“On what grounds do you know it's being grossly underestimated? It's a possibility, but many hypotheses have been proposed, and unless you have real evidence, you can’t say that it is,” said Dr. Michael Thun, vice president emeritus of epidemiology and surveillance research for the American Cancer Society.
Thun said the President’s panel overstates the concern about environmental causes when the best way to prevent cancer is to combat the largest risks that people encounter: tobacco, diet and sun.
But many environmental epidemiologists say quibbling over the numbers becomes a diversionary tactic.
They say the American Cancer’s Society’s statement sounds a bit like a principle espoused by industry groups – don’t act without absolute proof of harm. Many environmental epidemiologists are in favor of moving toward the precautionary principle – reducing people’s exposure to environmental pollutants even if there is uncertainty about the risks.
It’s an "erroneous exercise” to try to assign each chemical or exposure a specific fraction of cancer, said Richard Clapp of Boston University's School of Public Health, who co-authored a 2005 review and 2007 update on environmental and occupational causes of cancer.
"It's estimating a fiction, because nobody knows and nobody can know," said Clapp. "Why do we keep beating this dead horse? If there are things we can move on, let's work on those."
Cancer is the second leading killer of Americans, and the leading cause of death worldwide. Every year, about 1.5 million new cases are diagnosed in the United States and more than half a million people die from the disease, according to the American Cancer Society.
Experts agree that most cancers are caused by lifestyle factors such as smoking, diet and alcohol. Smoking alone accounts for at least 30 percent of all U.S. cancer deaths, and another one-third is attributed to diet, obesity and physical inactivity, according to the American Cancer Society.
But it’s the remaining cancers – about one out of every three – that trigger debate.
A 1981 report by two scientists, Sir Richard Doll and Sir Richard Peto, published in the Journal of the National Cancer Institute, estimated that two percent of cancer deaths were attributable to exposures to pollutants in the environment and four percent to exposures in occupational settings. In 2009, those percentages amounted to about 30,000 U.S. deaths.
“If you looked at the number of deaths per day, if that were a plane crash it would be a national news story,” Clapp said.
The 1981 report only considered deaths, not cancer cases. (About half of those diagnosed with cancer die.) Also, the study only included Caucasians under the age of 65, although many cancers increase with age and many minority groups are more highly exposed to environmental contaminants.
The old two percent estimate for environmentally induced cancers is still commonly used – despite advances in modern cancer biology.
New areas of cancer research are focusing on the potential for pollutants to interact with one another and with genetic factors. Carcinogens can act by damaging DNA, disrupting hormones, inflaming tissues, or switching genes on or off.
Also, exposure to hormonally active agents during critical periods of human development – particularly in the womb or during childhood – may trigger cancer later in life. For example, the risk of breast cancer could be influenced by exposures during puberty.
All these elements make it tricky to calculate the magnitude of environmentally induced cancers.
Scientists now know that getting cancer is like being attacked by a multi-headed monster: How can you really be sure which part did the most damage?
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23 Comments
Add CommentBenzene is exhaled by every living human. I can't understand why smokers are targeted regarding this as well as many other chemicals.
Reply | Report Abuse | Link to thisBenzene is exhaled by every living person. Why is it being targeted at and attributed to smokers only?
Reply | Report Abuse | Link to thisSo if all these other environmental, occupational, etc. chemicals cause cancers, including lung cancer, how is it they can pin a 60% on smoking. Are smokers the only people not exposed to arsenic in our drinking water? Have no smokers worked as mechanics? My husband used a cleaner for years that's known to cause cancer (provided by his employer). If he gets cancer, how do you attributed it solely to being a former smoker? I think this is all bull feces that smoking is the only cancer figure that's given a percentage. It's to demonize smokers and to force restrictive smoking and high taxes so they can save us from ourselves. Give me the percentages on all the other cancer causes and I'll take this article seriously. If you can't produce them, then stop spreading the lies. It gives SCIENCE a bad name.
Reply | Report Abuse | Link to thisI'll bet 6% is too high.
