Prof. Satoshi Mori has discussed the finding that amounts of radioactive silver (Ag-110m) have exceeded those of radioactive cesium in squid, octopus and crab caught off Fukushima prefecture.
This is significant because the half-life of Ag-110m is 250 days. The amounts of it should have dropped by 80% since the initial catastrophe in March 2011, yet it is still found in excess of cesium, which in the case of the Cs-134 isotope would have dropped by 50%, and Cs-137, which would have dropped just a tiny bit in that time frame.
Ag-110m is an activation product, which means it is produced by neutron irradiation of control rod materials, including nonradioactive silver. This implies that fission and criticalities are still going on, which create free neutrons, leading to neutron activation of these materials.
Radioactive silver levels were found to exceed cesium levels in 62% of marine products in November 2012. The latest tests appear to have been performed in April 2013, and there should have been substantial decay of this isotope since then. But the levels are still high.
This silver was found in the midgut gland of these sea creatures. This gland functions as sort of a combination liver and pancreas. Silver concentrates in the human liver. Nanoparticles of silver have been determined to induce the production of interleukin-8 in the liver, which is inflammatory and indicative of an autoimmune reaction.
But Ag-110m decays into the extremely toxic metal cadmium. This was the agent that caused an outbreak of Itai-itai disease in Japan from 1912-1946. Cadmium accumulates in the liver and especially the kidneys. Symptoms and risks of cadmium poisoning include:
…tracheo-bronchitis, pneumonitis, and pulmonary edema. Symptoms of inflammation may start hours after the exposure and include cough, dryness and irritation of the nose and throat, headache, dizziness, weakness, fever, chills, and chest pain.
Inhaling cadmium-laden dust quickly leads to respiratory tract and kidney problems which can be fatal (often from renal failure). Ingestion of any significant amount of cadmium causes immediate poisoning and damage to the liver and the kidneys. Compounds containing cadmium are also carcinogenic.
The bones become soft (osteomalacia), lose bone mineral density (osteoporosis) and become weaker. This causes the pain in the joints and the back, and also increases the risk of fractures. In extreme cases of cadmium poisoning, mere body weight causes a fracture.
The kidneys lose their function to remove acids from the blood in proximal renal tubular dysfunction. The kidney damage inflicted by cadmium poisoning is irreversible. The proximal renal tubular dysfunction creates low phosphate levels in the blood (hypophosphatemia), causing muscle weakness and sometimes coma. The dysfunction also causes gout, a form of arthritis due to the accumulation of uric acid crystals in the joints because of high acidity of the blood (hyperuricemia). Another side effect is increased levels of chloride in the blood (hyperchloremia). The kidneys can also shrink up to 30%. (Wikipedia)
According to a medical review article, diabetics are susceptible to cadmium-induced renal tubular damage. Women are more at risk than men for cadmium health effects, and people with low iron stores are more susceptible. Decreases in androgen levels and pathological testicular changes were found in rats. Zinc deficiency caused fetal malformations in rats exposed to cadmium.
So the risk from eating Pacific seafood does not necessarily fade away when the isotopes decay. They may turn into something else that is toxic.
The FDA has banned the importation of seafood from 14 Japanese prefectures. But the initial ocean plume from 2011 is thousands of miles from Japan already, and this ban actually does little to remove the poisoning threat from Pacific seafood from American tables.