A MAK value

Chromium(III) oxide is not included in the MAK list (Germany), the TLV list (USA), or in the list of hazardous occupational materials of the EC [3.72]. In practice, this means that chromium(III) oxide can be regarded as an inert fine dust with a MAK value of 6 mg/m3. 

What is meant by compliance Compliance with a MAK value meant that the value was not exceeded (allowing for the exemptions mentioned above for peak exposures etc.). Compliance with TRK values meant that they should not be exceeded and that working conditions should ensure a concentration significantly below the established value. To ensure this, the employer has an obligation to assess and evaluate the concentration of dangerous substances at the workplace (TRGS 402 ). The assessment and evaluation is divided into four steps ... 

For fiber-free finely divided SiC, the MAK value is 4mgm [253]. If the MAK ( Maximalzulassige- rbeitsplatz-Xonzentration ) is exceeded a dust ma.sk with a PI filter (for inert dusts) must be worn. Recent investigations, however, have shown that these SiC dusts are not fibrogenic [254], so that the need for a MAK value is questionable. 

Relevant threshold limit values for terpenes are rare because of a lack of basic information about specific terpene products and by-products on the one hand, and occupational and environmental exposures on the other hand. The threshold limit values which have been documented the best concern oil of turpentine. A MAK-value of 100 ppm is defined in German regulations and noted to be dermally sensitive. For other terpenes, such as d-limonene which is also classified as dermally sensitive, it has not yet been possible to establish a MAK-value because of a lack of information of their effects on animals or humans. With terpenes, as is often the case, aggregate concentration parameters are used as limit values such as the minimum level goals recommended by the former German Federal Flealth Authority. These suggested minimum values bear in mind actual levels detected in indoor areas. 

The U.S. Occupational Safety and Health Administration (OSHA) has set a ceiling level for iodine of 0.1 ppm in air. The American Conference of Government and Industrial Hygienists (ACGIH) estabUshed 0.1 ppm as the TLV (TWA) for iodine. The maximum allowable concentration in air (MAK value) is also 0.1 ppm (104—106). 

Elemental bromine is a readily evaporating liquid (pBr at 1 °C = 0.23 bar) with high reactivity. Because of the good solubility of Br2 in lipids, its aggressive and toxic properties affect skin and mucous membranes (bronchi). The MAK value of elemental Br2 is defined as 0.1 ppm (0.7 mg m 3), while the sense of smell is affected at a value of 0.01 ppm. The lethal concentration (around 100-200 ppm) is reached for example, by twice the MAK value, 5 min, eight times per working unit [91, 92]. 

Environment and health-related problems DCM is toxic for the central nervous system, for the liver and the kidneys (MAK-value 350 mg/m ), and it is absorbable via skin. Furthermore DCM is a suspected carcinogen (classification care, cat 3). DCM is low volatile and the vapour is heavier than air, thus high concentrations may occur at ground level during application. Activated-carbon-filters are ineffective and normal glove materials are penetrated within a few minutes. The required breathing equipment is, however, hardly used by craftsmen, which results in several deaths every year. 

Greim H (ed) Occupational Toxicants, Vol 13, critical data evaluation for MAK values and classification of carcinogens. Commission for the investigation of health hazards of chemical compounds in the work area, Bisphenol A, p 49. New York, VCH, 1999... 

The MAK values are mean concentrations over the complete time of exposure. Allowable concentration peaks are restricted to limited values of concentration highs, period of exposure and frequency of these events per shift. In rating the hazardous potential of chemical exposure, animal experiments arc used and in addition compared with those of known human exposure, thus a high safety standard is guarantied. 

MAK values can be best compared, at an international level, with the definition of the Threshold Limit Values (TLV) of the American Conference of Governmental Industrial Hygienists, which may be expressed as a time-weighted average (TWA), as a short-term exposure (STEL), or as a ceiling value (CL).8... 

In addition to MAK values, which are for healthy persons capable of earning a normal living, the DFG publication20 includes so-called BAT values (biological tolerance limits) for substances which show additional biological effects. These define maximum concentrations of a substance, or its metabolites, normally in the blood or urine of an employee. Only one fluorinated chemical was included in 1997. 2-bromo-2-chloro-l,l,l-trifluoroethane = Halo-thane, CAS-No. 151-67-7, with a BAT value for trifluoroacetic acid (its toxic metabolite) of 25 mg - L 1 in human blood determined after exposure/shift. 

Classified as a carcinogenic substance in Section III A1 of the list of MAK values. 

In the soon to be published new MAK-list in Germany (maximal allowable workplace concentration) ozone will be categorized as IHb which means a substance being justifiably suspected to be carcinogenic. The actual MAK value of 200 pg m 3 (= 0.1 ppm) will be suspended until it is known if ozone shows carcinogenic effects (n. n 1995). 

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... 

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 ... 

The MAK-values of Table A-13 are reproduced with permission of the Senatskommission zur Prtifung gesundheitsschadlicher Arbeitsstoffe of the Deutsche Forschungsgemeinschaft , Boim-Bad Godesberg, Federal Republic of Germany. 

So-called MAK values (maximum workplace concentrations) have been defined for individual chemical substances as a preventive measure against health problems due to inhaling, which must not be exceeded at the workplace. After these preliminary remarks, the prohibition of eating and smoking at the workplace is a logical consequence. Furthermore, the following aspects have to be considered ... 

MAK value the maximal concentration of a chemical substance (as gas, vapor, or particulate matter) in the workplace air which generally does not have known adverse effects on the health of the employee, nor cause unreasonably annoyance (e.g. by nauseous odor) even when the person is repeatably exposed during long periods, usually for 8 h daily, assuming on average a 40 h working week. 

New limit value concepts from 1 January 2005. Since 1 January 2005, with the new Ordinance on Hazardous Substances coming into force, the former limit value concept (health-based MAK values and technically-based TRK values) underwent a fundamental change. The core piece of the new Ordinance on Hazardous Substances, which transposes the Chemical Agents Directive 98/24/EC into German law, is its risk assessment provisions which - based on specific occupations - will evaluate the physical-chemical risks arising from the various possible exposure routes. 

---