Formaldehyde: This is a colourless, strong-smelling gas used in making building materials, many household and cosmetics products. It is widely used as preservatives in skincare and cosmetics and mainly used in nail polish, hair glues, makeup, lotions, deodorants and many other products. 

Dangers of Formaldehyde: It is a sensitizing agent that can cause an immune system response upon initial exposure. It is also a cancer hazard. Acute exposure is highly irritating to the eyes, nose, and throat and can make anyone exposed cough and wheeze. Subsequent exposure may cause severe allergic reactions of the skin, eyes and respiratory tract. Ingestion of formaldehyde can be fatal, and long-term exposure to low levels in the air or on the skin can cause asthma-like respiratory problems and skin irritation such as dermatitis and itching. Concentrations of 100 ppm are immediately dangerous to life and health.