Were Legos ever flammable in the past and if they were then what are the current requirements to prevent them from being flammable?

Because they react dangerously with fire. Thus, they are flammable.

water. i don't know what else but I'll get back to you

Flammability is defined at how easily something will burn or ignite, causing fire or combustion. The degree of difficulty required to cause the combustion of a substance is subject to quantification...

Yes. Very much so.Do not stand near hot surfaces such as an airtight stove or baseboard heaters. Rayon will heat up and can turn into flame very quickly.I learned that the hard way. =)

You better believe it is! Just stick it on a hot stove and let it sit there for to long while. It won't take long for flames to occur. (Note: this is sarcasm and it is not meant that anyone literally...