12.29.10
Chromium: Where's the balanced reporting?
By: Jack Dini, Hawaii Reporter
Hinkley, California, the town made famous in the Oscar-winning Julia Roberts movie Erin Brockovich, does not show any evidence of an increased or unusual rate of cancers.
This was reported by few media outlets during the week of December 13. (1, 2) One would have thought this was good news and should have been covered more widely. But the fact that it was good news meant that it was not news.
You would think this would have been cause for celebration -- no cancer clusters, no cancers above expected limits -- but not so. In fact, Erin Brockovich is back in Hinkley pursuing claims about a return of the chromium plume. (1)
"You know what I think is interesting," asks American Council on Science and Health's Dr. Gilbert Ross. "That The New York Times failed to cover the story. If the survey showed that there was an increased risk of cancer in Hinkley, you'd find the headline on page A1
We've seen this over and over again: whenever there's good news about health, The Times in particular, and many other media outlets tend to bury it; but if there's any bad news, it becomes a blaring headline." (3)
Then a strange thing happened a week later, almost seemingly by design intent. On December 20 a number of major media outlets headlined a study that found 'cancer-causing chromium' in tap water. The New York Times was prominent in the coverage. (4-7)
Honolulu was listed as one of the worst offenders in terms of chromium levels in the drinking water.
Who to Believe? What's going on? What to do?
Some background: Hinkley is the place where Erin Brockovich successfully took PG&E to court forcing it to pay a record $333 million class-action settlement because it was determined that the company allowed a toxic plume of hexavalent chromium 6 (Cr6) to be released from a natural gas pipeline.
Recently, the California Cancer Registry reported on three cancer studies
From 1996 to 2008, 196 cancers were identified among residents of the census tract that includes Hinkley -- a slightly lower number than the 224 cancers that would have been expected given its demographic characteristics. The survey did not attempt to explain why any individual in Hinkley contracted cancer, nor did it diminish the importance of PG&E's cleaning up of a plume of groundwater with elevated levels of Cr6.
"In this preliminary assessment we only looked at cancer outcome, not specific types of cancer," said epidemiologist John Morgan who conducted the studies. "However, we did look at a dozen cancer types in earlier surveys of the same census tract for the years between 1988 and 1998. Overall, the results of those surveys were almost identical to the new findings, and none of the cancers represented a statistical excess." (2)
All of the above was reported on December 13, but as mentioned above it was mostly ignored. Then a timely event happened on December 20. This time The New York Times joined the fray with the headline,"Probable Carcinogen Found in Tap Water of 31 US Cities." (4) They discussed a report by the Environmental Working Group (EWG) that said drinking supplies in 31 of 35 cities tested contained some level of Cr6, and 25 had higher levels than the California goal of 0.06 ppb.
According to EWG, the top five chromium-contaminated cities were: Norman, OK, 12.9 ppb, Honolulu, HI, 2.0 ppb, Riverside, CA, 1.69 ppb, Madison, WI, 1.58 ppb, and San Jose, CA, 1.34 ppb. (8)
Dr. Robert Baratz, an expert on metal exposure who teaches at the Boston University and Tufts Medical School, questions drawing scientific valid conclusions from the single samples EWG took from water taps in a variety of cities. (9) No mention was made of the lack of a cancer outbreak in Hinkley, or the fact that all of these values pale in comparison to the 580 ppb found in Hinkley during Brockovich's original investigation. (9)
The EWG reported that chromium caused cancer in laboratory mice and rats. In spite of this, Cr6 has never been shown to be carcinogenic to humans in any degree when dissolved in drinking water. The only cancer that can be attributed to Cr6 is with workers who inhaled massive amounts over many years. The EPA oral reference dose (RfD) for Cr6, which includes a monster safety factor of 300, is way above the levels of Cr6 detected by EWG. (10)
Deborah Proctor reports in the Journal of Toxicology and Environmental Health: "The preponderance of evidence from recent epidemiological studies of Cr6-exposed workers does not support an increased risk of cancer outside of the respiratory system; studies of four environmentally exposed populations are negative; there is only one lifetime animal feeding study, and the findings from that study are considered to be flawed and inconclusive; and recent kinetics and in vivo genotoxicity data demonstrate that Cr6 is reduced to nontoxic Cr3 in saliva, in the acidic conditions of the stomach and blood.
