「Xは実際に消費者が暴露する使用時濃度だけの規制が適切な方法であることをEU当局に訴えてきました。」という一文の適訳は、

X has appealed to the EU authorities that regulating only the concentrations during use—-which the customers would actually be exposed to—-is the appropriate method’)

ではなく、

X has already made an appeal to the European Commission to the effect that it would be appropriate to restrict only levels of concentrations at times that hair dyes are actually used, in other words at times when consumers would actually be exposed.

または

X has been making appeals to the European Commission to the effect that it would be appropriate to restrict only levels of concentrations at times that hair dyes are actually used, in other words at times when consumers would actually be exposed.

です。日本語では現在完了時制が使われていますが、英訳時には、現在完了時制または現在完了進行時制を使うのが良いでしょう。