Construction Health and Safety Technician (CHST) Practice Test

The correct choice identifies a characteristic that distinguishes blood toxins from other types of toxins. Blood toxins are substances that directly affect the blood's function or composition, leading to systemic effects throughout the body.

When discussing blood toxins, it's acknowledged that they can alter the composition of blood by affecting red blood cells, white blood cells, or plasma. Furthermore, these toxins can deprive tissues of oxygen, leading to cellular and tissue damage due to hypoxia. They are also known to cause changes in behavior, which may result from neurological effects or a general state of toxicity affecting brain function.

In contrast, the significant focus of blood toxins is not primarily on damaging the skin. While some toxins may have secondary effects on external tissues due to systemic issues or exposure routes, their primary action is within the bloodstream and its effects on overall health. Thus, the characteristic of causing damage mainly to the skin does not align with the fundamental actions of blood toxins, making this choice the correct answer.