Early life inhalation exposure to mine tailings dust affects lung development

Exposure to mine tailings dust from active and abandoned mining operations may be a very significant health hazard, especially to sensitive populations living in arid and semi-arid climates like the desert southwest of the US. It is anticipated that early life exposures during sensitive times of development can lead to adult disease. However, very few studies have investigated the effects of inhalation exposure to real world dusts during lung development. Using a mouse model, we have examined the effect(s) of inhalation of real world mine tailing dusts under three separate conditions: (1) Exposure only during in utero development (exposure of the pregnant moms) (2) exposure only after birth and (3) exposures that occurred continuously during in utero development, through gestation and birth until the mice reached adulthood (28 days old). We found that the most significant changes in lung structure and function were observed in male mice when exposure occurred continuously throughout development. These changes included increased airway hyper-reactivity, increased expression of epithelial to mesenchymal (EMT) transition protein markers and increased expression of cytokines related to eosinophils. The data also indicate that in utero exposures through maternal inhalation can prime the lung of male mice for more severe responses to subsequent postnatal exposures. This may be due to epigenetic alterations in gene regulation, immune response, molecular signaling, and growth factors involved in lung development that may make the neonatal lung more susceptible to continued dust exposure.