3-hydroxy-N-(o-tolyl)-4-[(2,4,5-trichlorophenyl)azo]naphthalene-2-carboxamide

Endpoint summary

Link to relevant study record(s)

Reference

Endpoint:

basic toxicokinetics

Type of information:

other: Expert statement

Adequacy of study:

other information

Study period:

2020

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Evaluation of available toxicologic data with regard to toxikokinetic behaviour

Justification for type of information:

REACH-regulations ask for an evaluation of available toxicologic data with regard to toxikokinetic behaviour in the absence of specific kinetic studies.

Objective of study:

other: Evaluation and Assessment of the Basic Toxicokinetic Properties of C.I. Pigment Red 112

Qualifier:

no guideline available

Principles of method if other than guideline:

Evaluation and Assessment of the Basic Toxicokinetic Properties of C.I. Pigment Red 112 based on available toxicologic and physical data

GLP compliance:

no

Type:

absorption

Results:

Based on the extremely low solubility bioavailability and, consequently, the internal dose delivered via all routes can be considered negligible.

Type:

distribution

Results:

As no absorption has been mesued nor is expected distribution is considered as not likely to occur

Type:

metabolism

Results:

As no absorption has been measued nor is expected metabolism is considered as not likely to occur

Type:

excretion

Results:

excretion, if any, is likely to occur via faeces

Details on absorption:

A prerequisite for a relevant absorption is that the substance can be dissolved in either aque-ous (e.g., gastrointestinal fluid, blood plasma, sweat) or lipophilic (e.g., lipoproteins, lipid membranes, triglycerides) media or in both. PR 112 can be considered insoluble because it has an extremely low solubility in water and n-octanol. Therefore, it is unlikely that PR 112 becomes systemically bioavailable after oral, dermal or inhalation exposure.
Based on the sub-acute oral toxicity study with C.I. Pigment Red112 absorption of toxico-logically significant amounts of C.I. Pigment Red 112 via the gastrointestinal tract is consid-ered unlikely, since it did not show any effects on inner organs and blood or urine.
The skin sensitisation studies with C.I. Pigment Red112 indicate no local dermal bioavaila-bility. Systemic availability also seems to be negligible after dermal exposure since no sys-temic signs of intoxication were seen after occlusive administration of up to 5000 mg/kg bw. C.I. Pigment Red 112 per kg body weight in rabbits in the acute dermal toxicity and irrita-tion studies.
Dermal absorption is, therefore, considered unlikely.
In the unlikely event of exposure to aerosolized pigment in respirable form, the substance is considered to behave like an inert dust. Therefore, the deposited pigment particles will mostly be cleared from the lung via the mucocilliary transport. As the pigment will not dis-solve in the lung surfactant, the only way the pigment can enter the body is via phagocyto-sis of pigment particles by lung macrophages followed by migration of the macrophages into the interstitium and into the draining lymph nodes. However, the internal dose deliv-ered via this mechanism can be considered negligible.

Details on distribution in tissues:

The Repeated Dose Toxicity Study with C.I. Pigment Red 112 did not indicate any relevant histopathological changes in any of the investigated organs. This may indicate that the pig-ment either does not affect special organs as targets, i.e., is non-toxic, or is not distributed within the body in significant amounts. As indicated above, the physico-chemical parameters of the pigment support the conclusion that the pigment is not absorbed into the body and thus does not become systemically available. There were also no other signs of deposition of the pigment in any organ including excretory organs, like the kidney, indicating that even exposure to high doses of the pigment does not lead to bioaccumulation in special compart-ments of the body.
Based on the available information on absorption distribution of the test material in the body in significant amounts is unlikely and specific hotspots of distribution cannot be identified.
Thus, it is concluded, that C.I. Pigment Red 112 is not systemically available at relevant con-centrations within the organism.
There were no signs of bioaccumulation of the test material. This view is supported by the physical-chemical properties (solubility in water).

Details on excretion:

Taking into account the physico-chemical properties and the molecular structure of the mate-rial and the absence of any indication of absorption and/or metabolism it is assumed that ex-cretion, if any, is likely to occur via faeces. This notion is confirmed by the discoloration of faeces observed in the subacute study as the only alteration.

Metabolites identified:

not measured

Details on metabolites:

This information is not available.

