Analysis of information sources in references of the Wikipedia article "Toxin" in English language version.
arsenic, a toxic metal, may occur as a natural contaminant ... or ... as a by-product of industrial activities. If the second case is true, such toxic substances are referred to as toxicants, rather than toxins.
the term "toxin" means the toxic material or product of plants, animals, microorganisms ...or a recombinant or synthesized molecule...
The Convention applies to all natural or artificially created toxins, "whatever their origin or method of production" (Article I). It thus covers toxins produced biologically, as well as those produced by chemical synthesis