Substitute solvent for diethyl ether?
It is strange that you are concerned about diethyl ether (which has been used as an anesthetic), but you are not concerned about THF. From the US Pharmacopoeia:  


  Permitted Daily Exposure
  Tetrahydrofuran 7.2 mg/day
  Diethyl Ether 50 mg/day
  Ethyl Acetate 50 mg/day


If you dry the product thoroughly (above 120°C), you should not have any problems with residual solvents.