Stranded false killer whales, Pseudorca crassidens, in Southern South America reveal potentially dangerous silver concentrations.

Silver (Ag) is a non-essential metal known to bioaccumulate in aquatic organisms. We determined Ag concentrations in five false killer whales stranded in South America. Silver concentrations (in dry weight basis) range as 6.62-10.78 μg g in liver, 0.008-7.41 μg g in spleen, 0.004-5.71 μg g in testis, 0.757-1.69 μg g in kidney, 0.011-0.078 μg g in lung and < 0.01-0.038 μg g in muscle, whereas in the single samples of uterus and ovary were 0.051 and 0.023 μg g; respectively. Overall, Ag concentration in liver and kidney exceeded the cetacean toxic thresholds, proposed as "unhealthy concentrations" and "critically dangerous" in liver and kidney. These results warrant further eco-toxicological studies, to examine biological effects of elevated silver levels for individuals and to assess the species' conservation status with respect to marine pollution.