For many centuries, lead was the favoured material for water pipes, because its malleability made it practical to work into the desired shape. (Such use was so common that the word "plumbing" derives from plumbum, the Latin word for lead.) This was a source of lead-related health problems in the years before the health hazards of ingesting lead were fully understood; among these were stillbirths and high rates of infant mortality. Lead water pipes were still widely used in the early 20th century, and remain in many households. In addition, lead-tin alloy solder was commonly used to join copper pipes, but modern practice uses tin-antimony alloy solder instead, in order to eliminate lead hazards.