pbs高端访谈:危险化学品六价铬污染美国饮水系统

 　　JEFFREY BROWN:And now to part two of our investigative look at the safety of America's drinking water.

　　Science correspondent Miles O'Brien reports on the toxic 1 chemical made famous in the movie "Erin Brockovich," its potentially harmful effect on human cells, and the agency charged with regulating it.
　　His report is the result of a partnership 2 with the Center for Public Integrity.
　　AMIE HOLMES, University of Southern Maine: There is some lead chromate in here and some zinc 3 chromate.
　　MILES O’BRIEN:At the Wise Laboratory at the University of Southern Maine, they are very wise indeed about a widely used heavy metal that gives millions of Americans shiny bumpers 4, vivid paint, and, possibly, cancer. It is hexavalent chromium, or chromium 6.
　　AMIE HOLMES:As you can see, there's a lot of different colors to chromium.
　　MILES O’BRIEN:Yes.
　　And there are many shades of gray to the story, right?
　　AMIE HOLMES:Yes.
　　MILES O’BRIEN:Chromium 6 was also used as a coolant here at a natural gas pumping station owned by Pacific Gas & Electric in Hinkley, Calif. The utility dumped 26 tons of the chemical into unlined holding ponds in the 1950s and '60s. It leeched 5 into the groundwater, poisoning the wells.
　　The health fallout and the David and Goliath legal battle against PG&E became the basis for the 2000 movie "Erin Brockovich" starring Julia Roberts.
　　JULIA ROBERTS, Actress: People are dying, Scott. You have got document after document here. Right under your nose, it says why, and you haven't said one word about it. I want to know how the hell you sleep at night.
　　MILES O’BRIEN:Hinkley is not alone.
　　Public utility testing records reveal more than 70 million Americans are now drinking tap water tainted 6 by chromium 6.
　　AMIE HOLMES:This is what happens when the cells are exposed to chromium.
　　MILES O’BRIEN:Wise researcher Amie Holmes showed me what scientists can say for certain about the link between chromium 6 and cancer. These are slides of human lung cells in the midst of replicating 7, a process called mitosis.
　　In normal cells, there are two centrosomes, the yellowish-white dots. They search and capture 46 chromosomes 8 each, then pull apart, making an identical daughter cell.
　　AMIE HOLMES:You want to make sure that each cell has the same amount of DNA 9 in each.
　　MILES O’BRIEN:Take a look at these lung cells exposed to chromium 6. Notice the yellowish-white centrosomes? Instead of two, there are four.
　　AMIE HOLMES:What's going to happen, and when this cell divides, instead of dividing into two, it could potentially pull the DNA into four or it's going to unevenly 10 separate the DNA.
　　MILES O’BRIEN:With four centrosomes, it's not going to end well.
　　AMIE HOLMES:It's not going to end well.
　　MILES O’BRIEN:Scientists call this centrosome amplification 11. They suspect chromium 6 changes the chemistry of the proteins in our cells, and that creates the extra centrosomes.
　　The resulting defective 12 cells that survive are what we call cancer.
　　JOHN WISE, University of Southern Maine: Yes, it causes cancer. That's the biggest health concern.
　　MILES O’BRIEN:We know that for sure?
　　JOHN WISE:Right. Yes.
　　MILES O’BRIEN:There's no doubt about that?
　　JOHN WISE:There's no doubt about it. It's considered a human carcinogen by all the major regulatory agencies in the world.
　　MILES O’BRIEN:So, what's in here?
　　JOHN WISE:Cells.
　　MILES O’BRIEN:Lab director John Wise can say that with certainty chromium 6 is carcinogenic when inhaled 13, occupational exposure in factories. But when the chemical is ingested in the stomach, it is a murkier 14 picture.
　　Sandy Wise offered me a demonstration 15. Water that is heavily contaminated with chromium 6, like this, turns bright yellow. Now watch what happens when she adds vitamin C, which is acidic, not unlike the human stomach.
