Limit Values at the Workplace

three types of limit values have been established within the European community  

In this section, an overview of the historical development of exposure limits, the legal criteria, and the existing limit values for chemical agents is given. 

Indicative Occupational Exposure Limit Values (lOELV) 

The first European framework directive 80/1107/EEC on occupational safety (now repealed and replaced by directives 89/391/EEC and 98/24/EC) foresaw in article 8 the estabhshment of indicative as well as binding limit values for certain chemical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. 

Concerning binding limit values, a committee has so far established limit values for 11 chemicals listed in annex I of EU directive 80/1107/EEC. For details, see Section 6.5.2. 

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An assessment of the hazardous substances and their limit values at the workplace. 

For more details and a complete list of substances and their indicative limit values, given in annex I of 91/322/EEC see Section 6.5 Limit values at the workplace . 

Limit Values at the Workplace 199 Table 6.9 Overview of existing binding occupational exposure limit values. 

Hence, organic solvents should be handled with care. In the USA, the threshold limit values [TL values) are used as a measure of the inhalation toxicity for chronic interaction with solvent vapours [90]. In the Federal Republic of Germany, the maximum concentration values at the workplace [MAK values) are used [91, 92]. Threshold limit values refer to airborne concentrations of substances and represent conditions under which it is believed that workers may be repeatedly exposed daily without adverse effect. They refer to time-weighted average concentrations for a normal 8-hour workday... 

An exposure limit value is a level of noise at the ear above which an employee must not be exposed. Therefore if the workplace noise levels are above this value, any ear protection provided to the employee must reduce the noise level to the limit value at the ear. 

The limit value for suspended matter is given in mg/m or multiples thereof for actual environmental conditions (temperature and pressure) at the workplace. The limit values for fibers are given in fibers/m or fibers/cm for actual operating conditions of temperature and pressure. It is possible to con vert one expression to the other using the formula... 

The first step is to identify the substances present at the workplace. As a starting point, knowledge of the process is needed in order to formulate a list of all chemical agents used in the establishment. The list should include not only primary products but also intermediate and final products, as well as reaction products and by-products. For the chemical agents in the list, it is necessary to know their chemical properties, especially hazardous ones their OEL values, including biological limit values and, where these are not available, other technical criteria that can be used to evaluate the risk. It is also helpful to include any information on the safety and health risks of those substances provided by the supplier or other readily available sources. This information on dangerous substances and preparations, in the form of safety data sheets, is intended primarily for industrial users, to enable them to take the measures necessary to ensure the safety and health of workers. 

This situation does not apply only to Germany. The Health and Safety Executive quotes specific figures for the UK, which give an idea of application of occupational health and safety legislation there In approximately 1.3 nullion British compaiues chemicals are handled. When questioned, only 16% of these compaiues were able to state the applicable law for handling chenucals or the limit values for these substances at the workplace. With regard to the need for protective measures, these 16% also rely almost entirely on the details contained in the safety data sheets. 

Industrial workers make up the segment of the population that is most vulnerable to chemical injury. To protect them from occupation-related harm, the American Conference of Governmental and Indnstrial Hygienists publishes annually revised threshold limit values (TLVs), guidelines for permissible chemical exposure at the workplace. http //www.acgih.org/Resources/press/HAL.htm... 

VOCs were present at about 0.2 ppm outside the refinery boundary. VOCs are a complex mixture of hydrocarbons with an unspecified (and variable) composition. In the absence of any reference data that specifies an acceptable concentration of VOCs outside the fence line, it is helpful to compare the concentration data to a common standard used to monitor health in the workplace, the threshold limit value (TLV). The American Conference of Government and Industrial Hygienists (ACGIH) has set a TLV of 300 ppm for workplace exposure to gasoline vapors, another hydrocarbon mixture of unspecified composition (ACGIH, 1990). Since the exposure for workers is different than that of residents outside the refinery, ACGIH TLVs cannot be used to determine exposure limits for the general population instead, they simply provide a benchmark for this discussion. 

