Lead paint

Lead white was being produced during the 4th century BC; the process is described by Pliny the Elder, Vitruvius and the ancient Greek author Theophrastus. The traditional method of making the pigment was called the stack process. Hundreds or thousands of earthenware pots containing vinegar and lead were embedded in a layer of either tan bark or cow dung. The pots were designed so that the vinegar and lead were in separate compartments, but the lead was in contact with the vapor of the vinegar. The lead was usually coiled into a spiral, and placed on a ledge inside the pot. The pot was loosely covered with a grid of lead, which allowed the carbon dioxide formed by the fermentation of the tan bark or the dung to circulate in the pot. Each layer of pots was covered by a new layer of tan, then another layer of pots. the heat created by the fermentation, acetic acid vapor and carbon dioxide within the stack did their work, and within a month the lead coils were covered with a crust of white lead. This crust was separated from the lead, washed and ground for pigment. This was an extremely dangerous process for the workmen. Medieval texts warned of the danger of 'apoplexy, epilepsy, and paralysis' from working with lead white. Despite the risks, the pigment was very popular with artists because of its density and opacity; a small amount could cover a large surface. It was widely used by artists until the 19th century, when it was replaced by zinc white and titanium white. The dangers of lead paint were considered well-established by the beginning of the 20th century. In the July 1904 edition of its monthly publication, Sherwin-Williams reported the dangers of paint containing lead, noting that a French expert had deemed lead paint 'poisonous in a large degree, both for the workmen and for the inhabitants of a house painted with lead colors'. As early as 1886, German health laws prohibited women and children from working in factories processing lead paint and lead sugar. In 1786, Benjamin Franklin wrote a letter warning a friend about the hazards of lead and lead paint, which he considered well-established. The League of Nations began efforts to ban lead paint in 1921. Lead paint is hazardous. It can cause nervous system damage, stunted growth, kidney damage, and delayed development. It is dangerous to children because it tastes sweet, therefore encouraging children to put lead chips and toys with lead dust in their mouths. Lead paint is dangerous to adults and can cause reproductive problems in men or women. Decreases in sperm production in men have been noted. Lead is considered a possible and likely carcinogen. High levels may result in death. Lead paint is banned in the European Union by the 2003 Restriction of Hazardous Substances Directive (RoHS), which forbids hazardous substances in consumer goods, including paint. This act superseded and harmonized existing laws of the member states, many of which had banned lead paint years before. To protect the painters' health, France had already passed in 1909 a law banning the use of paints containing lead for the painting of the interior and exterior of all buildings.