What is the recommended amount of iodine for humans?
Salt
The amount of iodine and the specific iodine compound added to salt varies from country to country. In the United States, the Food and Drug Administration (FDA) recommends [21 CFR 101.9 (c)(8)(iv)] 150 micrograms of iodine per day for both men and women. US iodized salt contains 46–77 ppm (parts per million), whereas in the UK the iodine content of iodized salt is recommended to be 10–22 ppm.
Iodine in biology
For U.S. food and dietary supplement labeling purposes, the amount in a serving is expressed as a percent of Daily Value (%DV). For iodine specifically, 100% of the Daily Value is considered 150 μg, and this figure remained at 150 μg in the May 27, 2016 revision. A table of the old and new adult Daily Values is provided at Reference Daily Intake. The original deadline to be in compliance was July 28, 2018, but on September 29, 2017, the FDA released a proposed rule that extended the deadline to January 1, 2020 for large companies and January 1, 2021 for small companies.
Lugol's iodine
Lugol's is available in various strengths from 1% to slightly less than 13% iodine (wt/v). The most commonly-used 15% solution consists of 5% (wt/v) elemental iodine (I) and 10% (wt/v) potassium iodide (KI) mixed in distilled water, and has a total iodine content of 126.5 mg/mL. The iodide combines with elemental iodine to form a high concentration of potassium triiodide (KI) solution.
Tincture of iodine
Iodine solution is used to sanitize the surface of fruit and vegetables for bacteria and virus. The common concentration for sanitization is 25 ppm idophor for 1 minute. However, the effectiveness depends on whether the solution penetrates into rifts, and whether dirt is effectively removed at first. But, oocytes of protozoan parasites will not be killed, and it is also doubtful that bacterial spores are killed. Iodine solutions should not be considered able to sanitize or disinfect salad, fruit or vegetables that are contaminated by feces. Thus, it should not be considered safe to eat raw fruit, salads and vegetables which are sanitized with iodine, if they could be contaminated by feces.
Iodine-131
The risk can be mitigated by taking iodine supplements, raising the total amount of iodine in the body and, therefore, reducing uptake and retention in the face and chest and lowering the relative proportion of radioactive iodine. However, such supplements were not distributed to the population living nearest to the Chernobyl nuclear power plant after the disaster, though they were widely distributed to children in Poland.
Iodine-131
To completely block the uptake of iodine-131 by the purposeful addition of perchlorate ions to a population's water supply, aiming at dosages of 0.5 mg/kg-day, or a water concentration of 17 ppm, would therefore be grossly inadequate at truly reducing radioiodine uptake. Perchlorate ion concentrations in a region's water supply would therefore need to be much higher, with at least a total dosage of 7.15 mg/kg of body weight per day needing to be aimed for, with this being achievable for most adults by consuming 2 liters of water per day with a water concentration of 250 mg/kg of water, or 250 ppm of perchlorate ions per liter; only at this level would perchlorate consumption offer adequate protection, and be truly beneficial to the population at preventing bioaccumulation when exposed to a radioiodine environment. This being entirely independent of the availability of iodate or iodide drugs.
Tincture of iodine
Nevertheless, the iodide in tincture of iodine used as a water disinfectant does supply more than adequate nutritional iodine, perhaps 30 or more times the recommended daily allowance per liter or quart. Application of tincture or Lugol's to the skin also results in absorption and bioavailability of some moderate fraction of the iodine.
Potassium
The U.S. Institute of Medicine (IOM) sets Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs), or Adequate Intakes (AIs) for when there is not sufficient information to set EARs and RDAs. Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes. The AIs for potassium are: 400 mg of potassium for 0-6-month-old males, 700 mg of potassium for 7-12-month-old males, 3,000 mg of potassium for 1-3-year-old males, 3,800 mg of potassium for 4-8-year-old males, 4,500 mg of potassium for 9-13-year-old males, and 4,700 mg of potassium for males that are 14 years old and older.
The AIs for potassium are: 400 mg of potassium for 0-6-month-old females, 700 mg of potassium for 7-12-month-old females, 3,000 mg of potassium for 1-3-year-old females, 3,800 mg of potassium for 4-8-year-old females, 4,500 mg of potassium for 9-13-year-old females, and 4,700 mg of potassium for females that are 14 years old and older.
The AIs for potassium are: 4,700 mg of potassium for 14-50-year-old pregnant females; furthermore, 5,100 mg of potassium for 14-50-year-old lactating females. As for safety, the IOM also sets Tolerable upper intake levels (ULs) for vitamins and minerals, but for potassium the evidence was insufficient, so no UL established.
Iodine-125
Iodine-125 is commercially available in dilute NaOH solution as I-iodide (or the hypohalite sodium hypoiodite, NaOI) . The radioactive concentration lies at 4 to 11 GBq/ml and the specific radioactivity is >75GBq/µmol. The chemical and radiochemical purity is high. The radionuclidic purity is also high; some I (t=13.1d) is unavoidable due to the neutron capture noted above. The I-126 tolerable content (which is set by the unwanted isotope interfering with dose calculations in brachytherapy) lies at about 0.2% atom fraction of the total iodine (the rest being I-125).
Nascent iodine (dietary supplement)
Nascent Iodine sometimes known by the generic term atomic iodine or generic trademark name Atomidine or by the detoxified iodine, is a liquid orally administered supplemental form of iodine, claimed to be in a and monatomic state, originating from a 1931 Edgar Cayce formula. The concept of nascent state has been debunked. Thus, nascent iodine does not exist and medicines purporting to contain this substance are misrepresentations.The preparation was first conceived in 1931 by American Christian mystic Edgar Cayce in two channelled "readings" for an Indian inventor by the name of Shankar Bhise who inquired about how to improve an iodine medicine. Cayce regarded this specially formulated "atomic" iodine as far easier to assimilate than other forms. Cayce recommended this atomic iodine or "Atomidine" as a therapeutic measure, in over 600 "readings". Extracts from some of his readings:
Nuclear fission product
One measure which protects against the risk from radio-iodine is taking a dose of potassium iodide (KI) before exposure to radioiodine. The non-radioactive iodide 'saturates' the thyroid, causing less of the radioiodine to be stored in the body.
Administering potassium iodide reduces the effects of radio-iodine by 99% and is a prudent, inexpensive supplement to fallout shelters. A low-cost alternative to commercially available iodine pills is a saturated solution of potassium iodide. Long-term storage of KI is normally in the form of reagent grade crystals.
Iodine deficiency
Iodine deficiency resulting in goiter occurs 187 million people globally (2.7% of the population). Certain areas of the world, due to natural deficiency and unavailability of iodine, are severely affected by iodine deficiency, which affects approximately two billion people worldwide. It is particularly common in the Western Pacific, South-East Asia and Africa. Among other nations affected by iodine deficiency, China and Kazakhstan have begun taking action, while Russia has not. Successful campaigns for the adoption of the use of iodized salt require education of salt producers and sellers and a communication campaign directed at the public. The cost of adding iodine to salt is negligible—"Only a few cents a ton."
Iodine
As of 2000, the median intake of iodine from food in the United States was 240 to 300 μg/day for men and 190 to 210 μg/day for women. The general US population has adequate iodine nutrition, with women of childbearing age and pregnant women having a possible mild risk of deficiency. In Japan, consumption was considered much higher, ranging between 5,280 μg/day to 13,800 μg/day from dietary seaweed or kombu kelp, often in the form of Kombu Umami extracts for soup stock and potato chips. However, new studies suggest that Japan's consumption is closer to 1,000–3,000 μg/day. The adult UL in Japan was last revised to 3,000 µg/day in 2015.
Iodine in biology
Worldwide, iodine deficiency affects two billion people and is the leading preventable cause of mental retardation. Mental disability is a result which occurs primarily when babies or small children are rendered hypothyroidic by a lack of dietary iodine (new hypothyroidism in adults may cause temporary mental slowing, but not permanent damage).
