Mechanical pencil applied at an angle. When excess vertical pressure is applied on the lead, the lead is automatically retracted inwards. Higher-end mechanical pencils often feature a lead hardness grade indicator and sometimes feature a retractable lead guide pipe. This allows the lead guide pipe to retract back into the pencil body, which will keep it protected in storage and during transit and makes it 'pocket-safe'. In spite of the name, pencil leads do not contain the toxic chemical element lead, but are typically made with graphite and clay, or plastic polymers. Compared to standard pencils, mechanical pencils have a smaller range
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