What is the specific industrial and transport safety risk associated with bulk transportation of finely ground agricultural powders (such as grain flour, starch, or pulverized coal / 粮食、淀粉、煤粉散装运输)?

1. Combustible dust explosion risk (粉尘爆炸): suspended fine particles in enclosed hoppers can violently ignite and explode from static sparks or open flames
2. Fine powder dissolves the vehicle's steel chassis on contact
3. Bulk flour generates gamma radiation when exposed to air
4. Grain dust freezes into solid ice at high summer temperatures