Which environmental contaminant can leach from old pipes?

Old pipes, particularly those made of lead or that have lead-based solder, can leach lead into the water supply. This is particularly concerning in older homes and buildings where the plumbing systems have not been updated. Lead is a toxic heavy metal that can pose significant health risks, especially to children and pregnant women, as it can affect brain development and result in various health issues.

Chlorine, although commonly used in water treatment, does not leach from old pipes; rather, it is added to the water supply to disinfect and maintain microbiological quality. Carbon monoxide is primarily produced from combustion processes and is not associated with leaching from plumbing materials. Volatile organic compounds (VOCs) can be contaminants in water, but they typically enter water supplies through industrial discharge or leaching from certain types of containers, not from old lead piping specifically. Therefore, lead is the primary concern when discussing leaching from old pipes, making it the correct answer to the question.