Xylenes toxicity

BTXE Benzene, Toluene, Ethylbenzene and Xylene Toxic chemicals which are associated with petroleum products. 

Xylene toxicity has received less study than that of toluene, but appears considerable less which supports attributed the neurotoxicity to toluene of mixtures of xylene, benzene and toluene with straight chain hydrocarbons such as gasoline. 

The xylenes are mildly toxic. They ate mild skin irritants, and skin protection and the cannister-type masks are recommended. The oral LD q value for rats is 4300 ppm. The STEL for humans is 150 ppm. Xylenes show only mild toxicity to fish, and the threshold limit for crop damage is 800—2400 ppm. Biodegradation with activated seed is slow, and sewage digestion is impaired by 0.1% concentrations. In the event of a spih, oil-skimming equipment, adsorbent foam, and charcoal maybe used for cleanup. 

Emulsives are solutions of toxicant in water-immiscible organic solvents, commonly at 15 ndash 50%, with a few percent of surface-active agent to promote emulsification, wetting, and spreading. The choice of solvent is predicated upon solvency, safety to plants and animals, volatility, flammabiUty, compatibihty, odor, and cost. The most commonly used solvents are kerosene, xylenes and related petroleum fractions, methyl isobutyl ketone, and amyl acetate. Water emulsion sprays from such emulsive concentrates are widely used in plant protection and for household insect control. 

The solubiHty of phosphoms in water is about 3 ppm. However, process water used in phosphoms manufacture or handling often catties larger amounts of phosphoms as particulates or small droplets, depending on the water temperature. Phosphoms-contaminated water is commonly called phossy water. Phosphoms has low solubiHty in most common solvents, but is quite soluble in carbon disulfide and some other special solvents. The solubiHty in CS2 and benzene was formerly used in phosphoms analyses, but toxicity and increasing waste disposal costs have led to mote use of toluene and xylene, and mote tecentiy to the use of nonchemical turbidity measurements. 

The PMBs, as higher homologues of toluene and xylenes, ate handled in a similar manner, even though their flash points are higher (see Table 1). Containers are tightly closed and use areas should be ventilated. Breathing vapors and contact with the skin should be avoided. Toxicity and primary... 

Solvents acetone, methyl ethyl ketone (MEK), toluene, xylene, glycol, ethers, alcohol defats and dries skin some may be absorbed may carry other components through skin high volatility, exposure possible irritation central nervous system depression (e.g. dizziness, loss of coordination) low to high toxicity, longterm effects... 

Of the top ten most frequently reported toxic chemicals on the TRI list, the prevalence of volatile chemicals explains the air intensive toxic chemical loading of the refining industry. Nine of the ten most commonly reported toxic chemicals are highly volatile. Seven of the ten are aromatic hydrocarbons (benzene, toluene, xylene, cyclohexane, 1,2,4-trimethylbenzene, and ethylbenzene). 

Toxicity and Environmental Fate Information for Xylenes (Mixed Isomers)... 

Benzene is a flammable liquid and its vapors are toxic and explosive. Low concentrations are dangerous on continued inhalation because benzene affects the blood forming function of the bone marrow and it is a cancirogen. Dermatitis may result from repeated skin contact. Alkyl derivatives such as toluene and xylenes are far less toxic and are, therefore, much safer than benzene for use in solvents. Some of the symptoms of benzene poisoning are dizziness, constriction of the chest, and tightening of the leg muscles. 

Although many of the aromatic compounds based on benzene have pleasant odors, they are usually toxic, and some are carcinogenic. Volatile aromatic hydrocarbons are highly flammable and burn with a luminous, sooty flame. The effects of molecular size (in simple arenes as well as in substituted aromatics) and of molecular symmetry (e.g., xylene isomers) are noticeable in physical properties [48, p. 212 49, p. 375 50, p. 41]. Since the hybrid bonds of benzene rings are as stable as the single bonds in alkanes, aromatic compounds can participate in chemical reactions without disrupting the ring structure. 

Toxicity. Picric Acid is more toxic than the nitro derivatives of toluene, xylene or naphthalene. It is, however, much less toxic than nitro derivatives of benzene... 

About 100 gal of process wastewater is typically generated from 1 t of coke produced.15 These wastewaters from byproduct coke making contain high levels of oil and grease, ammonia nitrogen, sulfides, cyanides, thiocyanates, phenols, benzenes, toluene, xylene, other aromatic volatile components, and polynuclear aromatic compounds. They may also contain toxic metals such as antimony, arsenic, selenium, and zinc. Water-to-air transfer of pollutants may take place due to the escape of volatile pollutants from open equalization and storage tanks and other wastewater treatment systems in the plant. 

Conversion of an organic compound to another organic compound without the microorganism using the compound as a nutrient. Resulting compounds may be as toxic (DDT to DDE or DDD) or less toxic (xylenes to toluic acid). 

Fugitive air emissions of volatile components released during hydrotreating may also be toxic components. These include toluene, benzene, xylenes, and other volatiles that are reported as toxic chemical releases under the EPA Toxics Release Inventory. 

Short-term (acute) hazards of lighter, more volatile, and water-solnble aromatic compounds (such as benzenes, toluene, and xylenes) include potential acnte toxicity to aquatic life in the water column (especially in relatively confined areas) as well as potential inhalation hazards. However, the compounds that pass through the water column often tend to do so in small concentrations and/or for short periods of time, and fish and ofher pelagic or generally mobile species can often swim away to avoid impacfs from spilled oil in open waters. Most fish are mobile and it is not known whether or not they can sense, and thns avoid, toxic concentrations of oil. 

There are indications that pure naphthalene (a constituent of mothballs, which are, by definition, toxic to moths) and alkylnaphthalenes are from three to 10 times more toxic to test animals than are benzene and alkylbenzenes. In addition, and because of the low water solubility of tricyclic and polycyclic (polynuclear) aromatic hydrocarbons (i.e., those aromatic hydrocarbons heavier than naphthalene), these compounds are generally present at very low concentrations in the water-soluble fraction of oil. Therefore, the results of this smdy and others conclude that the soluble aromatics of crude oil (such as benzene, toluene, ethylbenzene, xylenes, and naphthalenes) produce the majority of its toxic effects in the enviromnent. 

Petroleum refineries are a somce of hazardous and toxic air pollutants, such as BTEX compounds (benzene, toluene, ethylbenzene, and xylene). They are also a major source of criteria air pollutants particulate matter (PM), nitrogen oxides (NO t), carbon monoxide (CO), hydrogen sulfide (H2S), and sulfur oxides (SO ). 

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