Organic acids are toxic and corrosive. Corrosive is a form of toxicity to the tissues that the acid contacts. However, the organic acids have other toxic effects. Formic acid is corrosive to skin and tissues. It has a TLV of 5 ppm in air and an IDLH of 30 ppm. Pure acetic acid is toxic by ingestion and inhalation. It is a strong irritant to skin and tissues. The TLV is 10 ppm in air, and the IDLH is 1000 ppm. Propionic acid and is a strong irritant, with a TLV of 10 ppm in air. Butyric acid is a strong irritant to skin and tissues. The degree of toxicity varies with the different organic acid compounds. Review reference sources and MSDSs to determine the exact hazards of specific acids.