Occupational exposure limit setting

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. 

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

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. 

Exposures require control such that nearly all people would not suffer any adverse health effects even if exposed to a specific substance (or mixture of substances) day after day. For certain substances there are set occupational exposure limits refer to page 74. 

The easiest means for assessing occupational exposure hazards associated with materials used in a process is through the use of Permissible or Occupational Exposure Limits (OEL or PEL) which go by a variety of names for example, TLV (U.S. - American Conference of Government Industrial Hygienists), MAK (Germany), or individual company established values. Occupational exposure limits are usually set based on a combination of the inherent toxicological hazard of a chemical and a series of safety factors such as intraspecies variability in test results, nature and severity of the effect, adequacy and quality of... 

The different toxicity and bioavailability of Cr(III) and Cr(VI) are a public health concern and therefore require strict control. Cr(VI) is considered to be toxic and carcinogenic, especially for the respiratory tract. In occupational health, the OEL (Occupational Exposure Limits) for water soluble and certain water insoluble compounds in indoor air is set at 0.5 mg/m for Cr, 0.5 mg/m for Cr(III), and 0.05 mg/m for Cr(VI), reflecting the different toxicities of both species. 

There are no occupational exposure limits for many hazardous substances which may require control of inhalation exposures. The necessary data and other resources required for setting such limits is restricted and unlikely to match the potential demand. A hazard categorisation scheme was, therefore, developed for application within the chemical industry. The scheme used readily-available information on toxicological endpoints to place hazardous substances into a limited range of hazard categories, expressed as Occupational Exposure Bands. These Bands could be used as a basis for risk assessment and the selection of appropriate control regimes. 10 refs. EUROPEAN COMMUNITY EUROPEAN UNION UK WESTERN EUROPE... 

TABLE 14.5. Methods for Setting Occupational Exposure Limits (OELs)... 

OSHA sets the levels of chloroform allowed in workplace air in the United States. A permissible occupational exposure limit is 50 ppm or 240 mg/m (ceiling value) in air during an 8-hour workday, 40-hour workweek. 

In occupational settings, the concentrations of chemicals are often monitored in the working environment to monitor compliance with occupational exposure limits as required by various national laws. Moreover, medical surveys of workers are often performed including analyses of biomarkers for exposure and/or effects. In addition, workers also generally have the possibility to report signs and symptoms of nuisances related to their working environment. Such data, which in some cases are available in the open literamre, are relevant for use in a hazard assessment. 

The Nordic Expert Group for Criteria Documentation of Health Risks from Chemicals (NEG) consisted of scientific experts from the five Nordic countries representing different fields of science, such as toxicology, occupational hygiene, and occupational medicine. The main task was to produce criteria documents (Figure 3.10) to be used by the regulatory authorities of the Nordic countries as the scientific basis for setting Occupational Exposure Limits (OELs) for chemical substances. 

The Occupational Safety and Health Administration (OSHA) sets rules for cresol levels in the workplace. The occupational exposure limit for 8-hour workdays over a 40-hour work week is 22 milligrams of cresols per cubic meter of air (22 mg/m ), which is equivalent to 5 ppm. See Chapter 7 for more information on regulations and guidelines for cresols. 

OSHA regulates the level of chlorine dioxide in workplace air. The occupational exposure limit for an 8-hour workday, 40-hour workweek is 0.1 parts per million (0.28 milligrams per cubic meter [mg/m ]). The EPA has set a maximum contaminant level of 1 milligram per liter (mg/L) for chlorite in drinking water and a goal of 0.8 mg/L for both the maximum residual disinfectant level for chlorine dioxide and the maximum contaminant level for chlorite in drinking water treated with chlorine dioxide as a disinfectant. 

Ku RH. 2000. An overview of setting occupational exposure limits (OELs) for pharmaceuticals. Chem. Hlth Safety 7(1) 34-37. 

Feron VJ. (2003) Setting occupational exposure limits in the European Union. In Occupational Exposure Limits —Approaches and Criteria Proceedings from a niva course held in Uppsala, Sweden, 24—28 September 2001. Ed. Johanson G. Aibete och halsa, 2003 17, Stockholm, Sweden. 