Reply | Report Abuse | Link to thisIsn't this a bit like asking how many cancer causes fit on the head of a pin?
Reply | Report Abuse | Link to thisThe most general statement is that effectively all cancers are caused by environmental conditions and contributing genetic factors. As a result, it's important to identify the environmental factors that contribute the most to human suffering.
Endless debates over which accounting method to use do nothing to reduce human suffering. But it does inhibit any action against those who may be profiting from the production of environmental conditions producing cancers...
Perhaps society can start by identifying the consensus top ten problems and focus on their correction?
The Doll and Peto estimates for the proportion of cancers from environmental exposures gets an unfair bashing by the Panel. They say they are, “woefully out of date, given our current understanding of cancer initiation as a complex multifactorial, multistage process” but the “greatest shortcoming ... is that calculation of attributable fractions does not fully account for the fact that environmental contaminants interact with each other and that all avoidable causes of cancer are not known”. This is just scaremongering of the worst sort - we don't know the whole truth so it must all be terrible!
Reply | Report Abuse | Link to thisAlthough there seems to be a tendency for regulators to always go back to Doll and Peto there are more up-to-date assessments. For example, I have been involved in an evaluation of the cancer burden from occupational exposures in Britain, with the latest results of our work recently published in the British Journal of Cancer (1). This work shows that occupational cancers probably account for about 5% of all cancer deaths, which is not so different from the estimates from Doll and Peto (4%). However, what has changed is the agents that these deaths are attributed to - risk factors that have increased in importance since 1981 include asbestos, respirable crystalline silica, nightshift working and diesel engine exhaust; less important must be a range of manufactured chemicals that are now better controlled than they were in the past. It is very likely that the future occupational cancer burden, i.e. the deaths that will arise from current exposures, will be lower than current burden because most exposures have decreased steadily over the last 30 or 40 years.
It is a good idea for society to put more effort into understanding how to better assess and control risks from occupational and environmental cancer, but with the key purpose of deciding our priorities for action. Disappointingly this did not come through from the Panel's report.
In the meantime we should start tackling the serious problems that we know we have - for example, diesel exhaust particulate and shift work - rather than worrying about the probably small number of deaths that might arise from other environmental causes.
John Cherrie
www.OH-world.org
1. Rushton et al. Occupation and cancer in Britain. British Journal of Cancer (2010) vol. 102 (9) pp. 1428-1437.
@Soccerdad -
Reply | Report Abuse | Link to this"I'll bet 6% is too high".
And what do you base that upon - a wild ass guess or political alignment? At least this article is referring to studies and data that have been gathered.
You are certainly entitled to your opinion, but you are not entitled to your own facts.
Seems like environmental cancers are caused by genes that should be dormant turning on, ie. epigenetics. If there are chemicals that turn on genes, are there chemical that turn off genes or prevent the epigenetic trigger from being pulled?
Reply | Report Abuse | Link to thisCould it be that in some peoples genetic heritage that there are epigenetic triggers waiting to be pulled by the right substance, while in others that trigger is not cocked? Sorry for the analogies, but it's the only way I can envision it.
Reply | Report Abuse | Link to thisThe percentage of cancer caused by environmental factors is difficult to determine, as there is no direct proof that a particular agent has hit the normal cells and made them malignant. Some cancers occurring in some organs like prostate are age dependent. Smoking, drinking of contaminated water and food additives having hydrocarbons, asbestos, coal tar, etc. are factors provocateurs that turn a normal cell into a malignant one. Cancer is a multifactorial disease, caused by so many factors ranging from genetic, epigenetic, to environmental. The statement that six out of hundred cancers are due to environmental factors is a vague assessment and statement.
Reply | Report Abuse | Link to thisIt is pretty well established that exposure to asbestos among shipyard workers who also smoked caused 100% mortality within only a few decades. I follow this because I had huge exposure to asbestos as a younger man who milled and fitted asbestos concrete pipe wearing only paper air masks and taking them off too soon because they were uncomfortably hot when working for long periods.
