Mercury is the most poisonous substance present on earth and even a single atom is enough to degrade your health conditions. If lately, you have been experiencing frequent mood swings, nervousness, irritation, insomnia, tremors, muscle atrophy, and abnormal sensations then your doctor may ask you to undergo a test where the concentration of mercury is evaluated through hair specimens. With exposure to mercury, the concentration of mercury can become high in hair which will facilitate easy identifying the mercury levels in your body.