Human activity is causing toxic thallium to enter the Baltic sea, according to new study

Human activities account for 20% to more than 60% of toxic thallium entering the Baltic Sea over the past eight decades, according to new research. Currently, the amount of thallium, which is considered the most toxic metal for mammals, remains low in Baltic seawater. Much of the thallium in the Baltic, which is the largest human-induced hypoxic area on Earth, has been accumulated in the sediment thanks to sulfide minerals.