How do toxic materials primarily cause harm to humans?

Toxic materials primarily cause harm to humans through poisoning, which involves the absorption of harmful substances that can disrupt normal bodily functions. When toxic materials enter the body, they can interfere with biochemical processes, damage organs, and compromise the immune system, often resulting in serious health conditions or even death.

Poisoning can occur through various pathways, such as inhalation, ingestion, or dermal exposure. Once inside the body, toxic substances can lead to acute or chronic health effects depending on the dose, duration of exposure, and the specific toxic agent involved. This highlights the critical importance of understanding toxic materials, especially in environments like aviation where exposure risks may be present.

The other options involve harmful effects but do not align as closely with the overarching mechanism of how toxic materials specifically impact health. Physical injury refers to damage caused by force or trauma, explosions involve rapid releases of energy resulting in blasts, and chemical burns pertain to the destruction of tissues by corrosive substances. While these can certainly pose hazards, they are not fundamentally about the toxicological effects that characterize poisoning.