Researchers have discovered that natural compounds released from bacteria and fungi in soil, known as siderophores, can decrease the toxicity of asbestos fibers. According to the authors, their results support the feasibility of asbestos bioremediation, or using organisms such as bacteria to degrade contaminants at waste sites.
Asbestos fibers are highly toxic and have been linked to serious health conditions, including lung and stomach cancers. This toxicity is mostly attributed to the long shape of asbestos, which makes it harder for cells of the immune system to remove them from the lung.
Immune cells called macrophages generally destroy foreign materials, such as bacteria and particles like asbestos, by either engulfing the particles or producing reactive oxygen species (ROS) to destroy the material. Because asbestos fibers are often too large to be engulfed, macrophages produce excessive ROS, which can lead to inflammation and DNA damage and may eventually lead to tumor development. Previous studies have shown that the presence of iron, which is often on the outer layer of asbestos, can increase this ROS production.
Based on this connection between iron and asbestos toxicity, researchers explored whether natural soil concentrations of siderophores, which have an affinity to bind to iron, can remove iron from asbestos and thus lower its toxicity. Plants, bacteria, and fungi release siderophores to bind to iron in soil, facilitating iron uptake. The study, supported by the University of Pennsylvania Superfund Research Program (Penn SRP), was led by Jane Willenbring, Ph.D., currently at the Scripps Institution of Oceanography, University of California, San Diego, and first author Sanjay Mohanty, Ph.D., at the University of California, Los Angeles.