2.1.2. MAK Commission

18 

BLVs* derived by the second method are measures of exposure, which, for substances with healthbased OELs* or OELVs*, can be regarded as adequate to prevent adverse health effects. The second approach is the approach most commonly used by SCOEL*. It is important to note that for the use of this approach, measured human data (either experimental data from controlled volunteer studies or data from workplace settings) providing a link between airborne concentrations of the compound and concentrations of the compound or its metabolites in biological media is needed. If this was not available, SCOEL* did not usually derive a BLV*. Toxicokinetic modelling was rarely used for the setting of BLVs* (2-methoxyethanol and its acetate being the only case).

The documentation of a recommended BLV* needs to include a discussion of the toxicokinetic and toxicodynamic parameters that determine the sampling time, which is very important especially for substances with short biological half-lives (of several hours or less).

SCOEL* ceased in 2019 and its tasks were transferred to European Chemicals Agency’s (ECHA) Risk Assessment Committee (RAC). RAC applies the same approach for the setting of BLVs* as applied by SCOEL*. ECHA document (ECHA, 2019) describes that health based BLV* can be either derived directly from human studies containing data on biomarker levels and (early) biological effects, or from the OEL* or OELV* on the basis of established correlations between air levels and biomarker level. Detailed guidance is not available but (ECHA, 2019) refers to the ANSES* and MAK* guidance on recognized methods for the derivation of BLVs*. The main SCOEL methodology can be found in (SCOEL, 2017).

2.1.2. MAK Commission*

The Permanent Senate Commission of the German Research Foundation (Deutsche Forschungsgemeinschaft) for the Investigation of Health Hazards of Chemical Compounds in the Work Area (MAK Commission*) has established biomonitoring assessment values for more than 100 substances and substance groups, respectively. Assessment values in biological material were typically set in whole blood, serum or urine. The MAK commission* rated other matrices, namely saliva and hair analyses, as not suitable for occupational biomonitoring. The character of the assessment values varies from health-based limit values, which are called Biological Tolerance values (Biologische ArbeitsstoffToleranzwerte, BAT* values) and Biological Guidance Values (Biologische Leit-Werte, BLW*), to descriptive based values, like Biological Reference values (Biologische Arbeitsstoff-Referenzwerte, BAR*) and Exposure Equivalents for Carcinogenic Substances (Expositionsäquivalente für krebserzeugende Arbeitsstoffe, EKA). EKA are not specific limit values, but a set of data that describe the correlation between the concentration of a substance in air and a biomarker in biological material.

BAT* values are based on a relationship:

 between the systemic exposure and the resulting effect of the substance or  between external and internal exposure

The derivation of a BAT* value can be based on various constellations of scientific data, which reveal a quantitative relationship between exposure concentration and body burden and therefore permit the linking of biomonitoring values with the maximum workplace concentration (MAK*). These include studies that reveal a direct relationship between concentrations of a substance and metabolite in biological material (body burden) and adverse effects on health or studies which reveal a relationship between a biological indicator (effect parameter) and adverse effects on health.

The derivation of the BAT* value is based on the average of the systemic exposure. The BAT* value is exceeded when the average concentration of several examinations in an individual is greater than the BAT* value. Average values greater than the BAT* value must be evaluated in relation to occupational‐medical and toxicological data.

OCCUPATIONAL BIOMONITORING GUIDANCE DOCUMENT © OECD 2022