Testing countermeasures to reduce ⁹⁰Sr content in fish products

Area of Science:

• Environmental Science
• Radiological Health
• Aquatic Ecology

Background:

• Fish in the Chornobyl Exclusion Zone (ChEZ) exhibit high strontium-90 (Sr-90) concentrations, thousands of times above Ukraine's permissible levels.
• Previous lab studies suggested that transferring contaminated fish to clean water could reduce Sr-90 in muscle tissue.

Purpose of the Study:

• To assess the effectiveness of depuration in natural ChEZ conditions for reducing Sr-90 in fish muscle.
• To evaluate the feasibility of using "clean" water to lower radioactive contamination in fish.

Main Methods:

• Tench (Tinca tinca) were transferred from a highly contaminated lake (Lake Glubokoye) to a cage in a cleaner lake (Lake Starukha) within the ChEZ.
• Fish were kept in the "clean" water for 45 days.
• Sr-90 concentrations were measured in bone and muscle tissues before and after the depuration period.

Main Results:

• No significant reduction in Sr-90 content was observed in either the muscle or bone tissues of tench after 45 days in clean water.
• Strontium-90 is predominantly retained in the bone tissue of fish, with less than 0.01 retention factor in boiled bone tissue.

Conclusions:

• Depuration in "clean" water under natural ChEZ conditions is ineffective for reducing Sr-90 in tench muscle and bone.
• Establishing permissible Sr-90 levels in fish fillet (muscle) rather than the whole fish is appropriate for human radiation protection due to high Sr-90 bone accumulation.