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Press Release No. 51 | 25 July 2007
How Dangerous are Mycotoxins and Diesel Exhaust Gases?

DFG Senate Commission Evaluates Substances - 107 Modifications and New Entries in the 2007 MAK and BAT Values List

Sometimes referred to as the "Curse of the Pharaohs", aflatoxins - which are highly toxic and carcinogenic substances produced by moulds that are hundreds of years old, and can also occur in walnuts, peanuts or pistachio nuts - are found in the food industry, in agriculture and in laboratory tests. These substances have been known for quite some time, but now they have been evaluated for the DFG's annual MAK and BAT values list by the Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, established by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation). The result: aflatoxins are carcinogenic and damage germ cells, and they are not only hazardous when inhaled but also as a result of prolonged skin contact.

As with aflatoxins, the DFG's Senate Commission examined a total of 107 substances, and on this basis they were able to recommend new entries and modifications to the MAK and BAT list. This list states, on the one hand, the threshold values for the maximum concentration that chemical substances in the air can reach without having adverse health effects (MAK values), and on the other, the concentration of a substance to which a person can be exposed for the duration of their working life, without suffering adverse health effects (BAT values). The list has been submitted to the German Federal Ministry for Labour and Social Affairs. Until the end of the year, detailed written statements on each assessed substance can be requested from the Commission's Scientific Office and further data and comments can be added, which will in turn be verified and taken into consideration by the DFG's Senate Commission. The Senate Commission will then conclusively adopt the recommended values and justifications. These provide the legislator with recommendations for health protection at the workplace.
This year, the Commission also gave its attention to exhaust gases from diesel motors and checked the existing data concerning cancer causation in humans. It decided to leave unchanged the classification in Category 2 - with the remark that it is not yet possible to make any statements with regard to the most modern diesel motors. Category 2 contains substances that are to be considered carcinogenic for humans, because animal tests and to a certain extent also epidemiological tests or studies on the mechanism of action point to an appreciable contribution to cancer risk. This year, a total of 27 substances were examined by the Commission for carcinogenic effects or were incorporated in the MAK list for this reason. They checked another 13 for any undesirable effects on germ cells. The code "H" - not only dangerous on inhalation but also through skin contact - was assigned to 22 substances in all. The Commission checked the validity of this identifier for another nine substances, but retained it in every case.

With regard to phosgene, which was used as a chemical weapon during the First World War, but today has a key role in the production of plastics, the Commission established a revised, higher MAK value of 0.1 ml/m³, based on new more detailed studies. The maximum concentration of ascetic acid in the workplace should be 10 ml/m³. It also emerged that ascetic acid is not dangerous during pregnancy when the relevant MAK value is observed. In cooperation with the European and American commissions, the Commission also checked older MAK values for substances such as TNT, which is familiar as an explosive, and nitric acid. The first of these was found to cause cancer in animal tests and therefore no longer receives a MAK value. There is insufficient data available for nitric acid and the MAK value was therefore omitted. The MAK values of a total of 12 substances have either been changed or newly recommended. In four cases, the existing MAK values have been confirmed in the new tests. In five further cases, there was insufficient data available for the recommendation of reliable values. Furthermore, the Commission examined 17 chemical substances for any adverse health effects during pregnancy. Although their MAK values were lowered, the possibility that the substances 2-ethoxyethanol and 2-ethoxyethyl acetate, which are used as solvents, represent a health hazard could not be excluded; for the rest, there is no danger if the MAK values are adhered to.
The MAK and BAT values list also includes substances that trigger allergies of the respiratory tract and the skin. This year 10 substances were examined in this category. The best known of these is nickel and its compounds, which are all still evaluated as sensitising.

For the 2007 list, the BAT value has been specified for the first time as the average rather than the highest value to which a person can be exposed for the duration of their working life without their health being damaged. This provision makes allowance for the fact that the data can often only be recorded as mean values, and also allows the results to be compared with the international threshold values of the relevant European and American organisations (commissions). There were 10 modifications and new entries in the BAT list this year. The Commission listed new so-called biological guide values (BLW) for acrylamide and cadmium. The values are used to quantify substances that do not receive BAT values, e.g. because they are carcinogenic. A health risk is not excluded even when these BLW values are observed; however, they can be used as evaluation criteria in occupational health monitoring.
The MAK and BAT values list for 2007 is the last to be prepared under the long-standing chairmanship of Professor Helmut Greim. At the Commission's plenary session in March of this year, the chairmanship was assumed by Professor Andrea Hartwig, Technical University of Berlin.

Further Information

Additional information about the work of the Senate Commission can be found at

This includes further information on the contact persons at the DFG and contact details for the Commission's Scientific Office, where the scientific grounds for the modifications can also be requested.

Note to Editors:
Editors may request a free review copy from the DFG Head Office: Deutsche Forschungsgemeinschaft, Press and Public Relations Office, Kennedyallee 40, D-53175 Bonn, Tel.: +49 228 885-2109, Fax: +49 228 885-2180, E-Mail: Michael.Hoenscheid@dfg.de.