7,14,25,32-tetraazaundecacyclo[21.13.2.2²,⁵.0³,¹⁹.0⁴,¹⁶.0⁶,¹⁴.0⁸,¹³.0²⁰,³⁷.0²⁴,³².0²⁶,³¹.0³⁴,³⁸]tetraconta-1(36),2(40),3,5(39),6,8(13),9,11,16,18,20,22,24,26(31),27,29,34,37-octadecaene-15,33-dione; 7,14,25,32-tetraazaundecacyclo[21.13.2.2²,⁵.0³,¹⁹.0⁴,¹⁶.0⁶,¹⁴.0⁸,¹³.0²⁰,³⁷.0²⁵,³³.0²⁶,³¹.0³⁴,³⁸]tetraconta-1(36),2(40),3,5(39),6,8(13),9,11,16,18,20,22,26(31),27,29,32,34,37-octadecaene-15,24-dione

Endpoint summary

Description of key information

No expected bioavailability neither orally, dermally nor inhalative was suggested. No bioaccumulation potential assumed. The test substance is expected not to be metabolized in the body due to low solubility in both water and fat. Further, excretion was concluded to occur via feces. However, no experimental data concerning absorption, distribution, and metabolism have been conducted.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Absorption rate - oral (%):

0

Absorption rate - dermal (%):

0

Absorption rate - inhalation (%):

0

Additional information

Assessment of the Toxicokinetic Behavior

 

The test substance is a black solid dyestuff with a relative density of 1.515 g/cm³ at 20°C and a molecular weight of 536.6 g/mol. The test article has a vapor pressure of 0.000001 hPa at 20°C and is characterized by very low solubility in both water (< 0.005 mg/l at 20°C) and organic solvents (n-octanol: 0.056 mg/L). The log Pow was calculated based on the solubility to be 2.0 at 20°C. No studies are available investigating the toxicokinetic properties of the test substance. The toxicokinetic behavior is therefore assessed based on physic-chemical properties and on available toxicity studies.

 

Absorption

Oral:

Based on the very low water solubility and the low solubility in n-octanol (i.e. fat), bioavailability of the test substance is generally not expected. This is supported by the available toxicity studies. In an acute oral toxicity study female rats were given a single oral dose (gavage) of the test article at a concentration of 5000 mg/kg bw (RCC, 2005). No mortality occurred during the observation period and no macroscopic pathologic abnormalities were noted in the animals examined at the end of the observation period. In a 28-day gavage study in rats with daily doses of 0, 100, 300, and 1000 mg/kg body weight, no toxicologically relevant clinical, clinico-chemical, gross- and histopathological effects were observed which were clearly attributable to the test substance (Notox, 2006). Black contents of the gastro-intestinal tract observed in the high dose group (1000 mg/kg) were considered to represent the test substance. Black feces observed at 1000 mg/kg bw/day from week 3 of treatment onwards were considered to be due to staining properties of the test substance. Based on the results of this study, the NOAEL was established at 1000 mg/kg. In a reproduction/developmental toxicity screening study according to OECD guideline 421, the test substance was administered orally by gavage to groups of 10 male and 10 female Wistar rats (F0 animals) at dose levels of 100, 300 and 1000 mg/kg. The duration of treatment covered premating period of 2 weeks and a mating period (max. of 2 weeks) in both sexes, approximately 1 week post-mating in males, and the entire gestation period as well as 4 days of lactation in females. No signs of general systemic toxicity were observed in male or female parental animals of all test groups during the entire study period. All animals of test group 2 (300 mg/kg) and 3 (1000 mg/kg) showed black discolored feces. This finding was substance-related due to the black color of the dye stuff. Black discoloration of the gastro-intestinal tract of animals in test group 2 and 3 was observed at necropsy. No treatment-related changes were noted in any of the reproductive parameters investigated in this study (i.e. mating, fertility and conception indices). Thus, the NOAEL for reproductive performance and fertility as well as for general, systemic toxicity was 1000 mg/kg bw/day. The lack of systemic toxicity in these studies suggests poor bioavailability upon oral ingestion. As a result an accumulation of the test article in the body is not expected.