Reply | Report Abuse | Link to thisI wasn't a smoker but I was exposed to huge amounts of second hand smoke from the first wife and from a series of jobs in extremely smokyestablishments.
So far the old lungs show no mesothelioma and at retirement age I show no problems not related to diet and a sedentary lifestyle. Also for many years I was involved in spraying herbicides and pesticides in agriculture with minimal use of any protection except paper dust masks inconsistently worn.
One of the young men I worked with on a spraying crew died at a very young age of a brain tumor.
Also I had an interest in gold mining as a young rural Montanan which took me into a lot of old mine shafts that tended to read high in radon gas and the element radium and I once owned a Montana house that supposedly had a high radon gas level in the basement.
They say that Mt. Shasta in California tends to have very high levels of airborne asbestos due to seams of the stuff being exposed to high winds, and that certain areas of the world
are high in natural radioactivity, especially regions in Brazil where uranium is mined.
I have also flown a lot (up in the thousands of hours) which exposes one to radiation. When I was quite young a shoe store in Salt Lake City had an X-ray machine sales gimmick that probably zapped my feet with about a thousand times what would now be used by my orthopedist. I also knew a surgeon who in the early days of the 1950's used to set broken bones directly under a fluoroscope. This doctor eventually developed skin cancer on his hands, which he lost before passing in his late 50's.
A lot of Utah residents successfully argued that cancer rates in their families were too high because of down winder exposure to above ground nuclear testing in the 1950's. The over all Utah cancer rates were actually lower than the national average, but the lawyers successfully argued that most of these victims were Mormons who never smoked or drank and that therefore their cancer rates should have been much lower still. The government paid out, but I have always wondered about the people I knew who identified themselves as Mormon heritage but still smoked and drank.
The 60 percent figure is a combined Smoking and Diet figure. Only about 30 percent of cancer deaths are from smoking. What I would like to know is, why are there so many links in this article to cancer and smoking, but not one to cancer and diet?
Reply | Report Abuse | Link to thisThe panel got it right, when reporting the public is unaware of formaldehyde.
Reply | Report Abuse | Link to thisFormaldehyde increases asthma & cancer. 18-months after California Energy Commission (CEC) required homes be insulated (wrapped in formaldehyde), asthma & cancer rates rapidly increased. Three decades later, we remain puzzled, claiming we don't know why asthma & cancers increased.
California Air Resources Board's (CARB) report released on 12/15/2009 invetigated 2002-04 conventional site built homes found:
"Nearly all homes (98%) had formaldehyde concentrations that exceeded guidelines for cancer and chronic irritation..."
Summary: http://www.arb.ca.gov/research/apr/past/04-310exec_sum.pdf
Report: http://www.arb.ca.gov/research/apr/past/04-310.pdf
PowerPoint: http://iee-sf.com/resources/pdf/ResidentialVentilation.pdf
The 2005 California Energy Commission code requires home building shell be leak testing. The required sealing (to save energy) reduces the amount of natural dilution that had been occurring. Residential formaldehyde concentrations roughly doubled from 29 ppb to 50-75 ppb.
Green homes that are required to exceed the California Energy Code by 15% have formaldehyde concentration greater than 100 ppb: http://www.aihasynergist-digital.org/aihasynergist/201002?pg=32#pg32
The CARB report on CA homes built 2002-2004 shows 1 air exchange/hour is needed to control residential formaldehyde. Effctive 1/1/2010 the CEC requires 0.35 air exchange/hour. The anticipated result would be to have formaldehyde concentrations approaching 3 times what the California Office of Environmental Health Hazard Assessmets recommends.
CEC solely focused on energy completely irgnores health consequences of their decisions. I ask, How green is a home vacated to preserve the occupants health?
Homes with double pane windows and/or fiberglass wall insulation should be tested for formaldehyde. The Sierra Club discovered the FEMA trailers using passive badges. http://acsbadge.com/formaldehyde.shtml $39 includes lab analysis. No special skills required.
Increasing ventilation reduces formaldehyde. You can pay doctor bills or energy bills, your choice. Until the information is made available to the residents they cannot make an informed choice.
