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EC number: 251-807-1
CAS number: 34041-09-3
A comprehensive data gap analysis was
conducted for the entire substance portfolio of the REACH Metal
Carboxylates Consortium (RMC), covering 10 metal carboxylates in total
back in 2013. This literature screening effort included:
During the literature search and data
gap analysis it became obvious that the overall database on
substance-specific human health hazard data for the metal carboxylates
is too scant to cover all REACH endpoints. Therefore, the remaining data
gaps had to be covered by either experimental testing or read-across
from similar substances.
Selected endpoints for the human
health hazard assessment are addressed by read-across, using a
combination of data on the organic acid counterion and the metal (or one
of its readily soluble salts). This way forward is acceptable, since
metal carboxylates dissociate to the organic anion and the metal cation
upon dissolution in aqueous media. No indications of complexation or
masking of the metal ion through the organic acid were apparent during
the water solubility tests (please refer to the water solubility data in
section of the IUCLID and chapter of the CSR). Once the individual
constituents of the metal carboxylate become bioavailable (i.e. in the
acidic environment in the gastric passage or after phagocytosis by
pulmonary macrophages), the “overall” toxicity of the dissociated metal
carboxylate can be described by the toxicity of the “individual”
constituents. Since synergistic effects are not expected for this group
of metal carboxylates, the human health hazard assessment consists of an
individual assessment of the metal cation and the organic anion.
The hazard information of the
individual constituents was obtained from existing REACH registration
dossiers via a license-to-use obtained by the lead registrant. These
registration dossiers were submitted to ECHA in 2010 as full
registration dossiers, and are thus considered to contain relevant and
reliable information for all human health endpoints. All lead-registrant
dossiers were checked for completeness and accepted by ECHA, i.e. a
registration number was assigned.
In order to check whether read-across
from 2-ethylhexanoic acid, molybdenum salt to sodium molybdate is
justified, a combined water solubility and UV spectral analysis was
The water solubility study with
2-ethylhexanoic acid, molybdenum salt was conducted in accordance with
OECD 105 and under GLP. The test was conducted in triplicate vessels
over 16 days and the solubility of the substance was determined by
measuring dissolved Mo by ICP-OES after 1, 2, 3, 14,15 and 16 days. A
constant concentration of dissolved Mo was achieved, at ca. 13 mg Mo/L.
Throughout the experiment, the pH of the solutions was in the range 3.8
- 4. In order to assess the species of the dissolved molybdenum, UV
spectra were taken during each day of sampling.
A read-across approach for inorganic
molybdenum substances and molybdenum metal was developed by the
Molybdenum Consortium, which reports as follows:“The species in
solutions of sodium molybdate at concentrations 1–10 mg/L and pH ca 7 is
the the molybdate ion, [MoO4]2−with a UV
absorption maximum (peak) at 207–208 nm (48000 cm-1).
As the pH is lowered the [MoO4]2−ion becomes
protonated giving [HMoO4]−and [H2MoO4]
species, the peaks in the UV spectra shifting to lower energies (longer
wavelengths). From our UV spectra we shall see that the predominant
(>90%) species from our compounds in solution or in contact with water
are the [MoO4]2−and [HMoO4]−ions.
The UV spectral analysis has enabled us to describe the speciation in
water solutions of soluble molybdates (sodium and ammonium molybdates)
and in supernatant solutions of suspensions of poorly soluble molybdenum
substances (calcium molybdate, molybdenum metal, ferromolybdenum,
molybdenum dioxide, molybdenum trioxide, roasted molybdenum concentrate
and molybdenum disulfide). The solutions and supernatant liquids contain
the molybdate ion and, in addition at lower pHs, protonated molybdate.
At biological concentrations and pH the only molybdenum species produced
from the molybdenum substances studied is the molybdate, [MoO4]2-, ion.
