Systemic refers to a site of action other than the point of contact and presupposes absorption has taken place. For example, an inhaled material may act on the liver. For example, inhaled benzene affects the bone marrow. Cumulative poisons are characterized by materials that tend to build up in the body as a result of numerous chronic exposures. The effects are not seen until a critical body burden is reached.
Examples are heavy metals.
Synergistic or potentiating effects occur when two or more hazardous materials present at the same time have a resulting action greater than the effect predicted based on the individual substances. For example, workers exposed to benzene may show a direct toxicity in hematopoietic tissue and therefore be more susceptible to oxygen-displacing agents such as carbon monoxide. Other Factors Affecting Toxicity Rate of entry and route of exposure - how fast the toxic dose is delivered and by what means. Age - can effect the capacity to repair damaged tissue. Previous exposure - can lead to tolerance, increased sensitivity, or make no difference.