Concentration, maximum allowable

Elemental fluorine and the fluoride ion are highly toxic. The free element has a characteristic pungent odor, detectable in concentrations as low as 20 ppb, which is below the safe working level. The recommended maximum allowable concentration for a daily 8-hour time-weighted exposure is 1 ppm. 

Care should be taken in handling and using iodine, as contact with the skin can cause lesions iodine vapor is intensely irritating to the eyes and mucus membranes. The maximum allowable concentration of iodine in air should not exceed 1 mg/nu (8-hour time-weighted average -40-hour). 

The maximum permissible body burden for ingested polonium is only 0.03 microcuries, which represents a particle weighing only 6.8 x IO-12 g. Weight for weight it is about 2.5 x lOii times as toxic as hydrocyanic acid. The maximum allowable concentration for soluble polonium compounds in air is about 2 x lO-ii microcuries/cnu. 

Working with uranium requires the knowledge of the maximum allowable concentrations that may be inhaled or ingested. 

The maximum allowed concentration of chloride in a municipal drinking water supply is 2.50 X 10 ppnr Ch. When the supply of water exceeds this limit, it often has a distinctive salty taste. What is this concentration in moles Ck/liter ... 

Health and Safety Factors. Sulfur hexafluoride is a nonflammable, relatively unreactive gas that has been described as physiologically inert (54). The current OSHA standard maximum allowable concentration for human exposure in air is 6000 mg/m (1000 ppm) TWA (55). The Underwriters Laboratories classification is Toxicity Group VI. It should be noted, however, that breakdown products of SF, produced by electrical decomposition of the gas, are toxic. If SF is exposed to electrical arcing, provision should be made to absorb the toxic components by passing the gas over activated alumina, soda-lime, or molecular sieves (qv) (56). 

Toxicity. Sulfur tetrafluoride has an inhalation toxicity comparable to phosgene. The current OSHA standard maximum allowable concentration for human exposure in air is 0.4 mg/m (TWA) (54). On exposure to moisture, eg, on the surface of skin, sulfur tetrafluoride Hberates hydrofluoric acid and care must be taken to avoid bums. One case of accidental exposure of electrical workers to decomposed SF gas containing SF has been cited (108). 

The OSHA standard maximum allowable concentration for human exposure in air is 0.10 mg/m (TWA) (55). No commercial uses for this compound have developed. 

Hydrogen chloride in air is an irritant, severely affecting the eye and the respiratory tract. The inflammation of the upper respiratory tract can cause edema and spasm of the larynx. The vapor in the air, normally absorbed by the upper respiratory mucous membranes, is lethal at concentrations of over 0.1% in air, when exposed for a few minutes. HCl is detectable by odor at 1—5 ppm level and becomes objectionable at 5—10 ppm. The maximum concentration that can be tolerated for an hour is about 0.01% which, even at these levels, causes severe throat irritation. The maximum allowable concentration under normal working conditions has been set at 5 ppm. 

The U.S. Occupational Safety and Health Administration (OSHA) has set a ceiling level for iodine of 0.1 ppm in air. The American Conference of Government and Industrial Hygienists (ACGIH) estabUshed 0.1 ppm as the TLV (TWA) for iodine. The maximum allowable concentration in air (MAK value) is also 0.1 ppm (104—106). 

Health nd Safety Factors. The mononitrochlorobenzenes are toxic substances which may be absorbed through the skin and lungs giving rise to methemoglobin. Their toxicity is about the same as or greater than that of nitrobenzene. The para isomer is less toxic than the ortho isomer, and the maximum allowable concentration that has been adopted for -nitrochlorobenzene is 1 mg/m (0.1 ppm) (6). The mononitrochlorobenzenes are moderate fire hazards when exposed to heat or flame. They ate classified by the ICC as Class-B poisons. The same handling precautions should be used for these compounds as are used for nitrobenzene. 

Health and Safety Factors. The toxic effects of the mononitrotoluenes are similar to but less pronounced than those described for nitrobenzene. The maximum allowable concentration for the mononitrotoluenes is 2 ppm (11 mg/m ) (6). Mononitrotoluenes are low grade methemoglobin formers (4) and may be absorbed through the skin and respiratory tract. The toxicity of alkyl nitrobenzenes decreases with an increasing... 