As a community service, I have measured elevated formaldehyde in homes, advised what can be done to reduce the given concentrations, and verified reduced formadehyde. Nearly all parents reported improved health with some children being able to stop their asthma medicines without a single asthma attack.
It is a silly article. Almost all points of it could be argued. Just one for an example: 60% due to smoking. Then, how do you explain the fact that there is no correlation between smoking and lung cancer rate, if you study different countries separate. For instance, Greeks smoke the most cigarettes, but has the lowest lung cancer rate in Europe?
Reply | Report Abuse | Link to thisIt is a silly article. Too many points of it could be argued. Here is one as an axapmple: if smoking causes 60% of lung cancer, how do you explain the fact that there is no correlation between smoking and lung cancer rate country by country. For instance, Greeks smoke far most cigarettes, but still ther have the lowest cancer rate in Europe?
Reply | Report Abuse | Link to thisOn the other hand, it is good to draw attention to the environmental factors of cancer. If you think about the mechanism and physiology of cancer, you could end up with a conclusion: almost all cancers are caused by environmental factors (including not only air pollutants, but all those pollutants we eat or put on our skin). Of course not counting the few ones that are clearly caused by viruses...
Mike Cook - One of the most important things a person can do to minimize his risk is to VERY carefully pick his parents. Considering the exposures you list, you probably are blessed with excellent protoplasm. Knowing what you now know, you presumably are no longer tempting mother nature, because she can be a b***h.
Reply | Report Abuse | Link to thisThose physicians who worked with x-rays in the first half of the 20th century had no idea what they were dealing with. Our pathology class in the late sixties had some pretty gruesome specimens to examine, but the one that gave us all the "Willies" was the preserved, amputated arm of a physician radiologist, who had developed bone cancer in the arm he used while working with a flouroscope.
Lambness - I have no idea how scientifically sound it is, and I'm too lazy to check it out, but a book you might find interesting is titled "The China Study". Our youngest brought it home from college last year, suggesting we read it. I did, and while I have not attempted to evaluate the veracity of any claims it makes, somehow my appetite for meat and dairy products is much less than it used to be.
One of the difficulties for research in this area is that many studies that would yield valuable information cannot be ethically justified.
Just because most cancers are caused by smoking, doesn't mean environmental chemicals are OK - what about health risks that do not turn into cancers? I'm thinking of endocrine-disrupting chemicals and neurotoxins that can be causing diabetes, infertility and ADHD.
Reply | Report Abuse | Link to thiscandide - What facts? According to the article "scientists most likely will never be able to tease out the true role of environmental contaminants because environmental exposures, genetics and lifestyle seem to all intertwine." And, of the claim that the incidence of environmental cancers is greater than 6%, the American Cancer Society said that "there was no scientific consensus".
Reply | Report Abuse | Link to thisSo, since this is all pure speculation, I speculate that the "true" incidence rate is less than 6%. Speculation is just that, and by its nature one guess is not really any more valid than another one. Mine just took less paper.
Neither lifestyle nor smoking is a choice because most humans do not have free will. Most are hopelessly brainwashed by their cultural environment to do whatever social fad is passing through. Once they experiment a few times, habituation rears its ugly head.
Reply | Report Abuse | Link to thisI always argue that we are genetically predisposed to have a degree of predisposition to any particular thing. Everyone has some degree of predisposition to homosexuality or to alcoholism. The mechanisms of predisposition can be tricky because many alcoholics start with an extremely high tolerance for alcohol, which means they can drink a lot without getting as sick as most of us would get immediately.
The gay behaviors probably have some type of Darwinian value in extremely stable, secure, and rich societies with large cosmopolitan population centers. Where life is hard and brutally poor, the social norm tends to fixate around male/female bonding as being the ultimate survival unit. If a person is lucky enough to be equally yoked in marriage (to use a biblical analogy to oxen) it is a case of one plus one actually equalling the strength of three even before reproduction.
