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Reply
| | | From: Rene (Original Message) | Sent: 8/22/2006 10:41 PM |
It has come to our attention that the "Cancer News From Johns Hopkins" article we published in our most recent Archangel Health News ezine contained some false information. Therefore, in the interest of maintaining credibility and providing the most accurate and reliable information we can, you will find the corrected information below. We certainly apologize for the error and hope that this will serve to set the record straight.
Thank you for reading the Archangel Health News and, as always, we welcome any comments or questions you might have.
Sincerely,
Darrin and Sandi Quiles
Archangel Health News
aomega.com( The following was excerpted from a web page at the Johns Hopkins Bloomberg School of Public Health site at:
http://www.jhsph.edu/publichealthnews/articles/halden_dioxins.html )
Researcher Rolf Halden, PhD, PE, Dispels Myth of Dioxins and Plastic Water Bottles
The Internet has been flooded with email warnings to avoid freezing
water in plastic bottles so as not to get exposed to carcinogenic
dioxins. One hoax email has been erroneously attributed to Johns
Hopkins University since the spring of 2004. The Office of
Communications and Public Affairs discussed the issue with Rolf
Halden, PhD, PE, assistant professor in the Department of
Environmental Health Sciences and the Center for Water and Health at
the Johns Hopkins Bloomberg School of Public Health. Dr. Halden
received his masters and doctoral degrees researching dioxin
contamination in the environment. We sat down with him to set the
record straight on dioxins in the food supply and the risks
associated with drinking water from plastic bottles and cooking with
plastics.
Office of Communications and Public Affairs (OC&PA): What are dioxins?
Rolf Halden: Dioxins are organic environmental pollutants sometimes
referred to as the most toxic compounds made by mankind. They are a
group of chemicals, which include 75 different chlorinated molecules
of dibenzo-p-dioxin and 135 chlorinated dibenzofurans. Some
polychlorinated biphenyls (PCBs) also are referred to as dioxin-like
compounds. Exposure to dioxins can cause chloracne, a severe form of
skin disease, as well as reproductive and developmental effects, and
more importantly, liver damage and cancer.
OC&PA: Where do dioxins come from?
RH: We always thought dioxins were man-made compounds produced
inadvertently during the bleaching of pulp and manufacturing of
pesticides like Agent Orange and other chlorinated aromatics. But
dioxins in sediments from lakes and oceans predate these human
activities. It is now generally accepted that a principal source of
dioxins are various combustion processes, including natural events
such as wild fires and even volcanic eruptions. Today, the critical
issue is the incineration of waste, particularly the incineration of
hospital waste, which contains a great deal of polyvinyl chloride
plastics and aromatic compounds that can serve as dioxin precursors.
One study examined the burning of household trash in drums in the
backyard. It turns out that these small burnings of debris can put
out as much or more dioxins as a full-sized incinerator burning
hundreds of tons of refuse per day. The incinerators are equipped
with state-of-the-art emission controls that limit dioxin formation
and their release into the environment, but the backyard trash
burning does not. You set it ablaze and chemistry takes over. What
happens next is that the dioxins are sent into the atmosphere where
they become attached to particles and fall back to earth. Then they
bind to, or are taken up, by fish and other animals, where they get
concentrated and stored in fat before eventually ending up on our
lunch and dinner plates. People are exposed to them mostly from
eating meat and fish rich in fat.
OC&PA: What do you make of this recent email warning that claims dioxins can be released by freezing water in plastic bottles?
RH: No. This is an urban legend. There are no dioxins in plastics. In
addition, freezing actually works against the release of chemicals.
Chemicals do not diffuse as readily in cold temperatures, which would
limit chemical release if there were dioxins in plastic, and we do
not think there are.
OC&PA: So it is okay for people to drink out of plastic water bottles?
RH: First, people should be more concerned about the quality of the
water they are drinking rather than the container it is coming from.
Many people do not feel comfortable drinking tap water, so they buy
bottled water instead. The truth is that city water is much more
highly regulated and monitored for quality. Bottled water is not. It
can legally contain many things we would not tolerate in municipal
drinking water. Having said this, there is another group of
chemicals, called phthalates that are sometimes added to plastics to
make them flexible and less brittle. Phthalates are environmental
contaminants that can exhibit hormone-like behavior by acting as
endocrine disruptors in humans and animals. If you heat up plastics,
you could increase the leaching of phthalates from the containers
into water and food.
OC&PA: What about cooking with plastics?
RH: In general, whenever you heat something you increase the
likelihood of pulling chemicals out. Chemicals can be released from
plastic packaging materials like the kinds used in some microwave
meals. Some drinking straws say on the label "not for hot beverages."
Most people think the warning is because someone might be burned. If
you put that straw into a boiling cup of hot coffee, you basically
have a hot water extraction going on, where the chemicals in the
straw are being extracted into your nice cup of coffee. We use the
same process in the lab to extract chemicals from materials we want
to analyze. If you are cooking with plastics or using plastic
utensils, the best thing to do is to follow the directions and only
use plastics that are specifically meant for cooking. Inert
containers are best, for example heat-resistant glass, ceramics and
good old stainless steel.
Archangel Health News aomega.com August 21, 2006 |
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Reply
| | | From: Rene | Sent: 10/17/2006 11:15 PM |
Tons of PCBs Reaching the Deep Oceans
Toxic chemicals that have been released into the environment have turned up in some rather unexpected places. And while it has long been known that polychlorinated biphenyls (PCBs) and other persistent organic pollutants have been found in the surface waters of the oceans, especially the North Atlantic and Arctic, little was known about the quantity of PCBs that have reached the deep ocean.
In a paper published in Geophysical Research Letters, University of Rhode Island chemical oceanographer Rainer Lohmann and colleagues found that approximately 870 kilograms of PCBs per year make their way to the deep ocean at four subduction zones in the North Atlantic and the Southern Ocean.
According to Lohmann, 600,000 tons of PCBs were produced in Europe and North America in the 1950s and 1960s, and about 10 percent of that total has escaped to the atmosphere, soils, sediments and water column.
"In the oceans, the surface water has the highest concentrations of PCBs, and there is a slow exchange with the deeper waters as the chemicals attach themselves to phytoplankton and sink," Lohmann said. "At these subduction zones, though, even more PCBs are removed from the surface through deep water formation."
Subduction zones are where cold or highly saline water sinks below warm or less salty water, moving at a rate of 10 million cubic meters per second and carrying with it whatever chemicals are in the water column. By translating the known atmospheric concentrations of PCBs into dissolved levels in the surface water, the researchers determined that about 420 kilograms of PCBs per year are circulated to deep water in the Norwegian Sea subduction zone, while an additional combined total of 450 kilograms per year are removed from the surface waters annually in the Labrador, Ross and Weddell seas.
"There is tremendous interest in removing these toxic chemicals from the active environment where they could impact human health, so it is helpful to know how much has been removed from the surface," Lohmann said. "While the total amounts being removed from the surface waters is small when compared to the total PCBs produced, it’s still important to know just where those chemicals have gone. But it’s also useful to know that natural processes in the ocean will take a long, long time to remove all the PCBs from the surface water."
Because these chemicals are persistent in the environment over long periods of time, Lohmann said that they could be used to trace human activity back to the time they were made. "If we could switch off the release of PCBs today, we would still be able to see how a plume of PCBs from 50 years ago moved into deeper water. In 1,000 years, someone will still be able to trace those chemicals back to us," he said.
Source: University of Rhode Island
http://www.physorg.com/news80321723.html |
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