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Human Biomonitoring for Environmental Chemicals
Compared with measures of contaminants in air, water, or food, biomonitoring results are intrinsically associated with a person and thereby have far greater potential to generate concern and action, for good or ill.
The social and political climate in which the new technology of biomonitoring has emerged is itself volatile; contentious and potentially fractious policy debates and litigation surround the field and render it likely that studies will be conducted or interpreted to meet the agendas of specific parties unless great care is taken to establish uniformly agreed on scientific standards against which any study can be transparently judged.
Figure 4-1 presents a schematic diagram of the various considerations in the design of a biomonitoring study addressed in the chapter as well as Chapters 5 and 6 and their relationship to one another. The four stages of any biomonitoring study are study design, study conduct, data analysis, and communication and implementation of results. Each stage incorporates several steps, which follow in chronologic order and are linked in Figure 4-1 by thick arrows. Several disciplines and processes, linked to the main steps by thin arrows, can be engaged in concurrently and are used to inform decisions made for the main steps. For example, biomarker selection and validation usually follow from study hypothesis and population selection, precede participant enrollment and consent, and are informed by statistical considerations, toxicokinetics, ethics, and communication. Study-population selection must take place before study inception. The main steps from population selection through statistical analysis are described in this chapter. Chapter 5 takes up interpretation of results, and Chapter 6 deals with communication of results.
In sum, the purpose of this chapter is to lay out—for the scientific, medical, legal, and policy communities—broad guidelines aimed at guaranteeing that biomonitoring studies will lead efficiently to identification of environmental contaminants that are causing risk or harm while elucidating sufficient information regarding pathways of exposure and health effects to guide their future control and will avoid the creation of widespread anxiety or apathy about contaminants whose potential for personal or societal risk appears not to warrant that reaction.
The discussion will proceed by reviewing the major issues in selection of biomarkers for study, developing the sampling strategy to answer the study questions, and assessing the communication and ethical considerations that must be addressed before the study is conducted. Next, the chapter will review the major considerations regarding the execution of the study, selection of the appropriate matrix (such as, blood or urine), collection of samples, transportation of samples to the laboratory, analysis of the samples, and banking of the specimens, when relevant, for future additional analyses. Finally, we review key considerations in the statistical analysis of the laboratory results.