Maternal‐infant biomonitoring of environmental chemicals: The epidemiologic challenges

Abstract

There is growing concern about the potential health effects of exposure to various environmental chemicals during pregnancy and infancy. One of the key limitations of past epidemiologic research in this field has been the potential for exposure misclassification to lead to biases in the health risk estimate. The use of biomarkers in pregnancy cohort or case-control studies has significantly advanced the field; however, this is true only if the biomarker is a true measurement of exposure for the relevant time period of interest. There are a number of theoretical and practical constraints to their use, including difficulty interpreting biomonitoring data, high analytical and collection costs, potential participant selection biases, and ethical challenges in reporting results to study subjects. Identifying a representative sample and collecting biospecimens in the developmental window of interest can be problematic. Various strategies for identifying pregnant women range from the more representative but least efficient sampling of the general population to recruitment through early ultrasound clinics and local advertising. Whereas measurement of xenobiotic chemicals in cord blood, amniotic fluid, or meconium provides unequivocal evidence that the chemical has entered the fetal environment, analysis of maternal blood and urine can be used as a surrogate for fetal exposure. Use of stored midpregnancy serum collected for fetal screening and of large-cohort biobanks offer unique opportunities for biomonitoring data for birth defects studies. Future research is needed to explore less invasive matrices for biomonitoring of infants and to develop less costly analytical methods that require smaller sample volumes.

A Review of the Field on Children’s Exposure to Environmental Contaminants: A Risk Assessment Approach

“…Nevertheless the field of environmental biomarker research has greatly expanded in the last 10–20 years to look at various contaminants of health outcomes. Of particular interest to this article is the expansion of the field where biomarkers are being used to look at early life stage exposures (i.e., before conception, during pregnancy, after birth) and to better understand the adverse mechanistic molecular changes following exposure to contaminants [158,159]. …”

Cohort Profile: The Maternal‐Infant Research on Environmental Chemicals Research Platform

“…The results of MIREC may not be generalisable to the Canadian population or to each of the recruitment sites as the study is not population‐based. Past experience has highlighted the difficulties in trying to assemble a population‐based pregnancy/birth cohort that may be less representative as the cohort is followed over time …”

Phthalates and Perfluorooctanesulfonic Acid in Human Amniotic Fluid: Temporal Trends and Timing of Amniocentesis in Pregnancy

“…Exposures are ubiquitous and well documented in pregnant women (Adibi et al 2003; Fromme et al 2009; Woodruff et al 2011; Yan et al 2009). Direct fetal exposure, however, is less easily determined (Arbuckle 2010). Measurements in blood or urine from pregnant women may serve as proxies, but correlations with measures in fetal compartments can be low (Huang et al 2009; Latini et al 2003; Wittassek et al 2009).…”