The peritoneum is a membranous layer that is made up of two sub-layers called the parietal and visceral layers. The parietal layer covers the abdominal cavity, while the visceral layer surrounds abdominal organs. Together these two layers provide support and protection for abdominal organs and the abdominal cavity as a whole.
There are two main theories regarding how asbestos exposure leads to the development of peritoneal mesothelioma:

• Asbestos fibers are ingested and these fibers work their way from digestive organs into the peritoneal membrane.
• Asbestos fibers are inhaled and travel to the peritoneal membrane via the lymphatic system.

Regardless of how asbestos fibers actually enter the peritoneal layers, the body experiences difficulty in expelling them. Trapped asbestos fibers eventually cause changes in mesothelial cells, leading to irritation and inflammation. The exact way in which asbestos fibers cause these changes is uncertain, but researchers believe such changes are responsible for cancer development.