Polluters who contaminate drinking water and make people sick shouldn't get off easy. That has been the focus of my work for two decades, and I'm not planning to stop now.

My work focused the attention of the world on a carcinogen called hexavalent chromium (hex chrome). In 1996, Pacific Gas and Electric Co. – a multibillion-dollar corporation – paid $333 million in damages to the people of Hinkley for contaminating their drinking water and covering up the problem for decades while people got sick and died. This victory was immortalized in film. But the story doesn't end there.

More than 500 California communities and 30 million state residents drank water contaminated with hexavalent chromium at levels above safe levels between 1998 and 2003. Hex chrome has been detected in nearly 60 percent of the drinking water sources sampled in California.

These problems are especially widespread in the Central Valley and the Inland Empire. The PG&E-Kettleman case settled in 2006 for $335 million. Another PG&E site in Topock affected the Colorado River – a drinking water source for millions. In Burbank, contamination by Lockheed Martin affected thousands, and in Riverside, TXI Corp's cement kiln contaminated the soil. Even Disney is responsible for chromium contamination in the San Fernando Valley.

Communities all over the United States and around the world have been poisoned by this chemical. I am currently working on a case in Midland, Texas, with enormous levels of hexavalent chromium in well water. Chromium polluters include a Who's Who of major corporations. It doesn't take a genius to know that these polluters don't want people to realize the extent of the problem, since they'd be on the hook for an expensive cleanup.

So it doesn't surprise me that five years after California regulatory agencies were required by law to set an up-to-date enforceable standard for hex chrome in drinking water, consumers are still not protected. I've fought these powerful interests for years, and I know firsthand how good they are at delay tactics.

The good news is that Cal-EPA's Office of Environmental Health Hazard Assessment – the public health agency that the governor tried unsuccessfully to eliminate in the last budget cycle – has just come out with a proposed drinking water level that would protect Californians.

The new assessment uses research from the National Toxicology Program to identify the levels of hex chrome that cause cancer and then calculates a safe level for vulnerable populations including children. There was a public meeting in Oakland last week to accept comments on this proposal; written public input is welcome until Nov. 2.

I read through the 140-page Cal-EPA document with mixed feelings. On the one hand I felt vindicated, but I also felt saddened. The National Toxicology Program concluded in a 2007 study that hexavalent chromium is considered carcinogenic not only by inhalation but by ingestion. Gosh, who knew? Maybe if someone had believed all these people in Hinkley many years ago, many more lives would have been saved.

I was saddened by the descriptions of liver and kidney degeneration, blood abnormalities including anemia, testicular damage, infertility, miscarriage, fetal toxicity, chromosomal abnormalities and a litany of cancers. The clinical descriptions in the Cal-EPA document weren't abstract to me – they brought back the names and faces of people who I know who have lived and died with these illnesses.

Roberta Walker, the original client in the movie, was poisoned by Chromium 6. PG&E recently tested her new well at her new home and found levels of hexavalent chromium at 1.26 parts per billion, well over the proposed level of 0.06 ppb.

I congratulate the hard work of attorneys who fought on behalf of those poisoned and I applaud agencies and scientists for overseeing, setting and hopefully enforcing stricter standards. My fight for the people of Hinkley isn't over. To bring this dark chapter of history to a close, California must adopt a legally enforceable and truly health-protective standard for hex chrome in drinking water.

I cannot protect every contaminated community, but if we have a uniform standard, I will rest easier knowing that people won't be unknowingly drinking this dangerous substance. This chemical is a serious problem and I am glad it is being addressed. California has always led the way in setting standards that other states follow. We need to make prevention the goal of the future.

Erin Brockovich is an environmental investigator with Brockovich Research & Consulting and a longtime public health advocate.