California's environmentalists are calling for stricter regulations against the industrial solvent and pesticide ingredient TCP or trichloropropane. TCP is a known carcinogen and continually seeps through sources of drinking water. The chemical is no longer widely used as an active ingredient in pesticides but traces from its decades of use have found its way into the reservoir.

To recall, it is not just the environmental groups in California but in Hawaii as well who calls for sterner federal regulations against the TCP, according to Phys.org. The groups are also calling on other states like New Jersey, New York, Pennsylvania, and even overseas like Puerto Rico to step up against TCP. These places were known to have been affected by TCP contamination based on federal data.

To make the problem worse, environmentalists said that TCP can persist for a very long time. This can result in contaminated water that stays so for even a century. Having this worse scenario prompts the California State Water Resources Control Board to impose the maximum allowable TCP amount in tap water, the Coalition of Orange County Community Health Centers said. Come to think of it, California's five parts of TCP per trillions of water is even lower than that of Hawaii.

As to the perceived extent of the problem, the TCP contamination is said to affect millions of people from Sacramento to San Diego. The TCP level was found to be exceeding the tolerable limit in 94 public water systems. These data were collected in 2016 and the board fears that there are more water sources which the private sector operates that are contaminated as well.

Environmentalists believe that the primary source of contamination are from industrial and waste sites. There is no known direct source of TCP contamination as of present, making it hard to directly attribute the blame on anybody. Interestingly, the TCP contamination affects mostly those in the urban and suburban areas.