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EC number: 221-906-4
CAS number: 3277-26-7
Peat-based system: Visual observations of plants treated with ortho-,
monomethyl- and trimethyl silicic acids in the peat-based systems showed
no impairment of growth or development compared to the controls. However
the dimethyl silic acid induced the appearance of yellow streaks on
leaves which subsequently dried out and died. Furthermore,
concentrations of the substance as low as 0.1 mM still induced symptoms
of phytotoxicity (results not detailed in the publication).
Hydroponic system: X-ray analysis of the plants grown using Si-free
Hoagland solution showed no deposition of Si in the leaves. Plants grown
with the addition of orth silicic acid showed the presence of
silicaphile cells in the leaves. Treatment with monomethyl silicic acid
resulted in Si deposits in small pockets that were localised to the
areas of mildew presence. Those treated with trimethyl silicic acid
showed no visible deposits of Si within the leaves.
Analysis of silicon uptake by the plants showed that the highest
concentrations were found in the ortho silicic acid treatment.
Concentrations in the Control and trimethyl silic acid treatments were
similar while those in the monomethyl silicic acid treatment were
Orthosilicic acid provided the highest level of protection against
infection by powdery mildew while monomethyl- and trimethyl silicic
acids treatments were actually associated with higher levels of
infection compared to the Control.
There is no reliable study available with the registered substance and
its hydrolysis products. However, a read-across study is available with
aqueous solutions of silicone degradation products. In a short-term
toxicity to terrestrial plants study with the aqueous read-across
solutions of silicone degradation products, not conducted according to
any guideline and not specified if in compliance with GLP, it was
concluded that the test substance could induce phytotoxic symptoms and
interfere with plant growth (Côté-Beaulieu et al.,
There is no reliable study available with the registered substance or
its hydrolysis products, and the endpoint is waived.
However, a read-across study is available with aqueous solutions of
silicone ortho- monomethyl- dimethyl- and trimethylsilicic
acids, which correspond to silicic acid, methylsilanetriol,
dimethylsilanediol and trimethylsilanol respectively. In the study wheat
plants Triticum aestivum L. were exposed with Hoagland solutions
containing the test substances in peat based systems and in hydroponic
systems. During the hydroponic exposures, plants were infected with
fungus mildew. The study was not conducted according to
any guideline, and there is no indication it was conducted according to
GLP. The study
concluded the dimethylsilanediol could induce phytotoxic
symptoms and interfere with plant growth. The methods used were not in
accordance with any standard guideline, exposure was to aqueous
solutions and silica deposits were also detected in the shoots of the
controls in the peat-based studies. It is difficult to assess the
significance of the results for the standard REACH endpoints. Therefore,
the study is considered reliability 4 and the data are not considered to
be relevant for the risk assessment.
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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