Tuesday, December 04, 2007

Cancerous night-shifts?

I suppose we should be thankful that the article below admits that the conclusions it offers are speculative

Like UV rays and diesel exhaust fumes, working the graveyard shift will soon be listed as a "probable" cause of cancer. It is a surprising step validating a concept once considered wacky. And it is based on research that finds higher rates of breast and prostate cancer among women and men whose work day starts after dark. Next month, the International Agency for Research on Cancer, the cancer arm of the World Health Organization, will add overnight shift work as a probable carcinogen.

The higher cancer rates don't prove working overnight can cause cancer. There may be other factors common among graveyard shift workers that raise their risk for cancer. [Like being poor] However, scientists suspect that overnight work is dangerous because it disrupts the circadian rhythm, the body's biological clock. The hormone melatonin, which can suppress tumor development, is normally produced at night.

If the graveyard shift theory eventually proves correct, millions of people worldwide could be affected. Experts estimate that nearly 20 percent of the working population in developed countries work night shifts.

Among the first to spot the night shift-cancer connection was Richard Stevens, a cancer epidemiologist and professor at the University of Connecticut Health Center. In 1987, Stevens published a paper suggesting a link between light at night and breast cancer. Back then, he was trying to figure out why breast cancer incidence suddenly shot up starting in the 1930s in industrialized societies, where nighttime work was considered a hallmark of progress. Most scientists were bewildered by his proposal.

But in recent years, several studies have found that women working at night over many years were indeed more prone to breast cancer. Also, animals that have their light-dark schedules switched develop more cancerous tumors and die earlier. Some research also suggests that men working at night may have a higher rate of prostate cancer.

Because these studies mostly focused on nurses and airline crews, bigger studies in different populations are needed to confirm or disprove the findings. There are still plenty of skeptics. And to put the risk in perspective, the "probable carcinogen" tag means that the link between overnight work and cancer is merely plausible. Among the long list of agents that are listed as "known" carcinogens are alcoholic beverages and birth control pills. Such lists say nothing about exposure amount or length of time or how likely they are to cause cancer.

The American Cancer Society Web site notes that carcinogens do not always cause cancer. The cancer society doesn't make its own assessments of possible cancer-causing agents, but relies on analyses by the IARC and a U.S. agency. Still, many doubters of the night shift link may be won over by the IARC's analysis to be published in the December issue of the journal Lancet Oncology. "The indications are positive," said Vincent Cogliano, who heads up the agency's carcinogen classifications unit. "There was enough of a pattern in people who do shift work to recognize that there's an increase in cancer, but we can't rule out the possibility of other factors."

Scientists believe having lower melatonin levels can raise the risk of developing cancer. Light shuts down melatonin production, so people working in artificial light at night may have lower melatonin levels. Melatonin can be taken as a supplement, but experts don't recommend it long-term, since that could ruin the body's ability to produce it naturally.

Sleep deprivation may be another factor in cancer risk. People who work at night are not usually able to completely reverse their day and night cycles. "Night shift people tend to be day shift people who are trying to stay awake at night," said Mark Rea, director of the Light Research Center at Rensselaer Polytechnic Institute in New York, who is not connected with the IARC analysis. Not getting enough sleep makes your immune system vulnerable to attack, and less able to fight off potentially cancerous cells.

Confusing your body's natural rhythm can also lead to a breakdown of other essential tasks. "Timing is very important," Rea said. Certain processes like cell division and DNA repair happen at regular times. Even worse than working an overnight shift is flipping between daytime and overnight work. "The problem is re-setting your body's clock," said Aaron Blair, of the United States' National Cancer Institute, who chaired IARC's recent meeting on shift work. "If you worked at night and stayed on it, that would be less disruptive than constantly changing shifts."

Anyone whose light and dark schedule is often disrupted - including frequent long-haul travelers or insomniacs - could theoretically face the same increased cancer risk, Stevens said. He advises workers to sleep in a darkened room once they get off work. "The balance between light and dark is very important for your body. Just get a dark night's sleep."

Meanwhile, scientists are trying to come up with ways to reduce night workers' cancer risk. And some companies are experimenting with different lighting, seeking a type that doesn't affect melatonin production. So far, the color that seems to have the least effect on melatonin is one that few people would enjoy working under: red.


Anti-salt craze

Strange that they fail to mention that people on salt-restricted diets die SOONER!

The nation's top food regulators and the salt industry faced off at an FDA hearing Thursday, although it will be months, perhaps years, before the Food and Drug Administration rules on the salt reduction petition that sparked the hearing. The FDA's conclusion, however, could drastically reduce the amount of salt consumed by Americans every day.

Consumer and health advocacy groups say that after years of neglecting the issue, it's time for government to recognize the harmful effects of salt on blood pressure by imposing limits on salt content in foods sold in stores and to restaurants.

Salt industry representatives question the medical evidence linking salt to heart disease and stroke, and dispute the notion that limits on salt would make Americans healthier.

With each side claiming it has science on its side, and with indisputably high rates of elevated blood pressure in the United States, it is certain that the debate will continue. Even among members of the same family. Jeff Dax said he doesn't often frequent the fast food restaurants that dot Broadway, in Sacramento. He said he typically packs a lunch to eat on breaks from his job as a construction contractor. But that didn't happen Thursday, when he made his way to Taco Bell for a quick taco and quesadilla lunch with his father. Dax, himself an avid cook, said he'd welcome restrictions on salt content in fast foods, citing a family history of clogged arteries and heart disease. "You can always add more (salt)" he said. His father, Tom Dax, disagreed. Like food industry groups, he argues against regulation and for personal responsibility when it comes to diet. "I don't even salt my eggs," he said. "It's better to limit what you eat."

