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EC number: 233-138-7
CAS number: 10043-27-3
bibliographical review based on ca. 60 publications
(1964-2016), containing information on the accumulation of lanthanides (including
terbium, the rare earth element under consideration in this
yttrium and/or zirconium in aquatic organisms, was written to cover
this endpoint. Because of the similarity between findings for the
elements under consideration and those for (other) metals, such as the
influence of environmental conditions on bioaccumulation, the
observation of inverse relationships between bioaccumulation values
and concentrations in water, and the evidence for the existence of
internal regulatory mechanisms, the bioaccumulation thresholds (e.g.
for classification) used for organic substances are considered not
applicable, and the evaluation of aquatic bioaccumulation was
evaluated through expert judgment. This has led to the following
considerable decrease of bioaccumulation was observed when ascending
the trophic levels, this being obvious when comparing data in fish to
those in lower trophic levels.
yttrium and zirconium do not biomagnify through the aquatic food web.
on this pool of evidence, it was concluded that lanthanides, yttrium
and zirconium are unlikely to biomagnify in predatory organisms or
humans exposed via the environment.
REACH Regulation (EC) No 1907/2006, substances need to be assessed for
environmental hazard classification. Data on bioaccumulation are of key
importance in this process because they are considered, together with
degradation and ecotoxicity information, to assess the chronic hazard to
the aquatic environment.
has been often highlighted that bioaccumulation of metal and inorganic
substances follows a different paradigm relative to organic substances,
and this, for several reasons:
of Kow concept,
of environmental conditions,
relationship between bioaccumulation values and concentrations in water,
of internal regulatory mechanisms.
the concept that a substance may bioaccumulate is important for metal
and inorganic substances too and needs to be assessed even if the
thresholds and underlying mechanisms cannot be considered in the same
way as for organic substances. Evaluation should thus be performed on a
case-by-case basis and expert judgment can be used to conclude that a
substance is unlikely to pose a risk to predatory organisms or humans
exposed via the environment either: (i) based on the absence of food web
biomagnification and information showing that organisms in higher
trophic levels are not more sensitive than those in lower trophic levels
after long-term exposure, or (ii) because it is an essential element and
internal concentrations will be well-regulated at the exposure
concentrations anticipated (ECHA Guidance R7c, 2014).
an expert judgment was developed for lanthanides, yttrium and zirconium.
A bibliographical review was conducted by considering all studies on
bioaccumulation in aquatic organisms, resulting in a database composed of
ca. 60 publications (1964-2016) reporting laboratory and field
data on all elements and several trophic levels.
first conclusion that can be drawn from this review is that the elements
under consideration present particularities
common to those of (other) metals:
is influenced by environmental factors, resulting in substantial
high bioaccumulation values can be observed at relatively low exposure
concentrations, and inversely. The inverse bioaccumulation to
exposure relationship indicates that internal exposure does not rise
as quickly as exposure levels. This could be an indication for a
significant degree of physiological control over accumulation.
physiological regulation has been demonstrated in several species
for rare earths. While the essentiality of lanthanides, yttrium and
zirconium has never been convincingly demonstrated, the data compiled in
the review clearly show that mechanisms of regulation of internal
for (other) metals, it is clear from these findings that the mechanisms
underlying bioaccumulation cannot be considered in the same way as for
organic substances and that therefore, the thresholds used for organic
substances are not applicable. Based on expert judgment of the pool of
data available and described in the review document, the following
conclusions can be drawn for lanthanides, yttrium and zirconium:
considerable decrease of bioaccumulation was observed when ascending the
this being obvious when comparing data in fish to those in lower trophic
levels: The bioaccumulation estimates determined for fish
are fairly low with several publications reporting BAF/BCF values (well)
below 500. In comparison, higher BCF/BAF ranges have been reported for
aquatic plants and invertebrates than for fish. However, there are
indications that adsorption on organism surface and/or exposure to very
low, close to background, water concentrations play a significant role
in the high values determined especially for these lower trophic levels.
This makes it difficult to derive clear conclusions on the level of
uptake and consequent distribution in these organisms, based on the
available studies. Further, while there is no empirical proof that
lanthanides and yttrium are essential, they can be involved in cationic
competition: they can compete to bind at uptake sites of essential
cations (e.g. Mg2+, Ca2+). This constitutes
an additional hypothesis to explain the observed bioaccumulation in all
trophic levels. Note that no indication of interaction between zirconium
and essential cations has been found in scientific literature.
yttrium and zirconium do not biomagnify through the aquatic food web:
This is evidenced from the previous point, but also from the available
publications dealing with biomagnification. Most of the time, BMF values
are low (i.e. ≤ 1) and the only cases where those values are
higher than 1 correspond to trophic transfer in the lower levels of the
on this pool of evidence, it was concluded that lanthanides, yttrium and
zirconium are unlikely to biomagnify in predatory organisms or humans
exposed via the environment.
further details, please find the full bibliographic review attached in
IUCLID section 13 “Assessment reports”.
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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