Lead was once ubiquitous. In fact, the Latin name for the metal, plumbum, is the source of the word "plumbing." In ancient Rome, the pipes that were inherent to the city’s advanced for the time sewer system were made of lead, as were the famous aqueducts and the cups out of which they drank wine. When they did so, although the Romans watered down their wine, the alcohol wore away at the interior of the cups, and some lead got into the wine itself. This was exacerbated when they used lead pots to distill wine or cook with it, or deliberately added it to wine to sweeten it. Some scholars believe this ingestion of lead was a major contributing factor to the declining birthrates that hastened the fall of the Roman Empire.
That’s because lead, like mos heavy metals, is highly toxic to human organs, including the heart, digestive system, and reproductive system. Lead is also a neurotoxin, affecting intelligence and cognitive functioning, and when ingested by children can cause permanent neurological problems that result in behavioral issues and learning disabilities. Unfortunately, while the dangers of lead poisoning were recognized at least 2,500 years ago, lead has been widely used regardless for most of that time.
Although most new sources of exposure are in industrial settings, where people are enabled and encouraged to take precautions, lead paint was widely used until relatively recently, exposing many people to the danger. Children, especially, in homes with lead paint are prone to breathing it in or even ingesting it—since most lead paint is old by now, it is often peeling, or creating lead dust in the air. It has to be removed carefully however, lest removal worsen the problem it’s intended to solve. Lead was also added to gasoline, and its presence in exhaust cause people to inhale it and be exposed that way.
The effects of long-term lead exposure on the brain and central nervous system are irreversible, though some studies point to the possibility of repairing the harm. A very small number of children with lead encephalopathy—brain swelling caused by high levels of acute lead exposure—can avoid permanent brain damage with treatment. The other effects are largely treatable, however, using chelation therapy, which gets the lead to pass with urine rather than being stored by the body.