section_path: Biological role/Human exposure
section_name: Human exposure
paragraph_text: Human exposure
  
  In the US, the Occupational Safety and Health Administration (OSHA) has designated a permissible exposure limit (PEL) for copper dust and fumes in the workplace as a time-weighted average (TWA) of 1 mg/m. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 1 mg/m, time-weighted average. The IDLH (immediately dangerous to life and health) value is 100 mg/m.
  
  Copper is a constituent of tobacco smoke. The tobacco plant readily absorbs and accumulates heavy metals, such as copper from the surrounding soil into its leaves. These are readily absorbed into the user's body following smoke inhalation. The health implications are not clear.