American Chemical Society (ACS) Laboratory Safety Practice Test

The correct answer, absorption, refers to the process by which toxic chemicals enter the body through the skin. The skin acts as a barrier, but certain substances can permeate it and enter the bloodstream, potentially leading to systemic effects. This route is particularly significant in laboratory and industrial settings, where workers can be exposed to hazardous chemicals without direct contact through other routes.

Inhalation pertains to the entry of harmful substances through the respiratory system, primarily via breathing in airborne particles or gases. Injection involves a direct introduction of substances into the body, typically via a needle, which bypasses the skin barrier entirely. Ingestion describes the entry of substances through the digestive system, usually by swallowing, and would not involve skin contact. Understanding these routes is vital for implementing appropriate safety measures and protective equipment in environments where exposure to chemicals is possible.