Potassium iodide
SSKI (i.e., the "saturated solution of KI" rather than tablets) may be used in radioiodine-contamination emergencies (i.e., nuclear accidents) to "block" the thyroid's uptake of radioiodine, at a dose of two drops of SSKI per day for an adult. This is not the same as blocking the thyroid's release of thyroid hormone, for which the adult dose is different (and is actually higher by a factor of 7 or 8), and for which KI anti-radiation pills (not a common medical treatment form of KI) are not usually available in pharmacies, or normally used in hospitals, or by physicians. Although the two forms of potassium iodide are completely interchangeable, normally in practice the SSKI solution, which is the historical medical form of high dose iodine, is generally used for all medical purposes save for radioiodine prophylaxis. For protection of the thyroid against radioiodine (iodine-131) contamination, the convenient standard 130 mg KI pill is used, if available. As noted, the equivalent two drops of SSKI (equaling the dose of one KI pill) may be used for this purpose, if the pills are not available.
Iodine in biology
pmid: 29437784 DOI: 10.1530/ERC-17-0515Elemental iodine is an oxidizing irritant, and direct contact with skin can cause lesions, so iodine crystals should be handled with care. Solutions with high elemental iodine concentration such as tincture of iodine are capable of causing tissue damage if use for cleaning and antisepsis is prolonged. Although elemental iodine is used in the formulation of Lugol's solution, a common medical disinfectant, it becomes triiodide upon reacting with the potassium iodide used in the solution and is therefore non-toxic. Only a small amount of elemental iodine will dissolve in water, and adding potassium iodide allows a much larger amount of elemental iodine to dissolve through the reaction of I2-I3. This allows Lugol's iodine to be produced in strengths varying from 2% to 15% iodine.
Sodium selenite
The US Food and Drug Administration approved a selenium supplement to animal diets; the most common form is sodium selenite for pet foods. According to one article, "not much was known about which selenium compounds to approve for use in animal feeds when the decisions were made back in the 1970s .. At the time the regulatory action was taken, only the inorganic selenium salts (sodium selenite and sodium selenate) were available at a cost permitting their use in animal feed.”
Selenium is toxic in high concentrations. As sodium selenite, the chronic toxic dose for human beings was described as about 2.4 to 3 milligrams of selenium per day. In 2000, the U.S. Institute of Medicine set the adult Tolerable upper intake levels (UL) for selenium from all sources - food, drinking water and dietary supplements - at 400 μg/day. The European Food Safety Authority reviewed the same safety question and set its UL at 300 μg/day.
Halogen
Humans typically consume less than 100 micrograms of iodine per day. Iodine deficiency can cause intellectual disability. Organoiodine compounds occur in humans in some of the glands, especially the thyroid gland, as well as the stomach, epidermis, and immune system. Foods containing iodine include cod, oysters, shrimp, herring, lobsters, sunflower seeds, seaweed, and mushrooms. However, iodine is not known to have a biological role in plants. There are typically 0.06 milligrams per liter of iodine in human blood, 300 parts per billion of iodine in human bones, and 50 to 700 parts per billion of iodine in human tissue. There are 10 to 20 milligrams of iodine in a typical 70-kilogram human.
Vitamin K
The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for vitamin K in 1998. The IOM does not distinguish between K and K – both are counted as vitamin K. At that time, sufficient information was not available to establish EARs and RDAs for vitamin K. In instances such as these, the board sets Adequate Intakes (AIs), with the understanding that at some later date, AIs will be replaced by more exact information. The current AIs for adult women and men ages 19 and up are 90 and 120 μg/day, respectively. AI for pregnancy is 90 μg/day. AI for lactation is 90 μg/day. For infants up to 12 months, the AI is 2.0-2.5 μg/day; for children ages 1–18 years the AI increases with age from 30 to 75 μg/day. As for safety, the IOM sets tolerable upper intake levels (known as ULs) for vitamins and minerals when evidence is sufficient. Vitamin K has no UL, as human data for adverse effects from high doses are inadequate. Collectively, the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes.
Iron
The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for iron in 2001. The current EAR for iron for women ages 14–18 is 7.9 mg/day, 8.1 for ages 19–50 and 5.0 thereafter (post menopause). For men the EAR is 6.0 mg/day for ages 19 and up. The RDA is 15.0 mg/day for women ages 15–18, 18.0 for 19–50 and 8.0 thereafter. For men, 8.0 mg/day for ages 19 and up. RDAs are higher than EARs so as to identify amounts that will cover people with higher than average requirements. RDA for pregnancy is 27 mg/day and, for lactation, 9 mg/day. For children ages 1–3 years 7 mg/day, 10 for ages 4–8 and 8 for ages 9–13. As for safety, the IOM also sets Tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of iron the UL is set at 45 mg/day. Collectively the EARs, RDAs and ULs are referred to as Dietary Reference Intakes.
Thyroid storm
Iodine
Nascent iodine (dietary supplement)
The diatomic form of elemental iodine I2, has no electrical charge. Monoatomic iodine also has no electrical charge, but is unstable and highly reactive (free radical, labeled as an I with a dot, I* ). It can be produced by exposing I2 to ultraviolet light. Electric and magnetic fields won't do it, as is sometimes incorrectly suggested.I should mention a few points about Edgar Cayce's atomidine. This famous visionary wrote several articles about the best form of iodine supplement (18). Some claim that this was iodine trichloride, but that cannot be true as this compound is toxic by ingestion and damaging to mucous membranes. It decomposes to ICl and poisonous gas Cl2 at 77 degrees C and also in water at room temperature (19). Most likely Cayce's atomidine was simply a 1% iodine solution (I2) in 95% ethanol. I am surprised that there are educated people, even medical doctors who claim that "elemental monoatomic iodine" preparations (Atomidine, Nascent Iodine etc.) are the best forms of iodine supplements. May be it has something to do with efficient marketing? Elemental Iodine (I2) is soluble in glycerin. Replacement of ethanol with glycerol indeed makes these supplements more consumption-friendly, so they are sold by some vendors as superior products to Cayce's ethanol-formulated one. Personally, I think glycerol-based I2 supplements are inferior to iodides; however, they are excellent antiseptics.The best and safest form of iodine supplementation for a healthy adult is iodide. Iodides are naturally produced in larger quantities by various seaweeds.
Iodine-123
Dosing can vary; is recommended for thyroid imaging while an uptake test may use . There is a study that indicates a given dose can effectively result in effects of an otherwise higher dose, due to impurities in the preparation. The dose of radioiodine I is typically tolerated by individuals who cannot tolerate contrast mediums containing larger doses of iodine such as used in CT scan, intravenous pyelogram (IVP) and similar imaging diagnostic procedures. Iodine is not an allergen.
Iodine
Natural sources of dietary iodine include seafood, such as fish, seaweeds (such as kelp) and shellfish, dairy products and eggs so long as the animals received enough iodine, and plants grown on iodine-rich soil. Iodised salt is fortified with iodine in the form of sodium iodide.
Iobitridol
Xenetix 300 of Guerbet (Roissy, France) contains Iobitridol in 300 mg iodine/ml concentration. Recommended mean doses are 1.1 to 2.8 ml/kg body mass corresponding to 0,33 to 0,84 g iodine/kg human body mass. Injected into veins it will be filtered out by the kidneys. It is used also to fill joints or the uterus.
Iodine deficiency
Following is a list of potential risk factors that may lead to iodine deficiency:Iodine accounts for 65% of the molecular weight of T4 and 59% of the T3. There is a total of 15–20 mg of iodine in the human body which is primarily concentrated in thyroid tissue and hormones, but 30% of iodine is distributed in other tissues, including mammary glands, eyes, gastric mucosa, choroid plexus, arterial walls, the cervix, and salivary glands. In the cells of these tissues, iodide enters directly by sodium-iodide symporter (NIS).
