DFG presents the 2005 MAK and BAT value lists

07/22/05

Numerous changes and new entries – for the first time, it is now possible to submit comments on all new proposals by the end of the year

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 2005 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. It contains suggestions for MAK values, i. e. the maximum allowable concentration of a working substance in the workplace atmosphere as a gas, steam or aerosol that, according to current knowledge, does not impair the health of employees exposed during eight-hour working days over the long term. Furthermore, the working substances are classified according to their carcinogenic, germ cell mutagenic, reproduction-endangering, sensitising, and skin-absorptive effect. Compared to the previous year, there were 70 changes and new entries.

Changes to the 2004 list are marked with an asterisk (*). In addition, the procedure has also been changed. The Commission has made its proposals, but is leaving them up for discussion until 31 December 2005. Until this date, new data or scientific comments may be submitted to the Commission's office. The Commission will review the above and, where appropriate, take them into consideration for their final decision.

This year, two metals deserve particular notice, i. e. antimony and its inorganic compounds, as well as vanadium and its inorganic compounds, which were proven to be carcinogenic working substances in animal experiments. Furan and tetrafluorethylene were also proven to be carcinogenic in animal experiments and, like the above-mentioned metals, were assigned to carcinogenicity category 2.

Trinitroglycerol as a suspected carcinogenic working substance was placed in carcinogenicity category 3B, and the previous MAK value of 0.05 ml/m³ was suspended until the mechanism of action has been understood. Aminophene, 1,2 Dichloro-4-nitrobenzene, ethidium bromide, and 4-Chlorophenyl isocyanate were also assigned to this category as suspected carcinogens. There were 21 examinations or new listings for carcinogenic working substances.

In the course of examining suspected carcinogenic working substances in category 3 regarding a classification in the new categories 4 and 5, glutardialdehyde and hydrogen peroxide were reclassified in category 4 with a MAK value of 0.05 and 0.5 ml/m³, resp. Perfluorooctane acid and its inorganic salts were classified in this category with a MAK value of 0.005 mg/m³. This year, once again, no working substances were found for category 5, i. e. carcinogenic with no noteworthy increased risk at the existing MAK value.

Vanadium and its inorganic compounds are classified in gamete mutagenicity category 2 due to their mutagenic effect on gametes. Suspicion of a mutagenic effect of antimony, benomyl, and carbendazim (category 3A) and of ethidium bromide and propyleneimine (category 3B) on gametes has been substantiated.

The MAK value of perfluorooctane acid and its inorganic salts was set at 0,005 mg/m³. For 16 substances (acrylic acid, 2-butene-1,4-diol, N,N-dimethylformamide, 2-ethylhexanol, fluoride, hydrogen fluoride, d-limonene, methacryl acid, methylic acetate, N-methyl-2-pyrrolidone (steam), phosphorus pentoxide, phosphoric acid, m-phthalic acid, p-phthalic acid, tetrahydrothiophene, and hydrogen peroxide), MAK values changed or new ones were proposed; the values of five substances (glutardialdehyde, methyl methacrylate, phosphorus oxychloride, phosphorus pentachloride, and phosphorus trichloride) were confirmed after thorough reviews of recent literature. For 13 substances, no MAK values could be determined (benzyl alcohol, 3,4-Dichloroaniline, 4-Diiodomethylsulfonyltoluene, disulfur decafluoride (sulfur pentafluoride), gold, fluorine, hydroxyacetic acid butyl ester, 3-hydroxy-2-naphthalene carboxylic acid, iodine, and the d,l-limonene isomer compound, 4-isopropyl phenyl isocyanate, p-chloro-m-cresol, and o-phthalic acid) because of a lack of data.

The re-evaluation of earlier MAK values was conducted intensively, also in close cooperation with the European (SCOEL) and the American (TLV) Commissions. It was decided in the course of this examination to suspend the MAK values of three substances (antimony, trinitroglycerol, and vanadium pentoxide) because of their suspected carcinogenicity and of disulphur decafluoride, fluorine, and iodine because of insufficient data for a health evaluation.

Twenty-two working substances were also examined with respect to being particularly harmful during pregnancy. Acrylic acid, fluorides, d-limonenes, methacryl acid, perfluorooctane acid, phosphor pentachloride, phosphoric acid, and hydrogen peroxide were assigned to group C which contains those substances for which no teratogenicity is anticipated if the MAK values are adhered to. 2-ethylhexanol, hydrogen fluoride, glutardialdehyde, methyl acetate, methyl methacrylate, N-methyl-2-pyrrolidone, and phosphorus pentoxide remain in this group. By contrast, 2-butine-1,4-diol, phosphorus trichloride, m-phthalic acid, p-phthalic acid, and tetrahydrothiophene were assigned to pregnancy group D which essentially states that classification into group C is not yet possible due to the available data. A risk of harming the embryo currently appears unlikely if the MAK values are complied with but cannot be ruled out with sufficient certainty. Despite new studies, N,N-dimethylformamide remains in Group B for substances, for which teratogenicity cannot be ruled out even if the MAK value is not exceeded.

This year, a total of 16 working substances were examined for their respiratory tract and skin sensitising properties. New labelling was assigned to eleven chemicals, i. e. benomyl, bromelain, 2-butene-1,4-diol, tert-butylacrylate, p-chloro-m-cresol, 3,4-Dichloroaniline, farnesol, soluble gold compounds, methylmethacrylate, 4-isopropyl phenyl isocyanate, sesquiterpene lactone, and m-xylylenediamine.

A total of 14 substances, among them the carcinogenic compounds resorcinol diglycidyl ether, furane, 2-nitropropane, perfluorooctane acid, and their inorganic salts, tetranitromethane, 2,4-Toluylenediamine, 1,2,3-trichloropropane, vinylcyclohexene, and an N-nitrosamines were newly labelled with the warning "H", which means that absorption through the skin together with inhalation may significantly contribute to their toxicity at the workplace. This warning label was checked and confirmed for propyleneimine.

The section BAT values, biological guideline values and exposure equivalents for carcinogens includes seven changes and new entries. Exposure equivalents for carcinogenic working substances have been newly listed for 1,3-butadiene, cyclohexanone, and 1,4-dichlorobenzene, a reduced BAT value for mercury, and BLW for 4-aminobiphenyl, lead (EKA). No BAT values were derived for n-heptane, methyl-tert-butylether, and molybdenum.

The Senate Commission produced detailed scientific justifications for each new entry and change in the 2005 MAK and BAT value list. The above 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, phone: 49-0-8161-715601, fax: 49-0-8161-715618, e-mail: heidrun.greim@lrz.tum.de. Scientific comments and new data are requested to be submitted by the end of the year. After the above have been examined or considered, the documentation will be published by Wiley-VCH, Weinheim, Germany. Since early 2005, they have also been available online. As in every year, the examination and new entry of MAK values and classification of numerous substances is announced in the Yellow Pages of the MAK and BAT value list.

A list with all new entries and changes is available for download at http://www.dfg.de/aktuelles_presse/reden_stellungnahmen/download/mak2005.pdf.

Source: Eurekalert & others

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