Copying pencil Copying pencil A copying pencil, also indelible pencil or chemical pencil, is pencil whose lead contains a dye. The lead is fabricated by adding a dry water-soluble permanent dye to powdered graphite—used in standard graphite pencils—before binding the mixture with clay. Copying pencils were introduced in the 1870s and were originally marketed for copying documents, especially for making permanent copies of a permanent original. This was achieved by creating a hand-written document using a copying pencil, laying a moist tissue paper over the document and pressing down with a mechanical press. The water-soluble dye in the writing would be transferred
Blood lead level that may result in lead poisoning or an elevated blood lead level. For example, a child can ingest lead by chewing on a toy that is made of lead-contaminated metal or is painted with lead-contaminated paint. A major source of exposure to lead comes from inhalation. Factories and industries, vehicle exhaust (especially from vehicles using leaded gasoline), and even dust in the air that people breathe all have the potential of containing lead. Other major sources of lead exposure include ingestion and contact with products such as paint and soil that may contain lead. Many older claw-foot bathtubs have also