Iodine deficiency in China
The Chinese government implemented a program of regulating salt to contain iodine starting in 1995. A more recent study has confirmed that the availability of iodized salt in the provinces has increased since this date. Today, about one third of the Chinese population is living in areas with low concentrations of iodine in their water supply. Salt is available in China for less than the retail price in some other countries, at about 5 cents, and is consumed regularly in most diets. This is very cost effective for producers who now must abide by the iodized salt regulations and those for those who need to consume it. The black market, however, is laden with the non-iodized counterpart and partially accounts for the population still be fairly saturated with IDDs.
Iron
The European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL defined the same as in United States. For women the PRI is 13 mg/day ages 15–17 years, 16 mg/day for women ages 18 and up who are premenopausal and 11 mg/day postmenopausal. For pregnancy and lactation, 16 mg/day. For men the PRI is 11 mg/day ages 15 and older. For children ages 1 to 14 the PRI increases from 7 to 11 mg/day. The PRIs are higher than the U.S. RDAs, with the exception of pregnancy. The EFSA reviewed the same safety question did not establish a UL.
Radioactive iodine uptake test
The normal uptake is between 15 and 25 percent, but this may be forced down if, in the meantime, the patient has eaten foods high in iodine, such as dairy products and seafood. Low uptake suggests thyroiditis, high uptake suggests Graves' disease, and unevenness in uptake suggests the presence of a nodule.
Iobenguane
The FDA-approved dosing of potassium iodide for this purpose are as follows: infants less than 1 month old, 16 mg; children 1 month to 3 years, 32 mg; children 3 years to 18 years, 65 mg; adults 130 mg. However, some sources recommend alternative dosing regimens.
Calcium
Because of concerns for long-term adverse side effects, including calcification of arteries and kidney stones, both the U.S. Institute of Medicine (IOM) and the European Food Safety Authority (EFSA) set Tolerable Upper Intake Levels (ULs) for combined dietary and supplemental calcium. From the IOM, people of ages 9–18 years are not to exceed 3,000 mg/day combined intake; for ages 19–50, not to exceed 2,500 mg/day; for ages 51 and older, not to exceed 2,000 mg/day. The EFSA set the UL for all adults at 2,500 mg/day, but decided the information for children and adolescents was not sufficient to determine ULs.
Creswell Eastman
His preferred method of delivery for pregnant and lactating women is via oral iodine supplements. In his day to day practice at the Sydney Thyroid Clinic he will give priority to pregnant women. Eastman's work in China indicates that adequate iodine intake has resulted in an overall increase in the national IQ. He is of the opinion that recent testing of children in Australia that showed a decline in results in Australian children may be caused by iodine deficiency. This was a problem that he previously flagged in 2007: "If we don't address this in Australia then we are likely to see a lot of children born in coming years that have lower IQs, have problems with hearing, have great learning difficulties and they are less likely to fulfill their genetic potential."Eastman is married to Annette, whom he met while a medical student, and has four children Katherine (Kate), born 1966; Damien, born 1968; Phillipa, born 1970 and Nicholas, born 1974.
Iodine (medical use)
Iodine is used to treat and prevent iodine deficiency and as an antiseptic. For iodine deficiency it can be given by mouth or injection into a muscle. As an antiseptic it may be used on wounds that are wet or to disinfect the skin before surgery.
Common side effects when applied to the skin include irritation and discoloration. When taken by mouth or injection side effects may include allergic reactions, goitre, and thyroid dysfunction. Use during pregnancy is recommended in regions where deficiency is common, otherwise it is not recommended. Iodine is an essential trace element.
In 1811, Bernard Courtois isolated iodine from seaweed while in 1820 Jean-Francois Coindet linked iodine intake to goiter size. It initially came into use as a disinfectant and for goiter. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. Table salt with iodine, known as iodized salt, is available in more than 110 countries. In areas with low dietary iodine one dose of iodine a year at 0.32 USD per dose may be recommended.
Niacin
The U.S. Institute of Medicine (renamed National Academy of Medicine in 2015) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for niacin in 1998. The European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values (DRV), with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL defined the same as in United States. For women (including those pregnant or lactating), men and children the PRI is 1.6 mg niacin per megajoule (MJ) of energy consumed. As the conversion is 1 MJ = 238.8 kcal, an adult consuming 2388 calories should be consuming 16 mg niacin. This is comparable to U.S. RDAs. The niacin UL is set at 10 mg/day, which is much less than the U.S. value. The UL applies to niacin as a supplement consumed as one dose, and in intended to avoid the skin flush reaction. This explains why the PRI can be higher than the UL.
Iodine deficiency
It is well known that micronutrient deficiencies change the development of intelligence and iodine is no exception. Lacking in iodine during human development causes a fall, in average, of 12 IQ points in China.
Indocyanine green
Because the preparation contains sodium iodide, a test must be carried out for iodine intolerance. Because around 5% of iodide is added, the iodine content of a 25 mg ampoule is 0.93 mg. In comparison, preparations for a bone marrow CT (140 ml) contain 300 mg/ml and for a corona angiography (200 ml) 350 mg/ml of iodine. ICG has the ability to bind 98% to plasma proteins – 80% to globulins and 20% to alpha-lipoprotein and albumin – and thus, in comparison with fluorescein as a marker, has a lower leakage (slower emergence of dye from the vessels, extravasally). Because of the plasma protein binding, ICG stays for up to 20–30 minutes in the vessels (intravasally). When the eye is examined, it thus stays for a long time in tissues with a higher blood flow, such as the choroid and the blood vessels of the retina.
Iodised salt
Salt is an effective vehicle for distributing iodine to the public because it does not spoil and is consumed in more predictable amounts than most other commodities. For example, the concentration of iodine in salt has gradually increased in Switzerland: 3.75 mg/kg in 1952, 7.5 mg/kg in 1962, 15 mg/kg in 1980, 20 mg/kg in 1998, and 25 mg/kg in 2014. These increases were found to improve iodine status in the general Swiss population.
Iodised salt
Iodine Deficiency Disorders were detected as a major public health issue by Brazilian authorities in the 1950s, when about 20% of the population had goiter. The National Agency for Sanitary Vigilance (ANVISA) is responsible for setting the mandatory iodine content of table salt. The Brazilian diet averages 12 g of table salt per day, more than twice the recommended value of 5 g a day. To avoid excess consumption of iodine, the iodizing of Brazilian table salt was reduced to 15–45 mg/kg in July 2013. Specialists criticized the move, saying that it would be better for the government to promote reduced salt intake, which would solve the iodine problem as well as reduce the incidence of high blood pressure.
Iodine-131
The administration of known goitrogen substances can also be used as a prophylaxis in reducing the bio-uptake of iodine, (whether it be the nutritional non-radioactive iodine-127 or radioactive iodine, radioiodine - most commonly iodine-131, as the body cannot discern between different iodine isotopes). Perchlorate ions, a common water contaminant in the USA due to the aerospace industry, has been shown to reduce iodine uptake and thus is classified as a goitrogen. Perchlorate ions are a competitive inhibitor of the process by which iodide, is actively deposited into thyroid follicular cells. Studies involving healthy adult volunteers determined that at levels above 0.007 milligrams per kilogram per day (mg/(kg·d)), perchlorate begins to temporarily inhibit the thyroid gland’s ability to absorb iodine from the bloodstream ("iodide uptake inhibition", thus perchlorate is a known goitrogen). The reduction of the iodide pool by perchlorate has dual effects—reduction of excess hormone synthesis and hyperthyroidism, on the one hand, and reduction of thyroid inhibitor synthesis and hypothyroidism on the other. Perchlorate remains very useful as a single dose application in tests measuring the discharge of radioiodide accumulated in the thyroid as a result of many different disruptions in the further metabolism of iodide in the thyroid gland.
Iodised salt
Worldwide, iodine deficiency affects two billion people and is the leading preventable cause of intellectual and developmental disabilities. According to public health experts, iodisation of salt may be the world's simplest and most cost-effective measure available to improve health, only costing US$0.05 per person per year. At the World Summit for Children in
1990, a goal was set to eliminate iodine deficiency by 2000. At that time, 25% of households consumed iodised salt, a proportion that increased to 66% by 2006.
