Asphalt can be divided into three main types of coal-tar asphalt, petroleum asphalt and natural asphalt: The asphalt commonly used in industry today is coal-tar asphalt, which is the most toxic. It is the coal tar produced by the dry distillation of coal after refining the residual material, commonly known as tar. Asphalt is a black liquid, semi-solid or solid. Melting point (℃): boiling point (℃): <470 ℃. Flash point: 204, 4 ℃. Ignition temperature (℃): 485. in open flame, high heat can be ignited. Burning emits toxic and irritating smoke, containing carbon monoxide, carbon dioxide, benzene, anthracene, pyridine, carbazole, phenanthrene, pyrene, etc. Asphalt is insoluble in water, insoluble in acetone, ether, dilute ethanol, soluble in carbon disulfide, carbon tetrachloride, etc. Prohibited substances: strong oxidizing agent. Mainly used in coatings, plastics, rubber and other industries, as well as paving roads. 1, toxicological information (1) acute toxicity: rabbits with 30% coal tar toluene solution coated skin 3 times, local following the inflammation of hyperkeratosis and chaps. (2) poisoning mechanism: phototoxicity: asphalt and its anthracene, phenanthrene, acridine, etc. are phototoxic substances, can cause photobiological effects under the action of ultraviolet light. Asphalt phototoxic reaction due to asphalt in aerobic conditions through the role of photochemical reactions, the reaction generated by free radicals, peroxides cause cell damage, so it is a non-immune reaction. Systemic effects: coal coke asphalt coated skin on animal weight gain than petroleum asphalt for obvious effects, and coal coke asphalt skin application than its smoke inhalation on animals for the greater harm. Suggest that coal tar pitch has a certain systemic effect on animals, the extent of its effect is related to the absorption pathway. (3) irritation: irritating. Asphalt and its fumes in the main components of phenolic compounds, anthracene, naphthalene, pyridine, etc. on the skin and mucous membranes with irritation. (4) carcinogenicity: China with mice coated skin, experiments have also seen asphalt can cause skin cancer, mostly squamous epithelial cell carcinoma, a few for keratinized papilloma. It is generally believed that coal coke asphalt is the most carcinogenic, natural asphalt is not carcinogenic; the carcinogenicity of petroleum asphalt, the views are not yet consistent. (5) Environmental hazards: harmful to the environment, the atmosphere can cause pollution. 2, clinical features (1) local symptoms: asphalt burns are mostly caused by spills, falls and other accidents. High heat of the liquid asphalt to the skin caused by thermal burns. Due to the strong adhesion of asphalt, high temperature melting asphalt adhesion to the skin is not easy to remove. If the temperature is high, due to slow heat dissipation, often forming deep II or III degree burns; if the temperature has been lower, the damage may be less severe. Asphalt workers due to exposure of the skin and mucous membranes for a long time and asphalt fumes or dust contact, can cause a variety of skin damage such as: phototoxic dermatitis, lesions are limited to the face, neck and other exposed parts; melanosis, lesions are often symmetrically distributed in the exposed parts, in the form of flakes, brown - dark brown - brown-black; occupational acne; warts and verrucae . Asphalt dust and smoke damage to the eye is mainly blepharoconjunctivitis, sometimes accompanied by superficial patchy keratitis. High-temperature asphalt splashes into the eye can cause corneal burns, which can be seen as eyelid spasms, significant loss of vision, significant congestion of the bulbar conjunctiva, punctate burns, infiltrative clouding and fluorescein staining of the cornea, which can leave corneal clouding after healing. The nasopharynx often has dryness and burning sensation, which may also cause rhinitis and pharyngitis. (2) Systemic symptoms: Most often occur in those with large asphalt burns, and may include dizziness, headache, headache, chest tightness, weakness, nausea or cough, palpitations, tinnitus and other discomforts, or even coma and death. Individual patients present with transient one-cardiogram ST-T segment changes. It is more likely to occur in those injured while operating under the hot sun. It is often accompanied by fever. The blood picture may include abnormally high eosinophilic red blood cells and leukocytosis. Acute renal failure is often the main cause of patient death. 3, first aid treatment (1) trauma treatment: at the scene immediately with cold water rinse cooling. For larger burns, after the recovery and stabilization of shock, traumatic asphalt should be removed early to prevent toxic absorption and early diagnosis of burn depth for the next step of treatment. Removal solvents are turpentine, gasoline, etc. Large traumatic areas should be scrubbed with turpentine. As the current commercial gasoline contains lead, if a large amount of gasoline, and cause the risk of lead poisoning, and the effect is not as good as turpentine. Wipe off the asphalt and then rinse with water, and finally wash the trauma with chlorhexidine or Neosporin, and use exposure or bandage treatment as appropriate. (2) Treatment of irritant dermatitis and mucosal injury: stop exposure to asphalt and sun exposure, avoid photosensitive drugs such as flavamine, chlorpromazine, promethazine, etc., and if necessary, give antihistamines without photosensitizing effect, or even short-term use of corticosteroids. Topical mercury bromide red and methyl violet are prohibited on the skin. Indomethacin topical can have delayed or reduced UV-induced erythema reaction, conjunctivitis with saline rinse, and later with 0, 25% neomycin eye solution or aureomycin eye ointment, and ask the relevant departments to consult. (3) Systemic treatment: For those with systemic toxicity, inject calcium gluconate and high-dose vitamin C, sodium thiosulfate, etc. sedation. Pay attention to protect liver and kidney function. The rest of the treatment is the same as general thermal burns.