Risks of low level radiation - New Scientist Article

[Norman Cohen <ncohen12@HOME.COM>]

Hi all,

Have fun with the "bystander effect".

Norm



>  Source:

> <A HREF="http://www.newscientist.com/news/news.jsp?id=ns99991640";>

> http://www.newscientist.com/news/news.jsp?id=ns99991640</A>

> ==========================================================

> Risks of low-level radiation higher than thought

>

> 04  December  01

> Hazel Muir

>

> Sources of low levels of radiation - such as radioactive radon gas

> seeping

> into houses - might cause more genetic damage and cancer than anyone

> realised, say a team of US researchers.

>

> "The effects of radiation are very complex," concludes Hongning Zhou

> of

> Columbia University in New York, a member of the team. "We should

> reconsider

> the risks of low levels."

>

> Current estimates of the risks of radiation come mainly from studies

> of

> cancer rates in survivors of the 1945 atomic bomb blasts in Hiroshima

> and

> Nagasaki, where the levels of radiation were very high. Scientists

> work out

> the risks of less intense radiation assuming that the cell damage

> falls off

> in direct proportion to the radiation dose.

>

> But that might not be true. Over the past few years, experiments have

> shown

> that the effects of radiation in cells are unexpectedly complicated

> due to a

> so-called "bystander effect", in which a radiated cell can alter the

> protein

> production of neighbouring cells.

>

> Now a team led by Tom Hei of Columbia University has measured the

> destructive

> effect of alpha particles on the genetic machinery of neighbouring

> cells.

>

>

> Mystery damage

>

>

> The team prepared layers of thousands of cells that are sensitive to

> mutations and targeted some of their nuclei with alpha particles. When

> they

> zapped 10 per cent of the cells with alpha particles, the number of

> cells

> with damaged DNA was similar to the number of casualties when they

> zapped all

> the cells.

>

> Why the neighbours suffer damage is a mystery. But it seems to be

> linked to a

> type of chemical communication in which the targeted cell exchanges

> small

> molecules with its nearest neighbours. When Zhou's team severed these

> chemical chat lines and repeated the alpha-particle assault, only the

> target

> cells were damaged.

>

> Until there are detailed studies of low-level radiation on animal and

> human

> tissues, no one will know if this is cause for alarm. "The effects on

> animals

> and people are likely to be even more complicated," says Richard

> Setlow, a

> biophysicist Brookhaven National Laboratory in Upton, New York. "But

> this is

> a clue what to look for."

>

> The result could fuel concerns over radon building up in confined

> spaces,

> such as the insulated basements of homes, as the gas leaks out of soil

> and

> rocks. The health risks of radon are controversial, but some

> scientists think

> it is responsible for thousands of deaths from lung cancer each year.

>

> However, Setlow says that the risks of radon cannot be much higher

> than

> currently predicted. If they were, we would see far more cancer cases

> from

> regions where radon gas is a problem.

>

> Journal reference: Proceedings of the National Academy of Sciences

> (vol 98, p

> 14,410)

>

> ==========================================================

>

>

>                    Yahoo! Groups Sponsor

                        ADVERTISEMENT





> -



Coalition for Peace and Justice and the UNPLUG Salem Campaign; 321 Barr

Ave., Linwood, NJ 08221; 609-601-8537 or 609-601-8583 (8583: fax, answer

machine);  ncohen12@home.com  UNPLUG SALEM WEBSITE:

http://www.unplugsalem.org/  COALITION FOR PEACE AND JUSTICE WEBSITE:

http:/www.coalitionforpeaceandjustice.org   The Coalition for Peace and

Justice is a chapter of Peace Action.

"First they ignore you; Then they laugh at you; Then they fight you;

Then you win. (Gandhi) "Why walk when you can fly?"  (Mary Chapin

Carpenter)





************************************************************************

You are currently subscribed to the Radsafe mailing list. To unsubscribe,

send an e-mail to Majordomo@list.vanderbilt.edu  Put the text "unsubscribe

radsafe" (no quote marks) in the body of the e-mail, with no subject line.