Unusual 232Th and 238U contamination on some road surfaces in Taoyuan, Taiwan

Wushou P. Chang, Yuriy B. Nabyvanets, Min Hua Jen

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


At least eight bustling streets or approximately 3-5% of all the road surface of civilian utility in the downtown area of Taoyuan City, Taiwan, were inadvertently found to contain unusual levels of radioactivity during a routine environmental radiation surveillance in mid-1994. Crushed rock debris and coarse sands separated from the asphalt pavement were identified to be the source of excessive radioactivity. By employing gamma spectrometry, we have measured 232Th activity (via 228Ac) and 238U activity (via 214Bi) in some of the samples to be up to about 4,000 and 1,000 Bq kg-1, respectively. The dose rate on the road surface reached about 1.3 μSv h-1, as compared with the background level of 0.08 μSv h-1 in much of Taiwan. This unusual radioactivity was due to accidental mixing of road construction materials with materials enriched 232Th and 238U.

Original languageEnglish
Pages (from-to)602-604
Number of pages3
JournalHealth Physics
Issue number6
Publication statusPublished - 2001
Externally publishedYes


  • Contamination
  • Exposure, population
  • Spectrometry, gamma
  • Th

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Health, Toxicology and Mutagenesis
  • Epidemiology


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