What material is prohibited in general mail due to safety concerns?

Explosives are prohibited in general mail due to significant safety concerns. The transport of explosives poses a substantial risk not only to postal workers but also to the general public. They can cause severe harm if they inadvertently detonate during handling or transit, leading to catastrophic consequences. In mail operations, safety regulations are strictly enforced to prevent any incidents that could arise from sending hazardous materials. While other items, like live plants or certain household items, may have restrictions, they do not carry the same level of danger as explosives, which is why they are specifically banned from mailing.