A chemical that causes cancer has contaminated the tap water supply for millions of California residents.
The chemical 1,2,3-trichloropropane, or TCP, was previously used in pesticides manufactured by Shell and Dow, the Environmental Working Group reports.
The two companies made the D-D and Telone pesticides, and injected them into the soil to kill small worms called nematodes. Shell stopped making D-D in 1984 and Dow took TCP out of Telone, but by then it had already tainted the water supplies in many parts of the state -- especially in the San Joaquin valley.
"TCP was an unnecessary chemical byproduct that had no role in killing nematodes," said Asha Kreiling of the Community Water Center.
Several lawsuits have been brought against the two companies. Scientists claim the detrimental health effects of TCP were known as early as the 1950s, although it was only in the 1990s that research confirmed its link to cancer.
"Dow and Shell knew ... it could pollute groundwater and they were fully aware of the health impacts," added Kreiling. "They should have taken it out and disposed of it properly as a toxic waste. But that would have cost them a lot of money, so they left it in and continued to sell these pesticides to farmers throughout California."
Since 2001, TCP has been found in water supplies serving 8 million Californians. The chemical has reportedly tainted 562 water sources throughout the state, and many of the areas worst affected are agricultural and home to low-income residents. It has also been detected in other states, including Hawaii and New Jersey.
In California, TCP is on the list of substances that are known to cause cancer. But the chemical is not regulated at the state or federal level.
Staff at the Water Resources Control Board have proposed the implementation of a legal limit for TCP of five parts per trillion in drinking water. Such levels of TCP would represent an increased risk of cancer of one in 143,000.
"The cost of treatment should not be borne by residents of the impacted communities," attorney Todd Robins, who has represented communities in lawsuits against Dow and Shell, said. "Safe and affordable drinking water is a human right, and we are committed to see that every last well is treated, and that Dow and Shell are held responsible."
Lawsuits have accused Shell and Dow of having had a financial interest in keeping TCP in their products, a claim the companies have denied.
A 1983 Shell internal memo put the figure for sales of D-D at $6.4 million and noted that by not removing TCP, the company made "a savings of $3.2 [million] for cost avoidance for disposal in the allyl chloride operation."
The water board is set to make a decision later in April about regulating TCP, according to the American Civil Liberties Union of Northern California.
Sources: Environmental Working Group, American Civil Liberties Union of Northern California / Photo credit: Beyond My Ken/Wikimedia Commons