Iodine
People can be exposed to iodine in the workplace by inhalation, ingestion, skin contact, and eye contact. The Occupational Safety and Health Administration (OSHA) has set the legal limit (Permissible exposure limit) for iodine exposure in the workplace at 0.1 ppm (1 mg/m) during an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a Recommended exposure limit (REL) of 0.1 ppm (1 mg/m) during an 8-hour workday. At levels of 2 ppm, iodine is immediately dangerous to life and health.
Calcium in biology
The U.S. Institute of Medicine (IOM) established Recommended Dietary Allowances (RDAs) for calcium in 1997 and updated those values in 2011. See table. The 
European Food Safety Authority (EFSA) uses the term Population Reference Intake (PRIs) instead of RDAs and sets slightly different numbers: ages 4–10 800 mg, ages 11–17 1150 mg, ages 18–24 1000 mg, and >25 years 950 mg.
Iodine-131
A common treatment method for preventing iodine-131 exposure is by saturating the thyroid with regular, non-radioactive iodine-127, as an iodide or iodate salt. Free elemental iodine should not be used for saturating the thyroid because it is a corrosive oxidant and therefore is toxic to ingest in the necessary quantities. The thyroid will absorb very little of the radioactive iodine-131 after it is saturated with non-radioactive iodide, thereby avoiding the damage caused by radiation from radioiodine. The most common method of treatment is to give potassium iodide to those at risk. The dosage for adults is 130 mg potassium iodide per day, given in one dose, or divided into portions of 65 mg twice a day. This is equivalent to 100 mg of iodine, and is about 700 times bigger than the nutritional dose of iodine, which is 0.150 mg per day (150 micrograms per day). See potassium iodide for more information on prevention of radioiodine absorption by the thyroid during nuclear accident, or for nuclear medical reasons. The FDA-approved dosing of potassium iodide for this purpose are as follows: infants less than 1 month old, 16 mg; children 1 month to 3 years, 32 mg; children 3 years to 18 years, 65 mg; adults 130 mg. However, some sources recommend alternative dosing regimens.
Iodine in biology
Iodine vapor is very irritating to the eye, to mucous membranes, and in the respiratory tract. Concentration of iodine in the air should not exceed 1 mg/m³ (eight-hour time-weighted average).
Iodine in biology
The biological half-life of iodine differs between the various organs of the body, from 100 days in the thyroid, to 14 days in the kidneys and spleen, to 7 days in the reproductive organs. Typically the daily urinary elimination rate ranges from 100 to 200 µg/L in humans. However, the Japanese diet, high in iodine-rich kelp, contains 1,000 to 3,000 µg of iodine per day, and research indicates the body can readily eliminate excess iodine that is not needed for thyroid hormone production. The literature reports as much as 30,000 µg/L (30 mg/L) of iodine being safely excreted in the urine in a single day, with levels returning to the standard range in a couple of days, depending on seaweed intake. One study concluded the range of total body iodine content in males was 12.1 mg to 25.3 mg, with a mean of 14.6 mg. It is presumed that once thyroid-stimulating hormone is suppressed, the body simply eliminates excess iodine, and as a result, long-term supplementation with high doses of iodine has no additional effect once the body is replete with enough iodine. It is unknown if the thyroid gland is the rate-limiting factor in generating thyroid hormone from iodine and tyrosine, but assuming it is not, a short-term loading dose of one or two weeks at the tolerable upper intake level may quickly restore thyroid function in iodine-deficient patients.
Jean-Francois Coindet
After his findings became public, many other physicians also began to prescribe iodine which led to a high rate of adverse effects. This led to a public controversy over the use of iodine. Coindet advised to control the dose of iodine closely to limit adverse effects. In January 1821, the local authorities in Geneva prohibited the sale of iodine unless prescribed by a doctor.
Iodine
Iodine is the fourth halogen, being a member of group 17 in the periodic table, below fluorine, chlorine, and bromine; it is the heaviest stable member of its group. (The scarce and fugitive fifth halogen, the radioactive astatine, is not well-studied due to its expense and inaccessibility in large quantities, but appears to show various unusual properties due to relativistic effects.) Iodine has an electron configuration of [Kr]4d5s5p, with the seven electrons in the fifth and outermost shell being its valence electrons. Like the other halogens, it is one electron short of a full octet and is hence a strong oxidising agent, reacting with many elements in order to complete its outer shell, although in keeping with periodic trends, it is the weakest oxidising agent among the stable halogens: it has the lowest electronegativity among them, just 2.66 on the Pauling scale (compare fluorine, chlorine, and bromine at 3.98, 3.16, and 2.96 respectively; astatine continues the trend with an electronegativity of 2.2). Elemental iodine hence forms diatomic molecules with chemical formula I, where two iodine atoms share a pair of electrons in order to each achieve a stable octet for themselves; at high temperatures, these diatomic molecules reversibly dissociate a pair of iodine atoms. Similarly, the iodide anion, I, is the strongest reducing agent among the stable halogens, being the most easily oxidised back to diatomic I. (Astatine goes further, being indeed unstable as At and readily oxidised to At or At, although the existence of At is not settled.)
Malnutrition
Malnutrition in the form of iodine deficiency is "the most common preventable cause of mental impairment worldwide." "Even moderate deficiency, especially in pregnant women and infants, lowers intelligence by 10 to 15 I.Q. points, shaving incalculable potential off a nation's development. The most visible and severe effects—disabling goiters, cretinism and dwarfism—affect a tiny minority, usually in mountain villages. But 16 percent of the world's people have at least mild goiter, a swollen thyroid gland in the neck."
Pantothenic acid
The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for B vitamins in 1998. At that time there was not sufficient information to establish EARs and RDAs for pantothenic acid. In instances such as this, the Board sets Adequate Intakes (AIs), with the understanding that at some later date, AIs will be replaced by more exact information. The current AI for teens and adults ages 14 and up is 5 mg/day. AI for pregnancy is 6 mg/day. AI for lactation is 7 mg/day. For infants up to 12 months the AI is 1.8 mg/day. For children ages 1–13 years the AI increases with age from 2 to 4 mg/day. As for safety, the IOM sets Tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of pantothenic acid there is no UL, as there is no human data for adverse effects from high doses. Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes (DRIs).
Child health and nutrition in Africa
Inadequacies in iodine intake on the other hand impair the synthesis of thyroid hormones, which are critical for normal development and proper functioning of the brain and nervous system as well as the conservation of body heat and energy. Iodine deficiency causes endemic goitre and cretinism as well as stunting of mental and physical development. Globally, 1.6 million people are at risk of iodine deficiency disorders and 50 million children affected by them. About 100,000 children are born each year with mental retardation, most of them in Africa. This is due to the low consumption of iodine-rich foodstuffs (e.g. marine products) and the over-consumption of foodstuffs causing goitre, particularly bitter cassava, which is a staple in Central Africa.
Iodinated contrast
The term "iodine allergy" should be omitted because this kind of allergy does not exist. Seafood "allergy" is no contraindication for the use of iodinated contrast materials, because in seafood allergy the immune system is directed against the muscle protein tropomyosin. While iodine levels in seafood are higher than in non-seafood items, the consumption of the latter exceeds that of the former by far and there is no evidence that the iodine content of seafood is related to reactions to seafood. Available data suggest that seafood allergy increases the risk of a contrast-mediated reaction by approximately the same amount as allergies to fruits or those with asthma. In addition, those with an intolerance to alcohol should avoid use of this product due to chemical breakdown similar to ethyl alcohol. Studies show that B.A.C. has been shown to increase exponentially for up to 72 hours after contrast is administered, resulting in altered results of urine, blood, and breath alcohol screens? Over 85% of patients with seafood allergies will not have an adverse reaction to iodinated contrast. Finally, there is no evidence that adverse skin reactions to iodine-containing topical antiseptics (e.g., povidone-iodine) are of any specific relevance to administration of I.V. contrast material.
