Air pollution and the inflammatory bowel diseases

Extract

Overview

The inflammatory bowel diseases (IBDs) predominantly emerged in the industrialized world during the latter part of the 19th century.¹ Early in the 20th century the incidence of ulcerative colitis (UC) was higher than Crohn's disease (CD) in developed nations. While the incidence rates of UC stabilized in developed countries, the incidence of CD began to steadily rise in industrialized nations in the mid portion of the century. These trends were observed in Europe² and North America.³ In developing nations IBD was a rare occurrence; however, as these nations became more industrialized the incidence of UC increased. Initially the incidence of CD in developing nations remained low, although eventually the occurrence of CD has approximated that of UC.^4,5 Epidemiological studies that have explored the incidence of IBD have consistently demonstrated that IBD emerged in the developed world first and that IBD occurs more predominantly in urban versus rural regions.⁶ However, environmental risk factors associated with industrialization and urban predominance have been incompletely investigated.