is it an important component for a humans healthy life?
Yes -  It is required for the synthesis of the growth-regulating thyroid hormones thyroxine and triiodothyronine
Iodine
Recommendations by the United States Institute of Medicine are between 110 and 130 µg for infants up to 12 months, 90 µg for children up to eight years, 130 µg for children up to 13 years, 150 µg for adults, 220 µg for pregnant women and 290 µg for lactation. The Tolerable Upper Intake Level (UL) for adults is 1,100 μg/day. This upper limit was assessed by analyzing the effect of supplementation on thyroid-stimulating hormone.

The thyroid gland needs no more than 70 μg/day to synthesise the requisite daily amounts of T4 and T3. The higher recommended daily allowance levels of iodine seem necessary for optimal function of a number of body systems, including lactation, gastric mucosa, salivary glands, brain cells, choroid plexus, thymus, and arterial walls.
where is iodine found on the periodic table In the Halogen group what are some of its uses? Elemental iodine is used as a disinfectant; iodine compounds are used as catalysts, animal feed supplements, stabilisers, dyes, colourants etc. can it be poisonous? Yes - Elemental iodine is toxic if taken orally undiluted. The lethal dose for an adult human is 30 mg/kg, which is about 2.1–2.4 grams for a human weighing 70 to 80 kg
wiki:7685954
Iodine [SEP] Dietary intake
Recommendations by the United States Institute of Medicine are between 110 and 130 µg for infants up to 12 months, 90 µg for children up to eight years, 130 µg for children up to 13 years, 150 µg for adults, 220 µg for pregnant women and 290 µg for lactation. The Tolerable Upper Intake Level (UL) for adults is 1,100 μg/day. This upper limit was assessed by analyzing the effect of supplementation on thyroid-stimulating hormone. The thyroid gland needs no more than 70 μg/day to synthesise the requisite daily amounts of T4 and T3. The higher recommended daily allowance levels of iodine seem necessary for optimal function of a number of body systems, including lactation, gastric mucosa, salivary glands, brain cells, choroid plexus, thymus, and arterial walls.