Radium dial watches, a potentially hazardous legacy?

Gavin K Gillmore, Robin G M Crockett, Anthony R Denman, Alan Flowers, Richard Harris

Research output: Contribution to journalArticle

Abstract

This study re-examines the risk to health from radium (226Ra) dial watches. Ambient dose equivalent rates have been measured for fifteen pocket watches giving results of up to 30 μSv h− 1 at a distance of 2 cm taken with a series 1000 mini-rad from the front face (arithmetic mean ambient dose equivalent for pocket watches being 13.2 μSv h− 1). A pocket compass gave rise to a similar ambient dose equivalent rate, of 20 μSv h− 1, to the pocket watches, with its cover open. Eighteen wristwatches have also been assessed, but their dose rates are generally much lower (the arithmetic mean being 3.0 μSv h− 1), although the highest ambient dose equivalent rate noted was 20 μSv h− 1. A phantom experiment using a TLD suggested an effective dose equivalent of 2.2 mSv/y from a 1 μCi (37 kBq) radium dial worn for 16 h/day throughout the year (dose rate 0.375 μSv h− 1). For this condition we estimated maximum skin dose for our pocket watches as 16 mSv per year, with effective doses of 5.1 mSv and 1.169 mSv when worn in vest and trouser pockets respectively. This assumes exposure from the back of the watch which is generally around 60–67% of that from the front. The maximum skin dose from a wristwatch was 14 mSv, with 4.2 mSv effective dose in vest pocket. Radium (226Ra) decays to the radioactive gas radon (222Rn), and atmospheric radon concentration measurements taken around a pocket watch in a small sealed glass sphere recorded 18,728 Bq m− 3. All watches were placed in a room with a RAD7 real-time radon detector. Radon concentration average was 259 ± 9 Bq m− 3 over 16 h, compared to background average over 24 h of 1.02 Bq m− 3. Over 6 weeks highs of the order of 2000 Bq m− 3 were routinely recorded when the heating/ventilation system in the room was operating at reduced rates, peaking at over 3000 Bq m− 3 on several occasions. Estimates of the activity of 226Ra in the watches ranged from 0.063 to 1.063 μCi (2.31 to 39.31 kBq) for pocket watches and from 0.013 to 0.875 μCi (0.46 to 32.38 kBq) for wrist watches. The risk from old watches containing radium appears to have been largely forgotten today. This paper indicates a health risk, particular to collectors, but with knowledge and appropriate precautions the potential risks can be reduced
Original languageEnglish
JournalEnvironment International
Volume45
Early online date10 May 2012
DOIs
Publication statusPublished - 15 Sep 2012

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dials
radium
clocks
dosage
radon
vests
health
rooms
wrist
accident prevention
ventilation
accumulators

Keywords

  • Radium
  • radon
  • watches
  • health risks

Cite this

Gillmore, Gavin K ; Crockett, Robin G M ; Denman, Anthony R ; Flowers, Alan ; Harris, Richard. / Radium dial watches, a potentially hazardous legacy?. In: Environment International. 2012 ; Vol. 45.
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abstract = "This study re-examines the risk to health from radium (226Ra) dial watches. Ambient dose equivalent rates have been measured for fifteen pocket watches giving results of up to 30 μSv h− 1 at a distance of 2 cm taken with a series 1000 mini-rad from the front face (arithmetic mean ambient dose equivalent for pocket watches being 13.2 μSv h− 1). A pocket compass gave rise to a similar ambient dose equivalent rate, of 20 μSv h− 1, to the pocket watches, with its cover open. Eighteen wristwatches have also been assessed, but their dose rates are generally much lower (the arithmetic mean being 3.0 μSv h− 1), although the highest ambient dose equivalent rate noted was 20 μSv h− 1. A phantom experiment using a TLD suggested an effective dose equivalent of 2.2 mSv/y from a 1 μCi (37 kBq) radium dial worn for 16 h/day throughout the year (dose rate 0.375 μSv h− 1). For this condition we estimated maximum skin dose for our pocket watches as 16 mSv per year, with effective doses of 5.1 mSv and 1.169 mSv when worn in vest and trouser pockets respectively. This assumes exposure from the back of the watch which is generally around 60–67{\%} of that from the front. The maximum skin dose from a wristwatch was 14 mSv, with 4.2 mSv effective dose in vest pocket. Radium (226Ra) decays to the radioactive gas radon (222Rn), and atmospheric radon concentration measurements taken around a pocket watch in a small sealed glass sphere recorded 18,728 Bq m− 3. All watches were placed in a room with a RAD7 real-time radon detector. Radon concentration average was 259 ± 9 Bq m− 3 over 16 h, compared to background average over 24 h of 1.02 Bq m− 3. Over 6 weeks highs of the order of 2000 Bq m− 3 were routinely recorded when the heating/ventilation system in the room was operating at reduced rates, peaking at over 3000 Bq m− 3 on several occasions. Estimates of the activity of 226Ra in the watches ranged from 0.063 to 1.063 μCi (2.31 to 39.31 kBq) for pocket watches and from 0.013 to 0.875 μCi (0.46 to 32.38 kBq) for wrist watches. The risk from old watches containing radium appears to have been largely forgotten today. This paper indicates a health risk, particular to collectors, but with knowledge and appropriate precautions the potential risks can be reduced",
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Radium dial watches, a potentially hazardous legacy? / Gillmore, Gavin K; Crockett, Robin G M; Denman, Anthony R; Flowers, Alan; Harris, Richard.