　　SANDY WISE, University of Southern Maine: So, you can see it's starting to change color.
　　MILES O’BRIEN:The water turns green as the chromium 6 is transformed into trivalent chromium, or chromium 3.
　　Our cells don't absorb chromium 3 as they do chromium 6. So the human stomach offers a natural antidote 16 to chromium 6 in water. But what are the limits of this alchemy?
　　John Wise says we can't say for certain.
　　JOHN WISE:There's just holes in the data, so there's a lot that we don't know.
　　MILES O’BRIEN:What more science needs to be done?
　　JOHN WISE:I don't think we have enough studies to tell us whether—clearly whether it's a drinking water carcinogen or not.
　　MILES O’BRIEN:But there are studies that make the link. In 2008, the National Institutes of Health weighed in with an eye-opening rodent 17 study. It uncovered clear evidence that high doses of chromium 6 in drinking water caused cancer in rats and mice.
　　MILES O’BRIEN:Does it settle anything in your view?
　　JOHN WISE:I think that starts the conversation as to perhaps maybe it is a drinking water carcinogen, but it's just one study that needs additional work.
　　MILES O’BRIEN:In 2011, Wise joined eight colleagues on a panel that advised the EPA on the science that would be used to set a new standard for chromium 6 contamination in U.S. tap water.
　　The current standard, set 20 years ago, is 100 parts per billion, 5,000 times higher than the state of California's public health goal for chromium 6 in drinking water. Wise was among panelists who voted to delay a decision, allowing time for more study. At first, the agency said it needed another four years, even though it began the work in 2008.
　　The chromium standard is bogged 18 down in IRIS 19, the Integrated Risk Information System, which aims to insure the best science is employed as the EPA considers regulating risky 20 chemicals.
　　That's the idea. But the National Academy of Sciences has blasted IRIS for using faulty methodology, and not being clear and transparent 21. And the Government Accountability Office criticized IRIS for moving way too slowly. The GAO estimates it takes the EPA an average of about seven years to complete a scientific assessment 22 of a chemical.
　　Anger and frustration 23 over the logjam boiled over at this IRIS stakeholders meeting in November.
　　Richard Denison is with the Environmental Defense 24 Fund.
　　RICHARD DENISON, Environmental Defense Fund: Now, these delays have profound real-world consequences. They allow continued exposure and harm to health from the subject chemicals, because decisions that rely on IRIS are also delayed. Simply put, a decision delayed is health protection denied.
　　MILES O’BRIEN:So, why is the process so bogged down? The first clue comes from who showed up at the stakeholders meeting.
　　KATHLEEN ROBERTS, North American Metals Council: My name is Kathleen Roberts. I am with the North American Metals Council.
　　KIMBERLY WISE, American Chemistry Council: My name is Kimberly Wise. I am with the American Chemistry Council.
　　NINA HALLMARK, ExxonMobil Chemical: Good afternoon. My name is Nina Hallmark. I am with ExxonMobil Chemical.
　　RICK BECKER, American Chemistry Council: Thanks. Rick Becker with American Chemistry Council.
　　NANCY BECK, American Chemistry Council: Thanks. Nancy Beck, American Chemistry Council.
　　MILES O’BRIEN:Representatives of chemical manufacturers and their trade association, the American Chemistry Council, dominated the meeting.
　　David Fischer is a senior director at ACC.
　　MILES O’BRIEN:Is industry kind of overwhelming this process?
　　DAVID FISCHER, American Chemistry Council: No, I would say definitely not. Our member companies are populated by any number of employees, including scientists who perhaps have spent their careers studying a particular chemical that might be the subject of an IRIS assessment. So it stands to reason that all that important experience and knowledge should be brought to bear on the IRIS process.
　　MILES O’BRIEN:But the NewsHour and the Center for Public Integrity have learned the chemical industry is close to the scientific review process as well.
