Though previous research has suggested that prenatal exposures to persistent organic pollutants (POPs) may be harmful to a child’s developing immune system, few studies have investigated long-term outcomes in this regard. Findings reported in the January 2014 journal Environmental Health Perspectives provide evidence that exposure to certain POPs in the womb may be associated with an increased risk of developing asthma that persists into young adulthood. The researchers assessed POP levels in blood samples from 872 pregnant Danish women. All samples were collected between 1988 and 1989, during the 30th week of pregnancy. The researchers used registry data and self-reports on asthma diagnosis and medication use since age 6 to identify asthma cases. At age 20, children of mothers with the highest blood HCB (the pesticide hexachlorobenzene) concentrations during pregnancy were nearly twice as likely as children of mothers with the lowest concentrations to have been prescribed asthma medication. Authors report, “This is the first study to report an association between developmental HCB exposure and asthma in offspring, according to the researchers.” Similarly, children of mothers with the highest blood levels of one particular PCB (polychlorinated biphenyls) congener, dioxin-like PCB-118, were nearly twice as likely as children of mothers with the lowest levels to have used asthma medications. To read more, visit the journal’s website.