Chromosome damage in peripheral lymphocytes from American thorium workers

Area of Science:

• Radiation Biology
• Occupational Health
• Cytogenetics

Background:

• Thorium workers can accumulate internal radioactive burdens, potentially leading to health effects.
• Chromosome aberrations in lymphocytes are biomarkers of radiation exposure and genotoxicity.
• Previous studies on Thorotrast patients and Brazilian thorium workers suggest a link between internal dose and cytogenetic damage.

Purpose of the Study:

• To analyze the frequency of chromosome aberrations in lymphocytes of thorium workers.
• To investigate the relationship between internal radium-224 and bismuth-212 burdens and chromosome aberration rates.
• To assess the correlation between employment duration in the thorium industry and aberration frequency.

Main Methods:

• Lymphocytes from 47 thorium workers and 3 external controls were analyzed for chromosome aberrations.
• Workers were stratified into low, moderate, and high burden groups based on radium-224 and bismuth-212 body burdens.
• Aberration frequencies were compared between exposure groups and historical controls.

Main Results:

• A trend of increased two-break chromosome aberrations with higher radium-224 and bismuth-212 burdens was observed, though not statistically significant between exposure subgroups.
• The pooled higher body burden groups showed a highly significant increase in dicentric and centric ring chromosomes compared to historical controls.
• No significant positive relationship was found between the total months of employment and chromosome aberration frequency.

Conclusions:

• Internal burdens of radium-224 and bismuth-212 in thorium workers are associated with increased cytogenetic damage.
• The findings are consistent with previous studies on similar cohorts, supporting the use of chromosome aberrations as a biomarker for internal radiation exposure.
• Occupational exposure duration alone is not a reliable predictor of chromosome aberration frequency in this cohort.