 

Dermal:

Dermal absorption is equally unlikely based on the test compound’s very low solubility properties in both water and fat. In addition, substances with a molecular weight of greater than 500 may be too large for dermal uptake. In a dermal toxicity study performed with a structure analogue no signs of toxicity were observed with the limit dose of 2500 mg/kg, indicating a low systemic availability after dermal exposure. In conclusion, based on the low water solubility together with the results of acute dermal toxicity studies, dermal absorption of the test article is not expected.

 

Inhalation: 

No indications for absorption after inhalation are given from the available toxicity data and the physic-chemical properties of the test article. In an acute inhalation toxicity study, the test article was applied as dust for 4 hours at a measured concentration of 5.2 mg/I (Limit test) to 5 Wistar rats /sex (BASF, 2005). No mortality was observed during the observation period. Clinical signs of toxicity included visually accelerated respiration, pulmonary respiration sounds, squatting posture, piloerection and smeared fur. No pathological abnormalities of the organs were observed in all animals at termination of the study. The results of this study do not indicate systemic availability of the test article. Cascade impactor measurements performed during the inhalation study resulted in particle size distributions with mass median aerodynamic diameters (MMADs) of 3.0 and 3.1 µm, which are well within the respirable range. An additional particle size distribution analysis showed that 100% of the analyzed material was smaller than 26 µm and 66% of the substance was found in particles smaller than 10 µm. These data demonstrate that the test substance can be inspired and may reach the alveolar region upon dust inhalation. However, since the test article is neither soluble in water nor soluble in fat, absorption and systemic availability after inhalation is not expected. This is additionally confirmed by experimental studies for other category members including 5 and 90 d inhalation exposure where no treatment-related systemic effects could be observed. Particles deposited in the nasopharyngeal region will most likely be coughed or sneezed out and particles deposited in the trachea-bronchial region will be cleared by mucocilliary mechanisms and swallowed. Dust particles reaching the alveolar region will mainly be engulfed by alveolar macrophages and cleared via the ciliated airways or the lymphatic drainage. In conclusion, the test article can be inspired in the form of dust, however, as indicated by the acute inhalation toxicity study and based on the very low solubility, particles are expected to be not absorbed and not bioavailable.

 

Distribution and Accumulation 

Since the substances are water-insoluble molecules, they will not diffuse through aqueous channels and pores. Therefore, a distribution into different organs is not assumed. No bioaccumulation hazard is expected based on results of repeated dose toxicity data for different pigments of the category in rats and physicochemical properties.

A test on biosolubility (static) and on dissolution kinetics (dynamic) in phagolysosomal simulant fluids was performed with all pigments of the category, except Pigment Red 224 (CAS 128-69-8), to determine the persistence after uptake in cells, e.g., alveolar macrophages. All substances tested were insoluble in phagolysosomal simulant fluid at pH 4.5 in the static and dynamic dissolution assay.

 

Metabolism

Considering the chemical structure of the test article, Cytochrome P450 linked oxidations of the aromatic ring systems are possible steps in the metabolism. However, based on the low solubility property in both water and fat, the substance is most likely not absorbed and excreted unchanged. This is supported by the observation of colored feces in toxicity studies. Studies on genotoxicity (Ames assays, BASF, 2004, 2006 and in vitro cytogenetics, BASF, 2006) were negative, i.e. there is no indication of a reactivity of the test substance or its metabolites with biomacromolecules under the chosen test conditions.

The ability to induce biological oxidative damage in chemico was analyzed using the Ferric Reduction Ability of Serum (FRAS) assay and Electron Paramagnetic Resonance spectroscopy (EPR) for every category member except Pigment Red 224 (CAS 128-69-8). Most substances tested were classified as “passive” in both assays. Pigment Red 149 (CAS 4948-15-6) and 178 (CAS 3049-71-6) were classified in FRAS assay but as active in EPR assay.

Furthermore, none of these substances induced pro-inflammatory effects or cytotoxicity in rat alveolar macrophages according to the classification criteria of Wiemann et al. 2016.). Most substances tested were classified as “passive” in both assays. Pigment Red 149 (CAS 4948-15-6) and 178 (CAS 3049-71-6) were classified in FRAS assay but as active in EPR assay.

 

Excretion

Since the test article is not soluble in water and fat, excretion is expected to occur predominantly via the feces. This assumption is strengthened by the observation of dark colored feces in the toxicity studies. Overall, accumulation of test material within the body is not expected.