Biomedical subjects

H Sterzl-Eckert

Publications and source records attributed to H Sterzl-Eckert.

3 recordsLinked to original sources

PubMed1998

Maximum workplace concentration values and carcinogenicity classification for mixtures.

In Germany, the Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area (MAK Commission) generally sets maximum workplace concentration values (i.e., a proposed occupational exposure level [OEL]) for single substances, not for mixtures. For mixtures containing substances with a genotoxic and carcinogenic potential, the commission considered it scientifically inappropriate to establish a safe threshold. This approach is currently under discussion. Carcinogenic mixtures are categorized according to either the carcinogenicity of the mixture or the classification of the carcinogenic substances included. In regulating exposure to mixtures, an approach similar to that used by the American Conference of Governmental Hygienists is proposed: For components with the same target organ and mode of action or interfering metabolism, synergistic effects must be expected and the respective OELs must be lowered. However, if there is proof that the components act independently, the OELs of the individual compounds are not considered to be modified. In the view of the commission, calculating OELs for solvent mixtures according to their liquid phase composition is not justified, and the setting of scientifically based OELs for complex mixtures is not possible.

Carcinogens↗

PubMedDate not supplied

Examples of MAK values and carcinogenicity classification for mixtures.

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area (MAK Commission) generally sets MAK values for single pure substances. MAK values for mixtures are only established after specific toxicological evaluation of the particular mixture. In practice, there are a few cases in which a common MAK value for the sum of all components was set, such as for mixtures of isomers (e.g. xylenes) or mixtures of related compounds (e.g. Kathon), in which the components of the mixture show comparable toxicological effects. For mixtures of isomers with different toxicological potentials, different MAK values for the single isomers are usually established. The only exception is for the isomer mixture of alpha- and beta-hexachlorocyclohexane, for which a mathematically calculated MAK value was proposed. A safe threshold cannot be established for mixtures containing substances with a genotoxic and carcinogenic potential. These mixtures are categorized either according to the proven carcinogenicity of the mixture, such as alpha-chlorinated toluenes, or according to the carcinogenic substances included, as for pyrolysis products such as coal tars.

Animals↗

PubMedDate not supplied

Occupational exposure.

Regarding the risk evaluation of mixtures in the workplace, the Working Group discussed whether there is a need to consider combination effects at the workplace and whether there is sufficient information on combination toxicology to suggest a scientific strategy for the evaluation of any mixture at the workplace. It was concluded that analytical definition of the mixture is a basic prerequisite for evaluation. The Working Group agreed that there is a special situation at the workplace because chemical compounds may be present at concentrations close to their effective threshold level; therefore, combination effects have to be taken into consideration, as shown by the data presented during the conference. Furthermore, observed-effect levels for individual substances have to be modified if the substances have the same mode of action or have the same target organs; no modification is necessary if the opposite has been shown. It was also concluded that the scientific database to date is insufficient for the proposal of a general approach. The assumption of additivity in all cases lacking data may more or less over-estimate the risk.

Administration, Inhalation↗