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EC number: 215-686-9 | CAS number: 1344-08-7
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Toxicological Summary
- Administrative data
- Workers - Hazard via inhalation route
- Workers - Hazard via dermal route
- Workers - Hazard for the eyes
- Additional information - workers
- General Population - Hazard via inhalation route
- General Population - Hazard via dermal route
- General Population - Hazard via oral route
- General Population - Hazard for the eyes
- Additional information - General Population
Administrative data
Workers - Hazard via inhalation route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 2.89 mg/m³
- Most sensitive endpoint:
- repeated dose toxicity
- Route of original study:
- By inhalation
DNEL related information
- DNEL derivation method:
- ECHA REACH Guidance
- Overall assessment factor (AF):
- 25
- Modified dose descriptor starting point:
- NOAEC
- Value:
- 56 mg/m³
- Explanation for the modification of the dose descriptor starting point:
Not applicable
- AF for dose response relationship:
- 1
- Justification:
- adequate data available
- AF for differences in duration of exposure:
- 2
- Justification:
- subchronic to chronic
- AF for interspecies differences (allometric scaling):
- 1
- AF for other interspecies differences:
- 2.5
- AF for intraspecies differences:
- 5
- AF for the quality of the whole database:
- 1
- AF for remaining uncertainties:
- 1
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:
- 0.84 mg/m³
- Most sensitive endpoint:
- repeated dose toxicity
DNEL related information
- DNEL derivation method:
- ECHA REACH Guidance
- Overall assessment factor (AF):
- 10
- Dose descriptor:
- NOAEC
- AF for dose response relationship:
- 1
- AF for differences in duration of exposure:
- 1
- AF for interspecies differences (allometric scaling):
- 5
- AF for other interspecies differences:
- 2
- AF for intraspecies differences:
- 1
- AF for the quality of the whole database:
- 1
- AF for remaining uncertainties:
- 1
Acute/short term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 1.68 mg/m³
- Most sensitive endpoint:
- repeated dose toxicity
DNEL related information
- DNEL derivation method:
- other: SCOEL approach
- Overall assessment factor (AF):
- 2
- DNEL extrapolated from long term DNEL
Workers - Hazard via dermal route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- medium hazard (no threshold derived)
Acute/short term exposure
- Hazard assessment conclusion:
- medium hazard (no threshold derived)
DNEL related information
Local effects
Long term exposure
- Hazard assessment conclusion:
- medium hazard (no threshold derived)
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
Justification for read across
The derivation of the DNELs is based on read across to other sulfur based substances. Toxicological data specifically for Sodium sulfide (Na2(Sx)) from animal studies are not available. Therefore, because of the lack of appropriate experimental data, read-across from studies with H2S is proposed based on the following reasoning:
Unrestricted read-across between the substances Sodium sulfide (Na2(Sx)), sodium hydrogensulfide and dihydrogen sulfide is considered feasible, in view of the potential systemic toxicity being driven by the sulfide ion as the only relevant species released from any of the sulfide substances under physiological conditions. In this context, it is further considered to be very unlikely that the sodium ions add any toxicological concern.
Aqueous Na2Sx solutions are only stable at pH > 10. At lower pH values they are decomposed to H2S and S ([1, 2, 3, 4, 5])
The soluble compound Sodium sulfide (Na2(Sx)) can safely be assumed to be present dissociated in water and relevant biological media([6]). From Sodium sulfide (Na2(Sx)), hydrogen sulfide (H2S) may be formed according to the following equilibria:
Na2Sx+ H2O → NaOH + NaHSx(2 Na++ HSx-+ OH-)
NaHSx +H2O → (x-1)S + NaOH + H2S (Na++ OH-+ H2S)
The toxic effects resulting from the sodium ion is negligible. Hydrogen sulfide dissociates in aqueous solution to form two dissociation states involving the hydrogen sulfide anion and the sulfide anion:
H2S ↔ H++ HS-↔ 2 H++ S2-
The pKa values for the first and second dissociation steps of H2S are 7.04 and 11.96, respectively. Therefore, at physiological pH values, hydrogen sulfide in the non-dissociated form (H2S) and the hydrogen sulfide anion (HS-) will be present in almost equimolar proportion, whereas only very small amounts of the sulfide anion (S2-) will be present. In conclusion, under physiological conditions, inorganic sulfides or hydrogen sulfides as well as H2S will dissociate to the respective species relevant to the pH of the physiological medium, irrespective the nature of the “sulfide”, which is why read-across between these substances and H2S is considered to be feasible without any restrictions.
