What process is described as absorption when it comes to exposure to hazardous materials?

Absorption, in the context of exposure to hazardous materials, refers specifically to the process by which substances penetrate the body through the skin or mucous membranes. This route of exposure is significant because many hazardous materials can enter the bloodstream and cause systemic effects without needing to be ingested or inhaled.

In contrast, breathing in harmful gases describes inhalation, which is a different route of entry into the body. Swallowing toxic substances represents ingestion, another distinct method of exposure. Direct injection through needles involves penetrating the skin, but this method is specific and does not encompass the broader concept of absorption through skin or mucous membranes. Thus, the most accurate description of absorption aligns with the process of taking materials in through skin or mucous membranes.