A major source of childhood lead poisoning, still a serious problem in the United States, is paint. The dangers of lead were known even in the 19th century, and the particular dangers to children were documented in the English-language literature as early as 1904. During the first decades of the 20th century, many other countries banned or restricted the use of lead paint for interior painting. Despite this knowledge, the lead industry in the United States did nothing to discourage the use of lead paint on interior walls and woodwork. In fact, beginning in the 1920s, the Lead Industnes Association and its members conducted an intensive campaign to promote the use of paint containing white lead, even targeting children in their advertising. It was not until the 1950s that the industry, under increasing pressure, adopted a voluntary standard limiting the amount of lead in interior paints.