CO2 / Carbon Dioxide - CO2 decaffeination uses highly compressed carbon dioxide gas, which becomes a fluid under pressure. CO2 is totally safe and is effective at removing caffeine. The CO2 process is good at preserving flavor; its main downside is that it is expensive.
Methylene chloride is predominantly used as a solvent. The acute effects of methylene chloride inhalation in humans consist mainly of nervous system effects including decreased visual, auditory, and motor functions, but these effects are reversible once exposure ceases.