[1] E. Dachselt, „Thioplaste“, Deutscher Verlag für Grundstoffindustrie, Leipzig 1971, pp. 35
[2] M.B. Berenbaum, “Polysulfide Polymers” in N. G. Gaylord, ”Polyethers”, Interscience Publishers, 1962, 49-51
[3] D. Peschanski; G. Valensi, J. chim.Phys. 46(1949), pp. 602
[4] M. Menzel, Expert statement “Investigation of the reaction of sodium polysulfide solution with diluted hydrochlorioc acid”, AkzoNobel, Greiz (March 2010) (attached)
[5] Hagg-graph (attached)
[6] Beauchamp et al. (1984): A critical review of the literature on hydrogen sulfide toxicity; CRC Crit. Rev. Toxicol. 13, 25-97.
The long term exposure systemic inhalation DNELis based on the NOAEC derived from the 90-day inhalation study by Dorman et al. (2004) in Fischer 344 rats, Sprague-Dawley rats and B6C3F1 mice. In this study some minor effects were observed on food consumption and body weight. Otherwise no significant or relevant effect were seen in this study. Therefore, the concentration of 80 ppm H2S can be considered as NOAEC for systemic effects.
Modification of the dose descriptor to the correct starting point
Conversion of ppm to mg/m3
mg/m3 = (ppm) × (molecular weight of H2S)/(24.45)
mg/m3 = 80 ppm x (34.08/24.45)
mg/m3 = 111.15
NOAEC rat to NOAECCor.
NOAECCor.= NOAEC rat x (6h/d / 8h/d) x (6.7 m3 / 10 m3)
NOAECCor. = 111.15 x (6h/d / 8h/d) x (6.7 m3 / 10 m3)
NOAECCor. = 56 mg/m3
DNEL for H2S
Assessment factor |
Accounting for |
Default values applied |
Inter-species variability |
-correction for differences in metabolic rate (AS)* |
1 |
-remaining differences (e.g. toxicokinetics/-dynamics) |
2.5 |
|
Intra-species variability |
-workers |
5 |
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 |
DNEL (mg/m3) = NOAECCor./overall AF = 56/25 = 2.24 mg/m3
* not applicable, included the NOAEC rat to NOAECCor, see R8 page 25.
DNEL for Na2Sx (x = 1.5-5)
H2S = 34 g/mol = 2.24 mg/m3
S2- = 32 g/mol = 2.10 mg/m3
Na2Sx(x = 1,5-5) = 94.1- 206.35 g/mol
1.5*32 – 5*32 g/mol = 48-160gS2- : 94.1-206.35 g/mol = 0.5100-0.7753 = 51-77.5 % (mass percentage S2- in Na2Sx (x1.5-5)
51-77.5 % = 2.10 mg/m3 > 100 % (Na2Sx (x = 1.5-5))= 4.39 -2.89 mg/m3
Accordingly, a concentration of2.89mg/m3was derived as thelong-term DNEL for systemic effects in
workers exposed via inhalation to Na2Sx (x = 1.5-5)(representing Na2S (x=5) – as a worst-case).
The long term exposure local inhalation DNELThe long term exposure local inhalation DNEL is based on a NOAEC derived from the 90-day inhalation study by Dorman et al. (2004) in Fischer 344 rats, Sprague-Dawley rats and B6C3F1 mice. An increased incidence of olfactory neuronal loss (ONL) was observed at 30 and 80 ppm of hydrogen sulfide. Therefore a NOAEC of 10 ppm H2S for local effects was derived.
Modification of the dose descriptor to the correct starting point
Conversion of ppm to mg/m3
mg/m3 = (ppm) × (molecular weight of H2S)/(24.45)
mg/m3 = 10 ppm x (34.08/24.45)
mg/m3 = 13.94
NOAEC rat to NOAECCor.
NOAECCor.= NOAEC rat x (6h/d / 8h/d) x (6.7 m3 / 10 m3)
NOAECCor. = 13.94 x (6h/d / 8h/d) x (6.7 m3 / 10 m3)
NOAECCor. = 7 mg/m3
DNEL for H2S
Assessment factor |
Accounting for |
Default values applied |
Inter-species variability |
-correction for differences in metabolic rate (AS) |
1* |
-remaining differences (e.g. toxicokinetics/-dynamics) |
1* |
|
Intra-species variability |
-workers |
5 |
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 |
|
10 |
DNEL (mg/m3) = NOAECCor./overall AF = 7/10 = 0.7 mg/m3
* not applicable, see R8 page 25.
