1. ACGIH (American Conference of Governmental Industrial Hygienists) (2019) TLVs and BEIs. https://riesgosygestion.com/wp-content/uploads/2019/06/tlv2019_entire-book.pdf. Accessed 03 June 2022
2. Ahlström MG, Thyssen JP, Wennervaldt M, Menné T, Johansen JD (2019) Nickel allergy and allergic contact dermatitis: a clinical review of immunology, epidemiology, exposure, and treatment. Contact Dermat 81:227–241
3. Ashley K, Fairfax R (2016) Sampling and analysis of soluble metal compounds. NIOSH Manual of Analytical Methods, 5th ed. https://www.cdc.gov/niosh/docs/2014-151/pdfs/chapters/Chapter-SM.pdf. Accessed 02 June, 2022
4. Bradberry SM (2016) Metals (cobalt, copper, lead, mercury). Medicine 44:182–184
5. DOEL (Department of Employment and Labour) (2021) Hazardous Chemical Agents Regulations, 2021. https://www.gov.za/sites/default/files/gcis_document/202103/44348rg11263gon280.pdf. Accessed 09 Feb, 2022