Dose Assessment for Wood Fuels and Their Ashes Available in Austria

The aim of this study was to evaluate the radiological risk to the public due to the use of wood ash as a fertilizer in gardens. Dose assessment is a process in radiation protection that involves determining the amount of radiation to which a person or population has been exposed. It helps to evaluate potential health risks more effectively to ensure that radiation exposure remains within safe limits. Three pathways were considered: inhalation of ash, ingestion of locally produced food fertilized with ash, and direct ingestion of ash. It was assumed that a 0.01 cm, 0.5 cm, or 1-cm-thick layer of ash is used for fertilization per year and that half of the vegetables consumed annually come from one's own garden. The dose assessment for a member of the public older than 17 y using the highest concentrations of 137Cs and 90Sr measured in 27 wood (logs, chips, briquettes, and pellets) ash samples and fertilization with 0.01 cm of ash results in a calculated dose of 3.02 ± 0.24 μSv y-1. The primary exposure pathway is the ingestion of locally produced foods fertilized with wood ash. Besides radionuclides, ash also contains concentrated non-combustible components, including potentially harmful minerals, salts, heavy metals, and organic pollutants. These substances are found in particularly higher concentrations in ash from wood pellets and briquettes than in log and chip ash, so its use as fertilizer---especially in vegetable gardens---should be carefully considered.