What is a physiological effect of exposure to toxic substances?

Respiratory distress is a significant physiological effect of exposure to toxic substances, particularly because many hazardous materials can directly impact the respiratory system. When inhaled, toxic substances may cause inflammation, constriction of airways, or fluid accumulation in the lungs, leading to difficulty breathing, shortness of breath, and other related symptoms. This effect highlights the importance of assessing air quality and implementing proper safety measures when working with or near hazardous materials.

The other options, while valid physiological effects, are more general symptoms that can arise from a variety of health issues, not exclusively from toxic substance exposure. Skin irritation can occur from contact with irritants or allergens, nausea can result from numerous causes including toxins ingested or inhaled, and headaches can arise from stress, dehydration, or other conditions unrelated to direct exposure. Respiratory distress, however, is strongly linked to the inhalation of harmful substances, making it a critical concern in hazardous materials safety protocols.