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Description of key information

Default absorprtion factors for oral, inhalation and dermal absorption.

Key value for chemical safety assessment

Additional information

No data are available that describe the toxicokinetics of 1-vinyl-imidazole, therefore relevant substance properties and data from toxicity studies indicating systemic bioavailability were taken together to assess the general toxicokinetics of the substance.  

Physical-chemical properties

1-vinyl-imidazole is a liquid with a molecular weight of 94.1145 g/mol. The log Pow value is 0.54 and is completely miscible in water.

 

Data from acute and repeated dose toxicity studies

Oral toxicity

In an acute oral toxicity study in rats, exposure to gavage at 0.5, 1.0 and 2.0 cm3/kg (equivalent to ca. 520, 1040 and 2080 mg/kg bw) 1-vinyl-imidazole resulted in mortality in rats. The oral LD50 was 1040 mg/kg bw. (1953; RL2). In a GLP compliant combined repeated dose toxicity study with reproduction/developmental toxicity screening test, 1-vinyl-imidazole at dose levels of 5, 15, or 35 mg/kg/day was given to rats by oral gavage (2013, RL1). In both male and female mid- and high-dose parental animals clinical symptoms and decreased body weights/body weight gain were observed. The test substance did not influence fertility. Decreased pup weights and dissecting aneurysms in the great vessels of the heart were noted at 15 mg/kg bw/d and above. 

 

Inhalation toxicity

An inhalation risk test demonstrated that the inhalation of a saturated vapour-air-mixture represents an unlikely acute hazard (1953; RL2).

 

Dermal toxicity

In an acute dermal toxicity study in rabbits, exposure to 2000 mg/kg bw 1-vinyl-imidazole did not result in mortality, Clinical signs included: impaired general state, dyspnoea, lacrimation and chromodacryorrhea in both males and females. Further, red clammy snouts and eyelids and were observed from study day 1 until including study day 2 after administration in males and smeared fur was observed on females from study day 1 until including study day 2 after administration. Skin effects at the application site of 3 females comprised very slight and well defined erythema, scaling and superficial scabbing and were observed from study day 3 until including study day 10 after administration. No macroscopic pathologic abnormalities were noted in the animals examined at termination of the study (2005; RL1).

 

Absorption figures used for the DNEL derivation

The results of the acute oral and the repeated dose oral toxicity study with reproduction/developmental toxicity screening test indicate absorption of the test substance by the oral route. Secondly, 1-vinyl-imidazole has a log Pow value between -1 and 4, which favors absorption by passive diffusion. Furthermore, the molecular weight below 200 makes the test substance also favorable for adsorption. Overall, this suggests that 1-vinyl-imidazole may be readily absorbed by the gastrointestinal and respiratory tract.

Since it is likely that 1-vinyl-imidazole will be orally absorbed and in the absence of substance-specific inhalation or dermal absorption data, the default absorption values from the REACH guidance (Chapter 8, R.8.4.2) are used for DNEL derivation, namely: 100% for inhalation and 50% for oral and dermal absorption.