Which effect can result from a buildup of foul odors in an inadequately ventilated drainage system?

A buildup of foul odors in an inadequately ventilated drainage system can indeed lead to seals on traps not being maintained. Traps are designed to retain water, creating a barrier that prevents sewer gases from entering living spaces. When ventilation is insufficient, pressure imbalances can occur, causing the water in the traps to evaporate or siphon out. This can result in the loss of the water seal, allowing unpleasant odors and potentially harmful gases to emanate from the drainage system into homes or buildings. Therefore, the inability to maintain the seals on traps is a critical issue stemming from poor ventilation in a drainage system.