Radioactive Cesium-137 in Frozen Shrimp–where does the conta

[Oscar]

Radioactive Cesium-137 in Frozen Shrimp – where does the contamination come from?

Dear Friends and colleagues - September 10, 2025

A few weeks ago, reports about radioactively contaminated frozen shrimp imported from Indonesia caused a lot of consternation. Those imports have been temporarily suspended.

Cesium-137, a gamma-emitting human-made radioactive material was found in some of the packages of shrimp and the American public has been warned to discard certain lot numbers.

Much speculation has been raised about the origin of the radioactive cesium – was it from a nuclear reactor? From nuclear weapons facilities? From environmental contamination?

It is possible that the cesium-137 contamination came from a “food irradiation” plant.

As some of you may know, the two radioactive substances most used in “irradiation” facilities are cobalt-60 (mostly from Canada) or cesium-137 (mostly from the USA).

Both of these radioactive materials are human-made byproducts of nuclear fission. Both are powerful gamma-emitters. They can be - and are - used to sterilize medical equipment (needles, gloves, sutures, etc.) by blasting them with very high doses of gamma radiation to kill any microorganisms.

The same approach can be - and is - used to sterilize certain food items in “food irradiation” facilities using very large quantities of cobalt-60 or cesium-137. Shrimp is one such food item.

See the ccnr background on food irradiation (from decades ago) at [ https://ccnr.org/food_ccnr.html ] as well as
[ https://ccnr.org/food_irradiation.html ].

At that time, CCNR was fighting the industry’s efforts to have irradiated food packaged without any meaningful indication that it had been irradiated,,,, See [ www.ccnr.org/food_recs.html ].

In Canada, the only items that are currently authorized to be irradiated are (1) potatoes, (2) onions, (3) wheat, flour, whole wheat flour, and (4) whole or ground spices and dehydrated seasoning. See the link below.

Food Irradiation [ https://www.canada.ca/en/health-canada/ ... ation.html ]

However in other countries (especially in Asia) many more food products are allowed to be irradiated such as seafood and meat products. See [ https://inis.iaea.org/records/z4kjv-a0a32 ]

Irradiation of shrimp was considered in Canada but not authorized. See [ https://www.canada.ca/en/health-canada/ ... ocess.html ]

And irradiation of shrimp using cesium-137 is done all the time. See [ https://scispace.com/pdf/gamma-irradiat ... vpa7ym.pdf ]

Gordon Edwards, Ph.D., President,
Canadian Coalition for Nuclear Responsibility [ www.ccnr.org ]

Posted with Permission from Dr. Edwards.