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

[Ellen Thomas]

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.

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/services/food-nutrition/food-safety/food-irradiation/irradiation-shrimp-summary-submission-process.html

And irradiation of shrimp using cesium-137 is done all the time, see

Gordon Edwards, Ph.D., President,

Canadian Coalition for Nuclear Responsibility

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Here is one of several news stories -

FDA Recalls Walmart Frozen Shrimp 

over potential radioactive contamination

By Rachel Kelly, Prevention magazine, August 21 2025

• The U.S. Food and Drug Administration (FDA) has issued a recall of certain Great Value brand raw frozen shrimp sold at Walmart stores in multiple states due to concerns about possible contamination with Cesium-137 (Cs-137), a radioactive isotope.

The shrimp products were processed by PT Bahari Makmur Sejati (as BMS Foods) in Indonesia and distributed to Walmart stores in Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Missouri, Mississippi, Ohio, Oklahoma, Pennsylvania, Texas, and West Virginia.

The FDA was alerted by U.S. Customs & Border Protection after Cs-137 was detected in shipping containers at four ports (Los Angeles, Houston, Savannah, and Miami), leading to the discovery of Cs-137 in just one sample of breaded shrimp. The affected containers and products were not allowed into the U.S. If you believe you may have impacted products, do not eat them.

At this time, there’s been no confirmation that contaminated products have actually been distributed and sold within the U.S., but ongoing investigations by the FDA have suggested certain products were prepared under conditions that may pose a safety risk.

As of August 14, further imports from PR Bahari Makmur Sejati are not being accepted into the country until the FDA has determined that the conditions that allowed for contamination have been resolved.

What is Cs-137?

Cs-137 is a man-made radioisotope that can be found in trace amounts worldwide. The amounts detected in the sample of breaded shrimp were significantly lower than the would be concerning in and of themselves, per the FDA.

However, repeated low-level exposure may build up into a larger health concern over a longer period of time. Because Cs-137 exists in other environments, the FDA warns that contaminated shrimp could contribute to extended exposure to low-level radiation (example from sources such as certain medical procedures). This can cause an elevated risk of cancer.

Which products are being recalled?

Consumers should avoid the following Great Value frozen raw shrimp products sold at Walmart in the aforementioned states:

Great Value Frozen Raw White Vannamei Shrimp, 2 lb bag — 

Lot Code 8005540-1, best by 3/15/2027

Lot Code 8005538-1, best by 3/15/2027

Lot Code 8005539-1, best by 3/15/2027

What to do with recalled product

If you have any of the affected products at home, you should throw them away or return them to Walmart for a refund. The FDA recommends that anyone concerned about potential exposure to cesium should consult a healthcare provider directly and get further instructions on how to dispose of any potentially contaminated product.

Virus-free.www.avg.com