Workplace biomonitoring

The example given here is representative of many environmental pollutants that are ingested in food. The reasoning can be the same for biomonitoring of ambient air pollutants in the workplace, but the time scales would usually be minutes, hours, or days rather than days, months, or years. In conclusion, the half-life of the chemical needs to be considered in... 

ADAPTING WORKPLACE BIOLOGIC REFERENCE VALUES FOR INTERPRETING BIOMONITORING RESULTS... 

As developed in Chapter 6, workplace biomarker targets also provide context and a frame of reference for communicating general-population biomonitoring results. However, this raises a number of communication issues, given that workplace biomarker criteria are not directly relevant to the general public, for the reasons described previously and because the standards may be established with a different level of health protection than would be suitable for the general public. 

The approaches described previously can be used to relate biomonitoring results to a reference population or to workplace exposures, but they do not evaluate the risk associated with the amount of a chemical found in the body. To do that, one needs to develop a relationship between biomarker concentration and toxic response, a relationship that is not commonly derived in standard toxicologic practice. The following sections outline methods for deriving such a relationship. The approaches include the ideal case of existing risk assessments based on biomarker-response relationships established in epidemiologic research. Lead and mercury are used as examples of cases in which exposure was quantified according to hair or blood biomarkers and dose-response associations were developed on this basis. 

Another kind of uncertainty is related to the utility of occupational reference values for comparisons with general population biomonitoring results. The workplace targets are inappropriate for a general population that includes infants, the elderly, and the infirm. 

Chapter 5 described general limitations of extrapolating workplace biomarker indices, such as Biological Exposure Indices (BEIs) to the general public. However, biomarker-exposure dose relationships established in the workplace may have utility for developing pharmacokinetic models that could be used to interpret biomonitoring data on the general public. 

It is noteworthy that the styrene reference concentration (RfC) in the Integrated Risk Information System is based on the biomarker-response relationship found in workers (Mutti et al. 1984 EPA 1998). The Environmental Protection Agency (EPA) used the relationship of urinary biomarker to ambient-air concentration of workers to develop an RfC that was adjusted for the difference in exposure time between the workplace and the general population. That is a valid approach because it derives a workplace concentration-toxicity relationship in workers, which can then be adjusted for the general population to account for differences in exposure time and can take uncertainty factors into account. It is different from direct adjustment of the styrene BEI to evaluate human population biomonitoring data on styrene metabolites in urine, which would have the uncertainties described above and in Chapter 5. 

The exposure in the workplace is monitored via lead concentration measuring and also via biomonitoring -... 

Biomonitoring provides an assessment of the overall integrated measure of exposure and absorption of a chemical in one s environment (laboratory, workplace, or home), in one s foods, or in one s water, and can confirm exposure to a chemical. When measuring potential exposure to chemicals in the environment, it can be difficult to provide a good estimate as to what exposure really occurred because there are variables with the extent of exposure and the absorption of the dose. For example, even though a chemical was... 

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