GB No. 33535
CAS No. 108-38-3
Molecular Formula C8H10; C6H4 (CH3) 2
transparent colorless liquid that smells like toluene; vapor pressure 1.33kPa/28.3 ° C a flash point of 25 ° C; -47.9 ° C melting point; the boiling point of 139 ° C; solubility : do not dissolve in water, immiscible in ethanol, ethyl ether, chloroform, etc. Most organic solvents; density : relative density (water = 1) 0.86; the relative density (Air = 1) 3.66; Stability : stability; risk Marker 7 (flammable liquids); the main purposes : as solvents, pharmaceuticals, dyes intermediates , spices
2. The impact on the environment :
a health hazard
pathways : inhaled, ingested, percutaneous absorption.
health hazards : xylene eye and upper respiratory boost the role of high concentration on the central nervous system have a narcotic effect.
acute poisoning : short-term inhalation of high concentrations of nuclear weapons, there may be the eyes and upper respiratory tract irritation clear, eye and throat conjunctival hyperemia, dizziness, nausea, vomiting, lightheadedness, weakness, the sense of ambiguity, hobbling gait. Emphasis will be a quick temper, convulsions or coma, and some have hysteria - like attack.
chronic effects : long-term exposure to a neurasthenic syndrome, women have menstrual abnormalities, workers often dry skin, rhagadia, dermatitis.
two, toxicology information and environmental behavior
toxicity : is low toxicity category.
acute toxicity : LD505000mg/kg (rat oral); 14100mg/kg (rabbit percutaneous)
irritation : Rabbits open percutaneous stimulation experiment : 10 µ g (24 hours), the severe stimulation.
reproductive toxicity : rat inhalation poisoning minimum concentration (TDL0) : 3000mg/m3, 24 hours (7 ~ pregnant four days medication), the pre-implantation embryo mortality, fetal skeletal muscle morphology influential, embryo toxicity.
pollution sources : xylene is an important chemical raw materials, organic synthesis, synthetic rubber and paints and dyes, synthetic fibers, petroleum processing, pharmaceuticals, the production of cellulose factory effluents, and production equipment is not enclosed and workshop for ventilation, environment Xylene the main source. Transportation, storage overturned in the process, spills, fires will cause accidental pollution incidents.
metabolism and degradation : the human and animal body, inhalation of xylene than 3% to 6% of direct exhaled, the three xylene isomers have metabolic corresponding acid (60% of o-xylene, 80% ~ 90%, right - xylene), and then these acid and glucuronic acid and glycine reaction. In this process, a lot o-acid grapes and grain acid combination, and right-certainly between acid and glycine completely corresponding to form a maleimide and uric acid excreted. Meanwhile, the possible formation of a small amount of the corresponding xylenol (phenols) and hydrogenated 2-methyl-3-hydroxy benzoic acid (2%).
residues and accumulation : occupational exposure, xylene main entering the body through the respiratory tract. All right xylene isomers, from lung its vapor absorption in the same way, a total of 60% to 70% of the entire contact period, the capacity to absorb more constant. Xylene solution will be able to complete the skin to absorb an average rate of 2.25 µ g / (cm3 min) (range 0.7 to 4.3 µ g / (cm3 min)) absorption, xylene vapor percutaneous absorption and compared to direct contact with the liquid is negligible. Xylene and the remaining abalone stock is not serious, and we have said above enter the body of xylene, in the human body can NADP (switch-II) and NAD (switch - I) presence methacrylate acid, glycine and then combined to form a maleimide uric acid in the 18-hour period from almost all in vitro . Even after inhaling the residue in the lungs of 3% to 6% of xylene, also contacted after the three-hour period (half-life of 0.5 to 1 hour) were exhaled in vitro. Contact xylene evaluation of residual tests, mainly in urine within a maleimide uric acid levels, it was also suggested in Our gas or blood xylene levels, but the results are not always accurate. As a maleimide uric acid does not exist in the natural urine, and because it is almost all the stranded xylene metabolites, which in its existence is the best xylene exposure tests confirmed. Xylene can be very durable exist in drinking water. Tap water xylene concentration of 5 mg / L, the odor intensity is equivalent to five, xylene unique odor would have been seven to eight days to disappear; Odor intensity for three when required four to five days. River xylene odor maintain a shorter time, with initial concentration on the level, and can be retained for three to five days.
migration and transformation : xylene mainly crude oil, chemical process manufacturing, it is widely used paint, paint thinner, etc., printing, rubber and leather industries solvents. As a cleaning agent and the agent to oil, aviation fuel ingredient, a chemical factory and synthetic industrial raw materials and intermediate materials, paper and fabric paint and varnish. Xylene by mechanical exhaust and ventilation equipment into the atmosphere and cause pollution. A Refinery emissions into the atmosphere as much as the xylene 13.18 ~ 1145g / h, xylene can be with its production and use of units of the wastewater discharged into the water body, a production tons of xylene, xylene general discharge 300 ~ 1000 / L of 2 cubic meters of wastewater. Because xylene in aqueous solution volatile strong trend, which may be considered in the surface water is not persistent pollutants. Xylene in the environment can also biodegradable, but this process faster than the rate of volatilization is much lower. Essential to the air xylene may also be photolysis, which is the main migration and transformation process.
xylene by the breath and metabolites from the human body from the fast, 18-hour access to stop almost all excreted, xylene can be very durable exist in the drinking water. Because xylene in aqueous solution more volatile and, therefore, that its surface water is not persistent pollutants. Xylene in the environment can also biological and chemical degradation, but its rate is much lower than the volatile, volatile in the air to xylene can be photolysis. With the oxidizer reaction and high concentration of gas and air mixture explosion. Xylene is a medium level of risk of combustion. Due to its vapor is heavier than air, combustion flame spread along the ground. Xylene volatile, the incident will render filled with xylene-fang, a special flavor, the dumping into the water xylene can be floating in the water, or oil bar was located in the water, can cause fish and aquatic organisms death.
hazardous characteristics : flammable vapor and air can form explosive mixtures. Case fire, high-heat combustion caused the explosion. With a strong oxidant can respond. Velocity too fast, easy and accumulation of static electricity. Its vapor is heavier than air, will spread to the lower Department of considerable local and met the fire will generate a return to burning.
combustion (decomposition) products : carbon monoxide, carbon dioxide.
3. Emergency Monitoring Methods :
gas detector tube; The portable gas chromatography; Water testing tube
rapid detection tube method "sudden environmental pollution monitoring and emergency treatment and disposal technologies," 10,000 too editor
gas velocity measurement tube (Beijing as insurance products, product Germany 1940s)
4. Laboratory monitoring methods :
monitoring methods source
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