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Press Release No. 30 | 17 July 2013
From gallium to tin – revised limits for different metals and their compounds in the workplace

DFG Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area submits 2013 List of Maximum Workplace Concentrations and Biological Exposure Limits with 65 amendments and new additions

Various metals and their compounds are among the 65 amendments and new additions to the 2013 List of Maximum Workplace Concentrations (MAK) and Biological Exposure Limits (BAT), presented by the Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, a body of the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation). There are new MAK limits for organic methyl tin compounds and inorganic lithium compounds, the MAK limit for copper has been lowered, and that for selenium has been reconfirmed. The Commission has classified gallium arsenide together with 'Arsenic and its inorganic compounds' as 'carcinogenic' and underlined the need for research into lithium metal and its highly irritant inorganic compounds. Gallium arsenide or lithium are found in batteries in modern devices such as smartphones. Lithium salts are used in psychiatry and selenium is added to dietary supplements. The Commission has also reviewed and lowered the Maximum Workplace Concentration for methoxychlor, which is used in insecticides and is banned in Europe.

Every year the Senate Commission submits the MAK and BAT list to the Federal Minister of Labour and Social Affairs, laying the scientific foundation for the legislation that governs health and safety in the workplace. For each of the 65 reviewed substances there are detailed scientific justifications that make transparent the Commission's decision-making processes. The Maximum Workplace Concentration indicates the maximum concentration of a substance that may be present in the workplace in the form of a gas, vapour or aerosol without causing long-term damage. The list of MAK and BAT limits also indicates which substances are carcinogenic, damage germ cells or harm a developing foetus, sensitise the skin or respiratory tract, or are absorbed through the skin. The list also states the concentration of a substance in the body to which a person can be exposed for a working lifetime without adverse health effects (the Biological Exposure Limit). It also describes Biological Reference Limits (BLW) and Biological Substance Reference Values (BAR).

Maximum Workplace Concentrations are averages that cause no health hazards but are often insufficient for assessment purposes, so there are also what are known as short-term exposure categories. This is because short-term high exposure may also be harmful. The Commission has therefore classified copper and its inorganic compounds and methyl tin compounds in category II as resorptive substances with very high limit values, in addition to lowering the Maximum Workplace Concentrations. The teratogenic effect of both groups of substances was investigated and both groups were classified in group C: as long as the Maximum Workplace Concentration is complied with, there is no reason for concern. Some of the methyl tin compounds – namely those with three or four methyl groups, i.e. tri- or tetramethyl tin compounds – have been additionally identified with the letter H, indicating that these substances are absorbed through the skin and have a harmful effect even if the Maximum Workplace Concentration is complied with. No Maximum Workplace Concentrations are defined for substances for which there is no data for assessment. To this category IIb the Commission added, in 2012, lithium metal and its highly irritant inorganic compounds as well as zeolites, as used in cat litter.

The justifications for all the new additions and amendments to the 2013 MAK and BAT list are available for scientific comment until 31 December 2013; new data may also be submitted. After this date the Senate Commission will finalise the definitive proposed limits and justifications. Drawing up the MAK and BAT list is part of the DFG's mandate to advise government as defined in its statutes. The 2013 list is the second to be published in full online on an open access basis.

Further Information

Further information about the work of the Senate Commission and a detailed list, including all new additions and amendments, is available at:

Here you will also find the names of relevant contacts at the DFG and the contact details of the Commission's administrative office.

Information about health and safety at work is available in the DFG Magazine at:

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