Scientists are uncertain about the human health risks posed by trace levels of most POPs. Some, such as dioxins, carry risks even at very low levels. According to animal studies, as well as some human studies, exposure to these chemicals might raise the risk of cancer or other diseases, reduce fertility, alter hormones, damage brain development and interfere with immune function.
For some chemicals, the EPA has set reference doses—amounts deemed safe for daily consumption, based mostly on animal tests. None of the foods in Schecter’s 2009 study contained concentrations over these guidelines. Americans’ daily dietary intake of DDT, for example, is about half the reference dose.
But health officials don’t know enough about the effects of many of the chemicals to set reference doses, said Schecter. And they know even less about what happens when people are exposed to multiple contaminants.
“Where reference doses do exist, they’re for individual chemicals. And we have no reference doses for a combination of several chemicals,” he said.
Determining “safe” doses for combinations of chemicals would be difficult and expensive, and so far few studies have been conducted.
Dr. Alex Stewart, a public health doctor in the United Kingdom who published a paper on chemical mixtures in 2009, said pollutants may be more harmful when combined in our foods and bodies than they are individually. Some chemicals, such as dioxins, are likely to add up to cause effects because they affect the same body systems in teh same ways, he said.
The combined potential of some substances has been well-documented. “Everyone knows that smoking causes lung cancer, and if you breathe radon, that causes lung cancer. Both smoking and radon cause lung cancer, but if you are exposed to both, your risk is greater,” Carpenter said.
While long-banned contaminants carry on their legacy, a younger generation of pollutants is joining them.
One of these is a group of flame retardants called polybrominated diphenyl ethers or PBDEs. PBDEs have been used in a variety of consumer goods since the 1970s. In the decades since, human exposure has risen sharply, and levels in human breast milk and blood are orders of magnitude higher in North America than in other parts of the world.
PBDEs in food are highly variable. One sample of beef, for example, might have twice as much as another. But despite this variability, the average American diet includes some daily consumption of PBDEs, primarily from eating dairy and meat, according to Schecter’s study.
Animal studies have linked PBDEs to compromised thyroid and liver function and impaired brain development. Concern over their health effects prompted a U.S. ban of several PBDEs in 2004. Last year, they were added to the Stockholm Convention’s list of targeted pollutants.
The Stockholm Convention - an international effort of nearly 100 countries to eliminate or restrict POP production and use - was signed in 1991. The original list, called the “dirty dozen,” included several pesticides and PCBs still present in food. The list was expanded in 2009 to include nine new chemicals, many of which showed up in Schecter’s food study.
The study also identified trace amounts of perfluorooctanoic acid, or PFOA, a chemical that had not previously been identified in the food supply. Perfluorinated compounds are commonly used for manufacturing grease repellants and water-repellant consumer goods, including Teflon.
Some of these compounds have been banned or industry has reduced their use. But because they are still in consumer goods, people are exposed through both dust and diet.
It isn’t clear how perfluorinated compounds are getting into food, said Dr. Tom Webster, an epidemiologist at the Boston School of Public Health. It’s possible that they are bioaccumulating like other pollutants, but they may also be leaching directly into foods during the packaging process, he said.
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25 Comments
Add CommentWhat a bunch of ignorance. DDT has never been proven dangerous to humans. It was also never responsible for the deaths of birds or the weakening of bald eagle shells. This myth has been propigated by those that believe all "chemicals" are bad and must be replaced with ineffective "natural" approaches. Never mind the millions dying of malaria, they might be exposed to a white powder with a negligible health risk so we need to ban it! Besides, the west has already used DDT to virtually eliminate malaria so what do we care? Fools. Don't believe me, look at the studies. They've been trying to pin the tail on this donkey for decades and no scientifically reproducible results show any strong correlation to negative health effects. Our parents and grandparents practically ate the stuff during the peak of its use and both life expectancy and quality of health has increased steadily both during use and after the ban. Just more fearmongering to push political and economic agendas.
Reply | Report Abuse | Link to thisDDT is stored in fat cells & thus kept out of the body's systems. The only way it's released is through breast milk & ear wax. However, weight loss can cause DDT to be released back into the body, as 1950s Army recruits found out; beefy farm boys were slimmed down in basic training & then got very sick from the DDT going back into their systems!
Reply | Report Abuse | Link to this@Econ,
Reply | Report Abuse | Link to thisWhy do you repeat such easily debunked lies? A quick Google Scholar search of peer reviewed articles reveals that DDT has been implicated in a number of health and environmental problems.
