What factor contributes to soil and water contamination related to lead?

Improper waste management is a significant factor that contributes to soil and water contamination related to lead. When hazardous waste containing lead is not disposed of correctly, it can leach into the soil and nearby water sources. This contamination can occur through illegal dumping, insufficient containment of waste materials, and poor management of landfills. Over time, lead can accumulate in the environment, leading to negative health impacts for both humans and wildlife, particularly in areas where lead-based materials, such as batteries, paint, or construction debris, have been discarded improperly.

The other options, while they may have environmental impacts, do not directly address lead contamination in the same way. Pesticide application primarily relates to chemical contamination from agricultural practices, overpopulation can lead to increases in resource consumption and waste generation but is not a direct cause of lead-related contamination, and urban development can indeed introduce lead through renovation or demolition activities but also falls under circumstances involving poor waste management practices. Therefore, the direct link between improper waste management and the release of lead into the environment makes it the most relevant factor in this context.