Pollution from metals is very common, as they are used in many industrial processes such as electroplating, textiles, paint and leather. The wastewater from these industries is often used for agricultural purposes, so besides the immediate damage to the ecosystem it is spilled into, the metals can enter creatures and humans far away through the food chain. Mycoremediation is one of the cheapest, most effective and environmental-friendly solutions to this problem.
Many fungi are hyperaccumulators, therefore they are able to concentrate toxins in their fruiting bodies for later removal. This is usually true for populations that have been exposed to contaminants for a long time, and have developed a high tolerance. Hyperaccumulation occurs via biosorption on the cellular surface, where the metals enter the mycelium passively with very little intracellular uptake.
A variety of fungi, such as Pleurotus, Aspergillus, Trichoderma has proven to be effective in the removal of lead, cadmium, nickel, chromium, mercury, arsenic, copper, boron, iron and zinc  in marine environments, wastewater and on land.
Not all the individuals of a species are effective in the same way in the accumulation of toxins. The single individuals are usually selected from an older polluted environment, such as sludge or wastewater, where they had time to adapt to the circumstances, and the selection is carried on in the laboratory. A dilution of the water can drastically improve the ability of biosorption of the fungi.
The capacity of certain fungi to extract metals from the ground also can be useful for bioindicator purposes, and can be a problem when the mushroom is of an edible variety. For example, the shaggy ink cap (Coprinus comatus), a common edible mushroom found in the Northern Hemisphere, can be a very good bioindicator of mercury. However, as the shaggy ink cap accumulates mercury in its body, it can be toxic to the consumer.
The capacity of metals uptake of mushroom has also been used to recover precious metals from medium. For example, VTT Technical Research Centre of Finland reported an 80% recovery of gold from electronic waste using mycofiltration techniques.