Read across from sodium molybdate is therefore justified.”(International
Molybdenum Association (2009) Speciation of molybdenum compounds in
water - Ultraviolet spectra and REACH read across - Report for the
International Molybdenum Association REACH Molybdenum Consortium,
The UV spectral analysis of the
samples taken during water solubility testing of 2-ethylhexanoic acid,
molybdenum salt show that [MoO4]2−and [HMoO4]−ions
are formed upon dissolution of 2-ethylhexanoic acid, molybdenum salt in
aqueous media. The presence of the molybdate and the protonated
molybdate anion represent the dominant species at the pH of 3.8-4 being
observed in the water solubility test. Under physiological conditions
the molybdate anion will be the relevant molybdenum species liberated
form 2-ethylhexanoic acid, molybdenum salt.
2-ethylhexanoic acid, molybdenum salt
is the molybdenum metal salt of 2-ethylhexanoic acid, which readily
dissociates to the corresponding molybdate anion and 2-ethylhexanoic
acid anions. The molybdate anion and the 2-ethylhexanoic acid anion are
considered to represent the overall toxicity of the 2-ethylhexanoic
acid, molybdenum salt in a manner proportionate to the free acid and the
metal (represented by the readily soluble disodium molybdate, as
Although the term „constituent“ within
the REACH context is defined as substance (also being part of a
mixture), the term constituent within this hazard assessment is meant to
describe either part of the metal carboxylate salt, i.e. anion or
No skin sensitisation study with
2-ethylhexanoic acid, molybdenum salt is available, thus the skin
sensitisation potential will be addressed with existing data on the
dissociation products as detailed in the table below. Further details on
the skin sensitisation potential of the individual constituents within
the framework of regulation (EC) 1907/2006 are given below.
Table: Summary of
skin sensitisation data of 2-ethylhexanoic acid, molybdenum salt and the
2-ethylhexanoic acid, molybdenum salt(CAS# 34041-09-3)
2-ethylhexanoic acid, molybdenum salt
is not expected to show signs of dermal sensitisation, since the two
constituents molybdate and 2-ethylhexanoic acid have not shown any skin
sensitisation potential in experimental testing. Thus, 2-ethylhexanoic
acid, molybdenum salt is not to be classified according to regulation
(EC) 1272/2008 as skin sensitising. Further testing is not required. For
further information on the toxicity of the individual constituents,
please refer to the relevant sections in the IUCLID and CSR.
Migrated from Short description of key information:
2-ethylhexanoic acid, molybdenum salt is not expected to show signs
of dermal sensitisation.
Justification for selection of skin sensitisation endpoint:
According to the CLP regulation the
hazard identification and subsequently a proposal for classification as
“Respiratory sensitiser” will normally be based on human experience. In
this context, hypersensitivity is normally seen as asthma, but other
hypersensitivity reactions such as rhinitis/conjunctivitis and
alveolitis are also considered. The condition will have the clinical
character of an allergic reaction. However, immunological mechanisms do
not have to be demonstrated.
The evidence could be:
a) clinical history and data
from appropriate lung function tests related to exposure to the
substance, confirmed by other supportive evidence which may include:
i. in vivo immunological
test (e.g. skin prick test);
ii. in vitro immunological
test (e.g. serological analysis);
iii. studies that indicate
other specific hypersensitivity reactions where immunological mechanisms
of action have not been proven, e.g. repeated low-level irritation,
pharmacologically mediated effects;
iv. a chemical structure
related to substances known to cause respiratory hypersensitivity;
b) data from one or more
positive bronchial challenge tests with the substance conducted
according to accepted guidelines for the determination of a specific
Migrated from Short description of key information:
2-ethylhexanoic acid, molybdenum salt is not expected to show a
respiratory sensitising potential.
acid, molybdenum salt is not expected to show signs of dermal
sensitisation, since the two constituents molybdate and 2-ethylhexanoic
acid have not shown any skin sensitisation potential in experimental
testing. Thus, 2-ethylhexanoic acid, molybdenum salt is not to be
classified according to regulation (EC) 1272/2008 as skin sensitising.
In long-time industrial experience in
the production and handling of substance 2-ethylhexanoic
acid, molybdenum salt, no cases
of respiratory hypersensitivity have been observed.Classification as
respiratory sensitiser is not applicable.
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.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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