Iodine
The melting and boiling points of iodine are the highest among the halogens, conforming to the increasing trend down the group, since iodine has the largest electron cloud among them that is the most easily polarised, resulting in its molecules having the strongest van der Waals interactions among the halogens. Similarly, iodine is the least volatile of the halogens. Because it has the largest atomic radius among the halogens, iodine has the lowest first ionisation energy, lowest electron affinity, lowest electronegativity and lowest reactivity of the halogens.
The interhalogen bond in diiodine is the weakest of all the halogens. As such, 1% of a sample of gaseous iodine at atmospheric pressure is dissociated into iodine atoms at 575 °C. Temperatures greater than 750 °C are required for fluorine, chlorine, and bromine to dissociate to a similar extent. Most bonds to iodine are weaker than the analogous bonds to the lighter halogens. Gaseous iodine is composed of I molecules with an I–I bond length of 266.6 pm. The I–I bond is one of the longest single bonds known. It is even longer (271.5 pm) in solid orthorhombic crystalline iodine, which has the same crystal structure as chlorine and bromine. (The record is held by iodine's neighbour xenon: the Xe–Xe bond length is 308.71 pm.) As such, within the iodine molecule, significant electronic interactions occur with the two next-nearest neighbours of each atom, and these interactions give rise, in bulk iodine, to a shiny appearance and semiconducting properties. Iodine is a two-dimensional semiconductor with a band gap of 1.3 eV (125 kJ/mol): it is a semiconductor in the plane of its crystalline layers and an insulator in the perpendicular direction.
Iodine
Iodine is an essential element for life and, at atomic number "Z" = 53, is the heaviest element commonly needed by living organisms. (Lanthanum and the other lanthanides, as well as tungsten with "Z" = 74, are used by a few microorganisms.) It is required for the synthesis of the growth-regulating thyroid hormones thyroxine and triiodothyronine (T and T respectively, named after their number of iodine atoms). A deficiency of iodine leads to decreased production of T and T and a concomitant enlargement of the thyroid tissue in an attempt to obtain more iodine, causing the disease known as simple goitre. The major form of thyroid hormone in the blood is thyroxine (T), which has a longer half-life than T. In humans, the ratio of T to T released into the blood is between 14:1 and 20:1. T is converted to the active T (three to four times more potent than T) within cells by deiodinases (5'-iodinase). These are further processed by decarboxylation and deiodination to produce iodothyronamine (Ta) and thyronamine (Ta'). All three isoforms of the deiodinases are selenium-containing enzymes; thus dietary selenium is essential for T production.
Folate
The U.S. Institute of Medicine (IOM) updated Recommended Dietary Allowances (RDAs) and Tolerable upper intake levels (ULs) for folate in 2001. Collectively the EARs, RDAs, AIs, and ULs are referred to as Dietary Reference Intakes (DRIs). The European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL defined the same as in United States. For women and men over age 18 the PRI is set at 330 μg/day. PRI for pregnancy is 600 μg/day, for lactation 500 μg/day. For children ages 1–17 years the PRIs increase with age from 120 to 270 μg/day. These values differ somewhat from the U.S. RDAs. The United Kingdom's Dietary Reference Value for folate, set by the Committee on Medical Aspects of Food and Nutrition Policy (COMA) in 1991, is 200 μg/day for adults.
Methionine
The Food and Nutrition Board of the U.S. Institute of Medicine set Recommended Dietary Allowances (RDAs) for essential amino acids in 2002. For methionine combined with cysteine, for adults 19 years and older, 19 mg/kg body weight/day.
Vegan nutrition
One study reported a "potential danger of iodine deficiency disorders due to strict forms of vegetarian nutrition, especially when fruits and vegetables grown in soils with low [iodine] levels are ingested." Vegan diets typically require special attention for iodine, for which the only substantial and reliable vegan sources are sea vegetables, iodized salt and supplements. The iodine content of sea vegetables varies widely and may provide more than the recommended upper limit of iodine intake.
Nuclear Regulation Authority
On 19 July 2013, the NRA updated its guidelines for the distribution and use of stabilized iodine tablets. Under the old rules designed in 2002 by the former regulator, the NSA, iodine tablets were recommended for those up to the age of 40. These former guidelines were based on studies done on the health of the atomic bomb survivors of Nagasaki and Hiroshima. Later studies however showed that although older people had less risk of developing cancer, the risk was not zero. Therefore, the age limit of 40 was abandoned. Because tablets were needed for approximately 4.8 million people who live within 30 kilometers of a nuclear reactor, implementation may take some time with only one pharmaceutical firm in Japan available for the production. Distribution would be started soon, and local governments were ordered to hold briefings for their residents. The NRA also warned that the use of iodine tablets could cause hypothyroidism, a slow-functioning thyroid gland.
Potassium perchlorate
To completely block the uptake of Iodine-131 by the purposeful addition of perchlorate ions to a populace's water supply, aiming at dosages of 0.5 mg/(kg d), or a water concentration of 17 ppm, would therefore be grossly inadequate at truly reducing radioiodine uptake. Perchlorate ion concentrations in a regions water supply, would need to be much higher, at least 7.15 mg/kg of body weight per day or a water concentration of 250 ppm, assuming people drink 2 liters of water per day, to be truly beneficial to the population at preventing bioaccumulation when exposed to a radioiodine environment, independent of the availability of Iodate or Iodide drugs.
Vegetarian nutrition
One study reported a "potential danger of [iodine] (I) deficiency disorders due to strict forms of vegetarian nutrition, especially when fruits and vegetables grown in soils with low [iodine] levels are ingested." Iodine, however, is usually supplied by iodized salt and other sources in first world countries. Other significant vegetarian sources of iodine include edible seaweed and bread made with dough conditioners.
Magnesium in biology
The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for magnesium in 1997. If there is not sufficient information to establish EARs and RDAs, an estimate designated Adequate Intake (AI) is used instead. The current EARs for magnesium for women and men ages 31 and up are 265 mg/day and 350 mg/day, respectively. The RDAs are 320 and 420 mg/day. RDAs are higher than EARs so as to identify amounts that will cover people with higher than average requirements. RDA for pregnancy is 350 to 400 mg/day depending on age of the woman. RDA for lactation ranges 310 to 360 mg/day for same reason. For children ages 1–13 years the RDA increases with age from 65 to 200 mg/day. As for safety, the IOM also sets Tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of magnesium the UL is set at 350 mg/day. The UL is specific to magnesium consumed as a dietary supplement, the reason being that too much magnesium consumed at one time can cause diarrhea. The UL does not apply to food-sourced magnasium. Collectively the EARs, RDAs and ULs are referred to as Dietary Reference Intakes.
Iron-deficiency anemia
The National Academy of Medicine updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) in 2001. The current EAR for iron for women ages 14–18 is 7.9 mg/day, 8.1 for ages 19–50 and 5.0 thereafter (post menopause). For men the EAR is 6.0 mg/day for ages 19 and up. The RDA is 15.0 mg/day for women ages 15–18, 18.0 for 19–50 and 8.0 thereafter. For men, 8.0 mg/day for ages 19 and up. (RDAs are higher than EARs so as to identify amounts that will cover people with higher than average requirements.) The RDA for pregnancy is 27 mg/day, and for lactation, 9 mg/day. For children ages 1–3 years the RDA is 7 mg/day, 10 for ages 4–8 and 8 for ages 9–13. The European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intakes (PRI) instead of RDAs, and Average Requirements instead of EARs. For women the PRI is 13 mg/day ages 15–17 years, 16 mg/day for women ages 18 and up who are premenopausal and 11 mg/day postmenopausal. For pregnancy and lactation, 16 mg/day. For men the PRI is 11 mg/day ages 15 and older. For children ages 1 to 14 the PRI increases from 7 to 11 mg/day. The PRIs are higher than the US RDAs, with the exception of pregnancy.
Sodium iodide
Sodium iodide, as well as potassium iodide, is commonly used to treat and prevent iodine deficiency. Iodized table salt contains 10 ppm iodide.
