The term covers a broad range of cases united by one feature: the injury is alleged to have resulted from exposure to a harmful substance rather than from a single discrete event like a car accident or a fall.

Common sources include industrial chemicals, contaminated groundwater, air pollution, pesticides, and defective products containing hazardous materials, and the exposure can happen at home, at work, or in the community.

Toxic tort cases are often difficult because the plaintiff has to show not only that they were exposed to the substance, but that the specific substance actually caused their specific injury, as opposed to some other cause.

This is complicated by the fact that many toxic exposure injuries develop over long periods of time and can have multiple possible causes, making the connection between exposure and harm harder to isolate than in a typical accident case.

Because causation is so central and so difficult, toxic tort cases typically rely heavily on expert witnesses, including toxicologists, epidemiologists, and medical specialists, to establish both general causation and that the substance caused this specific plaintiff's injury.

Courts apply specific standards for evaluating whether this kind of expert testimony is reliable enough to be admitted, which makes the pretrial phase of these cases especially important.

When a substance harms many people in similar ways, such as an entire community exposed to the same contaminated water source, toxic tort claims are often consolidated or coordinated as mass tort litigation rather than pursued one by one.

Coordinating cases this way can make it more efficient to develop the shared scientific evidence needed to establish general causation, even though each plaintiff's individual damages are still evaluated separately.