Setting Exposure Limits

As we outlined in Chzpter 3, under Act 1568/85 (Chapter V, Article 24, Definitions) there were two types of exposure limit defined, Exposure limit values (OELs) and biological indicator limit valu. Subsequently Presidential Decree (P.D) 338 001 transcribed almost verbatim flie Dir tive 98/94/EC on the protection of the health and safety firom the risks related to chemical agente at work . It redefined exposure limit values as follows  

Greek OELs are the products of a compromise reached after considering health and administrative, political and economic issues. There is a two tier system in place to set OELs, comprising of a scientific advisory committee and a second level in the form of the National Council for Health and Safety at Work (SYAE) in which stakeholder interests are able to take account of health and administrative, political and economic issues. 

Negotiations t e place within SYAE on all matters pertaining to occupational health and safety. It is effectively an institutionalized forum for national consultation on which 17 different interest groups aro represented. Following agreement within SYAE, the General Directorate of Working Conditions of the Ministry of Labour, throu its 

Directorate of Working Conditions is responsible for formulating the summary information r ort of the emerging decision on the exposure limit as a Presidential Decree. 

Tf the assessment provided for in paragrq)h 1 reveals the pr ence of at least one of the foilowing conditions  

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The purpose of an HSG is to facilitate the application of the EHC guidelines for setting exposure limits in national chemical safety programs. 

The alarm levels for deployed ACAMS monitors at various facility sites are typically set at 20 percent of a specific airborne exposure limit or process control level. Thus, the absence of an ACAMS monitor alarm may be assumed to indicate that no agent concentrations of more than 20 percent of the airborne exposure limit have persisted for longer than the cycle period ( 3 to 8 minutes). The Army has set exposure limits and process controls at the levels mandated (in permits) for current disposal facility operations (U.S. Army, 1997a). These are reprinted in Table 2-2. The... 

Deterministic responses from exposure to hazardous chemicals generally are of concern in health protection of the public because many of the exposure limits derived from the assumed thresholds and the applied safety and uncertainty factors fall within the range of potential routine exposures. However, the possibility that the large safety and uncertainty factors normally used in setting exposure limits are quite conservative (pessimistic) could be taken into account in developing a risk-based waste classification system. Deterministic responses from exposure to radionuclides should not be of concern in health protection of the public or in classifying waste, because the dose limits intended to prevent deterministic responses are substantially higher than the dose limit intended to limit the occurrence of stochastic responses. 

At this point, the OEB or OEL becomes a guide in the development of a compound handling guidance. By using knowledge of expected exposure levels for worker activities in combination with knowledge about protection factors expected from controls, one can develop procedures for handling the compound in such a manner that the worker s exposure is below the set exposure limits. 

In general, the usefulness of the occupational studies in setting exposure limits is limited by methodology. In one study (Blanc et al. 1985), for instance,... 

Most of the risk assessments are performed for decision-making such as setting exposure limits for a chemical. The human cancer potency (q human) derived from oral route exposure data can be used to estimate chemical exposure or intake associated... 

Set exposure limits to toxic chemicals for all kinds of living organisms, including humans. 

The NOEL is used in setting exposure limits such as the Acceptable Daily Intake (ADI) for chemicals such as food additives or Threshold Limit Values (TLV) for industrial chemicals, usually with a 100-fold or sometimes greater safety factor to take account of species differences in response and human variability in response ... 

Exposure limits are mainly concerned with concentrations of silicon-containing compounds in air particles in industrial settings. Exposure limits recommended by the National Institute for Occupational Safety and Health (NIOSH) and the American Conference of Governmental Industrial Hygienists (ACGIH) are presented in Table 3.4. 

The Chemical Agents Directive 98/24/EC. The first comprehensive fi amework for Community legislation on chemicals in the woriqjlace was included in Coimcil Directive 80/1107/EEC, which set out measures for the control of risks due to chemical, ph ical d biological agents. It was amended in 1988 by the adoption of Directive 88/642/EEC that focused on the mechanism for setting exposure limits for hazardous chemicals. This directive repealoi on 5 May 2001 with... 

Procedtffwi for setting OELs. OELs are derived from entiflc data but are considered administrative limits since social, technical as well as economic aspects are all taken into account in setting them. Sweden had one of the frrst mdq>endent national systems frr setting exposure limits in Western Europe. Its first list was published in 1969 and although it was based almost entirely on the ACGIH list of TLVs, subsequent Swedish lists have contained valu that are substantially different from those of the American list. Indeed as Hanson (1998) shows the overall cluinge in Swedish OELs smce their inception in 1979 has been a steady trend towards lower values. ... 

The first European framework directive 80/1107/EEC on occupational safety (now repealed and replaced by directives 89/391/EEC and 98/24/EC) foresaw in article 8 the estabhshment of indicative as well as binding limit values for certain chemical substances. The aim of this mandate given to the European Council was to establish procedures and rules for deriving limit values and, of course, to set exposure limits based on these. In order to achieve this, the further harmonization and raising of occupational safety standards in relation to chemicals should be striven for as a practical step toward the realization of the social dimension of the common market in Europe. 

From the three items of information it is possible to find out if an exposure is hazardous. For some agents it is necessary to complete a computation to determine the hazard for an exposure. To determine if there is a hazard, it is necessary to compare the acmal exposure to a reference standard. Reference standards come from studies of illnesses and related exposures. In some cases scientific specialists recommend allowable exposures. In other cases, government agencies set exposure limits. Not all reference standards agree on allowable exposures and exposure limits. Over time, additional studies may lower recommended exposures. Government agencies in different countries will not agree on allowable exposures. The philosophies that influence reference standards may differ. 

There are numerous standards that set exposure limits that may rely on ventilation systems for the protection of workers, building occupants, and others. Other chapters have covered exposure standards and protection from other hazards. There are few standards that address ventilation methods, systems, and design. The Bibliography for this chapter lists references on ventilation technology and system planning and design. 

Table 4.66 lists the standards in Sec. 1910.1001 through 1910.1052 of Title 29, Chap. XVII, Sec. 1910.1000. These standards are detailed sets of regulations for individual substances. In addition to setting exposure limits, they require exposure monitoring and medical surveillance of exposed employees. 

In some circumstances, employers are required to measure the concentration of hazardous substances in the air. These include where the employer cannot be certain that set exposure limits are not being exceeded or that specific control measures are not working. In general, measuring concentrations is a job for specialists, although there are some simple techniques which can be used in-company. 

Describe control measures employees can take to protect themselves. OSHA sets exposure limits for airborne concentration of Cr(VI). Exposures to Cr(VI) can be reduced or eliminated through the use of engineering and work practice controls. If these control measures don t reduce exposvu es to, or below, OSHA s permissible exposure limit, employees must wear respirators. When eye or skin contact with Cr(VI) is possible, employees must use personal protective equipment. Describe to employees appropriate work practices, emergency procedures, and protective equipment to be used. 

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