What is Biodiesel?

Biodiesel is the name for a variety of ester-based oxygenated fuels made from
vegetable oils or animal fats.  The concept of using vegetable oil as a fuel
dates back to 1895 when Dr. Rudolf Diesel developed the first diesel engine to
run on vegetable oil. Diesel demonstrated his engine at the World Exhibition
in Paris in 1900 using peanut oil as fuel.

RESULTS

Results of the health effects testing concluded that biodiesel is non-toxic and biodegradable, posing no threat to human health. 

Also among the findings of biodiesel emissions compared to petroleum diesel emissions:

The overall ozone (smog) forming potential of exhaust emissions from biodiesel is 50% less.
The exhaust emissions of carbon monoxide (a poisonous gas and a contributing factor in the localized formation of smog and ozone) from biodiesel are 50% lower.
The exhaust emissions of particulate matter (recognized as a contributing factor in the respiratory disease) from biodiesel are 30% lower.
The exhaust emissions of sulphur oxides and sulphate's (major components of acid rain) from biodiesel are complete eliminated.
The exhaust emissions of hydrocarbons (a contributing factor in the localized formation of smog and ozone) are 95% lower.
The exhaust emissions for aromatic compounds known as PAH and NPAH compounds (suspected of causing cancer) are substantially reduced for biodiesel compared to diesel. 
Most PAH compounds were reduced by 75% to 85%.
All NPAH compounds were reduced by at least 90%.