Liz Applegate, a nutrition expert at the University of California, Davis, agrees. While acknowledging studies that show salt contributes to high blood pressure, she said it is foolish to single out the mineral for regulation. "If you cut in half the amount of sodium in, say, a TV dinner, is that going to improve the health of the nation?" she asks. "My answer is no. The bigger issue is too many calories are consumed, and we don't burn the calories. And we don't have enough fruits, vegetables and grains in our diet."

Health advocates pushing for limits on salt content acknowledge that America's health problems are not all rooted in salt consumption. "But this is the single easiest piece of the pie to tackle," said Dr. Stephen Havas, vice president for Science, Quality and Public Health at the American Medical Association, who testified at the FDA hearing Thursday. "You can actually engineer a public health solution. You can systematically reduce the salt in foods and people's palates will adjust very quickly."

Morton Satin, director of technical and regulatory affairs at the Salt Institute, the U.S. salt industry's trade group, disagreed. "They don't understand the role of salt in food," said Satin, citing the highly healthy but salty Mediterranean diet, which features olives, capers and anchovies. Satin, who referred to salt-reduction proponents as "bozos" and "Marx brothers in lab coats," argued that salt limits would make people even less likely to want to eat healthy foods, particularly vegetables like broccoli, which many people agree taste better salted.

Among the proposals before the FDA are a 50 percent reduction in sodium in processed foods, fast food products and restaurant meals over the next decade and improved labeling of food products, including warnings for foods high in sodium. Havas said consumers are still confused about food labeling, and the industry has not done enough voluntarily to make its products healthier. He cited efforts in some European countries, including Great Britain and Finland, to regulate the use of salt in processed foods and to clearly label foods' salt content.

Despite decades of public health messages about the dangers of too much salt, American consumption of salt has actually increased by 55 percent the past 30 years, said Michael F. Jacobson, director of the Center for Science in the Public Interest, which filed the petition with the FDA. Americans now consume about 4,000 milligrams of sodium per day, about twice the amount recommended by the federal government, Jacobson said. There are 2,300 milligrams in a teaspoon of salt. "We are not sending out the full message about cutting back on sodium, and people are eating more and more processed foods," said Havas.

That has resulted in a corresponding increase in hypertension, which affects more than 30 percent of U.S. adults. Hypertension, or high blood pressure, is a known risk factor for heart disease and stroke. Excessive salt causes the body to retain fluid, which can overload the body's circulatory system, putting increased pressure on the blood vessel walls, kidneys and heart, Havas said. He cited several studies that link salt consumption with high blood pressure, noting that the World Health Organization has called the evidence conclusive.



Just some problems with the "Obesity" war:

1). It tries to impose behavior change on everybody -- when most of those targeted are not obese and hence have no reason to change their behaviour. It is a form of punishing the innocent and the guilty alike. (It is also typical of Leftist thinking: Scorning the individual and capable of dealing with large groups only).

2). The longevity research all leads to the conclusion that it is people of MIDDLING weight who live longest -- not slim people. So the "epidemic" of obesity is in fact largely an "epidemic" of living longer.

3). It is total calorie intake that makes you fat -- not where you get your calories. Policies that attack only the source of the calories (e.g. "junk food") without addressing total calorie intake are hence pissing into the wind. People involuntarily deprived of their preferred calorie intake from one source are highly likely to seek and find their calories elsewhere.

4). So-called junk food is perfectly nutritious. A big Mac meal comprises meat, bread, salad and potatoes -- which is a mainstream Western diet. If that is bad then we are all in big trouble.

5). Food warriors demonize salt and fat. But we need a daily salt intake to counter salt-loss through perspiration and the research shows that people on salt-restricted diets die SOONER. And Eskimos eat huge amounts of fat with no apparent ill-effects. And the average home-cooked roast dinner has LOTS of fat. Will we ban roast dinners?

6). The foods restricted are often no more calorific than those permitted -- such as milk and fruit-juice drinks.

7). Tendency to weight is mostly genetic and is therefore not readily susceptible to voluntary behaviour change.

8). And when are we going to ban cheese? Cheese is a concentrated calorie bomb and has lots of that wicked animal fat in it too. Wouldn't we all be better off without it? And what about butter and margarine? They are just about pure fat. Surely they should be treated as contraband in kids' lunchboxes! [/sarcasm].

9). And how odd it is that we never hear of the huge American study which showed that women who eat lots of veggies have an INCREASED risk of stomach cancer? So the official recommendation to eat five lots of veggies every day might just be creating lots of cancer for the future! It's as plausible (i.e. not very) as all the other dietary "wisdom" we read about fat etc.

10). And will "this generation of Western children be the first in history to lead shorter lives than their parents did"? This is another anti-fat scare that emanates from a much-cited editorial in a prominent medical journal that said so. Yet this editorial offered no statistical basis for its opinion -- an opinion that flies directly in the face of the available evidence.

Even statistical correlations far stronger than anything found in medical research may disappear if more data is used. A remarkable example from Sociology:
"The modern literature on hate crimes began with a remarkable 1933 book by Arthur Raper titled The Tragedy of Lynching. Raper assembled data on the number of lynchings each year in the South and on the price of an acre's yield of cotton. He calculated the correla-tion coefficient between the two series at -0.532. In other words, when the economy was doing well, the number of lynchings was lower.... In 2001, Donald Green, Laurence McFalls, and Jennifer Smith published a paper that demolished the alleged connection between economic condi-tions and lynchings in Raper's data. Raper had the misfortune of stopping his anal-ysis in 1929. After the Great Depression hit, the price of cotton plummeted and economic conditions deteriorated, yet lynchings continued to fall. The correlation disappeared altogether when more years of data were added."
So we must be sure to base our conclusions on ALL the data. But in medical research, data selectivity and the "overlooking" of discordant research findings is epidemic.


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