Tetraethyllead and tetramethyllead – Addendum: re-evaluation of the BAT values and derivation of a BLW
Assessment Values in Biological Material – Translation of the German version from 2025
Annette Greiner1Hans Drexler1 (Head of the working group “Assessment Values in Biological Material” of the Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Deutsche Forschungsgemeinschaft)
Andrea Hartwig2 (Chair of the Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Deutsche Forschungsgemeinschaft)
MAK Commission3
1 Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute and Outpatient Clinic of Occupational, Social, and Environmental Medicine, Henkestraße 9–11, 91054 Erlangen, Germany
2 Institute of Applied Biosciences, Department of Food Chemistry and Toxicology, Karlsruhe Institute of Technology (KIT), Adenauerring 20a, Building 50.41, 76131 Karlsruhe, Germany
3 Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Deutsche Forschungsgemeinschaft, Kennedyallee 40, 53175 Bonn, Germany
Abstract
The German Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area (MAK Commission) re-evaluated the data for tetraethyllead [78-00-2] and tetramethyllead [75-74-1] considering all toxicological endpoints and derived a biological guidance value (BLW). Relevant studies were identified from a literature research. In 1994, the previous biological tolerance values (BAT values) for tetraethyllead and tetramethyllead were derived in correlation to the maximum workplace concentration (MAK value) of 50 µg as lead/m3. In 2023, the MAK value for organic lead compounds was lowered to 4 µg as lead/m3. There are no suitable studies for a corresponding reduction of the BAT value or the derivation of a specific BAT value for tetraethyllead. The former BAT values for tetraethyllead and tetramethyllead in urine are therefore withdrawn.
Tetraethyllead is metabolised to triethyllead, diethyllead and inorganic lead. Tetramethyllead is metabolised to trimethyllead, dimethyllead and inorganic lead. Exposure to inorganic lead can best be measured via the blood lead concentration. For inorganic lead, a BAT value of 150 µg lead/l blood was derived in 2022. As organic lead compounds are more lipophilic and lead to more pronounced neurological effects than inorganic lead compounds, adverse effects cannot be excluded with certainty by compliance with the value of 150 µg lead/l blood, making a BAT value inapplicable. As a result, for tetraethyllead and tetramethyllead, a BLW of 150 µg lead/l blood is derived. Sampling time is not fixed in the steady state.
