South Pasadena sues Dow Chemical and Shell Oil Company, alleging that for more than 4 decades, both firms willfully manufactured a pesticide containing a cancer causing chemical 1,2,3-trichloropropane, also known as TCP, that has contaminated the municipality's drinking water supply. TCP is a man-made chemical used as a cleaning and degreasing solvent. In addition to South Pasadena, Arcadia, Upland and Lake Hemet Municipal Water District are also suing Dow and Shell for TCP contamination.