Ventilation toxic laboratories

The Uniform Fire Code requires that pyrophoric, flammable, or highly toxic gases be within ventilated gas cabinets, laboratory fume hoods, or exhausted enclosures. ... 

Other properties of solvents which need to be considered are boiling point, viscosity (lower viscosity generally gives greater chromatographic efficiency), detector compatibility, flammability, and toxicity. Many of the common solvents used in HPLC are flammable and some are toxic and it is therefore advisable for HPLC instrumentation to be used in a well-ventilated laboratory, if possible under an extraction duct or hood. 

Ensure that the laboratory in which the apparatus is housed is well ventilated and is provided with an adequate exhaust system having air-tight joints on the discharge side some organic solvents, especially those containing chlorine, give toxic products in a flame. 

Cyanogen bromide is an extremely toxic chemical and should be used only in a well-ventilated fume hood using the appropriate personal protective gear. The following protocol is based on the method of March et al. (1974), as recommended by Bang s Laboratories. 

Just as laboratories are unique from other buildings, so are their ventilation systems. The laboratory chemical fume hood is the primary engineering control used to protect workers from potential serious exposures to toxic substances, yet they are often the last furnishings considered. 

Safety glasses must be worn in the laboratory at all times. Material safety and data sheets should be read prior to the start of the experiment. All chemicals should be considered hazardous from a standpoint of flammability and toxicity. Appropriate safety gloves must be worn when using organic solvents so that no skin contact is permitted. Care must be taken to use organic solvents either in a well-ventilated area or in a hood. Avoid breathing the fumes or sources of electrical sparks. The GPC instrument, including solvent reservoir and waste container, should be vented to a fume hood or other exhaust system. 

The laboratory should at least be well ventilated and safety glasses should be worn, particularly during distillation and manipulations carried out under reduced pressure or elevated temperatures. With this in mind we have endeavoured to warn users of this book whenever greater than usual care is needed in handling chemicals. As a general rule, however, all chemicals which users are unfamiliar with should be treated with extreme care and assumed to be highly flammable and toxic. The safety of others in a... 

Great care should be taken with the use of mercury on account of its toxicity. Spills should be dealt with immediately and mishaps avoided by the use of trays placed under the apparatus. Additionally, the laboratory should be well ventilated. 

After use in an electrochemical experiment, mercury should be redistilled. It is highly toxic, especially as vapour, so care should be exercised any drops that escape should be caught in a tray placed underneath the cells, and the laboratory must have good ventilation. 

Benzene can have both chronic and acute toxic effects. The risk of acute effects is low, since acute symptoms occur only at 1000 ppm or higher. Chronic vapor inhalation at the level of 25 to 50 ppm can cause changes in blood chemistry, and co/ rmoa7 exposure at 100 ppm can cause severe blood disorders. The OSHA exposure limits for benzene vapor are 1 ppm as an 8-hour time-weighted average and a ceiling of 50 ppm for no more than 10 min. In order to reach the level of 10 ppm in a laboratory of 750 m volume, 23 g of liquid benzene would have to evaporate into a closed atmosphere. Thus the hazards associated with the infrequent use of liquid benzene in a well-ventilated laboratory are very low. 

Great care must be used iu haudliug HCN. The lack of reported iucideuts, coupled with the widespread commercial use of volatile aud highly toxic HCN, points to the respect and care with which it is treated within industry. In a laboratory, HCN should be used only in small quantities in a well-ventilated fume hood. Vapors may be scrubbed or small samples (up to a few milliliters) may be disposed of by treatment with an equimolar mixture of caustic (NaOH) and hypochlorite bleach (NaOCl). Larger samples or vapor streams should be burned. The use of a buddy system and first response training is essential when using HCN. ... 

The most popular and generally effective method for lipid determination of fish is the modified BHght and Dyer method [44] see also [42]. The extraction of lipids is performed with a mixture of chloroform and methanol (1 1). For the procedure of this method see [42, 44]. Unfortunately, methanol is distinctly toxic, producing headaches if the laboratory is inadequately ventilated, and chloroform has been suspected of being carcinogenic. It is assumed that for these reasons this method was not accepted as an official OECD Guideline, although it was proposed for review panel in 1980. Therefore, this method should be used only if the results of extraction have to be compared with those of other laboratories. 

Numerous studies have been carried out on the effects of single chemicals on the liver, of which ethanol and carbon tetrachloride are the most notorious. [4,81 Other hepatotoxic chemicals, however, have also been widely studied, both in the laboratory and environmentally. For example, an outbreak of toxic liver disease was reported in a fabric coating company. Upon investigation, it was found that dimethylformamide, a known hepatotoxin, was used as a coating solvent in poorly ventilated areas without appropriate skin protection, and no other hepatotoxins were identified. 1121... 

Mercury and its compounds are highly toxic. Air saturated with mercury vapor contains about 15 mg Hg per in In badly ventilated laboratories the amounts of Hg vapor derived from spilt mercury In the air may suffice to induce chronic mercury poisoning. The inhaled mercuiy is only very slowly excreted via the urine. I )imethylniercury (CHj)2Hg is extremely toxic and can cause irreversible damage to the central nervous system. Ozone is a strong oxidising agent and very toxic. 

The safety of preparative processes depends on the flammability and toxicity of the solvent. Owing to the huge amounts of solvents handled in preparative chromatography, low flammability should be preferred. Flammability is described by the vapor pressure, the explosion limits or the temperature class of the solvent. Generally, the use of flammable solvents can not be avoided and thus the risk must be minimized by good ventilation and other precautions in the laboratory. 

Silanization steps are performed in a N2-filled glove bag in a ventilated hood. This is to prevent air-oxidation of the thiol-silane, as well as to protect laboratory personnel from inhaling silane fumes. Triethoxy silanes are used in preference to trimethoxy silanes, due to decreased toxicity. 

This means that spillages, whether on a small scale in the laboratory or on a large scale in an industrial plant, will give rise to vapour at a low level. Ventilation should therefore be designed to draw from this level and tests for flammable or toxic concentrations should be made at a low point. 

This is a very high velocity, which could hardly be used inside a paint shop. Our practical alternatives are to choose a less toxic solvent, for which the permitted concentration is higher, or to devise some kind of ventilation system, such as a laboratory fume hood, which will prevent the mixing of the benzene with the air that workers breathe. We also need to consider the air pollution consequences of emitting 200 kg/day of benzene to the atmosphere in most U.S. cities that would require a permit and probably some form of capture or destruction of the benzene. 

It is important to emphasize some aspects of safety. Cylinders of fuel and oxidant gases must be fastened to a wall or laboratory bench. The exhaust gases have to be channelled through an adequate ventilation system and released into the atmosphere. In some cases (e.g. when employing nitrous oxide) the exhaust gases are toxic. Special care has to be exercised when lighting and extinguishing the flame. 

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