Most chemicals have a certain degree of irritation and toxicity, long-term exposure to the body mucous membranes skin, respiratory and digestive, blood system will cause some harm. The ways of contact between chemicals and the body include contact through the skin and mucous membranes as well as contact with the respiratory and digestive tracts into the body. The hazards to the body vary greatly between chemicals of different natures. General non-toxic chemicals, such as cosmetics, detergents, long-term direct contact with the skin will appear dry, cracked, flaking; if the toxic chemicals, such as strong acid, alkali substances can cause skin burns, blisters, ulcers and other changes. Inhalation of chemical vapors such as hypochlorite, xylene, etc. will cause irritation of the respiratory system, sore throat and cough, serious cases can lead to bronchitis, interstitial pneumonia; long-term exposure to benzene substances can also cause chronic damage to the human blood system and the nervous system, bone marrow suppression, leukemia, as well as memory loss, lethargy, fatigue, and other neurological reactions. If accidentally taking toxic chemicals such as organophosphorus pesticides can cause poisoning of the body, the digestive tract, respiratory tract, the nervous system multiple system damage, serious cases can be fatal or lead to serious sequelae, need to be sent to the hospital urgently for treatment.