My opinion always starts heated discussions. 

Any bulk commodity can and will cause flash fires when handled if the dust created finds a source of ignition.
Coal, grains, dust from furniture manufacturing, you name it serious explosions have resulted. Working with ships & bulk cargos we always followed strict safety procedures. 

Most significant explosion with fatality & hand load quantity powder was Bushnell Smith, examined in detail by Col Hatcher in his book “Hatcher’s Notebook”

What mitigates the danger is careful attention to possible sources of ignition and most important working with small quantities. Dump a quarter pound of powder in your measure slight bit of dust rising, minimal risk. Larger quantity the risk increases dramatically 

Boats