Registration Dossier
Registration Dossier
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EC number: 241-234-5 | CAS number: 17194-00-2
Toxicological Summary
Administrative data
Workers - Hazard via inhalation route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- no hazard identified
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
Local effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 0.62 mg/m³
Acute/short term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 1.24 mg/m³
DNEL related information
Workers - Hazard via dermal route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- no hazard identified
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
Local effects
Long term exposure
- Hazard assessment conclusion:
- high hazard (no threshold derived)
Acute/short term exposure
- Hazard assessment conclusion:
- high hazard (no threshold derived)
Workers - Hazard for the eyes
Local effects
- Hazard assessment conclusion:
- high hazard (no threshold derived)
Additional information - workers
General Population - Hazard via inhalation route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- no hazard identified
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
Local effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 0.12 mg/m³
DNEL related information
- Overall assessment factor (AF):
- 5
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
General Population - Hazard via dermal route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- no hazard identified
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:
- no hazard identified
General Population - Hazard via oral route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 3.4 mg/kg bw/day
- Most sensitive endpoint:
- repeated dose toxicity
DNEL related information
- Overall assessment factor (AF):
- 25
- Modified dose descriptor starting point:
- NOAEL
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
General Population - Hazard for the eyes
Local effects
- Hazard assessment conclusion:
- low hazard (no threshold derived)
Additional information - General Population
Discussion
Long-term DNEL for general population – oral, systemic effects for Ba(OH)2
Selection of the relevant dose-descriptor
The available data in laboratory animals suggest that the toxicity of ingested barium is similar across species. The lowest NOAEL for nephrotoxic effects in rats or mice was identified from the 13-week drinking water study by Dietz et al. (1992) as the NOAEL of 61 mg Ba/kg bw/d in male rats. Therefore, the oral NOAEL of 61 mg Ba/kg bw/d for subchronic toxicity in male rats is used as a dose descriptor for calculation of DNEL values.
Modification of the dose descriptor to the correct starting point for Ba(OH)2
In principle, modification is not necessary because there are no differences in human (oral) and experimental animal (oral) exposure conditions. However, the oral NOAEL of 61 mg Ba/kg bw/d needs to be converted into the respective doses for the different barium compounds on the basis of the molecular weights.
Barium substances | Molecular weight [g/mol] | Oral NOAEL |
Ba(OH)2 monohydrate | 189.3 | 84.2 |
Application of assessment factors
The following aspects are taken into account: for inter-species variability (extrapolation from rodent data to humans) only a factor for remaining differences is considered; ECETOC recommendations for intra-species variability (variability in chemical sensitivity within humans) are introduced; differences in duration of exposure are considered; no further factors are applied for issues related to dose-response, and quality of the whole database.
Assessment factor | Accounting for | Default values applied |
Inter-species variability | - correction for differences in metabolic rate (AS)* | 11) |
| - remaining differences (e.g. toxicokinetics/-dynamics) | 2.5 |
Intra-species variability | - general population | 52) |
Exposure duration | - subchronic to chronic | 2 |
Dose response | - adequate data available | 1 |
Quality of whole data base | - no need for a further assessment factor | 1 |
Overall |
| 25 |
1) factor for allometric scaling; any metabolism of inorganic barium substances can be excluded. Therefore, it is considered justified to deviate from default assessment factors accounting for a correction for differences in metabolic rate by assigning a factor of “1” instead of using the default factor of 4.
2) This assessment factor is introduced since it is expected that a greater variability in response from the most to least sensitive human would be seen, relative to an experimental animal population. ECETOC (2003) has reviewed scientific literature on the distribution of human data for various toxicokinetic and toxicodynamic parameters to assess intraspecies variability within the human population, specifically by Renwick and Lazarus (1998) and Hattis et al. (1999). Considering that the data analysed by these authors includes both sexes, a variety of disease states and ages, the use of the 95th percentile of the distribution of the variability for these datasets is considered sufficiently conservative to account for intraspecies variability for the general population. Based on this, a default assessment factor of 5 is recommended by ECETOC (2003).
Calculation of DNEL general population – oral, systemic effects for Ba(OH)2
The DNEL is derived by applying the overall assessment factor to the corrected NOAEL as dose descriptor in the following way:
NOAEL
DNEL (mg/kg bw/d) = ------------------------ --> mg/kg bw/d
Overall AF (25)
The following corrected long-term DNELs for systemic effects in humans exposed orally are calculated for the different barium substances based on the above formula using NOAEL of 61 mg Ba/kg bw/d.
Barium substances | oral NOAEL | Overall AF | DNELcorr_general population |
Ba(OH)2 monohydrate | 84.2 | 25 | 3.4 |
Long-term DNEL for general population – inhalation, local effects for Ba(OH)2
No DNEL was derived for local effects in workers exposed by inhalation with Ba(OH)2 at the work place, because for soluble barium compounds an official indicative occupational exposure limit value is published in the Official Journal of the European Union (Commission Directive 2006/15/EC, 7 February 2006).
IOEL: 0.5 mg Ba/m3, corresponding to 0.62 mg/m3 Ba(OH)2
To account for a potential exposure of the general population, the application of an additional AF of 5 (according to ECETOC) for intra-species variability of the general population is considered which results in the following DNEL:
DNEL: 0.1 mg Ba/m3, corresponding to 0.12 mg/m3 Ba(OH)2
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