Ingested soil as a source of 137Cs to ruminants

Area of Science:

• Environmental Science
• Animal Science
• Radiochemistry

Background:

• Soil ingestion is a significant pathway for radionuclide uptake in grazing ruminants.
• Radiocaesium contamination in soil poses a potential risk to livestock and the food chain.

Purpose of the Study:

• To quantify the transfer of radiocaesium from ingested soil to sheep milk.
• To assess the influence of soil clay content on radiocaesium bioavailability in ruminants.

Main Methods:

• Bergamasca sheep were orally administered soil artificially contaminated with radiocaesium daily for 33 days.
• Two soil types with varying clay content (11% and 16%) were used.
• Radiocaesium transfer to milk was measured, and transfer coefficients (fm) were calculated at equilibrium.

Main Results:

• Low transfer coefficient (fm) values were observed for radiocaesium to sheep milk, ranging from 3.72 x 10(-4) to 6.11 x 10(-4) days l-1.
• These values were consistent across both soil types, indicating limited radiocaesium bioavailability.
• The data suggests radiocaesium remains bound to soil clay minerals within the sheep's gastrointestinal tract.

Conclusions:

• Ingestion of radiocaesium-contaminated soil by sheep results in minimal transfer to milk.
• Radiocaesium bioavailability is limited due to strong binding with clay minerals in the soil.
• This study indicates a low risk of radiocaesium accumulation in sheep milk from contaminated soil ingestion.