In 1952, the Pacific Gas and Electric Company (PG&E) installed a compressor station near the town of Hinkley in San Bernardino County, CA  part of a gas pipeline system linking Texas to California. Since then, the company has used a carcinogenic chemical compound named chromium-6 as a corrosion inhibitor in its cooling system. The contaminated water was discharged into unlined pools, thus leaking to the aquifer serving Hinkley’s residents water needs. The leakage occurred (at least) from 1952 to 1972, the year PG&E lined the discharging pools. However, it was not until 1977 that the California state passed a Law regulating the use of chromium-6 and limiting its concentration in water to 50 µg/L.

Chromium-6 is known for causing damage to several organs and different types of cancer. Moreover, the compound also modifies human DNA, which can prolong the effects of exposure to future generations. Local residents experienced several symptoms associated with chromium-6 contamination including prostate, cervical, breast and stomach cancers and respiratory problems. In 1987, PG&E officials informed the state of California of high levels on chromium-6 in underground water north of the discharge ponds. The levels were 10 times greater than the limits established by CA’s 1977 regulation. At that time, PG&E started buying properties affected by pollution. Yet, company officials told citizens the water was suitable for both drinking and agriculture.

Erin Brockovich, a clerk at ‘Masry and Vititoe’ Law firm, came across records on PG&E’s offers to buy Hinkley’s citizens properties while filing them. The fact that these documents were mixed with residents medical records raised Brockovich’s attention. The clerk decided to investigate the case and ended up convincing some of the people affected by contamination (and the lawyers she was working to) to start legal action against PG&E in 1993. Initially, there were 77 plaintiffs but the numbers raised to 648.

While PG&E lawyers tried to de-link people’s health problems from exposure to chromium-6, the plaintiffs showed that the company knew the contamination at least since 1965 and did nothing. PG&E eventually managed to take the case out of courts and reach a settlement through mediation. In 1996, PG&E agreed to pay the plaintiffs a total of 333 million dollars, to end the use of chromium-6 in its cooling system and to clean up the environment.

After several unsuccessful attempts (the contaminated plume kept growing) to clean up the contaminated aquifer, PG&E started buying people’s houses in 2012 and destroying them to avoid squatting. Two-thirds of the residents in the affected area agreed and moved elsewhere causing Hinkley’s population to fall considerably. Later studies by the California Cancer Registry stated that cancer figures in Hinkley weren’t abnormal in the period 1988-2006. However, the Center for Public Integrity questioned the validity of the findings due to methodology problems, exclusion of the most serious cases and lack of independence between researchers and the chemical industry lobby. 

-In July 2014 California became the first state to acknowledge that ingested chromium-6 is linked to cancer and as a result has established a maximum Chromium-6 contaminant level (MCL) of 10 parts per billion (ppb)

-Hexavalent chromium was an additive that prevented rust in the gas cooling towers, and it was disposed of in nearby pools. Under ideal circumstances, the dangerous heavy metals would be filtered out and reclaimed.