I should add that the Bible says that homosexuality is permissable to man, meaning something like "natural" when they said that. Because the Bible authors were basically living in a world that was hard and poor (you can tell because richness is defined as the number of goats in your herd) they emphasize that what is natural to man frequently is not what is beneficial. Their underlying view was that the natural world and its natural rules were hostile not only to the existence of humankind, but to the higher realm that we should be striving to achieve in which worldly satisfactions count for little or nothing (Islam, although derived from Judeo/Christianity, is unique in preserving the promise of worldly pleasure in the afterlife which is why a martyr would enjoy having dozens of virgins to cavort with.)
Today, of course, many people believe exactly the opposite about how wonderful nature is. Do whatever natural urge you may have, as "natural" is something to be worshipped for its own sake.
Well, the Bible, of course, predicts an end to civilizations like that which is positively Glenn Beckian it is so horrible.
I left open the possibility that a few humans do have free will. If this were not true, we would all be followers with no leaders, an impossible situation from a survival standpoint.
I had cancer, 7 years ago, the tests show me clear now and I lost 40 pounds to be healthier. We spent thousands of dollars researching diet and found that organic foods, less chemicals, and fresh salads were considered "cancer fighters". Well, we devised a "Cancer Fighter" salad, and share it with you free. See it in http://www.bootheglobalperspectives.com for details, or see the video: http://www.youtube.com/watch?v=qV3C68ozzAM
Reply | Report Abuse | Link to thisIt is ours free to you, with our blessings and good luck. Feel free to pass it on. Ben
Reply to Hawkeye--when I was in high school my girl friend's dad was the surgeon for the area. He also died in the 1970's because of skin cancer in his hands caused by setting bones under the fluoroscope. It seemed like a good idea at the time because it got a good result for the patient quickly.
Reply | Report Abuse | Link to thisThe only thing that's really out of date is the pseudoscience these charlatans use to falsely blame lifestyle and chemicals for diseases that are really caused by infection. They falsely pretend that merely comparing exposed versus nonexposed people while ignoring the role of infection is "rigorous" science, when it's really just a scam designed to exploit the circumstance that poorer people are more likely to be exposed to both chemicals and viruses. And the estimate of the percentage of cancer (17%) caused by viruses is out of date, too.
Reply | Report Abuse | Link to thisIn claiming that formaldehyde causes nasopharyngeal cancer, the NTP flagrantly ignored the fact that ALL NPCs, of every histology, contain clonal episomal EBV genomes, express specific EBV genes and are a clonal expansion of EBV-infected cells. This is called a clue! They fraudulently pretended that EBV is "ubiquitous," and could therefore be ignored, when there are enormous socioeconomic differences in exposure. Their only citation that mentions EBV merely inquired into a history of mononeucleosis, which is famously associated with higher socioeconomic class and later exposure! And these quacks still haven't admitted that EBV a is human carcinogen, although the IARC did so in 1997.
Similarly, they ignored the role of human papillomavirus in sinonasal cancer, and blamed styrene for non-Hodgkin's lymphoma and chronic lymphocytic leukemia, which are known to be EBV-associated. The NTP didn't admit that HPV is a human carcinogen until 2004, while the IARC did so in 1995. Yet no industry anywhere has ever challenged their charlatanism, while the quacks' media shills and fellow travelers brainwash the public with phony stories accusing industry of coverups! And the pathetic incompetents pretending to be scientists blather things like "It’s like looking at strands of a spider web and deciding which one is important," as if the link between EBV is merely an "association" with no more legitimacy than any chance association found via lifestyle questionnaire.
And look at the backgrounds of the members of the so-called "Expert Panel" behind the formaldehyde report! Of the roughly 841 studies listed under their collective names, only 2 dealt with viruses at all, both in mice, and none concerning EBV or HPV which are relevant to the human diseases at issue.
The real scientists are never invited to their little parties, and their work is never mentioned. They're nothing but echo chambers. That's how they make their reports "unanimous!"
http://www.smokershistory.com/percent.htm
If this is going on ,cancer is spreading rapidly,why WHO and other agencies are mum ? we must take strong action to conserve nature,environment and human heath.
Reply | Report Abuse | Link to thissuresh chopane ,India