DNEL for Na2Sx (x = 1.5-5)
H2S = 34 g/mol = 0.7 mg/m3
S2- = 32g/mol = 0.65 mg/m3
Na2Sx(x = 1,5-5) = 94.1- 206.35 g/mol
1.5*32 – 5*32 g/mol = 48-160gS2- : 94.1-206.35 g/mol = 0.5100-0.7753 = 51-77.5 % (mass percentage S2- in Na2Sx (x1.5-5)
51-77.5 % = 0.65 mg/m3 > 100 % (Na2Sx (x = 1.5-5))= 1.27-0.84 mg/m3
Accordingly, a concentration of0.84mg/m3was derived as thelong-term DNEL for local effects in
workers exposed via inhalation to Na2Sx (x = 1.5-5)(representing Na2S (x=5) – as a worst-case).
The long term exposure local inhalation DNEL based on NaOHbecause the second potential mechanism of local toxicity in the respiratory tract can be attributed to the presences of OH- ions formed after the rapid decomposition of sodium sulfide (Na2(Sx) x=1,5-5), a DNEL was also derived for local effects of NaOH, for purposes of comparison:
For NaOH aDNEL of 1 mg/m3was derived in the REACH registration dossier for long-term local effects in workers following inhalation exposure.
Calculation DNEL forsodium sulfide(Na2(Sx) x=1,5-5)
(i) NaOH = 40 g/mol = 1.00 mg/m3
(ii) OH- = 17 g/mol = 0.425 mg/m3
The calculation is based on the following equations for the solution of sodium sulfide (Na2(Sx) x=1,5-5)
in water:
Na2Sx + H2O → NaOH + NaHSx (2Na+ + OH- + HSx-)
NaHSx + H2O → (x-1)S + NaOH + H2S (Na+ + OH- + H2S)
Thus, it is concluded that 1 mol sodium sulfide (Na2(Sx) x=1,5-5) in solution will result in 2 mol OH- (worst-case assuming full conversion).
Converted to the unit “mol” the DNEL of 0.425 mg OH- equals:
(iii) 17 g OH- = 1 mol OH- → 0.425 mg OH- = 0.025 mmol OH
The value of 0.025 mmol OH-, as the no effect level, is the product of 0.025 mmol/2 = 0.0125 mmol
sodium sulfide (Na2(Sx) x=1,5-5), dissolved in water. This is reconverted to the unit of “milligrams” as follows:
(iv) 94.1- 206.35 g sodium sulfide (Na2(Sx) x=1,5-5) = 1mol → 0.0125 mmol sodium sulfide (Na2(Sx) x=1,5-5) = 1.17-2,58 mg sodium sulfide (Na2(Sx) x=1,5-5)
Accordingly, a concentration of1.17-1.57 mg/m3was derived as along-term DNEL for local effects of NaOH in workers exposed via inhalation tosodium sulfide (Na2(Sx) x=1,5-5), based on the pH effect.
Comparing the different DNEL values for g sodium sulfide (Na2(Sx) x=1,5-5) and sodium hydroxide shows that they are in the same range and thus both mechanisms are addressed adequately by applying this approach for DNEL derivation. The lower value is selected as DNEL for local effects. Therefore,0.84 mg/m3is selectedas the long-term DNEL for local effects in workers exposed via inhalation to Na2Sx (x = 1.5-5).
Acute DNEL, local effects by inhalation:sodium sulfide (Na2(Sx) x=1,5-5) is classified as corrosive. Therefore, and in accordance to the ECHA guidance on information requirements and chemical safety assessment – chapter R.8: Characterisation of dose [concentration]-response for human health, May 2008 a DNEL for acute inhalation toxicity should be derived based on the toxicological profile of the substance concerned. This should be derived for a specified fraction of the daily exposure duration (usually 15 minutes for workers).
SCOEL recommendations exist for H2SO4, HCL, H3PO4 and F2, all of which are classified either as R34 or R35 and without doubt have a higher corrosive potential compared to sodium sulfide (Na2(Sx) x=1,5-5) . The above mentioned documents all mention an 8-hour TWA as well as an STEL for 15 minutes. All STEL values are merely derived by applying a factor of 2 to the 8 hour TWA. Based on the toxicological observations as summarised in these SCOEL documents, a factor of 2 for the extrapolation from the long-term DNEL to an acute DNEL should be appropriate. Hence the DNEL for long-term inhalation, local effects for sodium sulfide (Na2(Sx) x=1,5-5) will be used for deriving a DNEL for acute inhalation effect, worker for sodium sulfide (Na2(Sx) x=1,5-5) by multiplying the long-term DNEL with a factor of 2.The long-term DNEL for local effects in workers exposed by inhalation for sodium sulfide (Na2(Sx) x=1,5-5) is 0.84 mg/m3, corresponding to a acute DNEL for local effects in workers for workers of 1.68 mg/m3..
General Population - Hazard via inhalation 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
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:
- hazard unknown but no further hazard information necessary as no exposure expected
Additional information - General Population
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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