Exposure to radon and ambient particle radioactivity during pregnancy and adverse maternal, fetal and perinatal outcomes: The current literature and potential mechanisms.

Radon is a colorless, odorless radioactive gas that is naturally occurring in the environment, originating from the decay of uranium that exists in the earth's crust. In addition to lung cancer, radon exposure has recently been associated with hypertension and cardiovascular disease. However, little consideration has been given to radon exposure during pregnancy, even though pregnant people are a more vulnerable population and ionizing radiation is a known risk factor for adverse maternal and fetal outcomes. There is also greater recognition of the potential effect of ambient particle radioactivity. The radioactivity of ambient particles is primarily due to the decay of radon progeny, and thus another source of exposure to radiation due to radon decay. We systematically searched and evaluated the literature and summarized the current evidence on radon and particle radioactivity exposure during pregnancy. While the literature is sparse, we identified eight human studies that address this topic. The accumulated evidence suggests that radon and particle radioactivity may be associated with a range of adverse pregnancy outcomes, including gestational diabetes and hypertension and fetal development. Additionally, we highlight several potential biological pathways by which radon may affect maternal and fetal health. The ubiquity of radon and ambient particle radioactivity exposure, biological plausibility and results of early studies all suggest radon exposure during pregnancy is an important topic that merits further investigation.