World War II-era German service watches, known for their historical significance and distinctive markings, are a topic of fascination for collectors and history enthusiasts. Among the notable features of these watches are the “DH,” “D,” “DU,” and the rarer “DIH” stamps on their casebacks. Special Kriegsmarine watches also exist with only a serial number on the caseback, but a “KM” mark on the dial. These watches were often painted with radium, which gave them a glow-in-the-dark capability. However, there are concerns about the potential dangers of radium, particularly regarding radiation exposure. In this post I want to clarify these concerns and demonstrate why these watches are generally safe to wear.
The Radium Connection
Radiation is dangerous. But only in certain levels. The universe has something called Cosmic background radiation that is leftover from the Big Bang, which is present in every occupiable space in the universe. The level of background radiation is about 0,1 – 0,3 MicroSievert (μSv) on earth. This is also the standard acceptable amount of radiation for humans for continued exposure. For reference 1 μSv equals 0.001 mSv. (https://www.radiationanswers.org/):
- 0 – 50 mSv received in a short period or over a long period is safe—we don’t expect observable health effects.
- 50 – 100 mSv received in a short period or over a long period is safe—we don’t expect observable health effects. At this level, an effect is either nonexistent or too small to observe.
- 10 – 500 mSv received in a short period or over a long period—we don’t expect observable health effects although above 100 mSv your chances of getting cancer are slightly increased. We may also see short-term blood cell decreases for doses of about 500 mSv received in a matter of minutes.
- 500 – 1,000 mSv received in a short period will likely cause some observable health effects and received over a long period will increase your chances of getting cancer. Above 500 mSv we may see some changes in blood cells, but the blood system quickly recovers.
- 1,000 – 2,000 mSv received in a short period will cause nausea and fatigue. 1,000 – 2,000 mSv received over a long period will increase your chances of getting cancer.
- 2,000 – 3,000 mSv received in a short period will cause nausea and vomiting within 24-48 hours. Medical attention should be sought.
- 3,000 – 5,000 mSv received in a short period will cause nausea, vomiting, and diarrhea within hours. Loss of hair and appetite occurs within a week. Medical attention must be sought for survival; half of the people exposed to radiation at this level will die if they receive no medical attention.
- 5,000 – 12,000 mSv in a short period will likely lead to death within a few days.
- >100,000 mSv in a short period will lead to death within a few hours.
Radium paint, used on the dials of these watches, made the numbers and hands visible in the dark. Radium is a radioactive element that emits three types of radiation: alpha, beta, and gamma. Understanding these types of radiation and their effects is crucial to dispelling the myths surrounding the safety of radium-painted watches.
Types of Radiation
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Alpha Radiation:
Characteristics: Alpha particles are heavy and can be stopped by a sheet of paper or even the outer layer of human skin.
Health Risks: Dangerous only if ingested or inhaled, as they can cause significant damage to internal tissues.
Relevance to Watches: Radium-painted watches primarily emit alpha radiation. The watch case and crystal typically prevent alpha particles from escaping. The primary risk comes from opening the watch, which could release radium dust. -
Beta Radiation:
Characteristics: Beta particles are lighter than alpha particles and can penetrate paper but are usually stopped by materials like plastic or glass.
Health Risks: Can cause skin burns and other damage if exposure is prolonged.
Relevance to Watches: Radium in watches emits very little beta radiation in its applied form, making this less of a concern for wearers. -
Gamma Radiation:
Characteristics: Gamma rays are highly penetrating and can pass through the human body and various materials.
Health Risks: Prolonged exposure to gamma radiation can be harmful and lead to radiation sickness or cancer.
Relevance to Watches: Radium emits low levels of gamma radiation. Given the small amount of radium used in watches, the gamma radiation emitted is minimal and dissipates quickly with distance.
Dispelling the Myths: Safety of Wearing Radium-Painted Watches
Radiation Levels
The results measured in the pictures in this post are made using the highest reading of μSv within 5 minutes of continued measuring. The radiation emitted by radium-painted watches is generally low and not harmful when the watch is intact. Here’s why:
- Alpha Radiation: As long as the watch remains closed, the alpha particles cannot escape. The watch’s case provides sufficient shielding to prevent any significant exposure.
- Gamma + Beta Radiation: The level of gamma and Beta radiation emitted is low. At a typical wearing distance (about 60cm, or 24″ from the face), the exposure is further reduced and considered negligible.
Practical Precautions
While the watches are generally safe to wear, some precautions can ensure safety:
- Avoid Opening the Watch: Unless necessary, avoid opening the watch to prevent any potential release of radium dust.
- Proper Handling: If the watch needs to be opened for repairs or maintenance, it should be done in a well-ventilated area, preferably by a professional familiar with handling radium-painted items. Wear a respirator and gloves. Dispose of the used filters in the respirator, gloves and used materials after working on the watch.
Historical and Collectible Value
The historical value of these watches is significant. They are not only timepieces but also artifacts that tell a story of the past. The distinctive markings on the casebacks are a testament to their origins and use during WWII. For collectors, understanding the safety and proper handling of these watches enhances their appreciation and ensures they can be enjoyed safely.