Lead has been a commonly used metal for almost 9,000 years, and humans have known of its negative effects since at least 200 B.C. People were attracted to its availability, malleability, and anti-corrosive properties, but as the Greek physican Dioscorides noted in the first century CE, lead makes the mind “give way”.
For centuries, lead was added to wine as a sweetener. Lead poisoning increased during the Industrial Revolution as heavy industry resulted in the smelting of lead ore. As factories continued to dump lead fumes into the air, in the 1920s, lead was added to gasoline to help with combustion. These fine particulates eventually settled into the soil, and could be tracked into homes or ingested through hand to mouth contact.
Lead was added to paint to create certain colors, allow the paint to dry faster, and resist friction and the elements. While France banned its use in interior paints in 1909, the United States did not completely ban lead paint from residential applications until 1978. If you live in a home built before 1978, it probably contains at least some lead paint.
Lead is not hazardous when it is intact, but when leaded paint begins to deteriorate, it becomes ingestible through dust and paint chips. Today, deteriorating leaded paint is considered to be the most common source of ingested lead.
Lead can still be found in a variety of household items, including cheaply made plastic toys, jewelry, lipstick, dishware, and art supplies. While lead in any level is harmful to all humans, the ability of lead to disrupt mental development makes it the most dangerous to children under six years of age.