5.1.4. Tiered approach OBLs* explained

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– ROBL*. The highest group are health-based levels: a more screening health-risk Tier 3 PROVISIONAL OCCUPATIONAL BIOMONITORING LEVEL – POBL* with some lower tier precautionary assumptions underlying, and a Tier 4 OCCUPATIONAL BIOMONITORING LEVEL –OBL*. The derivation of OBLs* and POBLs* is described in chapters 3.2 and 3.3

5.1.4. Tiered approach OBLs* explained

The tiers are such that they run from relatively simple assessment, interpretation and preliminary decision making to more complex assessment with more conclusive options in a health context. Exceedance of the Tier 1 TOBL* only means that exposure is indicated. It is not clear whether that exposure is work-related or not. Exceedance of the Tier 2 ROBL implies that there is exposure in workers in addition to general population exposure. Exceedance of the Tier 3 POBL* means a warning that health-risk maybe indicated. Non-exceedance means that health risks are unlikely according to the state of current knowledge. Exceedance of the Tier 4 OBL* means a stronger warning that health risk maybe indicated. Non-exceedance means that health risks are unlikely according to the state of current knowledge but with more confidence than non-exceedance of Tier 3 POBL*.

Non-health-based

TOBL*: The “Technical Occupational Biomonitoring Level” is not derived from a threshold or extent of health effects or linked to any risk level but is based on the ALARA principle (‘As Low As Reasonably Achievable’) and tries to follow the best available technique (BAT) approach. The TOBL describes the biomonitoring level in employees working in a state-of-the-art occupational environment, for which chemical exposure is limited as low as reasonably achievable. TOBLs are mainly derived for substances for which it is not possible to derive OBL*, POBL*, or ROBL*. Any exposure may imply an actual but non-quantifiable but still existing health risk, e.g., for genotoxic carcinogens for which insufficient data are available to set risk numbers. See lowest tier in Table 16. The suggested evaluation of a TOBL* is described in chapter 5.3.

ROBL*: The “Reference Occupational Biomonitoring Level” is a strictly statistically defined value, which is not linked to any health-related threshold or extent of health effects. The ROBL* describes the background level of a substance that is present concurrently at a particular time in a reference population of individuals of working age who are not occupationally exposed to the substance. The 95th percentile biomarker concentration from a general population biomonitoring survey is often used as a ROBL*. The ROBL* takes into account that every person is in somehow, usually to a limited extent, exposed to almost any substance even without a specific exposure situation. Supplemental occupational exposure in the individual or a group of workers can be identified by comparing the biomonitoring results with the ROBL*. A Standard Operating Procedure (SOP) for ROBL* is described in chapter 3.4.1.

Health-based

POBL*: The POBL* is the health-based “Provisional Occupational Biomonitoring Level”. The main purpose of POBL is risk screening. POBLs* are intended to identify and manage possible occupational health risks (see chapter 3.3.1 on POBL*). A POBL* can be derived for data-poor chemical substances and can be derived similarly to the derivation of the OBL* but with a lower quantity of data and less confidence than the OBL derivation. In principle, all methods used for refined OBL* derivation, but having a low overall confidence assessment might be used as POBL* for indicative risk assessment purposes.

OBL*: The “Occupational Biomonitoring Level” is the level for which there is high confidence. An OBL can be used for occupational risk assessment. The derivation is always health-based and can be derived with/via different main methods (see chapter 2.3):

 Establishment of OBL* using toxicity data (BMDL* or NOAEL*) or human epidemiology data and if needed appropriate assessment factors e.g., for interspecies

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