Here and here are two good overviews, unfortunately, both are in German.

• Cleaning of raw silicon requires hydrogen chloride. Not toxic but acidic, however, it is used in a closed circle (maybe excepting China).
  
• The manufacture of solar cells involves a range of acidic liquids, including smaller amounts of toxic bromides and phosphorides and hydrofluoric acid. These again are used in a closed circle (but that doesn't necessarily happen outside the West, including contract work for manufacturers in the West).
  
• The manufacture of cells also involves the toxic gas silane, and the manufacture of the latter involves silicon tetrachloride. The latter can be recycled (unfortunately with the known exception of some manufacturers in China).
  
• The manufacture of modules involves glues.
  
• The energy input of the manufacture is produced by the cell in 3-7 years.
  
• The silicon in solar cells can be recycled with less energy input than that for the preparation of newly mined silcon.

Of course, there is development on all these fields. For example, manufacturers are beginning to implement pre-financed recycling (f.e. First Solar), possibly pre-empting the requirement for greenfiield solar parks applicable from this year in Germany. Using less of the acidic liquids and better recycling of these also contributed/contributes to the reduction of production costs.

_{*Lunatic*, n.
One whose delusions are out of fashion.}