Jump to main navigation Skip to Content

DFG Logo: back to Homepage Deutsche Forschungsgemeinschaft

Press Release No. 37 | 20 July 2012
MAK Value Lowered for Chlorinated Biphenyls

Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area Submits 2012 List of MAK and BAT Values with 94 Changes and New Entries

Chlorinated biphenyls (PCBs) are a group of substances for which the 2012 List of MAK and BAT Values submitted by the Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area of the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) specifies new, and in this case, significantly lower values than previously recommended. The current list, which was presented to the German Federal Minister of Labour and Social Affairs as in every year, and which is the basis for legislation on protection of health in the workplace, included new data on 94 substances. These data are based on detailed scientific research and transparent decision-making processes. The List of MAK and BAT Values is also available under open access for the first time, as are all publications of the Commission since the beginning of this year.

That PCBs are toxic and carcinogenic has long been known. The "Stockholm Convention" banned these substances in 2001, which had been used up to the 1980s as hydraulic fluids in capacitors and in other electronic components, for example. Now the Senate Commission once again has to deal with this group of substances because of disposal problems. On the basis of current data, the Senate Commission suggests a drastic reduction of the MAK value for higher chlorinated biphenyls (with more than four chlorine atoms attached) from 0.1 to 0.003 mg/m³. The Commission has also classified the group of substances as carcinogenic. However, classification into Carcinogen Category 4 means that no contribution to the cancer risk in humans is to be expected if the MAK value is observed. The same applies to the effect on germ cells. A MAK value has yet to be determined for mono-, di- and trichlorinated biphenyls in this regard; they will continue to be monitored by the Commission. All chlorinated biphenyls should be avoided during pregnancy.

MAK values indicate the amount of a substance – either in the form of gas, vapour or aerosol in the air at the workplace – that will not cause adverse effects in the long term. In addition, the MAK list indicates whether these substances can cause cancer, damage germ cells or a foetus during pregnancy, sensitize the skin or the respiratory tract or be absorbed through the skin. The list also indicates the concentration of a substance in the body to which a person can be exposed for the duration of his or her working life without adverse effects on health (BAT values). The “Biologische Leit-Werte” and the “Biologische Arbeitsstoff-Referenzwerte” (BLW or BAR values) are also described.

Substances for which data are not available for an assessment are not assigned a MAK value. Some substances were removed in 2012 due to new information, for example camphor and silicon carbide. The values for these two materials were from the 1950s and have now been reviewed and subsequently rejected. The Commission re-examined the substance acetone as well. This did not result in a changed MAK value, but yielded a new assessment based on new data that a risk during pregnancy cannot be excluded even if the MAK value is observed. But not every review results in a lowering of the values: In the case of carbon tetrachloride, current studies served to reaffirm the previously defined value.

Scientific comments on the documentation for all new entries and changes in the 2012 List of MAK and BAT Values, including new scientific data when indicated, may be submitted until 31 December 2012. Only then will the Senate Commission officially adopt the proposed values and their documentation as the basis for legislation on health protection at the workplace. Compilation of the List of MAK and BAT Values is part of the DFG’s mission to provide policy advice to public authorities on questions relating to science and research, as laid down in its statutes.

The publication of the 2012 List of MAK and BAT Values is a further step in the provision of electronic research data via open access. It supplements the "MAK Collection" of the Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, which already contains data and detailed scientific documentation for more than a thousand substances, available online free of charge for users. The information is available on the website of the DFG's contract partner, the Wiley-VCH Verlag. The WileyOnlineLibrary allows an extensive search by German and English names of substances, their synonyms or by CAS numbers. In addition to the Internet pages, the site offers printable PDF documents.

Further Information

To find out more about the work of the Senate Commission and to obtain a detailed list of all new entries and modifications, please visit:

There, you can also find out more about contacts at the DFG and the contact data for the Commission's Scientific Office.

Information on the topic of health protection at the workplace can be found on the Internet in the DFG Magazine:

Note to editors:

Editors may request a free review copy from the DFG Head Office.

Contact person for press and public relations: