Although stable under normal conditions, it is highly flammable and can irritate nose, eyes, and throat. Hydrochloric acid is a colorless liquid with a pungent odor and should be handled with extreme caution since it can cause severe skin burns and eye damage. Sodium hydroxide is also corrosive and appears as white, odorless crystals in its solid form and clear, colorless liquid in solution. Although both hydrochloric acid and sodium hydroxide are corrosive, only a small amount of the chemicals (maximum of 1 mL) are used in heme extraction and therefore, are relatively safe. Regardless, proper personal protective equipment (PPE) such as gloves and safety goggles should be worn at all times when handling these chemicals.