Copper
The U.S. Institute of Medicine (IOM) updated the estimated average requirements (EARs) and recommended dietary allowances (RDAs) for copper in 2001. If there is not sufficient information to establish EARs and RDAs, an estimate designated [[Adequate Intake]] (AI) is used instead. The AIs for copper are: 200 μg of copper for 0–6-month-old males and females, and 220 μg of copper for 7–12-month-old males and females. The RDAs for copper are: 340 μg of copper for 1–3-year-old males, 440 μg of copper for 4–8-year-old males, 700 μg of copper for 9–13-year-old males, 890 μg of copper for 14–18-year-old males, and 900 μg of copper for males that are 19 years old and older. The RDAs for copper are: 340 μg of copper for 1–3-year-old females, 440 μg of copper for 4–8-year-old females, 700 μg of copper for 9–13-year-old females, 890 μg of copper for 14–18-year-old females, and 900 μg of copper for females that are 19 years old and older. The RDAs for copper are: 1,000 μg of copper for 14–50-year-old pregnant females; furthermore, 1,300 μg of copper for 14–50-year-old lactating females. As for safety, the IOM also sets [[Tolerable upper intake level]]s (ULs) for vitamins and minerals when evidence is sufficient. In the case of copper the UL is set at 10 mg/day. Collectively the EARs, RDAs, AIs and ULs are referred to as [[Dietary Reference Intake]]s.
Iodine
Iodine occurs in many oxidation states, including iodide (I), iodate (), and the various periodate anions. It is the least abundant of the stable halogens, being the sixty-first most abundant element. It is the heaviest essential mineral nutrient. Iodine is essential in the synthesis of thyroid hormones. Iodine deficiency affects about two billion people and is the leading preventable cause of intellectual disabilities.
Perchlorate
A study involving healthy adult volunteers determined that at levels above 0.007 milligrams per kilogram per day (mg/(kg·d)), perchlorate can temporarily inhibit the thyroid gland's ability to absorb iodine from the bloodstream ("iodide uptake inhibition", thus perchlorate is a known goitrogen). The EPA converted this dose into a reference dose of 0.0007 mg/(kg·d) by dividing this level by the standard intraspecies uncertainty factor of 10. The agency then calculated a "drinking water equivalent level" of 24.5 ppb by assuming a person weighs and consumes of drinking water per day over a lifetime.
Iodised salt
The United States Food and Drug Administration recommends 150 micrograms (0.15 mg) of iodine per day for both men and women.
Potassium iodide
Not all sources are in agreement on the necessary "duration" of thyroid blockade, although agreement appears to have been reached about the "necessity" of blockade for both scintigraphic and therapeutic applications of iobenguane. Commercially available iobenguane is labeled with iodine-123, and product labeling recommends administration of potassium iodide 1 hour prior to administration of the radiopharmaceutical for all age groups, while the European Association of Nuclear Medicine recommends (for iobenguane labeled with either isotope), that potassium iodide administration begin one day prior to radiopharmaceutical administration, and continue until the day following the injection, with the exception of new-borns, who do not require potassium iodide doses following radiopharmaceutical injection.
Period 5 element
Iodine is the heaviest essential element utilized widely by life in biological functions (only tungsten, employed in enzymes by a few species of bacteria, is heavier). Iodine's rarity in many soils, due to initial low abundance as a crust-element, and also leaching of soluble iodide by rainwater, has led to many deficiency problems in land animals and inland human populations. Iodine deficiency affects about two billion people and is the leading preventable cause of intellectual disabilities. Iodine is required by higher animals, which use it to synthesize thyroid hormones, which contain the element. Because of this function, radioisotopes of iodine are concentrated in the thyroid gland along with nonradioactive iodine. The radioisotope iodine-131, which has a high fission product yield, concentrates in the thyroid, and is one of the most carcinogenic of nuclear fission products.
Iodine deficiency
The recommended daily intake of iodine for adult women is 150–300 µg for maintenance of normal thyroid function; for men it is somewhat less at 150 µg.
Tincture of iodine
Iodine tincture is not a recommended source of solely-nutritional iodine. Nutritional iodine is better supplied in the form of the less toxic iodide (see SSKI) or iodate salts, which the body can easily convert to thyroid hormone.
Iodine
Iodine accounts for 65% of the molecular weight of T and 59% of T. Fifteen to 20 mg of iodine is concentrated in thyroid tissue and hormones, but 70% of all iodine in the body is found in other tissues, including mammary glands, eyes, gastric mucosa, fetal thymus, cerebro-spinal fluid and choroid plexus, arterial walls, the cervix, and salivary glands. In the cells of those tissues, iodide enters directly by sodium-iodide symporter (NIS). The action of iodine in mammary tissue is related to fetal and neonatal development, but in the other tissues, it is (at least) partially unknown.
Ethylenediamine dihydroiodide
EDDI is used as an additive in pet food and cattle feed with high bioavailability. Used to prevent iodine deficiency, this salt is one of the major uses of the element iodine. The United States Food and Drug Administration suggests a limit of intake to 50 mg/head/day. Although EDDI is generally recognized as safe (GRAS) only as a nutrient source of iodine, administration of EDDI also has preventative effects on foot rot in cattle.
Vanadium
Deficiencies in vanadium result in reduced growth in rats. The U.S. Institute of Medicine has not confirmed that vanadium is an essential nutrient for humans, so neither a Recommended Dietary Intake nor an Adequate Intake have been established. Dietary intake is estimated at 6 to 18 µg/day, with less than 5% absorbed. The Tolerable Upper Intake Level (UL) of dietary vanadium, beyond which adverse effects may occur, is set at 1.8 mg/day.
Iodine in biology
Excessive iodine intake presents symptoms similar to those of iodine deficiency. Commonly encountered symptoms are abnormal growth of the thyroid gland and disorders in functioning, as well as in growth of the organism as a whole. Iodide toxicity is similar to (but not the same as) toxicity to ions of the other halogens, such as bromides or fluorides. Excess bromine and fluorine can prevent successful iodine uptake, storage and use in organisms, as both elements can selectively replace iodine biochemically.
Selenium in biology
The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for selenium in 2000. If there is not sufficient information to establish EARs and RDAs, an estimate designated Adequate Intake (AI) is used instead. The current EAR for selenium for people ages 14 and up is 45 μg/day. The RDA is 55 μg/day. RDAs are higher than EARs so as to identify amounts that will cover people with higher than average requirements. RDA for pregnancy is 60 μg/day. RDA for lactation is 70 μg/day. For children ages 1–13 years the RDA increases with age from 20 to 40 μg/day. As for safety, the IOM sets Tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of selenium the UL is 400 μg/day. Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes (DRIs).
Iodine in biology
Iodine is an essential trace element in biological systems. It has the distinction of being the heaviest element commonly needed by living organisms as well as the second-heaviest known to be used by any form of life (only tungsten, a component of a few bacterial enzymes, has a higher atomic number and atomic weight). It is a component of biochemical pathways in organisms from all biological kingdoms, suggesting its fundamental significance throughout the evolutionary history of life.
Nickel
Dietary nickel may affect human health through infections by nickel-dependent bacteria, but it is also possible that nickel is an essential nutrient for bacteria residing in the large intestine, in effect functioning as a prebiotic. The U.S. Institute of Medicine has not confirmed that nickel is an essential nutrient for humans, so neither a Recommended Dietary Allowance (RDA) nor an Adequate Intake have been established. The Tolerable Upper Intake Level of dietary nickel is 1000 µg/day as soluble nickel salts. Dietary intake is estimated at 70 to 100 µg/day, with less than 10% absorbed. What is absorbed is excreted in urine. Relatively large amounts of nickel – comparable to the estimated average ingestion above – leach into food cooked in stainless steel. For example, the amount of nickel leached after 10 cooking cycles into one serving of tomato sauce averages 88 µg.
Radioactivity in the life sciences
Iodine-125 is commonly used for labeling proteins, usually at tyrosine residues. Unbound iodine is volatile and must be handled in a fume hood. Its maximum specific activity is 2,176 Ci/mmol (80.51 PBq/mol).
