Alkali salt of sulfonated aryl azo amino sulfonyl aryl azo sulfonyl aryl azo aryl sulfonate

Endpoint summary

Description of key information

Based on the results of the available Reactive Brown DYHY 0331/0334 did not show a conspicuous toxicokinetic behaviour. The dye has a very low oral or dermal absorption rate and does not accumulate in tissues or organs.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

Introduction

Toxicokinetic parameters such as uptake, distribution, metabolism and excretion form the essential toxicological profile of a substance. An approximate indication of the toxicokinetic pattern can be gained from the physico-chemical properties taking into account the molecular weight, the number of atoms (hydrogen bond donors and acceptors), the solubility in solvents, log K_OW, etc. and the results of basic toxicity testing of the test article. The assessment of the toxicokinetic properties of Reactive Brown DYHY 0331/0334 given below is based on the results obtained for, the following toxicological endpoints:

·       Acute oral toxicity in rats

·       Acute dermal toxicity in rats

·       Acute inhalation toxicity in rats

·       In vivo eye irritation in rabbits

·       Skin sensitising study in guinea pigs

·       Bacterial reverse mutation test

·       HPRT test

·       Micronucleus test in vivo in rats

·       Combined oral repeat-dose/developmental screening study in rats

Allstudieswere carried out according to the principles of Good Laboratory Practice and met the requirements of the OECD and EU-Guideline for the Testing of Chemicals.

Physico-chemical properties

Name:                                        Reactive Brown DYHY 0331/0334

IUPAC name:                            Reaction mass of
tetrasodium 5‐[2‐{2,4‐diamino‐5‐sulfonato‐3‐[2‐{4‐[2‐(sulfonatooxy)ethanesulfonyl]phenyl}diazen‐1‐yl]phenyl}diazen‐1‐yl]‐8‐[2‐{4‐[2‐(sulfonatooxy)ethanesulfonyl]phenyl}diazen‐1‐yl]naphthalene‐2‐sulfonate
and
pentasodium 5‐[2‐{2,4‐diamino‐5‐sulfonato‐3‐[2‐{4‐[2‐(sulfonatooxy)ethanesulfonyl]phenyl}diazen‐1‐yl]phenyl}diazen‐1‐yl]‐8‐[2‐{2‐sulfonato‐4‐[2‐(sulfonatooxy)ethanesulfonyl]phenyl}diazen‐1‐yl]naphthalene‐2‐sulfonate

Physical state:                          solid, powder

Empirical formula:                  C₃₂H₂₆N₈O₁₈S₆Na₄(DYHY 0331)
C₃₂H₂₅N₈O₂₁S₇Na₅(DYHY 0334)

Molecular weight:                   1095 g/mol (DYHY 0331)
1196 g/mol (DYHY 0334)                  (<500 daltons = good absorption)

Water solubility:                      > 242 g/L (DYHY 0331)
> 142 g/L (DYHY 0334)                                              (= soluble in water)

Partition coefficient (log K_ow):                                                                                      < -6.1 (DYHY 0331)
< -6.2 (DYHY 0334)                            (>-0.4 or <5.6 = good absorption)

Surface tension:                       58.6 mN/m                                                                 (<60 = surface active)

Vapour pressure:                     decomposition prior melting                                                  (not volatile)

Atom count (natoms):             64 (DYHY 0331)     68 (DYHY 0334)      (<70 =good bioavailability)

H-bond acceptor (nON):        26 (DYHY 0331)     29 (DYHY 0334)       (<10 = good bioavailability)

H-bond donor (nOHNH):        4 (DYHY 0331)      4 (DYHY 0334)        (<5 =good bioavailability)

Toxicological Profile

Administration of a single dose of 2000 mg/kg body weight of the test substance in the acute oral toxicity study did not cause any clinical signs or mortality. Hence, the oral LD₅₀ lies above 2000 mg/kg body weight in rats. The dermal treatment with 2000 mg/kg body weight also led to no toxicologically relevant effects, resulting in a dermal LD₅₀of above 2000 mg/kg body weight in rats. No deaths or adverse effects were noted in an inhalation toxicity study in rats at a limit concentration of 5030 mg/m³ air. Based on the results of acute dermal toxicity study as well as the skin irritation and sensitisation studies, and the significantly hydrophilic properties Reactive Brown DYHY 0331/0334 has no significant dermal absorption potential.

