1. The overall hazards of VOCs
(1) Harm to the environment
① Participate in the reaction of nitrogen oxides under the action of sunlight and heat to form ozone, which leads to poor air quality and is the main component of summer photochemical smog and urban haze;
② VOCs are important precursors for the formation of fine particles (PM2.5) and ozone. VOCs in the atmosphere account for about 20% to 40% of PM2.5, and part of PM2.5 is converted from VOCs;
③VOCs are mostly greenhouse gases-leading to global warming.
(2) Harm to health
① Irritation & toxicity
When VOCs exceed a certain concentration, they can irritate people's eyes and respiratory tract, causing skin allergies, sore throat and fatigue; VOCs can easily pass through blood-brain barriers and damage the central nervous system; VOCs can damage people's liver, kidneys, brain and nervous system.
② Carcinogenicity, teratogenicity and reproductive system toxicity
2. Specific hazards of common toxic VOCs
Skin: refers to the systemic effects caused by direct contact with the skin, mucous membranes and eyes of vapors, liquids and solids and absorption through intact skin;
Sensitivity: It has been confirmed by human or animal data that the substance may have allergenic effects;
G1: Refers to the carcinogen confirmed by the International Organization for Cancer (IARC); G2B: refers to the suspected human carcinogen.
3. Permissible concentration of common toxic VOCs
① China’s occupational exposure limits are in accordance with GBZ2.1-2007 "Occupational Exposure Limits for Hazardous Factors in the Workplace-Chemical Hazardous Factors".
②American standards are in accordance with NIOSH (Institute of Occupational Safety and Health) or OSHA (U.S. Occupational Safety and Health Administration) standards.
4. Benzene poisoning
(1) Causes of benzene poisoning
Mainly because benzene is oxidized to toxic intermediates of epoxybenzene under the action of cytochrome P450 monooxygenase in the liver. Epoxybenzene is metabolized in the liver and bone marrow to form phenol, o-benzene/hydroquinone and o-quinone. , P-benzoquinone and other metabolites, after entering the cell, these metabolites combine with the DNA in the nucleus, causing chromosomal changes until cancer.
(2) Benzene and leukemia
In 1897, Nenoir and Claude reported the first case of leukemia in benzene workers. Most of the leukemia patients have a history of contact with benzene and its organic products. The investigation of the health status of people exposed to benzene by health institutions shows that the incidence of leukemia is related to the time and concentration of benzene exposure. Leukemia caused by benzene mostly occurs after time and high concentration exposure, the shortest is 6 months, the longest is 23 years.
(3) Occupational contact
①Petroleum and chemical industries that use benzene as the final or intermediate product, such as dry leaching in coal chemical industry, coke oven gas, coal tar fractionation; continuous reforming, benzene extraction, styrene in petrochemical industry
Ethylbenzene, PX, ethylene, etc. from olefin, dry gas.
②Dyestuffs, medicines, perfumes, pesticides, plastics, synthetic rubber and other industries that use benzene as raw materials.
③Paint, printing, electroplating, ink, glue, resin, shoemaking and other industries that use benzene as solvent and thinner.
(4) Invasion route: inhalation, ingestion, absorption through skin
☆ When smelling the odor of benzene, its concentration is about 0.5-1.5ppm. At this time, you should be aware of the danger of poisoning.