The toxic dose levels of silver and silver compounds have been determined in animal toxicity studies (Sweet 1989). In mice, orally administered silver nitrate had an LD50 of 50 mg kg (the LD50 is the dose required to kill 50% of the test group), whilst silver sulfadiazene had an LD50 of 5000 mg kg. In occupational medicine, the MAK-value (maximum allowable concentration at the workplace) has been set at 0.1 mg m for metallic silver and 0.01 mg m for silver salts as Ag (DFG 2002). The same values were set as TLV (Threshold Limit Values) in the USA (ACGIH 2002). 

One fundamental change compared with the previous system is that in future only exposure to dangerous chemicals or mixtures will be evaluated and not any longer all chemicals / mixtures present at the workplace. The other important changes are the introduction of the new limit value system and the so-called traffic light system . The new limit value system is based on two risk-based limit values ... 

If the presence of one or more agents in gaseous, vaporous or suspended form in the air at the workplace cannot for certain be rul out, an assessment must be made to see whether the limit values are complied with. In this assessment, all... 

Wriedt, H. (2003). The European trade union approach threshold limit values as an instrument to reduce real life exposure of workers to carcinogens, paper presented at the National Conference on the Prevention of Risks of Cancer at the Workplace, Pisa, 20-22 February 2003. 

The workplace threshold value (AGW) is the limiting value for a time-averaged concentration of a substance in the air at the workplace related to a given time period of reference. It indicates the concentrations for which acute or chronic harmful effects on health are not generally to be expected (Para. 3, Sect. 6 Hazardous Materials Ordinance [48]). 

Occupational Exposure Limits, OELs, are set by the European Union. In 1990, at the request of the Council, the European Commission had set up an informal group of scientists, known as the Scientific Expert Group, SEQ to give advice on setting limit values, after having reviewed the different approaches in the Member States. To encourage the Occupational Exposure Limits, OELs, the European Commission decided to formalize the SEG and with its Decision 95/320/EC of 12 July 1995 has set up a formal base for the work on the scientific evaluation of risk at the workplace related to chemical substances. " The proposed values include ... 

TABLE 4. Threshold Limit Values (mg/m ) for Hazardous Substances in the Air at the Workplace as ... 

In former years the highest arsenic levels were measured in copper smelters. Arsenic trioxide is a byproduct of copper smelting. 29.8 mg/m is reported from one plant. This seems to be historical. Controls in U.S. showed average air concentrations also in formerly high-loaded areas of the plants below the threshold limit value (TLV) of 0.5 mg As/m. The corresponding German limits are 0.2 mg/m (maximum concentration at the workplace, or MAK value) and 0.1 mg/m (technical standard concentration, or TRK value) calculated as arsenic [17,36-40]. 

Inclusion of OSHA s method in this appendix in no way implies that it is the only acceptable way to measure employee exposure to formaldehyde. Other methods that are free from significant interferences and that can determine formaldehyde at the permissible exposure limits within 25 percent of the true" value at the 95 percent confidence level are also acceptable. Where applicable, the method should also be capable of measuring formaldehyde at the action level to 35 percent of the true value with a 95 percent confidence level. OSHA encourages employers to choose methods that will be best for their individual needs. The employer must exercise caution, however, in choosing an appropriate method since some techniques suffer from interferences that are likely to be present in workplaces of certain industry sectors where formaldehyde is used. 

In these adhesives, the polymers and resins are dissolved in organic solvents. The hazard potential is determined by the nature of the solvent (e.g., flammability, irritation potential). Due to the high volatility of the solvents, exposure by inhalation of the vapors is the bi est problem. For most solvents, the maximum concentration at the workplace and limiting factors are laid down (workplace limit value). Due to the small amounts of adhesive used by private users, these limit values are generally not reached or are only exceeded for a very short time. 

The maximum concentration at the workplace (MAK value) of HN3 in the Federal Republic of Germany is 0.1 ppm (0.27 mg/m ) occasional exposure to twice that concentration is tolerable for short periods of time [5]. A limit of 1 ppm to exposure is given in [6]. 

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