　　Although John Wise says he hasn't accepted any funding from industry in 15 years, two of his colleagues on the chromium 6 panel worked for PG&E during the Hinkley legal battles. And one of them, Joshua Hamilton of the Marine 25 Biological Lab at Woods Hole, got a call from PG&E asking him to work as a consultant 26 while he was serving on EPA's chromium 6 review panel.
　　The panel held its meeting on May 12, 2011. PG&E paid Hamilton to address a town hall meeting at the regional water board that governs Hinkley on June 8, 2011.
　　JOSHUA HAMILTON, Marine Biological Lab, Woods Hole: I am an independent toxicologist asked by PG&E to come here and speak about chromium health issues.
　　MILES O’BRIEN:The peer review report was released a month later. Dr. Hamilton declined our requests for an on-air interview. He later told us he reported his potential conflict to the government contractor 27 that manages peer reviews for the EPA and that they decided 28 this didn't represent a conflict of interests, particularly since he would participate in the panel before engaging with PG&E in the town hall meeting.
　　We did speak with PG&E. Sheryl Bilbrey is director of the chromium remediation team.
　　SHERYL BILBREY,Pacific Gas & Electric: And his role has been to explain the toxicity 29 of hexavalent chromium. He's not discussed any part of the regulatory process.
　　Well, again, PG&E expects anyone that works for us, that they will maintain their professional integrity and be completely independent of any regulatory process. So we wouldn't expect Josh to—or Dr. Hamilton to change any of his advice.
　　MILES O’BRIEN:Sometimes, though, the appearance of a conflict is a conflict, isn't it?
　　SHERYL BILBREY:Well, I don't think so, I think as long as everyone knows that Dr. Hamilton does work for us. And he is very well-respected, so I think his credentials 30 really speak for him.
　　MILES O’BRIEN:At the stakeholders meeting, the acting 31 director of IRIS, Vincent Cogliano, vowed 33 to make some changes in the program.
　　VINCENT COGLIANO, Integrated Risk Information System: And in addition, we will post the names of potential reviewers before the meeting so that we can get public comment on the expertise 34 and the conflicting interests of our reviewers. It is a shame that we don't have the highest-quality peer review and the most impartial 35 peer review that we can get.
　　MILES O’BRIEN:In a written statement, the EPA claims it is committed to using the best science, working to improve the IRIS review process and reduce any potential conflict of interests by increasing transparency and public input 36.
　　Despite that vow 32, the EPA refused our repeated requests for an interview. During the course of our five-month investigation 37, the agency did make a new promise, to decide on an updated chromium 6 standard in another year, instead of four. But what are they waiting for? A $4 million dollar study funded by the American Chemistry Council, which represents the chemical industry.
　　Ann Mason is a senior director with ACC.
　　ANN MASON, American Chemistry Council: So, essentially 38, Miles, ACC and its members do not have any direct link with any of the researchers that are part of this study.
　　MILES O’BRIEN:Right. But you're writing the check for the study?
　　ANN MASON:We're writing the check for the study, but in the process of putting this together, we have got a study director who is in direct link. We do not have any contact with the research -- researchers, nor with the peer review process. So we are trying to be as arm's-length away from this, the actual conduct of the work, as possible.
　　MILES O’BRIEN:In the U.S., industry doesn't need to prove a chemical is safe before it is used commercially. The chemical, not the people, get the benefit of the doubt. And so delays inevitably 39 favor industry.
　　Dr. Wise, what's the matter with setting a level and then continuing the science? And if the science tells you, hey, we can raise it a little bit later, do so.
　　JOHN WISE:That is certainly an approach one could take. It's just not typically the—it's the way these things are done, I guess. It's not—levels don't change all that often. It seems to be a fairly cumbersome 40, slow, expensive process.
　　MILES O’BRIEN:Cumbersome, slow and expensive, in Washington, that seems to be just part of the chemical equation.
　　JUDY WOODRUFF:Online, you can watch Miles' first report, explore a graphic 41 that tracks chromium levels across the country, and find tips on how to remove the chemical from your drinking water. That's all on our Science page.