Why does ethanol have a health rating of [2] in NFPA 704 whereas methanol, which is far more toxic, has a rating of only [1]? Why Ethanol has the blue health hazard rating of 2 in NFPA 704 where as both Acetone and Methanol which are far more toxic than Ethanol have a rating of only 1?    (Click on each link to see the NFPA diamond)


Ethanol
Methanol
Acetone
I believe that the rating is dependent on toxicity tests. 

The acute oral toxicity LD50 value of acetone is 5800 mg/kg

The acute oral toxicity LD50 value of methanol is 5628 mg/kg

The acute oral toxicity LD50 value of ethanol is 3450 mg/kg

Low LD50 values means that only a small amount of chemical is needed to kill someone. According to these values, you would need to ingest a larger amount of acetone or methanol to die.I am not sure how valid these toxicology test are. Fun fact: fructose is deadlier than methanol according to LD50 values.

Furthermore, there appears to be some variation in the values as well. Wikipedia lists the LD50 value of ethanol as 7,060 mg/kg. 
Maybe this question can be addressed at Biology SE.