Lugol's iodine
The World Health Organization classifies substances taken orally with an LD50 of 5–50 mg/kg as the second highest toxicity class, Class Ib (Highly Hazardous). The Global Harmonized System of Classification and Labeling of Chemicals categorizes this as Category 2 with a hazard statement “Fatal if swallowed”. Potassium Iodide is not considered hazardous.
Congenital iodine deficiency syndrome
Around the world, the most common cause of congenital hypothyroidism is iodine deficiency. It has affected many people worldwide and continues to be a major public health problem in many countries. Iodine is an essential trace element, necessary primarily for the synthesis of thyroid hormones. Iodine deficiency is the most common preventable cause of brain damage worldwide. Although iodine is found in many foods, it is not universally present in all soils in adequate amounts. Most iodine, in iodide form, is in the oceans, where the iodide ions oxidize to elemental iodine, which then enters the atmosphere and falls to earth as rain, introducing iodine to soils. Earth deficient in iodine is most common inland and in mountainous areas and areas of frequent flooding, but can also occur in coastal regions owing to past glaciation, and leaching by snow, water and heavy rainfall, which removes iodine from the soil. Plants and animals grown in iodine deficient soils are correspondingly deficient. Populations living in those areas without outside food sources are most at risk of iodine deficiency diseases.
Iodine in biology
The human body contains about 15–20 mg of iodine, mostly concentrated in thyroid tissue (70–80%). Extra-thyroidal iodine exists in several other organs, including the mammary glands, eyes, gastric mucosa, cervix, ovary and salivary glands. In the cells of these tissues the iodide ion (I) enters directly by the sodium-iodide symporter (NIS). Different tissue responses for iodine and iodide occur in the mammary glands and the thyroid gland of rats. The role of iodine in mammary tissue is related to fetal and neonatal development, but its role in the other tissues is unknown. It has been shown to act as an antioxidant and antiproliferant in various tissues that can uptake iodine. Molecular iodine (I) has been shown to have a suppressive effect on benign and cancerous neoplasias.
Chromium deficiency
The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for chromium in 2001. For chromium there was not sufficient information to set EARs and RDAs, so needs are described as estimates for Adequate Intakes (AIs). The current AIs for chromium for women ages 14 and up is 25 μg/day up to age 50 and 20 μg/day for older. AI for pregnancy is 30 μg/day. AI for lactation is 45 μg/day. For men ages 14 and up 35 μg/day up to age 50 and 30 μg/day for older. For infants to children ages 1–13 years the AI increases with age from 0.2 to 25 μg/day. As for safety, the IOM sets Tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of chromium there is not yet enough information and hence no UL. Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes (DRIs).
Vitamin E
The U.S. Institute of Medicine (renamed National Academy of Medicine in 2015) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for vitamin E in 2000. The EAR for vitamin E for women and men ages 14 and up is 12 mg/day. The RDA is 15 mg/day. RDAs are higher than EARs so as to identify amounts that will cover people with higher than average requirements. For infants up to 12 months the Adequate Intake (AI) is 4–5 mg/day. As for safety, Tolerable upper intake levels (ULs) are set for vitamins and minerals when evidence is sufficient. Hemorrhagic effects in rats were selected as the critical endpoint to calculate the UL via starting with the lowest-observed-adverse-effect-level (LOAEL) and processing that through an uncertainty factor calculation. The end result was a UL set at 1000 mg/day. Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes (DRIs).
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.
Methyl iodide
It is considered a potential occupational carcinogen by the U.S. National Institute for Occupational Safety and Health (NIOSH), the U.S. Occupational Safety and Health Administration and the U.S. Centers for Disease Control and Prevention. The International Agency for Research on Cancer concluded based on studies performed after methyl iodide was Proposition 65 listed that: “Methyl iodide is not classifiable as to its carcinogenicity to humans (Group 3).” the Environmental Protection Agency classifies it as "not likely to be carcinogenic to humans in the absence of altered thyroid hormone homeostatis," i.e. it is a human carcinogen but only at doses large enough to disrupt thyroid function (via excess iodide). However this finding is disputed by the Pesticide Action Network which states that the EPA’s cancer rating "appears to be based solely on a single rat inhalation study in which 66% of the control group and 54-62% of the rats in the other groups died before the end of
the study". They go on to state: "The EPA appears to be dismissing early peer-reviewed studies in favor of two nonpeer-reviewed studies conducted by the registrant that are flawed in design and execution." Despite requests by the U.S. EPA to the Pesticide Action Network to bring forth scientific evidence of their claims, they have not done so.
Puppy nutrition
To date, there is little information available about minimum requirements of dietary iodine for developing puppies. However, literature suggests that overdosage of iodine in puppies has deleterious effects on the thyroid gland. High dietary iodine may cause both hypothyroidism and changes in bone metabolism, considering that thyroid hormones are key factors in osteogenesis, as they stimulate osteoblasts, and promote collagen synthesis and mineralization of the osteoid. This is particularly important during juvenile development, as these hormones favor the action of growth hormone (GH) and its facilitator, insulin growth factor-1 (IGF-1) at the osteoplastic level. Hypothyroidism acquired at an early age presents a delay in the maturation and development of the ossification sites of newly-developing bone. It is therefore important to closely monitor the amount of iodine in puppy diets in order to prevent overdosage. The NRC states an adequate intake and recommended allowance of 900 μg/kg (DM) which translates into 220μg/1000 kcal. These values have been shown in multiple studies to be the recommended maximum allowance of iodine that would result in no abnormalities.
Xylidine
The U.S. Occupational Safety and Health Administration (OSHA) has set the legal limit (Permissible exposure limit) for xylidine exposure in the workplace as 5 ppm (25 mg/m) skin exposure over an eight-hour workday. The U.S. National Institute for Occupational Safety and Health (NIOSH) has set a Recommended exposure limit (REL) of 2 ppm (10 mg/m) skin exposure over an eight-hour workday. At levels of 50 ppm, xylidine is immediately dangerous to life and health.
Protein adulteration in China
In 2009, the World Health Organization (WHO) published a report on a December 2008 expert meeting held in conjunction with the FAO concluding, "inter alia", that "a tolerable daily intake (TDI) of 0.2 mg/kg body weight for melamine was established. The TDI is applicable to the whole population, including infants." However, the experts also noted: "This TDI is applicable to exposure to melamine alone. … Available data indicate that simultaneous exposure to melamine and cyanuric acid is more toxic than exposures to each compound individually. Data are not adequate to allow the calculation of a health-based guidance value for this co-exposure."
Kombu
"Kombu" contains extremely high levels of iodine. While this mineral is essential for normal growth and development, the levels in kombu can cause overdoses; it has been blamed for thyroid problems after drinking large amounts of soy milk in which "kombu" was an additive.
Potassium iodide
Potassium iodide is a chemical compound, medication, and dietary supplement. As a medication it is used to treat hyperthyroidism, in radiation emergencies, and to protect the thyroid gland when certain types of radiopharmaceuticals are used. In the developing world it is also used to treat skin sporotrichosis and phycomycosis. As a supplement it is used in those who have low intake of iodine in the diet. It is given by mouth.
Common side effects include vomiting, diarrhea, abdominal pain, rash, and swelling of the salivary glands. Other side effects include allergic reactions, headache, goitre, and depression. While use during pregnancy may harm the baby, its use is still recommended in radiation emergencies. Potassium iodide has the chemical formula KI. Commercially it is made by mixing potassium hydroxide with iodine.
Potassium iodide has been used medically since at least 1820. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. Potassium iodide is available as a generic medication and over the counter. In the United States a course of treatment is less than 25 USD. Potassium iodide is also used for the iodization of salt.
Iodine-131
Iodine in food is absorbed by the body and preferentially concentrated in the thyroid where it is needed for the functioning of that gland. When I is present in high levels in the environment from radioactive fallout, it can be absorbed through contaminated food, and will also accumulate in the thyroid. As it decays, it may cause damage to the thyroid. The primary risk from exposure to of I is an increased risk of radiation-induced cancer in later life. Other risks include the possibility of non-cancerous growths and thyroiditis.
