I'm not sure whether it's the right SE for this question, so please redirect me if it's not.
Are there any studies that show that heavy metals, for example from e-waste, can leak from landfills, into the groundwater, eventually into the human body and cause any harm to human health?
You can easily find information about dangers that, say, mercury vapors poses for human health. There are studies that show a high concentration of toxic metals in bodily fluids of people who engage in e-waste dismantling operations in developing countries (they burn imported e-waste to obtain metals).
There were experiments on animals that were exposed to mercury and then suffered from something or died. But it seems impossible to link a certain condition with heavy metals that escaped a landfill and were digested through running water. And yet, some researchers raise this issue of landfilled e-waste and heavy metals. They might say [1], "Heavy metals may escape landfills" and in another place, "Heavy metals may cause brain damage and neurological disorders". The two may not be explicitly connected but it's implied that heavy metal-contaminated e-waste dumped in landfills is a health issue.
Are there any grounds for that (given concentrations and everything)? Are those concentrations high enough for any long-term impact? And how far do those heavy metals travel through groundwater (maybe, soil filters it out at some point, idk). Please cite academic publications, if any are available.
[1]: 'Electronic waste management approaches: An overview', Waste Management, no. 33.