days. Body weight gains and liver weights were normal. The acute oral LD50 was therefore stated as greater than 4000 mg/kg. There were no significant changes seen at autopsy other than one haemorrhagic thymus.

ACUTE INHALATION TOXICITY

No acute toxicity studies by inhalation route are available on Acid Orange 067. Nevertheless, because of the physical state of the substance inhalation is not an appropriate route of exposure. The vapour pressure of the substance is estimated to be negligible; the particle size distribution showed that the 97 % of particles have a diameter higher than 100 µm and that the 99.9 % of particles has a diameter higher than 45 µm. Thus, Acid Orange 067 is characterized by particles not-respirable. This consideration, together with the consideration that the substance is manufactured and handled with suitable risk management measures and with the suitable personal protective equipments, lets to consider the possible absorption of the substance by inhalation route as negligible.

ACUTE DERMAL TOXICITY

The inhalation and the skin contact of Acid Orange 067 are unlikely.

According to the REACH Regulation, Annex VIII, Column 1 Standard information required, testing by the dermal route does not need to be conducted if the substance does not meet the criteria for classification as acute toxicity or STOT SE by the oral route and no systemic effects have been observed in in vivo studies with dermal exposure (e.g. skin irritation, skin sensitisation).

Furthermore, in the Commission Regulation (EU) 2016/863, amending Annexes VII and VIII to REACH Regulation (EC) No 1907/2006, it is explained that recent scientific analysis of available data from in vivo acute toxicity studies have shown that substances that are not toxic via the oral route may be expected with high certainty to be also non-toxic via the dermal route. Therefore, testing those substances via the dermal route does not provide essential information for their safety assessment. The amendment is the consequence of studies and scientific debates. In particular, the 15th Meeting of Competent Authorities for REACH and CLP (CARACAL, 2014) concluded that an adaptation of point 8.5.3 of Annex VIII to REACH is justified in order to not require information on acute dermal toxicity for substances that have shown no toxicity in acute oral toxicity test up to the limit dose of 2000 mg/kg bw.

In the oral acute toxicity tests no signs of systemic toxicity were recorded, either in the repeated dose toxicity test by oral route. The skin sensitisation potential was investigated in Local Lymph Node Assay (LLNA) in Mice and no test item-related systemic clinical signs were observed. No reason of concern is raised on the basis of the skin/eye irritation investigations.

In addition, an old experiment of low reliability is available; however, due to the fact that details on testing procedures and results are lacking, a reliability cannot be assigned. The 24-hour dermal toxicity was assessed in a group of three female rats. 2500 mg/kg of the material, as an aqueous paste, were applied for 24 hours under an occlusive dressing; the animals were observed for seven days. The skins were stained orange by the material, but no toxic signs were noted during the experimental period. The 24-hour dermal LD50 is therefore greater than 2500 mg/kg. At autopsy there were no gross or microscopic findings indicative of pathology.

Justification for classification or non-classification

According to the CLP Regulation (EC) No 1272/2008, 3.1 Acute toxicity section, substances can be allocated to one of four toxicity categories based on acute toxicity by the oral, dermal or inhalation route according to the numeric criteria. Acute toxicity values are expressed as (approximate) LD50 (oral, dermal) or LC50 (inhalation) values or as acute toxicity estimates (ATE).

The oral LD50 value was established to be greater than 2000 mg/kg body weight, therefore the test substance is out of any classification limit for acute oral toxicity (oral acute toxicity category 4: 300 < ATE ≤ 2000 mg/kg bw).

Dermal and inhalation exposure is unlikely, thus no acute toxicity value is available and no further investigation is required.

In conclusion, the test substance is non classified for oral acute toxicity, according to the CLP Regulation (EC) No 1272/2008.