[condor27596]

Don't forget the pool. From a modeled risk point of view the chlorine in the pool is off the charts.

[dosdan]

From a modeled risk point of view the chlorine in the pool

Yes, and I believe the air inside the bathroom shower enclosure, when the water is chlorinated, is not particularly good for you either.

Is your daily shower making you sick?

http://aje.oxfordjournals.org/content/165/2/148.abstract

http://www.ncbi.nlm.nih.gov/pubmed/16556748

Dan.

[condor27596]

Exactly!!!

---------- Post added 07-30-15 at 08:03 PM ----------

I'm moving to Fuji islands gonna use a Kodak 110 from here on out.

[lmd91343]

We live in a sea of ionizing radiation. We don't need to be alarmist, but we need to be intelligent in the way we conduct our lives. Obviously, the greater the exposure to that radiation, the higher the risk of cancer. Even thought he odds are small there is still a chance of the terrible.

Here is part of a press release from the National Academy of Sciences. The complete document's reference URL can be found below.

Date: June 29, 2005
Contacts: Vanee Vines, Senior Media Relations Officer
Megan Petty, Media Relations Assistant
Office of News and Public Information
202-334-2138; e-mail <news@nas.edu>

FOR IMMEDIATE RELEASE

Low Levels of Ionizing Radiation May Cause Harm

WASHINGTON -- A preponderance of scientific evidence shows that even low doses of ionizing radiation, such as gamma rays and X-rays, are likely to pose some risk of adverse health effects, says a new report from the National Academies' National Research Council.

"The scientific research base shows that there is no threshold of exposure below which low levels of ionizing radiation can be demonstrated to be harmless or beneficial," said committee chair Richard R. Monson, associate dean for professional education and professor of epidemiology, Harvard School of Public Health, Boston. "The health risks – particularly the development of solid cancers in organs – rise proportionally with exposure. At low doses of radiation, the risk of inducing solid cancers is very small. As the overall lifetime exposure increases, so does the risk." The report is the seventh in a series on the biological effects of ionizing radiation.

Home | The National Academies of Sciences, Engineering, and Medicine

[Digitalis]

don't look now....

Radioactive lens element from Takumar 50mm f/1.4

[Dlanor Sekao]

We live in a sea of ionizing radiation. We don't need to be alarmist, but we need to be intelligent in the way we conduct our lives. Obviously, the greater the exposure to that radiation, the higher the risk of cancer.

I guess this is why good ol Mom always said....."Wear Your Sunscreen" !
Of course being 13yrs old and "knowing everything".... I DIDNT listen....................... Now its Skin Cancer City at 52 and a constant battle.

[Clothears]

Hello. i am a new member of the forum. I was looking for a takumar 55mm 1.8 lens to buy to use adapted with my mirrorless camera. Anyways after doing a bit of research i learned that the lenses are radioactive. This of course worries me because radiation can't be good.

It seems to me you are worrying because you know nothing about it, but have been told by the media and others that anything radioactive is dangerous. This is not necessarily the case. You yourself are radioactive, as is everything on the planet, and this would still be the case whether or not humans had ever built nuclear reactors or made nuclear bombs.

Almost all Thorium consists of one isotope that, while radioactive, has a half-life of 14 billion years. This is extremely long; the longer the half-life of something, the weaker its radioactivity. As has been stated, Thorium gives off alpha particles which are unable to penetrate a sheet of paper, much less your skin. The decay products of Thorium either also give off alphas as they decay, or beta particles which are easily stopped by the lens or camera body. Radon was mentioned as being one such; most of the little amount produced will be inside the glass of the lens and won't make it into the atmosphere.

You might want to look at the Wikipedia article on Thorium, in particular the section on non-nuclear uses of Thorium where it talks about lenses, and under Precautions.

Frankly I wouldn't worry about it. Your body contains a tiny amount of Thorium anyway.

---------- Post added 31-07-15 at 19:05 ----------

I'm very intrigued by the idea that the alpha radiation converts to gamma radiation.

No it doesn't.

[stevebrot]

Don't forget the pool. From a modeled risk point of view the chlorine in the pool is off the charts.

Yep...In the case of a serious malfunction in the chlorination system of most public pools, there is potential to kill the neighborhood


Steve

[stevebrot]

Yes, and I believe the air inside the bathroom shower enclosure, when the water is chlorinated, is not particularly good for you either.

In my region, there is a fair amount of radon gas in the ground water such that the shower is a risk factor for lung cancer.


Steve

(...we won't even talk about outgassing into the crawlspace...)

[stevebrot]

don't look now....

Radioactive lens element from Takumar 50mm f/1.4

The damage to the tip of your thumb is readily apparent!!




Steve

[stevebrot]

You might want to look at the Wikipedia article on Thorium, in particular the section on non-nuclear uses of Thorium where it talks about lenses, and under Precautions.

Frankly I wouldn't worry about it. Your body contains a tiny amount of Thorium anyway.

---------- Post added 31-07-15 at 19:05 ----------

Quote Originally posted by condor27596 Quote
I'm very intrigued by the idea that the alpha radiation converts to gamma radiation.
No it doesn't.

You are correct. It doesn't. However, there are limits to what you might read in the Wikipedia. There is concomitant gamma decay* of immediate short-lived daughter nuclei in materials containing naturally occurring thorium. This is readily measurable with a Geiger or scintillation probe in proximity to thoriated glass.


Steve

* Gamma decay is qualitatively different than nuclear decay with the photons discharged not considered decay products per se.

[Clothears]

You are correct. It doesn't. However, there are limits to what you might read in the Wikipedia. There is concomitant gamma decay* of immediate short-lived daughter nuclei in materials containing naturally occurring thorium. This is readily measurable with a Geiger or scintillation probe in proximity to thoriated glass.

* Gamma decay is qualitatively different than nuclear decay with the photons discharged not considered decay products per se.

Ah, interesting, thanks. Looking elsewhere I see there are four decay isotopes that are "significant gamma emitters". I'd view that as an important omission by whoever wrote the Wiki article. I shall endeavour to discover the energy of these gammas and their range.

I still think it likely that the OP, if he's going to worry about Thorium, had better consider the Thorium in his body rather than worry about the glass. That's when the alphas become significant, as that Poor Russian former spy in London found out to his cost.

[Digitalis]

The damage to the tip of your thumb is readily apparent!!

I used to bite my nails.



this thread has gathered some interesting tags so far...

[monochrome]

I recommend you carry your lens carefully in both hands down your stairs, out to your garage and place it gently on the passenger seat of a new car equipped with a passenger seat airbag. Drive to the nearest landfill and throw the lens as far out into the abyss as your lowly human arm can throw it. Then drive home.

That is if you are improficient at estimating personal risk.

[stillshot2]

I just realized that there aren't any videos or data I could find of radioactivity measured from these lenses when mounted on a camera. Has anyone here measured radiation levels at the viewfinder and perhaps behind the screen?

---------- Post added 07-31-15 at 09:16 PM ----------

By the way my Takumar has been sitting under an led the last 2 days. It's nearly cleared up, but it was so yellow that photos did not look too good to me, and worse was that I could tell I was loosing nearly a whole stop of light from the discoloration. The yellow had to go... but indoors this lens is razor sharp even at f1.4 if I nail the focus correctly! Outdoors there is a dreamy fuzzy look in harsh light wide open. I am going to see if a deep hood helps clear it up.