Panic! Dropped and Broke Thorium Lens

CámaraLiberada · 2025-12-04T22:55:09-0500

The day has arrived where I accidentally dropped and broke a thorated lens. I have encountered and repaired a few of them, though I understand it is rarely risky as long as you don't drop or eat them. Well, today I accidentally knocked a box of lens parts off the shelf and SHATTERED the thorated element.

I wore mask and gloves when cleaning it up, and used a wet paper towel. Did I deal with this correctly? Should I be worried about thorium dust I may have breathed in as it broke?

mshchem · 2025-12-05T01:13:30-0500

Probably have a million other things to worry about. Here in the US lead poisoning, either in the water or in hunting season
Seriously it's not something I would be overly concerned about. You did the right thing in taking precautions.

koraks · 2025-12-05T02:26:55-0500

CámaraLiberada said:
Should I be worried about thorium dust I may have breathed in as it broke?

Nope. Nothing to worry about.

Sorry about the lens though!

Donald Qualls · 2025-12-05T08:44:18-0500

You've handled it as correctly as is possible for an amateur. The level of radioactivity in thoriated lens elements was very low when they were new, though it tends to climb very slowly over time (thorium has decay products that are more active than the parent isotopes); still, the only significant hazard even from dust and fragments of a shattered element are if you get them inside your body, where the alpha particle emissions are a known carcinogen. If you live in a radon zone and have a basement, you're at much higher risk from just living in your house than from cleaning up that broken lens element.

The thorium salt or oxide itself is dissolved into the glass, so it would have been glass dust you'd have inhaled if anything, and that's very unlikely; particles from shattering glass are much too coarse to float in the air (this is a hazard if you're grinding or polishing the lens element, but not for cleaning up a broken piece).

CámaraLiberada · 2025-12-05T09:10:12-0500

Donald Qualls said:
You've handled it as correctly as is possible for an amateur. The level of radioactivity in thoriated lens elements was very low when they were new, though it tends to climb very slowly over time (thorium has decay products that are more active than the parent isotopes); still, the only significant hazard even from dust and fragments of a shattered element are if you get them inside your body, where the alpha particle emissions are a known carcinogen. If you live in a radon zone and have a basement, you're at much higher risk from just living in your house than from cleaning up that broken lens element.

The thorium salt or oxide itself is dissolved into the glass, so it would have been glass dust you'd have inhaled if anything, and that's very unlikely; particles from shattering glass are much too coarse to float in the air (this is a hazard if you're grinding or polishing the lens element, but not for cleaning up a broken piece).

Good answer thanks! I don't live in a Radon area, though I still worry about that too.

Panic! Dropped and Broke Thorium Lens

CámaraLiberada

mshchem

koraks

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Donald Qualls

CámaraLiberada

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