Center for Biological Diversity

For Immediate Release, February 11, 2015

Contact: Hollin Kretzmann, (415) 436-9682 x 333, 

Cancer-causing Chemicals Found in Fracking Flowback From California Oil Wells

Analysis of State Documents Reveals High Levels of Benzene, Chromium-6

SAN FRANCISCO— Flowback fluid from fracked oil wells in California commonly contains dangerous levels of cancer-causing chemicals, a new analysis by the Center for Biological Diversity has found.

Flowback fluid is a key component of oil-industry wastewater from fracked wells, which is commonly disposed of in injection wells, which often feed into aquifers, including some that could be used for drinking water and irrigation. Oil wastewater is also dumped into open pits.

Benzene levels over 1,500 times the federal limits for drinking water were found in fracking flowback fluid tests dating back to April 2014 obtained and analyzed by the Center. Benzene in excess of federal limits was found in 320 tests, and chromium-6 was detected 118 times. Both chemicals can cause cancer.

“Cancer-causing chemicals are surfacing in fracking flowback fluid just as we learn that the California oil industry is disposing of wastewater in hundreds of illegal disposal wells and open pits,” said Hollin Kretzmann, the Center lawyer who conducted the analysis. “Gov. Brown needs to shut down all the illegal wells immediately and ban fracking to fight this devastating threat to California’s water supply.”

Hundreds of injection wells were recently revealed to be illegally dumping oil industry wastewater into scores of California aquifers, including some that supply water for drinking and farming irrigation. Central Valley water officials also recently revealed that at least 383 oil industry wastewater pits are operating without permits or oversight. Most wastewater pits are unlined and don’t have covers.

Among the concerns revealed by the Center’s analysis of fracking flowback testing:

  • High chromium-6 levels: Chromium-6 was found in fracking flowback at levels up to 2,700 times the recommended level set by the Office of Environmental Health Hazard Assessment.
  • Missing reports: At least 100 fracking flowback tests are missing from the reporting website managed by California’s Division of Oil, Gas and Geothermal Resources, in violation of state law.
  • Missing benzene data: Only 329 of the 479 fracking fluid chemical tests on the state oil agency’s website measured for benzene.
  • Benzene common: Of those 329 chemical tests that measured for benzene, 323 detected benzene while only six did not.
  • Dangerous toluene levels: Toluene, a toxin that can affect the central nervous system and harm developing fetuses, was found to exceed federal-mandated limits for drinking water 118 times.

The Center for Biological Diversity is a national, nonprofit conservation organization with more than 800,000 members and online activists dedicated to the protection of endangered species and wild places.

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