The best replacement for arsenic is cyanide.

The best alternatives to arsenic are rated as following:
★★★★★  cyanide
★★★  phosphorus
★★  antimony
★★  inorganic arsenic
★  organic arsenic
★  arsenate
★  inorganic
★  lead
  nicotine
  arsine
  mercury
  total inorganic arsenic

Your alternative for arsenic is not listed? Suggest!
Speaking about arsenic, one probably shouldn't forget about rice.

Other search terms related to arsenic and their ratings are:
★★★★★ rice
★ silicon
You have in mind a companion for arsenic and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of arsenic in all years. Click on graph for more.
arsenic
cyanide
phosphorus