Registration Dossier
Registration Dossier
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EC number: 205-502-5 | CAS number: 141-79-7
Toxicological Summary
Administrative data
Workers - Hazard via inhalation route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 20.4 mg/m³
- Most sensitive endpoint:
- repeated dose toxicity
- Route of original study:
- By inhalation
DNEL related information
- DNEL derivation method:
- other: German MAK commission
Acute/short term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 40.8 mg/m³
DNEL related information
- DNEL derivation method:
- other: German MAK commission
- DNEL extrapolated from long term DNEL
Local effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 20.4 mg/m³
- Most sensitive endpoint:
- irritation (respiratory tract)
DNEL related information
- DNEL derivation method:
- other: German MAK commission
Acute/short term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 40.8 mg/m³
DNEL related information
- DNEL derivation method:
- other: German MAK commission
- DNEL extrapolated from long term DNEL
Workers - Hazard via dermal route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
- Explanation for the modification of the dose descriptor starting point:
No hazard identified as no dermal study is available.
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
Local effects
Long term exposure
- Hazard assessment conclusion:
- no hazard identified
Acute/short term exposure
- Hazard assessment conclusion:
- medium hazard (no threshold derived)
Workers - Hazard for the eyes
Local effects
- Hazard assessment conclusion:
- medium hazard (no threshold derived)
Additional information - workers
Mesityl oxide toxicity data were reviewed by the German MAK Commission (MAK 2007) and by the US Occupational Safety and Health Administration (OSHA 1988). ACGIH has set an 8h TLV (threshold limit value) of 15 ppm (60 mg/m³) as TWA for a normal 8-hour work day but provide no information is provided on how this value has been established.
The MAK-Commission, providing detailed documentation of their assessment (MAK 2007), took into account the OECD 422 study by Bernard & Faber (1992) as well as the human inhalation study from Silverman (1946). They established a maximum workplace concentration of 5 ppm (20.4 mg/m³) which shall be used as DNEL. This approach is in accordance with the current ECHA Guidance on information requirements and chemical safety assessment Appendix R. 8-13 (ECHA 2012).
ECHA (2012) further recommends that “the approach used for setting the national OEL should be compared to the approach for deriving DNELs as described in the in the main body of this chapter [Guidance on information requirements and chemical safety assessment Chapter R.8], and any differences in approach should be taken into account.”
Under consideration of the current guidance chapter R.8 a DNEL derivation for mesityl oxide is performed as follows:
DNEL derivation originates from dose descriptor of 25 ppm (102 mg/m³).
The studies of Bernard & Faber (1992) and Silverman (1946) find almost equal results at a similar concentration range despite very different study duration. It can therefore be assumed that the observed effects are dependent on test atmosphere concentration and not on study duration, eliminating the necessity for adaption of exposure time.
As the effects are due to local irritation and have been observed in humans as well as in rats, the assessment factor for inter-species variation can be set to 1.
To account for the intra-individual sensitivity of workers (who are the only population exposed) an assessment factor of 5 was applied.
No additional assessment factor for dose-response was applied as the majority of the exposed subjects deemed a 25 ppm concentration acceptable for an 8 hour work shift and because the observed effect in the 25 ppm dose group was of only slight nature.
Deriving from a starting point of 25 ppm and using a total assessment factor of 5, the DNEL for mesityl oxide (long-term, worker, inhalation) is 20.4 mg/m³ (5 ppm).
In their assessment the German Commission (MAK 2007) came to the same value thus being in accordance with the current guidance document.
General Population - Hazard via inhalation route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 2.4 mg/m³
DNEL related information
- DNEL derivation method:
- other: the DNEL is derived from the MAK value after adaptation to the exposure of the general population
Acute/short term exposure
- Hazard assessment conclusion:
- hazard unknown but no further hazard information necessary as no exposure expected
DNEL related information
Local effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 2.4 mg/m³
DNEL related information
- DNEL derivation method:
- other: the DNEL is derived from the MAK value after adaptation to the exposure of the general population
Acute/short term exposure
- Hazard assessment conclusion:
- hazard unknown but no further hazard information necessary as no exposure expected
DNEL related information
General Population - Hazard via dermal route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- hazard unknown but no further hazard information necessary as no exposure expected
Acute/short term exposure
- Hazard assessment conclusion:
- hazard unknown but no further hazard information necessary as no exposure expected
DNEL related information
Local effects
Long term exposure
- Hazard assessment conclusion:
- hazard unknown but no further hazard information necessary as no exposure expected
Acute/short term exposure
- Hazard assessment conclusion:
- hazard unknown but no further hazard information necessary as no exposure expected
General Population - Hazard via oral route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- hazard unknown but no further hazard information necessary as no exposure expected
Acute/short term exposure
- Hazard assessment conclusion:
- hazard unknown but no further hazard information necessary as no exposure expected
DNEL related information
General Population - Hazard for the eyes
Local effects
- Hazard assessment conclusion:
- medium hazard (no threshold derived)
Additional information - General Population
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