Although all wild dendrobatids are at least somewhat toxic, levels of toxicity vary considerably from one species to the next and from one population to another.
In addition, some of the drugs used in treatment are antiquated, with high levels of toxicity.
The tanks contain 330,000 tonnes of water with varying levels of toxicity.
"These processes result in major differences in toxin composition, and these different toxins cause different pathologies or levels of toxicity when they are injected, and they also undermine antivenom treatment," Casewell said.
In China, such are the levels of toxicity in the air of most of its major cities that more than 800,000 cases of lung cancer a year are predicted by 2020.
"The high levels of toxicity aren't too surprising, as quite a lot of venomous animals go in for what's been called 'overkill'", said geneticist John Mulley, a Lecturer at Bangor University, who was not part of this study.
In its liquid form, elemental mercury, the type in the meters, is not nearly so dangerous as organic mercury, or methylmercury, which can cause extreme levels of toxicity in lakes and fish.
Though the residues are below levels of toxicity, the cumulative effects of those exposures are not known.
Its many compounds have varying levels of toxicity, and it is more likely to produce lingering fatal illness than immediate death.
Women reported higher levels of toxicity.
After studies in primates showed high levels of toxicity from GDNF, Amgen halted further human trials.
