Could Prenatal POP Exposure Lead to Long-Term Asthma?

Environmental wellness is always a concern to consider, but this becomes even more vital when you’re pregnant. Not only are you watching out for your own wellbeing; you also have a baby growing inside of you and the outside toxins you’re exposed to could put your baby’s wellness at risk. It’s no secret that prenatal exposure to persistent organic pollutants (POPs) may be harmful to a child’s developing immune system – this has been suggested by plenty of previous research – but few studies have looked into the long-term health outcomes of POP exposure, until now. Findings recently published in Environmental Health Perspectives show that if your baby is exposed to certain POPs while still in the womb, he or she may have an increased risk of developing asthma that persists into young adulthood.


Todd Jusko, an environmental epidemiologist at the University of Rochester, who was not involved in the study, comments, ‘The focus in immunotoxicity studies has often been on immunologic intermediates, such as immune cell counts. This study is unique in that it looks at a long-term clinically relevant outcome.’ For the study, Danish researchers evaluated the relationship between asthma and prenatal exposure to polychlorinated biphenyls (PCBs), the pesticide hexachlorobenzene (HCB), and dichlorodiphenyl- dichloroethylene (DDE) – which is a daughter compound of the pesticide DDT. Lindsey Konkel, editor for Environmental Health News and The Daily Climate, explains, ‘PCBs, HCB, and DDT have been banned or restricted for many years due to concerns over human health effects, but they persist in the environment and the human body. Although levels of these chemicals have been dropping in the human population, diet—especially seafood consumption—remains an important route of exposure.’


Konkel notes, ‘Past studies have reported an association between prenatal exposure to DDE and asthma in children at ages 44 and 7–10. Prenatal HCB exposure has been associated with airway hyper reactivity in rats. Other studies examining prenatal exposure to PCBs and asthma-like symptoms have yielded mixed results; two studies found an association with wheeze in infants and allergic sensitivity in children at age seven while another reported an inverse association with allergic disease.’ However, the authors of the new study argue that previous studies have not followed up with subjects past childhood, and this may be the reason for the divergent findings. According to lead author Susanne Hansen, a doctoral candidate in epidemiology at the Statens Serum Institut in Copenhagen, ‘A twenty-year follow-up allows us to distinguish between [true] asthma and asthma-like symptoms, such as wheeze, which may resolve in the first six to seven years of life.’


For the study, the researchers examined the blood POP levels of 872 pregnant Danish women. At the age of 20, the children of the mothers who had had the highest blood HCB concentrations during pregnancy were nearly twice as likely to have been prescribed asthma medication as the children of mothers with the lowest concentrations. If the mother had a high level of one particular PCB congener, dioxin-like PCB-118, the child was nearly twice as likely as children of mothers with the lowest levels to have used asthma medications. Michele La Merrill, a developmental toxicologist at the University of California, Davis, asserts, ‘The association between dioxin-like PCB 118 and asthma is an interesting one but not sufficient to suggest a general link between all dioxin-like chemicals and asthma.’ The possibility of such a general link, says Merrill, is ‘a provocative question that would be worth continuing to ask in future studies.’ If you’re pregnant and worried about the long-term effects of POPs, look online or speak to a health professional for ways to reduce your exposure.

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