Toxicological Information. The toxicity of the higher olefins is considered to be virtually the same as that of the homologous paraffin compounds. Based on this analogy, the suggested maximum allowable concentration in air is 500 ppm. Animal toxicity studies for hexene, octene, decene, and dodecene have shown Httle or no toxic effect except under severe inhalation conditions. The inhalation LD q for 1-hexene is 33,400 ppm for these olefins both LD q (oral) and LD q (dermal) are >10 g/kg. 

Table 1. Maximum Allowable Concentrations of Significant Constituents in Municipal (Domestic) Water Supplies ...

Because pulp bleaching agents are, for the most part, reactive oxidising agents, appropriate precautions must be taken in their handling and use. For example, it is important to ensure that the threshold limit values (TLV) (20) in Table 2 are not exceeded in the workplace air. These are airborne concentrations in either parts per million by volume under standard ambient conditions or mg per cubic meter of air. They "represent conditions under which it is beUeved that nearly all workers may be repeatedly exposed, day after day, without adverse effect" (20). TWA refers to a time-weighted average for an 8-h workday STEL is a short-term exposure limit or maximum allowable concentration to which workers can be continuously exposed for 15 minutes. 

One of perspective development trends of methods of heavy metals contents reification in natural waters is the creation of selective and express test-method with a possibility of detection at a level and above than maximum allowable concentrations (MAC) of metals - toxiferous. 

Thus excess of Mn(IV) hydroxide represents itself as a collector of thallium which practically completely passes into a deposit, and interfering metal ions (Cu, Cd, Pb, Ni, etc.) remain in a solution and are separated providing high selectivity of thallium determination. Effect of some factors on the value of analytical signal of thallium has been investigated at the stages of water pretreatment. Based on of these data the unified technique for thallium determination has been developed and tested on natural waters. The method proposed allows to determine content of thallium in waters which is 10 times lower than it is required by maximum allowable concentration limits. 

Toxicity information Toxic hazard rating Hygiene standard (e.g. OLE, TLV) Maximum allowable concentration (MAC) Lethal concentration (LC50) Lethal dose (LD50) ... 

In the early development of such limits, they were generally known as Maximum Allowable Concentrations or MACs, sometimes called Maximum Acceptable Concentrations, or Maximum Permissible Concentrations. 

Ceiling exposure limit The maximum allowed concentration of a contaminant to which a worker may be exposed, set by legislation. 

Maximum allowable concentration (MAC) An old American definition used before the term TLV came into use (the term is still used in Germany). See Threshold limit value (TLV). 

Food Products That May Contain Specific Colorants and Maximum Allowed Concentrations... 

Threshold Limit Value (TLV)—The maximum concentration of a substance to which most workers can be exposed without adverse effect. TLV is a term used exclusively by the ACGIH. Other terms used to express the same concept are the MAC (Maximum Allowable Concentration) and PEL (Permissible Exposure Limits). 

In a design situation there will be constraints on the possible values of the objective function, arising from constraints on the variables such as, minimum flow-rates, maximum allowable concentrations, and preferred sizes and standards. 

A hold tank is installed in an aqueous effluent-treatment process to smooth out fluctuations in concentration in the effluent stream. The effluent feed to the tank normally contains no more than 100 ppm of acetone. The maximum allowable concentration of acetone in the effluent discharge is set at 200 ppm. The surge tank working capacity is 500 m3 and it can be considered to be perfectly mixed. The effluent flow is 45,000 kg/h. If the acetone concentration in the feed suddenly rises to 1000 ppm, due to a spill in the process plant, and stays at that level for half an hour, will the limit of 200 ppm in the effluent discharge be exceeded ... 

NY Effluent standards Maximum allowable concentrations into saturated or unsaturated zones 0.05 mg/L CELDS 1990a... 

Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants, Volume 1 (1994), Volume 2 (1996), Volume 3 (1996), Volume 4 (2000)... 

NRC (National Research Council). 1992. Guidelines for Developing Spacecraft Maximum Allowable Concentrations for Space Station Contaminants. Washington, DC National Academy Press. 

Ministry of Social Affairs and Employment (SDU Uitgevers). 1999. Nationale MAC (Maximum Allowable Concentration) List, 1999. The Hague, The Netherlands. 

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