Registration Dossier
Registration Dossier
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EC number: 202-874-0 | CAS number: 100-64-1
Endpoint summary
Administrative data
Link to relevant study record(s)
Description of key information
Cyclohexanone oxime (CHO) is almost completely absorbed via the oral route. The absorption after dermal exposure is in the range of 5%. Metabolism of the main metabolite hydroxylamine leads to the formation of nitric oxide and a nitrosylhemoglobin complex, the latter being the probable causative reactive intermediate for the observed haematotoxicity. Within 24 h most of the administered compound is eliminated.
Key value for chemical safety assessment
- Bioaccumulation potential:
- no bioaccumulation potential
- Absorption rate - oral (%):
- 100
- Absorption rate - dermal (%):
- 5
Additional information
After oral exposure of rats to CHO, 68 -87% of the administered dose was excreted in the urine, elimination in the feces accounted for 5-9% of the dose, 2% were expired as CO2 and very low levels of radioactivity (2-3%) were retained in the tissues 24 hours after exposure.
No information is available for inhalation exposure.
Within 24 h after dermal application, 3.9% of the administered dose was excreted in urine and 0.1% in feces, 4.5% remained at the application site and 23% had volatilised within 3-5 min after application. Therefore the systemic uptake after dermal exposure is in the range of 5% of the administered dose. The substance is cleaved to cyclohexanone and hydroxylamine. Cyclohexanone is further oxidised to cyclohexanol and cis- and trans-cyclohexane-1,2-diol, which are then conjugated by glucuronic acid. Metabolism of the main metabolite hydroxylamine: electron paramagnetic resonance analysis showed the in vivo formation of nitric oxide and a nitrosylhemoglobin complex (considered to be generated from hydroxylamine), the latter being the probable causative reactive intermediate for the observed haematotoxicity of cyclohexanone oxime. Nitric oxide is a more potent haematotoxin compared to cyclohexanone oxime.
The main metabolites in urine after oral exposure of rats were monoglucuronides of cis- and trans-cyclohexane-1,2-diol, and the glucuronide of cyclohexanol. It can be assumed that absorption after oral exposure is nearly complete.
Distribution and elimination after dermal application were not different from those observed after oral administration.
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