Diabetes:
Jones, Oliver AH; Maguire, Mahon L; Griffin, Julian L (January 26, 2008). "Environmental pollution and diabetes: a neglected association" (PDF). Lancet 371 (9609): 287288.
http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6T1B-4RNK38J-B-1&_cdi=4886&_user=4420&_orig=browse&_coverDate=02%2F01%2F2008&_sk=996280390&view=c&wchp=dGLbVtb-zSkzS&md5=49ceb153cf41f91572ac41664bcf057e&ie=/sdarticle.pdf
^ Turyk, Mary (March 6, 2009). "Organochlorine Exposure and Incidence of Diabetes in a Cohort of Great Lakes Sport Fish Consumers". Environ. Health Perspect.. http://www.ehponline.org/docs/2009/0800281/abstract.html.
http://ehp03.niehs.nih.gov/article/fetchArticle.action?articleURI=info:doi/10.1289/ehp.0800281
Other Health Hazards Reported
Breast Cancer
Cohn BA, Wolff MS, Cirillo PM, Sholtz RI (October 2007). "DDT and breast cancer in young women: new data on the significance of age at exposure". Environ. Health Perspect. 115 (10)
Endocrine System Pathologies:
Rogan WJ, Ragan NB (2003). "Evidence of effects of environmental chemicals on the endocrine system in children". Pediatrics 112 (1 Pt 2): 24752
http://www.ncbi.nlm.nih.gov/pubmed/12837917
Miscarriages:
Chen A, Rogan WJ (2003). "Nonmalarial infant deaths and DDT use for malaria control". Emerging Infect. Dis. 9 (8): 9604.
http://www.ncbi.nlm.nih.gov/pubmed/12967494
Egg Shell Thinning
Lundholm, C.E. (1997). "DDE-Induced eggshell thinning in birds". Comp Biochem Physiol C Pharmacol Toxicol Endocrinol 118 (118)
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1874172/
Holm L, Blomqvist A, Brandt I, Brunstr�m B, Ridderstr�le Y, Berg C (October 2006). "Embryonic exposure to o,p'-DDT causes eggshell thinning and altered shell gland carbonic anhydrase expression in the domestic hen". Environ. Toxicol. Chem. 25 (10): 278793.
http://www3.interscience.wiley.com/journal/122675732/abstract?CRETRY=1&SRETRY=0
That is not even half of what I found. So my question for you is: Why lie? Does you ideology blind you to the real risks being poised that these findings of science are inconsequential?
econ_101, you're just unbelievable...really.What kind of a fool does it take to disbelieve the facts when it is all around you. I reckon that the next thing you will say, "All this mental and physical retardation acclaimed by chemical exposure from plastic while the fetus is being formed is really caused only by our population increase and has nothing to do with chemical exposure."
Reply | Report Abuse | Link to thisIf econ_101 has a degree in biology and can prove it I'll eat my shorts.
Reply | Report Abuse | Link to thisSarah Palin called. She wants her ignorance back.
Reply | Report Abuse | Link to thisI grew up within a wetland area with drained lowlands. A large produce production farm there relied heavily on pesticides, including DDT. Over five decades, the bird population decreased, and then flourished, directly in proportion to the use, then withdrawal, of DDT. The response was dramatic. When the crop dusting started, the populations fell sharply the next year. This population decrease continued until nearly all the birds were gone within and adjacent to the industrial farm area. When the crop dusting stopped, populations rose each year, slowly at first. The population was stunted for well over a decade after the DDT ban. When you see it with your own eyes, it is difficult to forgive the naysayers. I suspect the same production farm owner who killed off all the birds around my home would be among this group. To this individual, the land was purely an outdoor factory, which he "owned" to pollute at his will. There are none as blind as those who choose not to see.
Reply | Report Abuse | Link to thisI grew up within a wetland area with drained lowlands. A large produce production farm there relied heavily on pesticides, including DDT. Over five decades, the bird population decreased, and then flourished, directly in proportion to the use, then withdrawal, of DDT. The response was dramatic. When the crop dusting started, the populations fell sharply the next year. This population decrease continued until nearly all the birds were gone within and adjacent to the industrial farm area. When the crop dusting stopped, populations rose each year, slowly at first. The population was stunted for well over a decade after the DDT ban. When you see it with your own eyes, it is difficult to forgive the naysayers. I suspect the same production farm owner who killed off all the birds around my home would be among this group. To this individual, the land was purely an outdoor factory, which he "owned" to pollute at his will. There are none as blind as those who choose not to see.