In short, at concentrations at least as high as the current US maximum contaminant level (100 ppb), and probably at least an order of magnitude higher, Cr6 is reduced to Cr3 prior to or upon systemic absorption. The weight of scientific evidence supports that Cr6 is not carcinogenic in humans via the oral route of exposure at permissible drinking-water concentrations." (11) Other research also supports the reductive capacity of gastric juices. (12)
What about chromium in our bodies, food and cigarettes?
John Emsley reports, "Chromium is essential to some species, including humans. The daily human intake varies according to the diet; it can be as much as 1 milligram, but is more likely to be in the range 15-100 micrograms.
Chromium is an essential element because it is needed to help the body utilize glucose, and its presence in RNA may indicate a second role." (13) Thomas Jukes calculates that the approximately 6 mg of chromium in each of our bodies supplies 0.7 x 106 molecules per cell. (14)
Chromium is present in many foods; those with the most, more than 300 ppb, are oysters, calf's liver, egg yolk, peanuts, grape juice, and black pepper. Many commonly eaten foods have some chromium, such as potatoes (18 ppb), beans (9 ppb), carrots (18 ppb) and apples (8 ppb). Emsley adds,
"Chromium is not seen as a major environmental pollutant although it has caused problems in rivers taking untreated industrial water, especially that from tanneries. Soluble chromate in soils gradually turns into insoluble Cr3 salts and then becomes unavailable to plants. In this way the food chain is protected against excess chromium which cannot pass the barrier between soil and plant roots, so that even chromate-rich sewage from industrial areas does not pose a threat. (13)
Tobacco has been reported to contain around 5,000 ppb Cr6. (15)
Steve Milloy sums this up well: "EWG specializes in efforts to scare people about the mere presence of chemicals and metals in drinking water. The group seems to be impervious to Paracelsus' 450-year-old basic technology principle that the dose makes the poison." (10)
References:
- Tim Cavanaugh, "Erin Brockovich: Town Shows No Cancer Cluster", Reason Magazine, December 13, 2010
- Warner Todd Huston, "No Cancer in Hinkley, California: Activist Hollywood Wrong AGAIN!", Canada Free Press, December 16, 2010
- "Julia Roberts only plays good gals, Right? American Council on Science & Health Dispatch, December 15, 2010
- Elana Schor, "Probable Carcinogen Found in Tap Water of 31 US Cities," The New York Times, December 20, 2010
- "Hexavalent Chromium Cancer-Causing Toxin, Common in Tap Water: What To Do," cbsnews.com, December 20, 2010
- Wendy Koch, "Study find likely carcinogen in 31 US cities' water," USA Today, December 21, 2010, Page 2A
- Lyndsey Layton, Study finds probable carcinogen in 31 US cities' tap water," The Washington Post, December 20, 2010
- Rebecca Sutton, "Cancer-causing Chromium-6 Pollution in US Tap Water," Environmental Working Group
- Eliza Barclay, "Some Scientists Skeptical of Report on Chromium in Drinking Water," NPR's Health Blog, December 22, 2010
- Steve Milloy, "EWG pulls an 'Erin Crockovich,'" junkscience.com, December 20, 2010
- Deborah M. Proctor, "Is Hexavalent Chromium Carcinogenic Via Ingestion? A Weight-of-Evidence Review," Journal of Toxicology and Environmental Health, Part A, 65, 701, May 2002
- Brent D. Kerger et al., "Refined Exposure Assessment for Ingestions of Tap-Water Contaminated with Hexavalent Cr," Journal of Exposure Analysis and Environmental Epidemiology, 6, 163, 1996
- John Emsley, Nature's Building Blocks, (Oxford, Oxford University Press, 2011), 111
Thomas H. Jukes, "Chasing a Receding Zero," in Rational Readings on Environmental Concerns, - Jay H. Lehr, Editor, (New York, Van Nostrand Reinhold, 1992), 329
Tor Norseth, "The Carcinogenicity of Chromium," Environmental Health Perspectives, 40, 121, 1981
To track the status of the ongoing risk assessment:
http://cfpub.epa.gov/ncea/iristrac/index.cfm?fuseaction=viewChemical.showChemical&sw_id=1107