dross vs toxic waste

dross

noun
  • Waste or impure matter. 

  • Worthless or trivial matter. 

  • The impurities in metal. 

  • Residue that forms on the surface of molten metal from oxidation. 

  • A waste product from working with metal. 

verb
  • To remove dross from. 

toxic waste

noun
  • Any waste that can cause death or injury to living creatures, especially poisonous chemical compounds. 

How often have the words dross and toxic waste occurred in a corpus of books? (source: Google Ngram Viewer )