National exposure limits

Several steps have been taken towards a more harmonised methodology within the more general area of risk assessment of chemicals. The EU has proposed a number of principles for assessment of risks to man and the environment in directive 93/67/EEC (EC 1993) as well in the Technical guidance documents in support of directive 96/67/EEC on risk assessment (EC 2003), to further common practices in risk assessment. A harmonisation of national exposure limits is to be expected, since the EU sets both binding and indicative OELs for each member state to consider in its national regulations. However as noted by Vincent (1998) a full international harmonisation of OELs is unlikely and may not even be the most... 

The final column in Table 9.4 displays the geometric similarity measure for the current lists of OELs. This similarity measure can only range between 0 and 1. The closer the national exposure limits are to EU exposure limits, the closer is the geometric similarity to one. As can be seen in Table 9.4 the Estonian exposure limits are the ones most similar to the EU OELs. Least similar to the EU OELs are the Swedish exposure limits. The geometric similarity of the national OELs tends to increase over time. This means that the national exposure limits are approaching the EU level. 

COMPARATIVE NATIONAL EXPOSURE LIMITS FOR PHOSGENE IN OCCUPATIONAL AIR... 

There must be a clear definition of what is to be considered dangerous or unacceptable. EC s approach is to use short-term exposure data and to compare them to the STEL, which it defines as the maximum acceptable TWA concentration over a 15-min period. The anticipated value, somewhat conservative, is 0.5 ppm. At the time of publication of this standard, various national exposure limits were between 0.5 and 1.0 ppm, averaged over an 8-hr day, with STELs most frequently at 1.0 ppm. 

The National Institute of Occupational Safety and Health (NIOSH), under the Department of Health and Human Services, works with OSHA. It is NIOSH s responsibihty to determine safe exposure limits for chemical substances and to recommend to OSHA that these limits be adopted as standards. 

Other toxicological effects that may be associated with exposure to benzyl chloride based on animal studies are skin sensitization and developmental embryo and/or fetal toxicity. A 1980 OSHA regulation has estabhshed a national occupational exposure limit for benzyl chloride of 5 mg/m (1 ppm). Concentrations of 160 mg/m (32 ppm) in air cause severe irritation of the eyes and respiratory tract (68). 

Binding occupational exposure limit values reflect feasibility factors related to social acceptability. When the results of environmental monitoring have to be compared with OELs, factors that influence exposure and that entail preventive policies are considered. For these values member states shall establish a corresponding national binding occupational exposure limit value based on but not exceeding the community limit value. That is, a binding limit means a minimum requirement. 

An indicative limit value is a more common type of limit that reflects expert evaluation based on scientific data where it is possible to identify the highest level of exposure along with the corresponding reference time period for which one can have confidence that there will be no adverse effects on health. For any chemical agent for which an indicative occupational exposure limit value is established at the community level, member states shall establish a national occupational exposure limit value, taking into account the community limit value and determining its nature in accordance with national legislation and practice. 

Health hazard due to exposure to contaminants by inhalation is the most important issue. International or national health and building regulations or codes and recommendations are used as basis for the discussion of what requirements should be used for design. In regulations, worker exposure limits for airbctrne gases are normally expressed as... 

EL = emissions level ERA = Environmental Protection Agency HSDB = Hazardous Substances Data Bank lARC = International Agency for Research on Cancer IRIS = Integrated Risk Information System NIOSH = National Institute of Occupational Safety and Health OEL = occupational exposure limit OSHA = Occupational Safety and Health Administration PEL = permissible exposure limit RAC = reference air concentration REL = recommended exposure limit RCRA = Resource Conservation and Recovery Act RfD = reference dose TLV = threshold limit value TWA = time-weighted average WHO = World Health Organization... 

Recommended Exposure Limit (REL)—A National Institute for Occupational Safety and Health (NIOSH) time-weighted average (TWA) concentrations for up to a 10-hour workday during a 40-hour... 

Mineral oil is the major chemical component of mineral oil hydraulic fluids. Mineral oil belongs to a larger class of chemicals called petroleum distillates. The Occupational Safety and Health Administration (OSHA) regulates petroleum distillate and mineral oil mist levels in workplace air. The occupational exposure limits for an 8-hour workday, 40-hour workweek are 2,000 milligrams per cubic meter (mg/m3) in air for petroleum distillates and 5 mg/m3 for mineral oil mists. The National Institute for Occupational Safety and Health (NIOSH) recommends an exposure limit of 350 mg/m3 of petroleum distillates for a 10-hour workday, 40-hour workweek. 

EPA = Environmental Protection Agency NIOSH = National Institute for Occupational Safety and Health OPPT = Office of Pollution Prevention and Toxics OSHA = Occupational Safety and Health Administration OSW = Office of Solid Waste STEL = Short Term Exposure Limit TWA = Time-Weighted Average USCG = U.S. Coast Guard... 

Information on occupational exposure to lead is obtained primarily from the National Occupational Exposure Survey (NOES) and industry surveys of workers. While occupational exposure is widespread, environmental monitoring data on levels of exposure in many occupations are not available. OSHA has established a permissible exposure limit (PEL) for lead of 50 pg/m3 for workplace air (OSHA 1991). NIOSH has estimated that more than 1 million American workers were occupationally exposed to inorganic lead in more than 100 occupations (NIOSH 1977a, 1978a). According to NOES, conducted by NIOSH between 1980 and 1983, an estimated 25,169 employees were exposed to tetraethyl lead (not used in gasoline since December 31, 1995) approximately 57,000 employees were exposed to various lead oxides mostly in non-ferrous foundries, lead smelters, and battery plants 3,902 employees were exposed to lead chloride and 576,579 employees were exposed to some other form of lead in the workplace in 1980 (NIOSH 1990). Workers who operate and maintain solid waste incinerators are also exposed to air lead levels as high as 2,500 pg/m3 (Malkin 1992). 

NRC (National Research Council). 1984b. Emergency and Continuous Exposure Limits for Selected Airborne Contaminants, Vol. 2. Washington, DC National Academy Press. 

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