Bioaccessibility (or Bioavailability) testing results:

See chapter : Absorption

Conclusions:

Based on all available data, C.I. Pigment Red 112 does not exhibit conspicuous toxicokinetic behaviour in the sense of accumulative and/or delayed effects with regard to the individual parameters absorption, distribution, metabolism and excretion.
The results from studies with dermal exposure indicate that C.I. Pigment Red 112 has a no relevant dermal absorptive potential. C.I. Pigment Red 112 is most probably not absorbed from the gastrointestinal tract in significant amounts.
Indications of an intense metabolism or a bio-accumulative potential do not exist as no tox-icity occurred. Additionally, no systemic effects were observed in the subacute oral toxicity study, which points to no bio-accumulation potential and complete excretion of all possibly available C.I. Pigment Red 112 and/or metabolites.

Executive summary:

Based on an evaluation of all available physico-chemical and toxicologic data, C.I. Pigment Red 112 does not exhibit conspicuous toxicokinetic behaviour in the sense of bioavailability, bio-accumulation and/or delayed effects with regard to the individual parameters absorption, distribution, metabolism and excretion.

The results from studies with dermal exposure indicate that C.I. Pigment Red 112 has a no relevant dermal absorptive potential. C.I. Pigment Red 112 is most probably not absorbed from the gastrointestinal tract in significant amounts.

Indications of metabolism or a bio-accumulative potential do not exist as no toxicity occurred. Additionally, no systemic effects were observed in the subacute oral toxicity study, which points to no bio-accumulation potential and complete excretion of all possibly available C.I. Pigment Red 112 and/or metabolites.

Description of key information

The toxicokinetic profile of a substance comprises its absorption into the body, its distribution in the body, its metabolism in the body and its excretion from the body. Taking into account the physicochemical properties and the toxicological test results, qualitative estimates for these aspects may be deduced for Pigment Red 112.

 

Absorption: a prerequisite for a relevant absorption is that the substance can be dissolved in either aqueous (e.g., gastrointestinal fluid, blood plasma, sweat) or lipophilic (e.g., lipoproteins, lipid membranes, triglycerides) media or in both. Pigment Red 112 can be considered insoluble because it has an extremely low solubility in water and n-octanol. Therefore, it is unlikely that Pigment Red 112 becomes systemically bioavailable after oral, dermal or inhalation exposure.

The results of acute oral toxicity, acute dermal toxicity and repeated oral toxicity studies also give valuable indications with regard to absorption of the test substance.

Based on the acute oral toxicity and the 28-day oral toxicity studies, which did not reveal any systemic effects that would indicate that the pigment had entered the body, no indications of significant absorption via the gastrointestinal tract have to be assumed.

Pigment Red 112 does not have particular skin or eye irritating or skin sensitizing properties that would imply a dermal absorptive potential.

In the unlikely event of exposure to aerosolized pigment in respirable form, the substance is considered likely to behave like an inert dust. Therefore, the deposited pigment particles will mostly be cleared from the lung via the mucocilliary transport. As the pigment will not dissolve in the lung surfactant, the only way the pigment can enter the body is via phagocytosis of pigment particles by lung macrophages followed by migration of the macrophages into the interstitium and into the draining lymph nodes. However, the internal dose delivered via this mechanism can be considered negligible.

 

Distribution: the 28-day oral repeated dose toxicity study did not indicate any relevant histopathological changes in any of the investigated organs. This may indicate that either the pigment does not affect special organs as targets, i.e., is non-toxic, or is not distributed within the body in significant amounts. As indicted above, the physico-chemical parameters of the pigment support the conclusion that the pigment is not absorbed into the body and thus does not become systemically available. There were also no other signs of deposition of the pigment in any organ including excretory organs, like the kidney, indicating that even exposure to high doses of the pigment does not lead to bioaccumulation in special compartments of the body. 

 

Metabolism: Since the dissolution of the substance in cellular fluid or cellular membranes is a prerequisite for its metabolism, it is unlikely that the insoluble pigment becomes accessible for metabolizing systems in relevant amounts. The results of the mutagenicity tests provide useful indications for qualitative consideration of the metabolic fate of Pigment Red 112. In the mutagenicity tests, the pigment proved to be non-toxic and non-mutagenic in the absence as well as in the presence of an exogenous metabolizing system, indicating that the pigment is not converted into toxic or genotoxic metabolites. This conclusion is also supported by the lack of any morphological and histopathological changes of organs involved in xenobiotic metabolism, such as the liver, in the repeated dose toxicity study.

 

Excretion: the available data indicate that Pigment Red 112 is not absorbed into the body. In line with this conclusion, the 28-day oral repeated dose toxicity study did not indicate morphological or histopathological effects of the pigment on organs involved in excretion of chemicals from the body, such as the kidney. There was no indication that the substance was present in the urine. Moreover, from the repeated oral toxicity studies, it can be concluded that, after oral exposure, the pigment is excreted unchanged via the faeces.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential