Monday, April 22, 2013
Hard graft leads to heart attacks, research finds
There's a mix of two studies reported below. The Greek study is pretty obviously just another instance of poorer people having worse health.
The Belgium/Denmark study is reasonably interpreted in the final sentence below and is a warning that exercise is not always beneficial
Those working in physically demanding jobs are more susceptible to heart disease than their desk-bound counterparts, according to new research.
The study in Greece found that those who did a day's work involving physical exertion were at least 20 per cent more likely to suffer from cardiovascular disease than those in an office.
A second study from Belgium and Denmark suggested that out-of-work exercise, such as in a gym, improved the coronary health of office workers but had a detrimental effect on those who already carried out manual labour as part of their job.
Men whose jobs involved strenuous physical work were four times more likely to have coronary heart disease when they also exercised in their leisure time, researchers reported.
Dr Demosthenes Panagiotakos, who led the Greek study, said the surprising results might be attributed to the extra stress experienced by people in physically demanding jobs.
However, he also said people in manual roles were more likely to be lower paid - which is linked to poorer health, with more unhealthy food and less access to healthcare.
Dr Els Clays, who led the Belgian and Danish study, added: "From a public health perspective it is very important to know whether people with physically demanding jobs should be advised to engage in leisure time activity.
"The results of this study suggest that additional physical activity during leisure time in those who are already physically exhausted from their daily occupation does not induce a 'training' effect but rather an overloading effect on the cardiovascular system."
Natural Resources Defense Council (NRDC) Champions Shoddy Journalism on Endocrine Active Chemicals
As Jon Entine of the Genetic Literacy Project reports, the NRDC is not exactly known for scientific nuance. So, there was little surprise when blogger Mae Wu took to the cyberwaves recently to plug an NBC Dateline story promoting the alleged dangers of “endocrine disrupting” chemicals.
According to Wu, we should all be shocked—yes shocked—that an NBC producer and her family found trace chemicals in their urine—microscopic amounts of BPA, triclosan and phthalates—all of which are approved and not harmful as commonly used, according to the Environmental Protection Agency.
But that didn’t stop NBC and Wu from hyping what amounted to chemophobia. The scare tactic in this case was insinuating that the presence of common chemicals in our urine is dangerous. Journalists who do not understand risk analysis make this mistake all the time—ignorantly more than likely by NBC, as the reporter had no background in toxicology or science in general, but cynically by NRDC, whose unstated mission it seems is to scare people about chemicals.
What NBC and Wu never disclosed is that the presence of chemicals in our urine is neither unusual nor, in almost all cases, anything to be remotely concerned about. Miniscule traces of substances found in our urine can sometimes be meaningful but it’s usually just data noise—an artifact of high tech ultra sensitive biomonitoring devices; the dose and exposure time, not the presence of a chemical, determines its toxicity.
NBC found tiny amounts of BPA, a chemical investigated and approved numerous times by the Environmental Protection Agency—most recently one year ago in a direct rebuke of an NRDC suit. The Centers for Disease Control and Prevention (CDC) has previously found traces of BPA in the urine of more than 90% of adults and children. That sounds frightening but not to a scientist. How scientists and journalists frame this often-stated fact is a good barometer of their understanding of toxicological risk—whether they genuinely wrestle with complex science or are mouthpieces, intentionally or not, for a predetermined, chemophobic perspective
Yes, we encounter BPA, phthalates and dozens of other common chemicals every day; and yes, they show up in our urine. It’s estimated that more than 160 chemicals can be detected in human urine, many of which are potentially dangerous if consumed at high enough doses over a long enough period of time. However, our liver regularly detoxifies chemicals from the environment and food, which is why we don’t keel over from drinking coffee, which has dozens of “killer” chemicals.
The CDC has repeatedly stated that while biomonitoring “can … help scientists plan and conduct research on exposure and health effects,” the presence of a chemical—whether BPA, triclosan, a phthalate or some other substance targeted by advocacy groups—does not mean that it’s harmful … or cause(s) an adverse health effect,” the CDC has written.
