1. 9. UK Soil Observatory, “NSI Topsoil Lead,” http://www.ukso.org/nsi/Lead.html.
2. 3. World Health Organization (WHO), “Lead Poisoning and Health Fact Sheet” (updated August 2017), http://www.who.int/mediacentre/factsheets/fs379/en.
3. 4. “Reference Blood Lead Levels (BLL) for Adults in the US” (National Institute for Occupational Safety and Health [NIOSH], 2015), http://www.cdc.gov/niosh/topics/ables/pdfs/Reference%20Blood%20Levels%20for%20Adults-2015-12-18_508.pdf.
4. 21. “Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment” (Directive 2011/65/EU of the European Parliament, 2011).
5. 11. “Lead Recycling” (International Lead Association, 2015), https://www.ila-lead.org/UserFiles/File/ILA9927%20FS_Recycling_V08.pdf.