Reply | Report Abuse | Link to thisSorry about the double entry, I was having difficulty with the sign-in system
Reply | Report Abuse | Link to thisI have a suggestion for a science fiction story:
Reply | Report Abuse | Link to thisSlowly introduce a large variety of long-term persistent molecules that bioaccumulate.
Once they become common enough in the background, they self-assemble, perhaps drawing energy from background radio waves, build replicators, pull together into more complex structures, download further instructions.
Better alien invasion through chemistry.
@Econ,
Reply | Report Abuse | Link to thisI'm sure you're next claim will be that this report on DDT can be directly attributed to Obama an the Democrats. Really, read more!
@Econ,
Reply | Report Abuse | Link to thisI'm sure your next claim will be that this report on DDT and other “persistent organic pollutants” is an Obama conspiracy perpetrated by the Democrats to push some nefarious socialistic agenda. What are you even doing making such a ridiculous claim in Scientific American? This is NOT a political website for BS right wing rhetoric.
I lurk here often, and must say I'm surprised by how forthright some of you are with with your constant misunderstanding of how to discern between arguments, facts, and politics.
Reply | Report Abuse | Link to thisecon_101 isn't even wrong.
Good job econ_101 for injecting some perspective into this poorly written article.
Reply | Report Abuse | Link to thisTrent1492, try actually reading some of the references you listed before you call anyone a liar. For example, the study on DDT and infant mortality suggests dubious causal relationships between DDE accumulation and lactation duration, then a further sketchy relationship between lactation duration and infant mortality, ultimately implying that DDE accumulation increases infant mortality. Its obvious that much more research needs to be done before any such dramatic conclusions can be drawn. In fact many studies of DDT and PCBs use similar weak analysis to draw apparently strong conclusions that, when examined more carefully, are nothing of the sort. Just because someone does a study and publishes it doesn't mean a thing if it's inconclusive, flawed, poorly done, or unsupported by other evidence.
Relationships between DDE accumulation and endocrine problems or breast cancer as yet have NOT been established.
The egg-shell thinning studies were debunked 3 decades ago. Stress, environmental encroachment, dietary changes, even noise pollution can cause egg-shell thinning. DDT doesnt.
The real historical ignorance going on here is on the part of the author who hasn't taken time to discover the debunked DDT studies and perpetuates the myth that DDT is an evil chemical. In fact the opposite is true. Its estimated that more than 25 million lives have been saved by using DDT to kill malaria-infected mosquitoes and typhus-carrying lice, diseases which were common in America before DDT. The reason malaria is practically unheard of now in the U.S. and Europe is because of an extensive DDT-spraying and swamp-draining campaign back in the 1940's. Count your blessings that you live in a country wealthy enough and ambitious enough to eradicate malaria. Unfortunately Africans weren't so lucky.
Paul Muller was awarded a Nobel Prize for the synthesis of DDT. Few synthetic chemicals have been so beneficial to mankind.
As for PCB's and other chemicals that bioaccumulate....sigh. Some of course are harmful and have been banned, but just because we have scientific instruments that can detect chemical traces as minute as a few parts per billion doesn't mean they have a deleterious effect on us. In fact, just like DDT, many of the studies are inconclusive. We need to carefully weigh the benefits and the REAL, well-established negative impacts before we malign chemicals just because theyre synthetic.
@Laurena,
Reply | Report Abuse | Link to thisSorry but you simply declaring multiple studies "dubious" does not make it so. How about some details?. What peer reviewed studies can you cite that debunk this body of work?
"Relationships between DDE accumulation and endocrine problems or breast cancer as yet have NOT been established."
Why do you think that declarative sentences without a hint of peer review work are trustworthy? Here let me make some declarative statements without substantiation.
Saddam Hussein and Al-Queda are in cahoots.
Evolution has been proven to be a fraud.
Cigarettes do not cause cancer.
See how easy it is just pull assertions just out of thin air?
"The real historical ignorance going on here is on the part of the author who hasn't taken time to discover the debunked DDT studies and perpetuates the myth that DDT is an evil chemical. In fact the opposite is true. Its estimated that more than 25 million lives have been saved by using DDT to kill malaria-infected mosquitoes and typhus-carrying lice, diseases which were common in America before DDT."
Yea, that must be why since DDT use in America has been curtailed the the mortality rate for those diseases has sky rocketed. Do you ever think before you type?
"The egg-shell thinning studies were debunked 3 decades ago. Stress, environmental encroachment, dietary changes, even noise pollution can cause egg-shell thinning. DDT doesnt."
Remember what I said about bald assertions without a hint of substantiation? What peer review work can you cite that debunks these studies? E.G here is some of the peer reviewed work on egg shell thinning.
