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EC number: 231-130-8
CAS number: 7440-21-3
According to REACH information
requirements, a two-generation reproduction toxicity study is the
standard information requirement at above 1,000 t/year. No such test has
been conducted with silicon or related substances (amorphous silica or
silicates). However, the REACH guidelines do not require reproduction
toxicity testing if, e.g., all of the following circumstances exist:
substance exhibits a) low toxicological activity and b) negligible
systemic absorption and c) no or no significant human exposure. In
addition, before any specific reproductive toxicity testing is
suggested, a detailed review of all existing toxicological data to
identify any specific alerts and testing requirements should be
conducted. If this kind of weight-of-evidence analysis shows that there
is sufficient data to permit a robust conclusion on reproductive
toxicity potential, no further testing is required.
Based on the acute and repeated dose
toxicity data on synthetic amorphous silica, silicon ion is virtually
non-toxic, showing no systemic toxic effects even at very high oral
doses (see Chapter Repeated Dose Toxicity). No harmful effects on
reproductive organs have been described in repeated dose toxicity tests.
After ingestion, amorphous silica is absorbed from the gastrointestinal
tract but it usually has very little effect on systemic silicon ion
levels i.e. the levels of silicon in blood, urine or tissues. Silicon in
different forms is ubiquitous in nature. Diet is the main factor
affecting the blood/urine silicon levels. Diet also causes large
inter-individual variability in blood/urine silicon levels. Silicon in
different forms is a commonly used food additive and EFSA (2009) has
concluded that the use of silicon dioxide up to 1,500 mg SiO2/day
(equal to 700 mg/day) added to food supplements is of no safety concern.
OECD (2004) concluded on the basis of weight of evidence that prolonged
exposure to synthetic amorphous silica, applied before and during
pregnancy at high doses, is not expected to produce harmful effects on
the reproductive performance in experimental animals. This conclusion is
based on the information that subchronic studies with amorphous silica
and a dominant lethal study with calcium silicate have failed to
demonstrate any histopathological changes or deleterious effects in the
reproductive organs of treated animals. Calcium
silicate can be used for the read across in the case of both amorphous
silica and silicon since it is also a sparingly soluble silicon compound
which releases silicon in the body. In
addition, the inherent physico-chemical properties and ubiquitous nature
of synthetic amorphous silicas suggest that there is no structural alert
to indicate any potential for reproductive toxicity.
According to available comparativein
vitro dissolution data, the dissolution of silicon from elemental
silicon and synthetic amorphous silica (Aerosil Ox50) is similar,
Aerosil Ox50 showing somewhat better release than elemental silicon.
Thus, the bioaccessibility (and bioavailability) of silicon is likely to
be similar or lower than that of synthetic amorphous silica. In
circulation, silicon exists in the form of moniosilicic acid in both
cases. Thus, the reproductive
hazards are likely to be the same, which means that exposure to silicon
is not expected to produce harmful effects on the reproductive
performance. A detailed description of the justifications
for read-across is available in Section 13 of the Iuclid dossier.
Main impurities, present in silicon at
levels over 0.3% and released from it, include aluminium, iron and
calcium. Iron is an essential mineral, with no reproductive toxic
properties, and widely used dietary supplement also during pregnancy.
Same applies to calcium. Soluble species of aluminium are widely used as
antacidal drugs and they have not been shown to exert effects on
reproduction or development and are therefore indicated also during the
pregnancy. In addition, the dissolution of these elements from silicon
matrix is restricted because of the protective silicon oxide layer and
has been shown not to differ significantly from the release of these
elements from pyrogenic amorphous silica. Thus,
it can be concluded that the known impurities are unlikely to have any
impact on silicon reproductive toxicity.
Conclusion: Silicon is regarded not
to cause fertility effects. No classification or further testing of
fertility effects is suggested.
Available animal data on developmental toxicity of synthetic amorphous silica, calcium silicate and sodium aluminium silicate, which can be used for read-across do not suggest developmental toxicity or teratogenicity. The inherent physico-chemical properties and ubiquitous nature of silicon ion suggest that there is no structural alert to indicate any potential for developmental toxicity.
limited data available on the developmental toxicity of amorphous
silica. In these studies, high-dose or long-term oral
administration of hydrophilic silica gel did not induce
developmental toxicity in several species.However,
the teratogenic effects of calcium silicate and sodium aluminium
silicate have also been tested in different animal species. All
tests showed negative results at high doses.Thesedata
support the conclusion that amorphous silica has no toxic effect
Also OECD (2004) concluded in its
assessment on the hazards of synthetic amorphous silica that on
the basis of weight of evidence prolonged exposure to synthetic
amorphous silica is not expected to produce harmful effects on the
embryonic/foetal development in experimental animals.
The comparative in vitro data
on the dissolution kinetics of silicon and amorphous silica in
different artificial biological fluids shows that the dissolution
of silicon from silicon particles in vitro is similar or lower
than from amorphous silica particles (pyrogenic silica Aerosil
Ox50). In blood, silicon exists in the form of monosilicic acid
regardless of the source. Thus, based on the read-across from
synthetic amorphous silica, calcium silicate and sodium aluminium
silicate, silicon is not likely to exert developmental toxicity. A
detailed description of the justifications for read-across is
available in Section 13 of the Iuclid dossier.
Conclusion: Silicon is regarded
not to cause developmental toxicity. No classification or further
testing of developmental toxicity is suggested.
Subchronic studies with amorphous
silica and a dominant lethal study with calcium silicate have
failed to demonstrate any histopathological changes or deleterious
effects in the reproductive organs of treated animals. The
inherent physico-chemical properties and ubiquitous nature of
silicon ion suggest that there is no structural alert to indicate
any potential for reproductive toxicity.
Available animal data on
developmental toxicity of synthetic amorphous silica, calcium
silicate and sodium aluminium silicate, which can be used for
read-across, do not suggest developmental toxicity or
teratogenicity. The inherent physico-chemical properties and
ubiquitous nature of silicon ion suggest that there is no
structural alert to indicate any potential for developmental
toxicity. Silicon contains no reprotoxic impurities.
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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