The recent water crisis in Flint, MI has drawn national attention to the crisis of lead contamination. In fact, the health risks posed by the substance have been recognized since at least the Middle Ages. In the US, there are laws in place to limit the health impacts, but many people still come in contact with the substance through materials that predate the regulations. While aging water infrastructure is certainly a cause for concern, it is far from the only way humans are exposed to unsafe levels of lead. It is far more common for people to be exposed through the paint inside their home or office. Before renewating older buildings, it is critical to perform a lead inspection and take precautionary measures to prevent it from entering the blood.
In Flint, the state appointed a city manager to take over the city's finances after it declared bankruptcy. That manager made a financial decision to stop purchasing water from nearby Detroit and instead connect the intake pipes to the Flint River, which flows through town. While the decision was fiscally sound, it led to unintended consequencing resulting in one of the worst public health crises in US history. The water in the river was loaded with chlorides, a corrosive chemical. The city failed to perform a lead inspection on the water pipes and, when the chloride-laden water hit the pipes, it typically piled the heavy metal into the mix. The people who bathed, drank, and washed with that water were exposed to the toxic metal and suffered severe health consequences. As the images of those consequences flooded television screens across the country, many people were (understandably) concerned with the safety of their drinking water, but they did not consider the exposure posed by paint.
Lead pigment has been used since at least 400 BC The writings of Pliny the Elder and Theophrastus describe an extraction method using vinegar to isolate the white pigment that was used for makeup and clothing dye. In the Middle Ages and the Renaissance, the white pigment was the primary source of white in artistic paintings. Writings from this period attest to the risk of apoplexy and paralysis from prolonged exposure to the substance. Still, despite this awareness, it continued to be used in white paint to improve the durability and gloss of the cover.
By the 1960s, a growing body of clinical science demonstrated the full extent of the harm, and not only harm to those subjected to prolonged exposure. Even with clear data demonstrating the cause and effect, it was not until 1978 that it was finally outlawed. For homes built prior to 1978 (the majority of housing stock in most urban areas), there is a high statistical probability that lead-based paint was used at some point. Before starting any work, a lead inspection is essential. Sanding prep work can release particles into the air, where they can be inhaled, posing a risk not just to the workers but any people in the immediate area. Those concerned about their exposure should contact the EPA or their state health agency for further information.