Which of the following is an example of a systemic effect of toxic materials on the body?

The correct answer highlights a systemic effect of toxic materials on the body. When we talk about systemic effects, we refer to those reactions that affect the entire body or multiple organ systems, rather than being localized to a specific area.

In this case, heart damage signifies an impact on the cardiovascular system, which can result from exposure to various toxic substances. This type of damage can affect overall body function and health, illustrating the wide-reaching consequences that toxic materials can have. Such effects can involve biochemical alterations and pathological changes that extend beyond the initial site of exposure.

In contrast, the other options reflect localized or less systemic effects. Dermatitis and cracking of skin are primarily related to skin damage and represent local reactions to irritants or toxins, rather than systemic involvement. Similarly, swelling can occur in response to localized inflammation, which does not necessarily indicate a broader systemic effect on the body.