Nielsen G.D., 0vreb0 S. (2008) Background, approaches and recent trends for setting health-based occupational exposure limits a minireview. Regulatory Toxicology and Pharmacology 51(3) 253-269. 

Several years later, official EU risk-reduction strategies (RRS) for DEGBE and DEGME were produced, but discussions of possible restrictions largely focussed on applications outside industrial settings relevant to France. France therefore decided to adopt much lower occupational exposure limits than those decided at the EU level, essentially banning most industrial uses of the two substances. 

Several years later, EU risk assessment data confirmed TCE as a carcinogen, but a RRS has yet to be completed. TCE is a commonly used solvent that has several applications that may not easily be substituted, so several Member States have adopted different national regulatory controls for TCE [246]. Achieving future consensus on EU action to control this substance may therefore prove particularly difficult. Evidence suggests that, with the possible exception of setting (minimal) occupational exposure Limits, developing and implementing RRS to protect occupational health should remain at the national level for this substance. 

The TL and MAK values should be used as guides in the control of health hazards. They are not constants that can be used to draw fine fines between safe and dangerous concentrations. Nor is it possible to calculate the TL or MAK values of solvent mixtures from the data in Table A-13, because antagonistic action or potentiation may occur with some combinations. It should be noted that occupational exposure limits such as the TL and MAK values are not intended for use as a comparative measure of one solvent against another. The values set airborne concentration limits on chemical exposure, but do not describe the ease with which that airborne limit is achieved. In addition, the vapour pressure of the solvent must also be considered. The lower the vapour pressure, the lower the airborne concentration. In order to better compare the safety of volatile compounds such as organic solvents, the use of the vapour hazard ratio ( VHR) has been recommended as a feasible measure [175], The vapour hazard ratio is defined as the quotient of the saturation concentration of a solvent (in mg/m at a given temperature and pressure) and its occupational exposure limit (in mg/m e.g. TL or MAK values), according to ... 

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. ... 

Observe normal precautions appropriate to the circumstances and quantity of material handled. Microcrystalline cellulose may be irritant to the eyes. Gloves, eye protection, and a dust mask are recommended. In the UK, the occupational exposure limits for cellulose have been set at 10 mg/m long-term (8-hour TWA) for total inhalable dust and 4 mg/m for respirable dust the short-term limit for total inhalable dust has been set at 20mg/m i >... 

Acute and chronic adverse effects have been observed in workers handling the related substances methyl methacrylate and poly(methyl methacrylate) (PMMA). ° In the UK, the occupational exposure limit for methyl methacrylate has been set at 208mg/m (50ppm) long-term (8-hour TWA), and 416mg/m (100 ppm) short-term. ... 

In the UK, the occupational exposure limit for potassium hydroxide has been set at 2mg/m short-term. ... 

The OSHA sets safe and healthy workplace standards. When OSHA was formed, they adopted the then current ACGIH TLV - TWAs and TLV-Cs as occupational exposure limits and made them federal standards. However, instead of calling them TLV -TWAs, OSHA called them PELs. OSHA has both TWA and ceiling values for various chemicals. PELs are listed in Title 29 of the Code of Eederal Regulations (CER), Part 1910, Subpart Z, General Industry Standards for Toxic and Hazardous Substances. Emergency responders should understand that ACGIH and OSHA values are not always the same for each chemical. 

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. 

Several other types of occupational exposure limits are derived in addition to the OELs derived to protect against airborne chemical exposures in traditional workplace settings. 

As a result of inadequate toxicity data, no occupational exposure limits have been set by NIOSH. Also, there are no acute or chronic reference exposure levels. 

Many examples of the use of animal exposures to study the respiratory tract toxicity of inhaled chemicals are discussed in portions of this entry describing indicators of respiratory tract response. Examples cited here demonstrate ways in which animal studies are used to help protect human populations and guide assessment of human risk. For most chemicals that pose a potential inhalation risk to workers, there are insufficient human data to set safe occupational exposure limits. Using inorganic nickel compounds as an example, epidemiological data indicate an... 

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