It tops most agency lists as the most toxic of all substances.
Lead continues to be a health hazard.
High exposure to it can have devastating effects on young children and fetuses. Lead itself does not break down in the environment. It's also important to note that lead, like most metals, seems to be everywhere in the environment because it is a naturally occurring substance. The most common form of lead exposure continues to be lead-based paint, which, because of the nature of the problem, predominantly affects the poor. On the Agency for Toxic Substances and Disease Registry's annual list of the top 20 hazardous substances, it vies with mercury for first place.