Exposure limits set

WEEL Workplace Environmental Exposure Limit set by the American Industrial Hygiene Association (AIHA). 

These effects are generally associated with higher exposure levels than occur now. The current exposure limit set by the OSHA (Occupational Safety and Health Administration) in the USA is i ppm. This is the amount a worker can be exposed to for an eight-hour working day or for a forty-hour working week. ... 

Of the lanthanides, only yttrium has occupational exposure standards. The other lanthanides have low levels of toxicity similar to or less toxic than yttrium and therefore the exposure limits set for yttrium are generally used for the other lanthanides. 

The exposure limits (permissible exposure limits) set by the Occupational Health an Safety Administration is 0.05 mg m for skin in both general industry and construction industry. This is the same limit (0.05 mgm ) established by ACGIH (TLV) and the National Institute for Occupational Safety and Health (recommended exposure limit). 

Permissible Exposure Limit (PEL)—An exposure limit set by OSHA that is required by law. 

Trace Components The trace components of landfill gas mainly comprise a range of alkanes and alkenes, and their oxidation products (aldehydes, ketones, alcohols and esters). Waste Management Paper 26 (DoE, 1986) lists 108 compounds, or groups of compounds found in landfill gas sampled at six different landfill sites. Many of these trace compounds in landfill gas are recognised toxicants when present in air at concentrations which exceed established toxicity threshold limit values (TLVs) or the Occupational Exposure Standards (OESs) set by the Health and Safety Executive. Anyone coming into contact with landfiU gas is therefore potentially at risk from the toxic nature of the minor components, and under the Control of Substances Hazardous to Health Regulations (COSHH, 1988), landfill operators are legally responsible for the health of employees and are required to comply with OES s and exposure limits set by the Health and Safety Executive (HSE). 

UEL - Upper Flammability Limit the maximum concentration of a chemical in air at which flame propagation can occur. WEEL - Workplace Environmental Exposure Limit set by the American Industrial Hygiene Association (AIHA). 

At the present time, the exposure of people at work to chemical hazards is controlled by reference to the limits set by safety authorities, i.e. the occupational exposure limits set by the Health and Safety Executive in the UK and threshold limit values set by the Occupational Safety and Health Association in the USA. In the UK two types of limits are currently in operation recommended limits and control limits. 

Exposure limits (threshold limit value or TLV) are those set by the Occupational Safety and Health Administration and represent conditions to which most workers can be exposed without adverse effects. The TLV value is expressed as a time weighted average airborne concentration over a normal 8-hour workday and 40-hour workweek. 

Handling and Toxicity. Tungsten hexafluoride is irritating and corrosive to the upper and lower airways, eyes, and skin. It is extremely corrosive to the skin, producing bums typical of hydrofluoric acid. The OSHA permissible exposure limits is set as a time-weighted average of 2.5 mg/kg or 0.2 ppm (22). 

The mean exposure limit value for 3-methyl-1-butanol in the air of workplaces was set at 100 ppm in 1984 by the ACGIH (135). Standards have not been set for the other alcohols (135). 

Occupational Safety and Health. OSHA has set no specific limits for sodium and potassium sibcates (88). A pmdent industrial exposure standard could range from the permissible exposure limit (PEL) for inert or nuisance particulates to the PEL for sodium hydroxide, depending on the rate of dissolution and the concentration of airborne material. Material safety data sheets issued by siUcate producers should be consulted for specific handling precautions, recommended personal protective equipment, and other important safety information. 

The threshold limit value (TLV) set by the American Conference of Industrial Hygienists (ACGIH) for teUurium and its compounds is 0.1 mg/m which is about ten times the amount which has been known to produce the adverse garUc odor (45,50). The ACGIH TLV for teUurium hexafluoride is 0.1 mg/m or 0.02 ppm of air. Likewise, the U.S. Occupational Safety and Health Administration (OSHA) has estabUshed its permissible exposure limit (PEL) for teUurium and its compounds at 0.1 mg/m the PEL for teUurium hexafluoride is 0.2 mg/m or 0.02 ppm of air (50). 

Thiophene and 3-methylthiophene are Hsted on the TSCA chemical substances inventory. Thiophene is regulated as a hazardous material under OSHA and also regulated under the Clean Air Act, Section 110, 40 CFR 60.489, but there are no exposure limits or controls set for 3-methylthiophene. Both materials are regulated under sections 311/312 of the Superfund Amendments and Reauthorization Act, 1986 (SARA), as materials with an acute health and fire hazard, and under the Resource Conservation and Recovery Act, as ignitable hazardous wastes (DOOl). 

