July 18 (UPI) -- California officials are poised Tuesday to regulate a substance in water that experts say is a powerful cancer-causing agent in water worldwide.
The substance -- called 1,2,3 trichloropropane, or TCP -- is prevalent in the Central Valley of California as a degreasing agent used in the production of plastic products.
The majority of residents in the San Joaquin Valley rely on groundwater as their drinking water. In 2016, 63 percent of California public water systems that detected nitrates, including TCP, were in the Valley, according to the State Water Resources Control Board.
The Environmental Working Group, an advocacy organization, released a report in April that found 94 water systems serving eight million Californians are contaminated with 1,2,3-trichloropropane.
It then updated its report to say additional analysis found the substance as a contaminant in the drinking water of at least 17 states. It plans to issue more details on the nationwide tests.
Residents of the Central California farming communities are blaming their sickness on the TCP.
"The word that really captures all of it is 'outrage,'" said Jerry Tinoco, 45, a resident of the city of Arvin who told NBC News and at least three close family members have been diagnosed with cancer. "It's a man-made chemical, so someone is to blame."
No research shows the chemical has caused cancer spikes in specific communities, but some residents and experts told NBC News that research has yet to be done in towns like Arvin.
But the U.S. Environmental Protection Agency has concluded it's "likely to be carcinogenic to humans." The California Water Board warns residents not to shower with tainted water because they might inhale the chemical.
The Water Board plans to set a legally permitted limit -- a Maximum Contaminant Level, or MCL -- requiring public utilities to test their water and, if needed, install filters to lower the level of the chemical.
So far, Hawaii is the only state with a legal limit -- 600 parts per trillion.
"If you drink water over a lifetime that contains 1,2,3-TCP at concentrations higher than the PHG, there is an increased lifetime risk of developing cancer," the Water Board said on its websitre. "The increased risk depends on 1,2,3-TCP concentration in the water. For water with a 1,2,3-TCP concentration of 5 ppt, the increased lifetime cancer risk is less than one cancer case per 100,000 people. For water with a 1,2,3-TCP concentration of 70 ppt, the increased lifetime cancer risk is about one in 10,000 people.
Paul Tratnyek, a professor at the Institute of Environmental Health at Oregon Health and Science University has studied TCP for the Defense Department.
"Even the slightest amount of TCP in the water would be considered to be a potential health effect," Tratnyek said.
In Arvin, the city tested the water for TCP. A state-certified lab found more than six times the amount the state says is acceptable.
In California's Central Valley, the high TCP levels are attributed to two industrial giants that recycled TCP by packaging it with agricultural pesticides.
"TCP got into drinking water in the Central Valley because Dow Chemical Company and Shell Oil Company saw an opportunity decades ago to take a hazardous waste stream at their chemical plants, put it in barrels and sell it to farmers, who would then inject it into the ground," said lawyer Toss Robbins, who represents 30 communities that are suing Dow and Shell to get them to pay for the multi-million dollar filtration process required to clean water supplies.
In 2010, the companies prevailed in a 2010 lawsuit filed by the city of Redlands. But the companies have settled other suits. In a Central Valley city two hours north of Arvin, a jury awarded Clovis $22 million to treat contaminated water and remove TCP from its wells.
In a statement, Shell said that the product has been out of use for years, it contained only "trace amounts" of TCP and that it was approved by the federal and California governments.