Registrant must clarify aquatic toxicity of smallest nanoparticles
Echa’s Member State Committee (MSC) agreed a draft decision on the evaluation of silver nanomaterials, at its meeting on 25-29 April.
The requirements were brought by the Dutch competent authority, whose evaluation of silver includes two nanomaterial forms.
The committee heard that the main concern with silver is aquatic toxicity. The registrants put forward the hypothesis that the ionic form is most toxic.
However, the committee decided it needs to be demonstrated that the size, surface area and surface treatment of the nanomaterial are less important. It unanimously agreed that toxicity tests on Daphniawater fleas, algae and microorganisms were necessary, but only for the smallest nanomaterial.
MSC chairman Watze de Wolf said: “If, in future, more silver nanoforms are registered with smaller size or different surface treatments, then the registrant will have to show that this hypothesis still holds.”
He added that if the nanoforms do show greater toxicity than the ionic form, further testing will be needed on the fate of silver nanoparticles in soil.
Silver is the second substance with nanoforms, drawn from the Community Rolling Action Plan (Corap).
Silicon dioxide, also brought by the Netherlands, was the first to be addressed by the MSC. A Decision was sent to the registrants, only for a group of companies to contest Echa's Decision to make silicon dioxide subject to evaluation because of concerns related to the nanoform.
The companies lodged an appeal with Echa's Board of Appeal last year, and the case has wider importance for nanomaterials. If the contested Decision is allowed to stand, it could set precedents for the evaluation of other nano substances, including silver.
Titanium dioxide, zinc oxide, graphite, cerium dioxide and multi-walled carbon nanotubes are also listed in the Corap and will be evaluated in future.