In the case of BPA, the FDA, reflecting the emerging scientific consensus that there is far more smoke than fire on the issue of so-called endocrine disruption, concluded, “[O]ral BPA administration results in rapid metabolism of BPA to an inactive [and therefore harmless] form.” The same mechanism is in place to detoxify many other so-called endocrine disrupting chemicals. The same is true for phthalates and triclosan, the other chemicals demonized by both NBC and the NRDC.
Phthalates in the crosshairs
Wu makes hash of the genuine scientific knowledge about all three chemicals. To dissect her shoddy reporting, I’ll just focus on one—the class called phthalates. Phthalates are plasticizers used to increase the flexibility and durability of a product. There are dozens of different types, but nine major ones used in thousands of consumer and industrial applications including, cosmetics, cables, flooring, medical devices and children’s vinyl backpacks and toys. NRDC’s website lumps them all together indiscriminately:
Phthalates are known to interfere with the production of male reproductive hormones in animals and likely to have similar effects in humans. Their effects in animal studies are well recognized and include lower testosterone levels, decreased sperm counts and lower sperm quality. Exposure to phthalates during development can also cause malformations of the male reproductive tract and testicular cancer. Young children and developing fetuses are most at risk.
A review of the evidence suggests that NRDC is far off the mark when it casually writes that phthalates are “likely to have similar effects in humans.” No study—not one—has shown that. Few chemicals on the market today have undergone as much scientific scrutiny as phthalate esters. Activists and industry groups pitted against each other in the debate have no shortage of studies they can invoke as ammunition. But one thing is clear: almost all of the evidence cited by anti-chemical campaigners is based on research linking phthalates to reproductive problems in rodents exposed to dose levels far higher than any human might face.
The NRDC’s misstatements about phthalates are compounded by the fact that, like many activist organizations, it willfully confuses different types of the chemical. Scientists draw distinctions between so-called low molecular weight ones—DEHP, BBP, DBP and DIBP— and high weight ones such as such as DINP, DIDP and DPHP. The low weight phthalates are slightly more volatile and can release minute amounts of off gasses—though not at toxic levels. As in the case of BPA, science bodies around the world have found low phthalates taken into the body are safely metabolized. Nonetheless, some regulatory bodies have voted in precautionary bans based entirely on rodent studies.
The long-term regulatory fate of the high phthalates is less sure. The chemical is ubiquitous, used in PVC/vinyl products as well as in hoses, shoe soles, sealings and many industrial processes. From a chemical perspective, high-weight phthalates are tightly bound, more stable and more resilient than low phthalates. They’ve been found safe time and again. Under the eye of activist groups and required by order of Congress, the US Consumer Product Safety Commission (CSPC) research organization known as the Chronic Hazard Advisory Panel or CHAP is expected to issue an updated scientific review soon. Pending the results of the CHAP review, there now exists a temporary ban on any child-care article that contains more than 0.1 percent of DINP, DIDP or DNOP.
It’s purely precautionary and unwarranted based on the death of evidence. The CDC offers a comprehensive list of links to a slew of scientific research on the chemical—none of which point to any serious human consequences. There is no cumulative buildup and the chemical is metabolized quickly by the body and excreted, noted Antonia M. Calafat of the CDC. “There is no consensus at present whether the phthalates are causing adverse health effects in humans,” added.
Two state of the art reports involving monitoring humans make hash of the NRDC’s fear mongering. A comprehensive study conducted in 2004 by the Children’s National Medical Center and the George Washington University School of Medicine showed no adverse effects in organ or sexual functioning in adolescent children exposed to phthalates as neonates. The same team evaluated infants in a 2010 study and reconfirmed the negative findings. Another more recent study has shown that even high levels of phthalates showed no effect on the genital development of marmosets, let alone humans—activist claims to the contrary.
More HERE (See the original for links)
Posted by jonjayray at 12:17 AM