DFG presents the 2006 MAK and BAT value list

Focus on health protection during pregnancy

The Senate Commission of the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) on the Investigation of Health Hazards of Chemical Compounds in the Work Area has presented the 2006 Maximum Allowable Concentrations (Maximale Arbeitsplatzkonzentrationen – MAK) and Biological Tolerance Values (Biologische Arbeitsstofftoleranzwerte – BAT) list and submitted it to the German Federal Minister of Economics and Labour. There have been 155 modifications and new entries since last year. The report provides the current scientific basis for the maximum permissible concentrations of substances such as gas, smoke or aerosol in the workplace atmosphere. This year the Commission paid particular attention to the criteria for assessing the danger of chemical compounds during pregnancy. Following the publication of an amended Ordinance on Hazardous Substances, the Commission examined 47 substances for which insufficient data had been available up to now to make an unambiguous classification, and assigned a value to 37 of these substances. Further investigations are intended for clarification of the remaining ten substances. After further tests, two substances, lead and o-toluidine, have been classified as carcinogenic in animal tests and carcinogenic for humans, and as mutagens for germ cells.

Following a change of procedure, new data or scientific comments may be presented to the Commission's Scientific Office after publication of the list up until 31 December 2006; these comments will be examined by the Commission and, if necessary, taken into consideration in the final version. In 2005 comments on eight substances were submitted, resulting in a re-evaluation of antimony and its inorganic compounds.

This year, the following modifications have been made:

Due to the newly determined criteria for the evaluation of health hazards during pregnancy, the Commission tested a total of 62 chemical compounds in the work area. Acetylacetone, adipic acid dimethyl ester, succinic acid dimethyl ester, glutaric acid dimethyl ester and their compounds, aminobutane (all isomers), 2-aminopropane, aniline, tert-butanol, 2-Butin-1, 4-diol, tert-butyl acetate, n-butyl acrylate, carboxylic acid (C4-C6) dimethyl ester, chloroacetic acid methyl ester, 5-Chlor-2-methyl-2,3-dihydroisothiazole-3-on and 2-methyl-2,3-dihydroisothiazole-3-on, 1,1-dichlorethane, diethanolamine, 2-diethylaminoethanol, diisopropylether, dimethoxymethane, 1,4-dioxan, 1,3-dioxolane, diphenylether, dipropylenglycol, nitrous oxide, 1-ethoxy-2-propanol, 1-ethoxy-2-propyl acetate, ethyl acrylate, ethyldiglycol, ethyl-3-ethoxypropionate, 2-ethylhexyl acrylate, glycerol, copper, naled, natriumfluoracetat, pentane, p-phenylenediamine, white and yellow phosphorous, phosphorus trichloride, m-phthalic acid, p-phthalic acid, hydrogen sulphide, carbon tetrachloride, tetrahydrothiophen, thiram, trichlorbenzol, triethylenglycol and trimethylamine were classified as chemical compounds which, in complying with MAK values, pose no threat to embryos (group C). After an inspection of the data, 2-butoxyethanol and sulphuric acid remain in this group. However, dust containing aluminium, aluminium oxide and aluminium hydroxide, methylcyclohexane, 4-methylpent-3-en-2-on, 1,1,1,2-Tetrachlor-2,2-difluoroethane and 1,1,2,2-Tetrachlor-1,2-difluoroethane were assigned to pregnancy group D, which means that their classification cannot yet be made on the basis of available data. The data for eight further substances is also insufficient for their assignment to another group. As no data on reproduction toxicology was available, the substances that were previously listed in section IIc of the MAK and BAT values list have also been assigned to group D, "No conclusive evaluation possible at this time".

In the group of carcinogenic chemical compounds, o-toluidine, which was shown to be carcinogenic for humans, and lead and its inorganic compounds, which were shown to be carcinogenic in animal tests, should be noted in particular. Cyclopenta[cd]pyrene has also proven to be carcinogenic in animal tests and has been assigned to carcinogenic category 2. In addition, the suspicion of a mutagenic affect on germ cells by o-toluidine and lead (category 3A) as well as by 2-butenal and cyclopenta[cd]pyrene (category 3B) has been confirmed.

In the course of the investigation of suspected carcinogenic substances that could not be conclusively evaluated until now, aniline was evaluated as carcinogenic but as posing no serious risk of cancer once it is within the MAK values (category 4), and the MAK value of 2 ml/m3 was confirmed. The data on acrylamide is not sufficient for any reclassification; its classification as carcinogenic and as considerably increasing the risk of cancer is therefore unchanged (category 2). As a carcinogenic chemical compound, diethanolamine has been moved from category 3A to category 3B until its mechanism of action has been clarified. As the substance is not genotoxic, a MAK value of 1 mg/m³ could be determined. N-nitrosodiphenylamine, 3-nitrotoluol and 4-nitrotoluol were also assigned to this category for suspected carcinogens. There were 12 examinations or new listings for carcinogenic chemical compounds.

