Go read Cadillac Desert. Damns do more harm to the environment that you might expect.

- Dams stop natural sediment flow, resulting in downstream river erosion

- Fish breeding / migration

- Increased irrigation enabled by dams causes pollution of ground water aquifers (increased salinity etc)

- Methane released decaying plant matter in non-oxygenated stagnant dam water

I am not a doctor, but I don't think this is a new condition. In the Northeast US, workers who shuck clams for a living have a similar ailment from handling a clam opener all day. Clams are opened (by hand anyway) using a short blade with a round stubby handle - very similar to the part of the Playstation controller that rests in your palm. People who do a lot of digging with shovels can also suffer from this condition as well.