Mees Lines
Definition
Transverse white bands across the fingernails that follow acute or repeated chronic exposure to arsenic, thallium or selenium. Appear 4 to 8 weeks after exposure as the nail grows. Width and position date the exposure within the 6-month nail growth window.
- Appearance
- Transverse white bands across the nail
- Associated toxins
- Arsenic, thallium, selenium
- Onset after exposure
- 4 to 8 weeks
- Dating window
- Up to 6 months, via nail growth rate
Common questions
How do toxicologists use Mees lines to date an exposure event?+
Because nails grow at a roughly known rate, the distance of the line from the cuticle at the time of examination indicates how long ago the exposure occurred, and measuring the band's position across all ten nails can corroborate a single acute poisoning event.
Are Mees lines specific to poisoning, or can other conditions cause them?+
Mees lines can also follow severe illness, chemotherapy, or major trauma unrelated to toxic metal exposure, so their presence raises suspicion but toxicologists confirm the cause with tissue or nail-clipping analysis for the specific metal rather than relying on the lines alone.
Related terms
- Bhasma
- Calcined heavy-metal preparation in classical ayurvedic and siddha pharmacopoeia. Includes naga bhasma (lead), parad bhasma (mercury), tamra bhasma (copper). Heavy metals are...
- Chelation Therapy
- Administration of a polydentate ligand that forms a stable water-soluble complex with the metal cation and increases urinary excretion. BAL (dimercaprol) is...
- Marsh Test
- Sensitive 1836 method for arsenic in which the acidified sample is added to zinc and dilute sulphuric acid. The evolved arsine gas...
- Reinsch Test
- Classical screen for arsenic, antimony, mercury and bismuth. A clean copper strip is immersed in the acidified sample (concentrated HCl, near-boiling) for...
- Speciation
- Determining the chemical form of a metal in a sample, not just the total. Critical for arsenic because As(III) trivalent arsenite is...