Extract of New report
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SOURCE:
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.

EXTRACT:
The Internet has been flooded with email warnings to avoid freezing
water in plastic bottles so as not to get exposed to carcinogenic
dioxins. Recently, one hoax email has been attributed to Johns
Hopkins University. We sat down with Dr. Halden 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...

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.

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.

[HE GOES ON TO MENTION BACKYARD BONFIRES!]...

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 don't think there are.

OC&PA: So it's 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's 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.

FOR FULL REPORT GO TO:
http://www.jhsph.edu/publichealthnews/articles/halden_dioxins.html