Is Ichor (blood of the gods) actually toxic to mortals? If it is, I can't find any sources that say this. If it is, it is lethal only for consumption or can it kill a mortal merely by touching?
in Greek mythology the masculine noun ἰχώρ (ancient Greek letters)- transliterated as “ichór”- is the immortal etherial juice, NOT blood, which flows LIKE blood in the veins of the gods, who “eat not bread neither drink wine and therefore they are bloodless, and are called immortals”, as you can read in Homer's Iliad, Book 5, line 340 ff.
Also, we find the term ἰχώρ /ichór just as a fluid that flows in the veins of the savage race of the Giants in Strabo’s Geography, book 6, chapter 3, section 5 .
Apart from the above quotations where the “ichór” is attributed to the gods in place of blood, there is no classical source in Greek literature that tells of the “ichór” as a fluid which can be toxic to mortals or can kill a mortal merely by touching.
Therefore I have to point out that in Greek mythology the ἰχώρ (ancient Greek letters), transliterated as “ichór”, is only the juice, not blood, that flows in the veins of gods.
Lastly, I must tell you that sometimes the term “ichór” has been later used as a synonym of “αἷμα” transliterated as “áima” (“blood”) or in the sense of “serum”( the watery part of blood) as well as in the sense of “sero-purulent discharge”,though neither "serum" nor “sero-purulent discharge” have no reference to the gods nor to mortals.
To conclude, in Greek mythology the “ichór” has nothing lethal or toxic to anybody, as it is simply a juice that flows in the veins of gods just like blood,but it is not blood.