Date on Senior Honors Thesis

11-2025

Document Type

Senior Honors Thesis

Degree Name

B.S.

Department

Biology

Committee Chair

Mikus Abolins-Abols

Committee Member

Rachel Neal

Committee Member

Julie Bunck

Author's Keywords

Air pollution; genotoxicity; American Robin; micronucleus

Abstract

A rise in industry and vehicle emissions in the last 20 years has led to an increase in exposure to air pollution. Air pollution has been identified as a major threat to both human and animal health and it has been linked to elevated oxidative stress. One of the most severe consequences of oxidative stress is genotoxic damage. Birds have been identified as promising sentinels for human health, but the effects of air pollution on genotoxicity in birds is understudied. In this study, I evaluated the association between air pollution and markers of genotoxicity in American Robins (Turdus migratorius) to assess the health risk of pollution to local wildlife and humans. Nuclear abnormalities, including the presence of micronuclei, have been identified as biomarkers for genotoxicity. I obtained blood samples from 67 robin nestlings from 32 different nests in the Green Heart Louisville study area. I evaluated the frequency of micronuclei and other nuclear abnormalities in red blood cells of 67 robin nestlings. Of the 67 birds counted, nineteen birds had nuclear abnormalities. Of these, seven birds had micronuclei present. Ultrafine particulate matter (UFP) counts were significantly positively associated with the presence of nuclear abnormalities. NO2 concentrations were not significantly associated with the presence of nuclear abnormalities or micronuclei at any distance. This study shows that particulate air pollution is associated with genotoxicity in a common urban bird, suggesting that it could be used as a sentinel organism to assess health risks of air pollution in human and wildlife populations.

Lay Summary

A rise in industry and vehicle emissions in the last 20 years has led to an increase in exposure to air pollution. Combustion processes often emit harmful compounds such as ultrafine particulates or NO2. Air pollution has been identified as a major threat to both human and animal health. For example, air pollution has been linked to oxidative stress. Oxidative stress occurs when there is an imbalance of oxidative chemical compounds and antioxidants within an organism. One of the possible consequences of oxidative stress is DNA damage, which can be assessed by inspecting the shape of the cell nucleus - DNA damage often leads to misshapen and fragmented nuclei. DNA damage is linked to a wide array of negative health effects, including cancer, cardiovascular, and respiratory disease. While the link between air pollution and DNA damage has been extensively studied in humans, we know less about how air pollution affects wildlife, such as birds. In this study, I evaluated the link between air pollution and marker of DNA damage in American Robins (Turdus migratorius) to assess the health risk of pollution levels on local wildlife. I evaluated the frequency of micronuclei and other nuclear abnormalities from blood samples in 67 robin nestlings in the Green Heart Louisville study area. The Green Heart Louisville project is a large-scale interventional environmental health study focusing on the link between air pollution, greenness, and the cardiovascular health of the local human population. Of the 67 birds counted, 19 birds had nuclear abnormalities. Of the nineteen birds with nuclear abnormalities, seven birds had micronuclei present. Ultrafine particulate matter (UFP) counts were significantly positively associated with the presence of nuclear abnormalities. NO2 concentrations were not significantly associated with the presence of nuclear abnormalities or micronuclei at any distance. This study shows that air pollution is associated with DNA damage and suggests that birds could be used as bioindicators to assess health risks of air pollution in humans and wildlife.

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