What additional factors beyond state-of-the-art analytical methods are needed for optimal generation and interpretation of biomonitoring data?

Abstract

Background: The routine use of biomonitoring (i.e., measurement of environmental chemicals, their metabolites, or specific reaction products in human biological specimens) to assess internal exposure (i.e., body burden) has gained importance in exposure assessment.

Objectives: Selection and validation of biomarkers of exposure are critical factors in interpreting biomonitoring data. Moreover, the strong relation between quality of the analytical methods used for biomonitoring and quality of the resulting data is well understood. However, the relevance of collecting, storing, processing, and transporting the samples to the laboratory to the overall biomonitoring process has received limited attention, especially for organic chemicals.

Discussion: We present examples to illustrate potential sources of unintended contamination of the biological specimen during collection or processing procedures. The examples also highlight the importance of ensuring that the biological specimen analyzed both represents the sample collected for biomonitoring purposes and reflects the exposure of interest.

Conclusions: Besides using high-quality analytical methods and good laboratory practices for biomonitoring, evaluation of the collection and handling of biological samples should be emphasized, because these procedures can affect the samples integrity and representativeness. Biomonitoring programs would be strengthened with the inclusion of field blanks.

Keywords: BPA; DEHP; contamination; extraction efficiency; field blank; phthalates.

Figure 1

DEHP metabolizes into its hydrolytic monoacid (“monoester”) MEHP and, after enzymatic oxidation of the alkyl chain (R), to various oxidative metabolites. MEHP and the oxidative metabolites can be excreted in the urine unchanged or as phase II glucuronide conjugates [R = CH₂CH(C₂H₅)(CH₂)₃CH₃ (MEHP); CH₂CH(C₂H₅)(CH₂)₂CH(OH)CH₃ (MEHHP); CH₂CH(C₂H₅)(CH₂)₂COCH₃ (MEOHP); CH₂CH(C₂H₅) (CH₂)₃COOH [mono(2-ethyl-5-carboxypentyl) phthalate (MECPP)].