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EC number: 231-131-3
CAS number: 7440-22-4
is a non-guideline study, published in peer reviewed literature and
considered suitable for use as a key study for this endpoint. The
freshwater 48 hour LC50 values for Daphnia magna when exposed to
silver nitrate are 0.18 to 0.26 µg Ag/L based on measured total silver
concentration and 0.22 µg Ag/L based on measured filtered silver
Read across from ionic silver
Plus supporting published data from several studies included in the
REACH dossier as Endpoint Study Records with various sizes of
nanoparticles and coating types, showing that nanosilver is less toxic
than ionic silver
of available data for uncoated and coated nanosilver
and relevant data on the short-term toxicity of uncoated and coated
nanosilver to invertebrates are available from 12 studies (Griffitt et
al. 2008, Gao et al. 2009, Kennedy et al. 2010, Li et al. 2010, Gaiser
et al 2011, Gaiser et al. 2012, Hoheisel et al. 2012, McLaughlin and
Bonzongo 2012, Poynton 2012, Wang et al. 2012, Zhao and Wang 2012,
Blinova et al. 2013).
total of 55 LC50 values are available from studies investigating
effects on five species (Daphnia magna, Daphnia pulex, Ceriodaphnia
dubia, Thamnocephalus platyurus, Chydorus sphaericus).
However, data predominantly relate to the crustacean species
conventionally used in laboratory ecotoxicity testing i.e. Daphnia
magna (seven studies – 35 LC50 values) and Ceriodaphina
dubia (three studies – seven LC50 values).
available reliable data includes various sizes of nanoparticles and,
in addition to uncoated nanosilver materials, a range of
coating/capping materials, including: PVP, citrate, EDTA, lactate and
sodium dodecylbenzene sulfonate.
predominantly report effects of spherical nanoparticles but there are
also data for mixtures of spherical particles and nano rods (Kennedy
et al. 2012), mixtures of spherical, prismatic and rod-shaped colloids
(Li et al. 2012) and face-centred cubic crystal structures (McLaughlin
and Bonzongo 2012). All studies were conducted in freshwater media.
particle size of raw nanomaterials across the studies ranged from 8.4
to 123.9 nm (Particles >100 nm would not usually fall under the
proposed definition of a nanomaterial, but as this threshold is not
based on any scientific criteria toxicity data from studies with
particle sizes >100 nm are included in this assessment for
completeness). However, the majority of studies report effects
associated with primary particle sizes between 8.4 and 51.86 nm (10th
to 90th percentile). Aggregation/agglomeration behaviour of primary
particles within experimental media or stock solutions varied between
studies but in almost all instances authors report that some degree of
aggregation/agglomeration in the test systems occurs, increasing the
size of particles in environmental media. The characterisation results
for nanosilver in test systems report particle sizes after
aggregation/agglomeration of between 50.7 and 1,584 nm, with the
majority of studies reporting particle sizes between 50.7 and 360.0 nm
(10th to 90th percentile).
values range from 0.43 µg/L to 221 µg/L, after 48 hour exposure.
Interestingly, both of these LC50 values are from the study by
McLaughlin and Bonzongo (2012) which investigated the toxicity of
uncoated nanosilver particles (25.4 nm) to Ceriodaphnia dubia
in both synthetic and natural waters. The greatest toxicity (LC50
value of 0.4 µg/L) was recorded in river water, whilst the lowest
toxicity was recorded in water from a wetland. A similar observation
was recorded in Pseudokirchnerialla subcapitata exposed to
nanosilver in the same water. Differences in observed toxicity may be
the result of variable bioavailability of silver in these waters. The
10th to 90th percentile range of LC50 values for all forms of
nanosilver assessed for acute invertebrate toxicity range from 1.31 to
of the nanosilver LC50 values are less sensitive than the 48 hour LC50
of 0.22 µg/L for Daphnia magna (Bianchini et al. 2002)
used in the REACH CSR for silver.
addition, where studies undertook a comparative assessment of the
relative toxicity of nanosilver and ionic silver within their own
study designs (Griffitt et al. 2008, Kennedy et al. 2010, Zhao and
Wang 2012, Poynton 2012, Hoheisel et al. 2012, Wang et al. 2012,
Blinova et al. 2013) nanosilver was only observed to be more toxic
than ionic silver on a single occasion (Griffitt et al. 2008 – 48 hour
exposure of C. dubia neonates). The relative toxicity of bulk
silver (0.6 - 1.6 µm particles) in comparison to nanosilver was tested
on a single occasion (Gaiser et al. 2011). In this test, bulk silver
was approximately an order of magnitude less toxic than nanosilver.
there is no statistically significant correlation between smaller
particle sizes and increased toxicity (Kendall test, p>0.05). However,
Hoheisel et al. 2012 report a clear reduction in toxicity (greater
LC50) with increasing particle size. This relationship was effectively
normalised when results were expressed on the basis of surface area
rather than mass concentration, which suggests that the toxicity
observed was related to the dissolution rate of silver ions from the
surface of the particles. Smaller particles have much greater surface
area than larger particles.
the LC50 values from materials with different coatings were compared
using a non-parametric ANOVA procedure (Kruskal-Wallis, p<0.05) a
statistically significant difference between coating material and LC50
value was identified. Protein coated nanosilver materials appear to
have lower toxicity than other coating materials and uncoated
materials. However, this cannot be confirmed using a statistical
post-hoc test as the variance and normality of the different treatment
groups was homogenous.
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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