17. Maternal exposure to metals and persistent pollutants and cord blood immune system biomarkers (lay summary)

Ashley-Martin J, Levy AR, Arbuckle TE, Platt RW, Marshall JS, Dodds L. Environmental Health. 2015 Jun 18;14:52. doi: 10.1186/s12940-015-0046-3

The fetal period is a critical window of immune system development resulting in increased susceptibility to the potentially harmful effects of environmental exposures. Scientists have speculated that certain metals, pesticides, and polychlorinated biphenyls (PCBs) may have toxic effects on the immune system, which may become evident as a changed immune system profile at birth. The immune system biomarkers immunoglobulin E (IgE), thymic stromal lymphopoietin (TSLP), and interleukin-33 (IL-33) play a key role in the cause(s) of childhood allergies and are detectable at birth. [A biomarker is any measurable substance in an organism that can be used as an indicator of a particular disease state, environmental exposure, or some other physiological state. IgE is an antibody component of the immune system, and TSLP and IL-33 are cytokines (i.e., small proteins that are important in cell signalling)].

In this study led by researchers at Dalhousie University, the relationship between levels of metals (e.g., lead, mercury), PCBs, and a range of pesticides (e.g., DDT metabolites, organophosphorus pesticide metabolites) in maternal blood or urine, and elevated levels of IgE, TSLP, and IL-33 in the umbilical cord blood of newborn infants was examined. [This study is parallel to a similar one done by these same researchers and titled “Prenatal Exposure to Phthalates, Bisphenol A and Perfluoroalkyl Substances and Cord Blood Levels of IgE, TSLP and IL-33”]. The study used data collected in the MIREC Study involving 2,001 pregnant women, 1,258 of whom had a singleton, term birth and provided a cord blood sample.

In this primarily urban Canadian population of pregnant women and their newborn infants, the researchers found that levels of PCBs, pesticides, and metals in maternal blood or urine were not associated with adverse effects on the infant immune system.

Further research is needed to see if the results observed in this study are seen in other studies and populations.