Which of the following is NOT a leading cause of lead contamination?

Excessive rainfall is not typically considered a leading cause of lead contamination in the context of common sources and pathways for lead exposure. The presence of lead contamination is often associated with more direct human activities or environmental factors that introduce lead into the soil or water systems.

Industrialization, for example, can lead to the release of lead from factories, smelters, and other industrial activities, contributing to contamination through air, soil, and water. Chemical dumping involves the improper disposal of hazardous materials that may contain lead, posing significant contamination risks. Abrasion and chipping refers to the deterioration of lead-based paints or other materials where lead can be released into the environment, especially in older buildings.

In contrast, while excessive rainfall can facilitate the spread or leaching of existing lead from contaminated sources, it does not serve as an independent source of lead like the other options do. Therefore, identifying excessive rainfall as not being a leading cause aligns with understanding the pathways of lead contamination better.