Fingernails and toenails are made of a tough protein called keratin. Along with hair and teeth they are an appendage of the skin. These tissues accumulate
metals that circulate in the blood stream, due to the growth pattern both hair and nail reflect past or chronic exposure.
The average nail growth has been noted by different authors between 2-3mm per months, and is considered about 1/3 the growth rate of hair. A complete nail replacement may take between 3 to 6 months, and toenails require 12 to 18 months. The actual growth rate is dependent upon age, gender, season, exercise level, diet, and hereditary factors. Pregnancy causes a change in nail growth as it does in hair growth.
Arsenic and other elements in hair, nails, and skin-scales of arsenic victims in West Bengal, India.
Samanta G., Sharma R., Roychowdhury T., Chakraborti D. Department of Civil and Environmental Engineering, University of Houston, N 107 Engineering Bldg 1, Houston, TX 77204-4003, USA. firstname.lastname@example.org. Sci Total Environ. 2004 Jun 29;326(1-3):33-47.
For the first time, biological tissues (hair, nails, and skin-scales) of arsenic victims from an arsenic affected area of West Bengal (WB), India were analyzed for trace elements. Analysis was carried out by inductively coupled plasma-mass spectrometry (ICP-MS) for 10 elements (As, Se, Hg, Zn, Pb, Ni, Cd, Mn, Cu, and Fe). A microwave digester was used for digestion of the tissue samples. This study reveals the higher levels of toxic elements As, Mn, Pb, and Ni in the tissue samples compared with available values in the literature. The elevated levels of these toxic metals in the tissues may be due to exposure of these elements through drinking water and food. This study reveals that in the arsenic-affected areas of WB, the concentrations of other toxic elements in drinking water and foodstuff should be monitored to evaluate the arsenic poisoning.
Biological materials are widely used as a bio-indicator for environmental Pollution with heavy metals. Among These are hair and nails, which are also recommended by the World Health Organization (WHO) for worldwide environmental Monitoring. Heavy metals Cd, Cu, Pb and Zn were determined in fingernails and scalp hair from different sexes and ages of school children, adults and workers from polluted and unpolluted Areas of Aswan, Egypt. The results reveal that people living in polluted Areas show higher concentration of metals in nails and hair. The study proves that nails and hair can be used successfully as biological indicators for the assessment of heavy metal Pollution.
The above excerpt is from the research paper by Rashed MN and Hossam F: HEAVY METALS IN FINGERNAILS AND SCALP HAIR OF CHILDREN, ADULTS AND WORKERS FROM ENVIRONMENTALLY EXPOSED AREAS AT ASWAN, EGYPT