Permissible Exposure Limits in Air. Occupational exposure to insoluble tungsten needs to be controlled so that employees are not exposed to insoluble tungsten at a concentration greater than 5 mg tungsten/m air, determined as a TWA concentration for up to a 10-h workshift in a 40-h workweek. An STEL value of 10 mg/m has been set by ACGIH in 1983. 

Toxicity Data on Af- Vinyl-2-Pyrrolidinone. Results of a chronic inhalation study in rats warrant a review of industrial hygiene practices to assure that VP vapor concentrations are maintained at a safe level. One of the manufacturers, ISP, recommends that an appropriate workplace exposure limit be set at 0.1 ppm (vapor) (9). Additionally, normal hygienic practices and precautions are recommended, such as prompt removal from skin and avoidance of ingestion. In case of accidental eye contact, immediately flush with water for at least 15 minutes and seek medical attention. Refer to the manufacturers Material Safety Data Sheets for more detailed information. Table 3 provides some toxicity data. 

Effective Dec. 10, 1987, the existing standard for benzene was amended under OSHA (29 CER, Part 1910.1028). The revised standard reduced the permissible exposure limit from 10 ppm (32 mg/m ) to 1 ppm (3.2 mg/m ) iu an 8-h TWA. The short term exposure limit (STEL) of 5 ppm was set over a 15 min period. The standard also established action level requirements for exposure over 0.5 ppm. 

For worker exposure to trichloroethylene vapor, OSHA set a maximum eight-hour time-weighted average (TWA) concentration of 100 ppm. This severely restricted certain appHcations, and many organizations converted to other chlorinated solvents. As a result, U.S. production of trichloroethylene declined about 70% from a peak in 1970 (Table 2). In 1989, OSHA lowered the permissible exposure limit (PEL) from 100 ppm eight-hour TWA to 50 ppm eight-hour TWA (33). This added further pressure for some users to consider changing to alternative solvents. 

Exposure occurs almost exclusively by vapor inhalation, which is followed by rapid absorption into the bloodstream. At concentrations of 150—186 ppm, 51—70% of the trichloroethylene inhaled is absorbed. MetaboHc breakdown occurs by oxidation to chloral hydrate [302-17-OJ, followed by reduction to trichloroethanol [115-20-8] part of which is further oxidized to trichloroacetic acid [76-03-9] (35—37). Absorbed trichloroethylene that is not metabolized is eventually eliminated through the lungs (38). The OSHA permissible exposure limit (PEL) eight-hour TWA concentration has been set at 50 ppm for eight-hour exposure (33). 

Exposures require eontrol sueh that nearly all people would not suffer any adverse health effeets even if exposed to a speeifie substanee (or mixture of substanees) day after day. Eor eertain substanees there are set oeeupational exposure limits refer to page 78. 

Control of Substances Hazardous to Health Regulations (COSHH). Guidance on Setting In-House Occupational Exposure Limits (Regulation 7 (1990)... 

This concentration should be compared against permissible exposure limits estabhshed by OSHA (Occupational Safety and Health Act) and allowable discharges limits set by federal (EPA) and local emissions regulations. 

Thus, there is a clear need to establish the relationship between the health effects of hazardous chemical agents in the environment and the level of occupational exposure to the body by means of an occupational exposure limit, in which a reference figure for the concentration of a chemical agent is set. In fact, occupational exposure limits (OELs) have been a feature of the industrialized world since the early 1950s. They were introduced, primarily in the United States, at a time when measures to prevent occupational diseases were considered more beneficial than compensating victims, and in this sense OELs have played an important part in the control of occupational illnesses. 

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

Toxicologists tend to focus their attention primarily on c.xtrapolations from cancer bioassays. However, tlicrc is also a need to evaluate the risks of lower doses to see how they affect the various organs and systems in the body. Many scientific papers focused on tlic use of a safety factor or uncertainty factor approach, since all adverse effects other than cancer and mutation-based dcvclopmcnUil effects are believed to have a tlu cshold i.e., a dose below which no adverse effect should occur. Several researchers have discussed various approaches to setting acceptable daily intakes or exposure limits for developmental and reproductive toxicants. It is Uiought Uiat an acceptable limit of exposure could be determined using cancer models, but today tliey arc considered inappropriate because of tlircsholds. ... 

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