In: Environment International, Vol. 45, 15.09.2012.

Research output: Contribution to journalArticle

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T1 - Radium dial watches, a potentially hazardous legacy?

AU - Gillmore, Gavin K

AU - Crockett, Robin G M

AU - Denman, Anthony R

AU - Flowers, Alan

AU - Harris, Richard

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N2 - This study re-examines the risk to health from radium (226Ra) dial watches. Ambient dose equivalent rates have been measured for fifteen pocket watches giving results of up to 30 μSv h− 1 at a distance of 2 cm taken with a series 1000 mini-rad from the front face (arithmetic mean ambient dose equivalent for pocket watches being 13.2 μSv h− 1). A pocket compass gave rise to a similar ambient dose equivalent rate, of 20 μSv h− 1, to the pocket watches, with its cover open. Eighteen wristwatches have also been assessed, but their dose rates are generally much lower (the arithmetic mean being 3.0 μSv h− 1), although the highest ambient dose equivalent rate noted was 20 μSv h− 1. A phantom experiment using a TLD suggested an effective dose equivalent of 2.2 mSv/y from a 1 μCi (37 kBq) radium dial worn for 16 h/day throughout the year (dose rate 0.375 μSv h− 1). For this condition we estimated maximum skin dose for our pocket watches as 16 mSv per year, with effective doses of 5.1 mSv and 1.169 mSv when worn in vest and trouser pockets respectively. This assumes exposure from the back of the watch which is generally around 60–67% of that from the front. The maximum skin dose from a wristwatch was 14 mSv, with 4.2 mSv effective dose in vest pocket. Radium (226Ra) decays to the radioactive gas radon (222Rn), and atmospheric radon concentration measurements taken around a pocket watch in a small sealed glass sphere recorded 18,728 Bq m− 3. All watches were placed in a room with a RAD7 real-time radon detector. Radon concentration average was 259 ± 9 Bq m− 3 over 16 h, compared to background average over 24 h of 1.02 Bq m− 3. Over 6 weeks highs of the order of 2000 Bq m− 3 were routinely recorded when the heating/ventilation system in the room was operating at reduced rates, peaking at over 3000 Bq m− 3 on several occasions. Estimates of the activity of 226Ra in the watches ranged from 0.063 to 1.063 μCi (2.31 to 39.31 kBq) for pocket watches and from 0.013 to 0.875 μCi (0.46 to 32.38 kBq) for wrist watches. The risk from old watches containing radium appears to have been largely forgotten today. This paper indicates a health risk, particular to collectors, but with knowledge and appropriate precautions the potential risks can be reduced

AB - This study re-examines the risk to health from radium (226Ra) dial watches. Ambient dose equivalent rates have been measured for fifteen pocket watches giving results of up to 30 μSv h− 1 at a distance of 2 cm taken with a series 1000 mini-rad from the front face (arithmetic mean ambient dose equivalent for pocket watches being 13.2 μSv h− 1). A pocket compass gave rise to a similar ambient dose equivalent rate, of 20 μSv h− 1, to the pocket watches, with its cover open. Eighteen wristwatches have also been assessed, but their dose rates are generally much lower (the arithmetic mean being 3.0 μSv h− 1), although the highest ambient dose equivalent rate noted was 20 μSv h− 1. A phantom experiment using a TLD suggested an effective dose equivalent of 2.2 mSv/y from a 1 μCi (37 kBq) radium dial worn for 16 h/day throughout the year (dose rate 0.375 μSv h− 1). For this condition we estimated maximum skin dose for our pocket watches as 16 mSv per year, with effective doses of 5.1 mSv and 1.169 mSv when worn in vest and trouser pockets respectively. This assumes exposure from the back of the watch which is generally around 60–67% of that from the front. The maximum skin dose from a wristwatch was 14 mSv, with 4.2 mSv effective dose in vest pocket. Radium (226Ra) decays to the radioactive gas radon (222Rn), and atmospheric radon concentration measurements taken around a pocket watch in a small sealed glass sphere recorded 18,728 Bq m− 3. All watches were placed in a room with a RAD7 real-time radon detector. Radon concentration average was 259 ± 9 Bq m− 3 over 16 h, compared to background average over 24 h of 1.02 Bq m− 3. Over 6 weeks highs of the order of 2000 Bq m− 3 were routinely recorded when the heating/ventilation system in the room was operating at reduced rates, peaking at over 3000 Bq m− 3 on several occasions. Estimates of the activity of 226Ra in the watches ranged from 0.063 to 1.063 μCi (2.31 to 39.31 kBq) for pocket watches and from 0.013 to 0.875 μCi (0.46 to 32.38 kBq) for wrist watches. The risk from old watches containing radium appears to have been largely forgotten today. This paper indicates a health risk, particular to collectors, but with knowledge and appropriate precautions the potential risks can be reduced

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KW - radon

KW - watches

KW - health risks

U2 - 10.1016/j.envint.2012.03.013

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M3 - Article

VL - 45

JO - Environment International

JF - Environment International

SN - 0160-4120

ER -