Formaldehyde is a chemical used in embalming and tissue preservation, as well as in cold sterilization. Acute exposure to formaldehyde may result in pulmonary edema (fluid in the lungs), central nervous system (CNS) depression, or pneumonitis (inflammation of the lung tissue). Chronic exposure may cause irritation of the skin, mucous membranes or respiratory tract. Repeated exposure to formaldehyde may result in an allergic response. It is also a potential carcinogen. Primary exposure routes are inhalation and skin absorption.