Who'd have thought oxalic acid could be a human killer, too?

From https://www.iloencyclopaedia.org/part-xviii-10978/guide-to-chemicals/item/1029-acids-and-anhydrides-organic/

Oxalic acid is a strong acid which, in solid form or in concentrated solutions, can cause burns of the skin, eyes or mucous membranes; oxalic acid concentrations as low as 5 to 10% are irritating if exposure is prolonged. Human fatalities have been recorded following ingestion of as little as 5 g of oxalic acid. The symptoms appear rapidly and are marked by a shock-like state, collapse and convulsive seizures. Such cases may show marked renal damage with precipitation of calcium oxalate in the renal tubules. The convulsive seizures are thought to be the result of hypocalcaemia. Chronic skin exposure to solutions of oxalic acid or potassium oxalate have been reported to have caused a localized pain and cyanosis in the fingers or even gangrenous changes. This is apparently due to a localized absorption of the oxalic acid and a resultant arteritis. Chronic systemic injury from inhalation of oxalic acid dust appears to be very rare, although the literature describes the case of a man who had been exposed to hot oxalic acid vapours (probably containing an aerosol of oxalic acid) with generalized symptoms of weight loss and chronic inflammation of the upper respiratory tract. Because of the strongly acid nature of the dust of oxalic acid, exposure must be carefully controlled and work area concentrations held within acceptable health limits.