Oysters are cold-blooded organisms so their body temperature changes with environmental temperature. Lannig observed that cadmium levels increased the basic metabolic rate (BMR) of oysters at 20ºC and 24º. For oysters at 28ºC, cadmium did not increase the BMR, but it significantly reduces its chances of survival. "One possible mechanism for this observation is increased damage of mitochondria in cadmium-exposed oysters with increasing temperature", Lannig explains, "these organelles become significantly more sensitive to cadmium as temperature rises, so that cadmium levels which were not damaging to mitochondria at lower temperature become strongly toxic with increasing temperature."
Cadmium circulates continually between air, water and soils. As it moves easily through the food chain, high levels are reported in seals. In humans, cadmium interferes with calcium metabolism and deposition in the bone. Accumulation over time can cause serious illnesses such as itai itai disease. Future research will focus on to what extent cadmium reduces thermal tolerance of cold-blooded species.
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