Lundholm, C.E. (1997). "DDE-Induced eggshell thinning in birds". Comp Biochem Physiol C Pharmacol Toxicol Endocrinol 118 (118):
Holm L, Blomqvist A, Brandt I, Brunstr�m B, Ridderstr�le Y, Berg C (October 2006). "Embryonic exposure to o,p'-DDT causes eggshell thinning and altered shell gland carbonic anhydrase expression in the domestic hen". Environ. Toxicol. Chem. 25 (10): 278793. doi:
What is the matter with these studies? What peer reviewed studies can you cite that throw doubt on these particular studies? You waving your hands around and declaring them to be unsubstantiated and debunked will not cut that cut. Now please cite those empirically based peer reviewed studies that address the specifics of these papers.
You have been shown a large body of scientific works documenting the deleterious effects of DDT and your only response has been to declare those studies to be "inconclusive" and "debunked". Pitiful.
What a bunch of ignorance. DDT has never been proven dangerous to humans. It was also never responsible for the deaths of birds or the weakening of bald eagle shells." - Econ-101
Reply | Report Abuse | Link to thisOh look. Another Republican Liar. And he claims to have some association with economics.
Surprise... Surprise...
"econ_101 isn't even wrong." - John Boy Walton
Reply | Report Abuse | Link to thisNo. He is a liar. There is a difference.
"You have been shown a large body of scientific works documenting the deleterious effects of DDT and your only response has been to declare those studies to b
Reply | Report Abuse | Link to thisbe "inconclusive" and "debunked". Pitiful." - Trend1942
Ya, but you see, there is some KKKonservative KKKookfart Blog written by some garbage man named Boyd Bobank, who lives in Skraig South Carolina who claims that DDT never did done do diddily.
Boyd raises chickens for youngens to eats and have as pets, and he says that when he was spoken to Gawd, the Holy Spirit set him aside and tolds hem that cause he has blessed his chickens that he's getten one of Gods telling things so anhow the next time he grew some chickens then those chickens were kinda talking to him in his sleep and saying that DDT didn't kill no chickens and the like so boyd knows, and that thing with his wife is all a lie because she fell down that flight of stairs cause it wasn't his fault so that evils gubderment thats telling him he owz taxes to is a lie cause paying taxes in unconstigutional and it's like communiz or something, but back to the chickens cause they taste good and you can't taste DDT cause he's tried so you can bet on that.
And that is why DDT is safe.
Just ask Boyd.
"Salmon was the most contaminated food, with traces of six types of PCBs, two flame retardants and 25 pesticides, including DDT, dieldrin and toxaphene. Samples of canned sardines and catfish also contained numerous banned chemicals."
Reply | Report Abuse | Link to thisWaste of good flame retardant! Salmon are water cooled.
"Salmon was the most contaminated food, with traces of six types of PCBs, two flame retardants and 25 pesticides, including DDT, dieldrin and toxaphene. Samples of canned sardines and catfish also contained numerous banned chemicals."
Reply | Report Abuse | Link to thisSalmon are water cooled, what a waste of flame retardants.
Sounds like you must have a vested finacial interest in the continued sale of these dangerous chemicals? Or you are just plain ignorant!!! First of all those ineffective natural ingrediants are the ingrediants for a lot of the prescription drugs on the market that have helped alleviate different illnesses, not to mention that there are a lot of cultures that are a lot healthier than America that refuse to knowingly use chemicals in their lifes and instead use herbs, plants and other natural products for their health and everyday benefits. You need to either do more research on the subjects you are claiming to be informed about or quit your job as a paid lobyist for the chemical companies that because of there greed are threatening the very exsistance of the Human species.
Reply | Report Abuse | Link to thisnice article(instead of the normal snip)...also enjoyed the comments....
Reply | Report Abuse | Link to thisecon 101: I think you're just yanking our chains. Nobody is really that stupid.
Reply | Report Abuse | Link to thisI remember riding my bike behind the DDT truck with my friends. We really enjoyed breathing the "fake fog". While I have multiple health issues, every last one is traceable back through the generations far past the advent of DDT.
Reply | Report Abuse | Link to thisI think the truth is that we don't know enough to really determine the impact of these chemicals over time. The truth is probably somewhere between the 2 extremes in the comments.
There was a time when lead was good for make-up and water pipes and paint. Then they figured out that it kills people. Conversely, people used to think tomatos were deadly. Now we know they are very healthy for us to eat.
Ike Greil111 was here
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HALO REACH BETA TESTER