The MAK values, the concentrations of dust containing aluminium, aluminium oxide and aluminium hydroxide, which, according to the current state of knowledge, do not affect the health of employees, even after long-term, eight-hour per day exposure, were established as 4 mg/m³ breathable dust content and 1,5 mg/m³ respirable dust content. For 24 other substances, (acetylacetone, adipic acid dimethyl ester, succinic acid dimethyl ester, glutaric acid dimethyl ester and their compounds, 1,3-Dioxolane, Dipropylenglycol, 1-ethoxy-2-propanol, 1-ethoxy-2-propyl acetate, ethyldiglycol, ethyl-3-ethoxypropionate, glycerol, triethylenglycol, aminobutane (all isomers), 2-butoxyethanol, diethanolamine, 2-ethylhexyl acrylate, 4-methylpent-3-en-2-on, naled, calcium sulfate, white and yellow phosphorus, hydrogen sulphide, 1,1,1,2-Tetrachlor-2,2-difluoroethane and thiram), the MAK values have changed or new values have been suggested. In six cases, (2-aminopropane, aniline, methylcyclohexane, Natriumfluoracetat, sulphuric acid and 1,1,2,2-Tetrachlor-1,2-difluoroethane), the values could be confirmed after detailed examination of the new literature. Due to insufficient data, no MAK values could be established for eight substances (alkylbenzenesulfonate C10-C14, tert-butylamine, dibromodifluoromethane, isoflurane, 3-methoxy-n-butyl acetate, red phosphorus, linear polydimethylsiloxane and propylenglycol).

The re-evaluation of earlier MAK values was conducted intensively, and in close cooperation with the European (SCOEL) and the American (TLV) commissions. While conducting this evaluation, it was decided, due to the fact that 3- and 4-nitrotoluol are suspected carcinogens and as a result of insufficient data being available for a health evaluation of tert-butylamine, dibromodifluoromethane and red phosporous, to delete these from the list of MAK values.

This year a total of nine chemical compounds were examined for their respiratory tract and skin sensitising properties. Seven chemicals received new classifications: acrylamide, aniline, 1,4-butandiol diglycidylether, Dispers blue 106/124, 1,6-Hexandiol-diglycidylether, naled and phenol formaldehyde condensation products. The classification of diethanolamine as skin sensitising remains, but it is removed for triethanolamine.

Fourteen substances, including the carcinogenic compounds acetylaceton, bromoethane, cyclopenta[cd]pyrene, 1,3-dioxolane, 1-ethoxy-2-propanol, ethyl-3-ethoxypropionate, iodomethane, 4-methylpent-3-en-2-on, naled, N-nitrosodi-n-butylamine, N-nitrosodiisopropylamine, N-nitrosoethylphenylamine, N-nitrosomethylethylamine and N-nitrosomethylphenylamine received the warning indicator "H", which means that absorption through the skin, as well as inhalation, essentially contributes to toxicity at the workplace. This classification was examined for 15 other substances and in one case it was removed (aminobutane).

The section entitled "BAT values, BLW and EKA" includes seven changes and new entries. Exposure equivalents for carcinogenic substances were changed for cobalt and its compounds and completed for ethylbenzene, as well as vanadium and its inorganic compounds. There is a new BAT value for perfluorooctanoic acid and its inorganic salts. New biological guideline values (BLW) will be derived for bisphenol A, 4,4'-diaminodiphenylmethane and diphenylmethane-4,4'-diisocyanate. No BAT value could be established for dioxane.

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Further information

All substances whose values have changed since the previous year are marked in the MAK and BAT values list with an asterisk (*). As every year, a detailed scientific explanatory statement accompanies each new addition and modification. This may be requested from the DFG's Senate Commission on the Investigation of Health Hazards of Chemical Compounds in the Work Area, Hohenbachernstraße 15-17, 85350 Freising-Weihenstephan, Germany, phone: +49 (0) 8161-715601, fax: +49 (0) 8161-715618, e-mail: heidrun.greim@lrz.tum.de. Scientific comments or new data for those substances in the MAK and BAT values list that are masked with an asterisk (*) can be sent to the Commission's Scientific Office up until the end of the year. After such comments have been examined or taken into account, the documentation will be published by Wiley-VCH, Weinheim, Germany. The explanatory statements have also been available online since early 2005. The examination and new entry of MAK values and classification of numerous substances are announced in the "yellow pages" of the MAK and BAT value list.

A list of all new entries and modifications can be found on the internet at
www.dfg.de/aktuelles_presse/reden_stellungnahmen/download/mak2006.pdf.

Note for editors
After 20 July 2006 editors may request a free review copy from the DFG Head Office:
Deutsche Forschungsgemeinschaft
Press and Public Relations Office
Kennedyallee 40, 53175 Bonn, Germany
phone: +49 (0) 228-885-2109
fax: +49 (0) 228-885-2180
e-mail: Heike.Klebe@dfg.de.


Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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