1. Ab Razak NH, Praveena SM, Hashim Z (2015) Toenail as a biomarker of heavy metal exposure via drinking water: a systematic review. Rev Environ Health 30(1):1–7
2. Agahian B, Lee JS, Nelson JH, Johns RE (1990) Arsenic levels in fingernails as a biological indicator of exposure to arsenic. Am Ind Hyg Assoc J 51(12):646–651
3. All India Institute of Hygiene and Public Health (1996) Vol. 3. Kolkata. Newsletter of Indian Training Network and All India Institute of Hygiene and Public Health, pp 1–12. Available at: http://www.iisc.ernet.in/currsci/jan102002/38.pdf . Downloaded 30 Nov 2018
4. American Conference of Governmental Industrial Hygienists (ACGIH) (2003) Documentation of the threshold limit values and biological exposure indices, 7th edn. American Conference of Governmental Industrial Hygienists, Inc., Cincinnati
5. Arcega-Cabrera F, Fargher LF, Oceguera-Vargas I, Norena-Barroso E, Yanez-Estrada L, Alvarado J, González L, Moo-Puc R, Pérez-Herrera N, Quesadas-Rojas M, Pérez-Medina S (2017) Water consumption as source of arsenic, chromium, and mercury in children living in rural Yucatan, Mexico: blood and urine levels. Bull Environ Contam Toxicol 99(4):452–459