Soy Lecethin is “considered” to be a good healthy additive -primarily an emulsifier in many foods, you will have seen it as an ingredient in many things we eat.
The process to extract this oil from the soya bean uses a chemical called Hexane! The effects of Hexane are as follows (for short term exposure). Hexane affects the central nervous system (brain) and can cause headaches, dizziness, confusion, nausea, clumsiness, drowsiness, and other effects similar to intoxication.
In addition, Hexane can be found in common household products, such as spray adhesives, contact cement, arts and craft paints, and stain removers.
Below are some links for you to check out!
http://rawforbeauty.com/blog/soy-lecithin-how-it-negatively-affects-your-health-and-why-you-need-to-avoid-it.html Very informative link about side effects
http://www.drugs.com/sfx/soya-lecithin-side-effects.html Side effects link
The next link is a guide to the food bars and company that sell them and whether they contain hexane and soya bean.