Formaldehyde!

Formaldehyde - a known carcinogen (causes cancer). Causes allergic, irritant and contact dermatitis, headaches and chronic fatigue. The vapour is extremely irritating to the eyes, nose and throat (mucous membranes).
Formaldehyde - A colorless gaseous compound, HCHO, the simplest formaldehyde, used for manufacturing melamine and phonetic resin, fertilizers, dyes, and embalming fluid and in aqueous solutions (dissolved in water) as a preservative and disinfectant.