Reactive Brown DYHY 0331/0334was not mutagenic in the Ames test with and without metabolic activation. Furthermore, Reactive Brown DYHY 0331/0334 was not mutagenic in V79 hamster cells in vitro with and without metabolic activation. It was negative in an in vivo Micronucleus test proving that the test substance is not clastogenic.

Reactive Brown DYHY 0331/0334 did not cause any adverse effects up to the limit dose in the combined repeated dose toxicity study with the reproduction/developmental toxicity screening test in rats. During the study, brown staining of the tail was recorded in the mid- and high-dose group animals. Furthermore, at observation of the cage tray, violet staining and/or dark faeces were recorded in the mid- and high-dose group rats during treatment. These findings disappeared few days after the end of treatment during the recovery phase. At necropsy, the most relevant changes were dark mucoid contents in the caecum and/or dark colour in the mesenteric lymph nodes, testes and kidneys in the high dose group. All occurrences of discolouration were attributed to the chemical properties of the test item, which is a dark brown textile dye.

Evaluation and Assessment

Based on all available data, Reactive Brown DYHY 0331/0334 does not exhibit conspicuous toxicokinetic behaviour.

Reactive Brown 0331/0334 is a dark brown powdered solid at room temperature conditions. The degree of purity of the substance is ca. 57%. The substance decomposed prior to melting with a calculated melting point of above 300°C; therefore, a significant inhalation exposure to vapours is not expected. In view of the low n‑octanol/water partition coefficient (log Kow < ‑6 at 20°C), systemic bioavailability after dermal exposure is not anticipated. This is in accordance with the extremely good solubility of the test substance in water and with the molecular weight and number of H-bond acceptors, giving evidence of a poor systemic bioavailability. Hence, the dye has a very low acute toxic potential and no or only a very low dermal absorption potential.

According to its atom count and H-bond donors, Reactive Brown DYHY 0331/0334 should be absorbed from the gastrointestinal tract to some extent, whereas the molecular weight, log Kow and number of H-bond acceptors indicate a low absorption of the test substance. The results of the subacute study demonstrate a limited absorption by the gastrointestinal tract, which manifested in the discoloration of faeces, urine and some inner organs.

Due to the hydrophilic nature, a potential to bioaccumulate can be excluded, as proved by the urine staining, which is a good indication of the bioelimination of absorbed Reactive Brown DYHY 0331/0334 or its metabolites. According to the molecular weight, excretion of Reactive Brown DYHY 0331/0334 is most likely predominantly eliminated via intestine, as substances with a molecular weight above 300 g/mol are preferentially excreted via the faeces in rats. However, the test results showed that the test compound is at least partly eliminated via kidneys/urine, too.

Reactive Brown DYHY 0331/0334 was not genotoxic; therefore, metabolisation towards genotoxic structures by bacterial or mammalian species can most probably be excluded.

Summary

The results of basic toxicity testing give no reason to anticipate unusual characteristics with regards to the toxicokinetics of Reactive Brown 0331/0334. The data indicate that there is little or no dermal absorption. No signs of a significant systemic toxicity associated with absorption potential have been observed. Bioaccumulation of Reactive Brown 0331/0334 can most probably be excluded due to the available data. Based on the results of genotoxicity assays, a metabolisation towards genotoxic metabolites can also be excluded.

On the basis of the results, it is anticipated that the substance does not undergo significant metabolic activity; rather it is metabolised for excretion with little subsequent toxicity. The substance is therefore not considered to be of concern for ADME related effects.