Registration Dossier
Registration Dossier
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EC number: 203-438-2 | CAS number: 106-88-7
Toxicological Summary
Administrative data
Workers - Hazard via inhalation route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- no-threshold effect and/or no dose-response information available
- Value:
- 3 mg/m³
Acute/short term exposure
DNEL related information
Local effects
Long term exposure
- Hazard assessment conclusion:
- DMEL (Derived Minimum Effect Level)
- Value:
- 3 mg/m³
- Most sensitive endpoint:
- carcinogenicity
DNEL related information
- Overall assessment factor (AF):
- 500
- Dose descriptor:
- T25
Acute/short term exposure
DNEL related information
Workers - Hazard via dermal route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- no-threshold effect and/or no dose-response information available
Acute/short term exposure
- Hazard assessment conclusion:
- no-threshold effect and/or no dose-response information available
DNEL related information
Local effects
Long term exposure
- Hazard assessment conclusion:
- no-threshold effect and/or no dose-response information available
Acute/short term exposure
- Hazard assessment conclusion:
- no-threshold effect and/or no dose-response information available
Workers - Hazard for the eyes
Additional information - workers
The most critical effect is tumorigenicity. Butylene oxide has caused nasal and lung tumors in rats (2 years inhalation). This indicates that Butylene oxide is a potential carcinogen, at least at high concentrations at the port of entry. Inhalation appears to be the most important route of exposure and the resultes 2 years inhalation study (see below) provide a basis for a quantitative estimation of the risk of exposure. For dermal exposure such data are lacking. On the other hand, skin exposure does not appear to be a common route of exposure and the high vapour pressure and volatility of the material and its irritating properties indicate that dermal exposure will be minimal. Therefore, no DNELs/DMELs were derived for dermal exposure. Furthermore, no DNELs/DMELs are proposed for acute exposure for the material is a local carcinogen at the port of entry and with effects being concentration dependent and no data are available so far which would definitely support for acute exposures a clearly higher concentration than the chronic DMEL. The chronic DMEL is based on the local tumours obtained at the port of entry. It is further proposed that the DMEL derived for these local tumours provides also sufficient protection from any systemic effects.
The following tumor incidences were obtained in male rats:
| Dose | Nasal adenoma | Lung adenoma plus carcinoma |
| 0 ppm | 0 | 0 |
| 200 ppm | 0 | 8.9% |
| 400 ppm | 24.2% | 17.6% |
At 400 ppm there was a markedly decreased survival in male rats. In females, a low tumor response was seen only at 400 ppm. For the nasal tumors in males a T25 of 413 ppm is obtained. For lung tumors in males a T25 of 568 ppm (calculated from the top dose) or 562 ppm (calculated from the lower dose ) is obtained. A linear extrapolation from a T25 of 500 ppm as a point of departure would indicate a numerical risk of 1:2000 at 1 ppm. However, the real risk is assumed to be lower due to a likelyhood for non-linear elements in the dose response relation at lower doses (as has been shown for propylene oxide). 1 ppm (= 3 mg/m3) can therefore serve as a preliminary DMEL for butylene oxide.
General Population - Hazard via inhalation route
Systemic effects
Acute/short term exposure
DNEL related information
Local effects
Acute/short term exposure
DNEL related information
General Population - Hazard via dermal route
Systemic effects
Acute/short term exposure
DNEL related information
General Population - Hazard via oral route
Systemic effects
Acute/short term exposure
DNEL related information
General Population - Hazard for the eyes
Additional information - General Population
No DNEL/DMEL is proposed for the general population, since the material is not foreseen in consumer products.
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