Iodine in biology
Iodine is critical to the proper functioning of the vertebrate endocrine system, and plays smaller roles in numerous other organs, including those of the digestive and reproductive systems. An adequate intake of iodine-containing compounds is important at all stages of development, especially during the fetal and neonatal periods, and diets deficient in iodine can present serious consequences for growth and metabolism.
Methadone maintenance
Methadone maintenance has been used to treat opioid dependence for more than 45 years (invented in 1937). Therapeutic dosing is contingent upon individual patient needs, and the therapeutic dosage range is generally between 25 and 150 mg. Such a dose would not be tolerated by an opioid-naive individual. The amount of oral Methadone that an addicted individual will require is dependent on the amount of illicit substance that they have previously been used to, but as a general rule 1 gram of street Heroin is roughly equivalent to 50 to 80 mg of methadone. Methadone is taken either orally as DTF (Drug Tariff Formula) methadone mixture 1 mg/1ml which is supplied as a red or clear liquid, but can now also be prescribed as a mixture containing 10 mg of methadone in 1ml of liquid (green color) or methadone 20 mg in 1ml (brown color). This is often used when a person is on a large amount of methadone and is rarely permitted for consumption unsupervised, because these formulations are not as viscous as the 1 mg/1ml mixture, they are more prone to mis-use as they are easier to inject, and also due to the high risk of diverted medication causing an overdose in an individual that is not used to such a large dose. An individual who is prescribed 200 mg would only have to ingest 20ml of 10 mg/1ml mixture, thus making it easier to take. Methadone Maintenance can also be delivered by either IV or IM injection, and ampoules come in various strengths from 10 mg up to 50 mg, this method is often used for individuals who have a "needle fixation" and who would otherwise revert to using iv heroin. Methadone is widely distributed to body tissues where it is stored and then released into the plasma. This combination of storage and release keeps the patient comfortable, free from craving, and feeling stable.
Zinc
The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for zinc in 2001. The current EARs for zinc for women and men ages 14 and up is 6.8 and 9.4 mg/day, respectively. The RDAs are 8 and 11 mg/day. RDAs are higher than EARs so as to identify amounts that will cover people with higher than average requirements. RDA for pregnancy is 11 mg/day. RDA for lactation is 12 mg/day. For infants up to 12 months the RDA is 3 mg/day. For children ages 1–13 years the RDA increases with age from 3 to 8 mg/day. As for safety, the IOM sets Tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of zinc the adult UL is 40 mg/day (lower for children). Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes (DRIs).
Potassium iodide
Product labeling for diagnostic iodine-131 iobenguane recommends potassium iodide administration one day before injection and continuing 5 to 7 days following administration, in keeping with the much longer half-life of this isotope and its greater danger to the thyroid. Iodine-131 iobenguane used for therapeutic purposes requires a different pre-medication duration, beginning 24–48 hours prior to iobenguane injection and continuing 10–15 days following injection.
Iodine
Iodine-131 (usually as iodide) is a component of nuclear fallout, and is particularly dangerous owing to the thyroid gland's propensity to concentrate ingested iodine and retain it for periods longer than this isotope's radiological half-life of eight days. For this reason, people at risk of exposure to environmental radioactive iodine (iodine-131) in fallout may be instructed to take non-radioactive potassium iodide tablets. The typical adult dose is one 130 mg tablet per 24 hours, supplying 100 mg (100,000 micrograms) of ionic iodine. (The typical daily dose of iodine for normal health is of order 100 micrograms; see "Dietary Intake" below.) Ingestion of this large dose of non-radioactive iodine minimises the uptake of radioactive iodine by the thyroid gland.
As an element with high electron density and atomic number, iodine absorbs X-rays weaker than 33.3 keV due to the photoelectric effect of the innermost electrons. Organoiodine compounds are used with intravenous injection as X-ray radiocontrast agents. This application is often in conjunction with advanced X-ray techniques such as angiography and CT scanning. At present, all water-soluble radiocontrast agents rely on iodine.
Iodine deficiency
With iodine supplementation, goiters caused by iodine deficiency decrease in size in very young children and pregnant women. Generally, however, long-standing goiters caused by iodine deficiency respond with only small amounts of shrinkage after iodine supplementation, and patients are at risk for developing hyperthyroidism. Following the adoption of iodised salt in the United States in 1924, there was a gradual increase in average intelligence of 1 standard deviation, 15 points in iodine-deficient areas, 3.5 points nationally, but also an increase in deaths of older people in iodine-deficient areas due to hyperthyroidism.
Iodised salt
Iodised salt (also spelled iodized salt) is table salt mixed with a minute amount of various salts of the element iodine. The ingestion of iodine prevents iodine deficiency. Worldwide, iodine deficiency affects about two billion people and is the leading preventable cause of intellectual and developmental disabilities. Deficiency also causes thyroid gland problems, including "endemic goitre". In many countries, iodine deficiency is a major public health problem that can be cheaply addressed by purposely adding small amounts of iodine to the sodium chloride salt.
Chromium
The National Academy of Medicine (NAM) updated the Estimated Average Requirements (EARs) and the Recommended Dietary Allowances (RDAs) for chromium in 2001. For chromium, there was not sufficient information to set EARs and RDAs, so its needs are described as estimates for Adequate Intakes (AIs). The current AIs of chromium for women ages 14 through 50 is 25 μg/day, and the AIs for women ages 50 and above is 20 μg/day. The AIs for women who are pregnant are 30 μg/day, and for women who are lactating, the set AIs are 45 μg/day. The AIs for men ages 14 through 50 are 35 μg/day, and the AIs for men ages 50 and above are 30 μg/day. For children ages 1 through 13, the AIs increase with age from 0.2 μg/day up to 25 μg/day. As for safety, the NAM sets Tolerable Upper Intake Levels (ULs) for vitamins and minerals when the evidence is sufficient. In the case of chromium, there is not yet enough information and hence no UL has been established. Collectively, the EARs, RDAs, AIs and ULs are the parameters for the nutrition recommendation system known as Dietary Reference Intake (DRI). Australia and New Zealand consider chromium to be an essential nutrient, with an AI of 35 μg/day for men, 25 μg/day for women, 30 μg/day for women who are pregnant, and 45 μg/day for women who are lactating. A UL has not been set due to the lack of sufficient data. India considers chromium to be an essential nutrient, with an adult recommended intake of 33 μg/day. Japan also considers chromium to be an essential nutrient, with an AI of 10 μg/day for adults, including women who are pregnant or lactating. A UL has not been set. The EFSA of the European Union however, does not consider chromium to be an essential nutrient; chromium is the only mineral for which the United States and the European Union disagree.
Iodophor
The optimum concentration is >200 mg/l free iodine with a contact time of 2 minutes and 100 mg/l free iodine for cleaned and dried equipment. In a nonfood-contact application the concentration may rise to 500 – 800 mg/l.
Portable water purification
Iodine used for water purification is commonly added to water as a solution, in crystallized form, or in tablets containing tetraglycine hydroperiodide that release 8 mg of iodine per tablet adaptation to chronic tetraglycine hydroperiodide. The iodine kills many, but not all, of the most common pathogens present in natural fresh water sources. Carrying iodine for water purification is an imperfect but lightweight solution for those in need of field purification of drinking water. Kits are available in camping stores that include an iodine pill and a second pill (vitamin C or ascorbic acid) that will remove the iodine taste from the water after it has been disinfected. The addition of vitamin C, in the form of a pill or in flavored drink powders, precipitates much of the iodine out of the solution, so it should not be added until the iodine has had sufficient time to work. This time is 30 minutes in relatively clear, warm water, but is considerably longer if the water is turbid or cold. Iodine treated drinking water, treated with tablets containing tetraglycine hydroperiodide, also reduces the uptake of radioactive iodine in human subjects to only 2% of the value it would otherwise be. This could be an important factor worthy of consideration for treating water in a recent post nuclear event survival situation, where radioactive iodine ingestion is a concern for internal radiotoxicity. If the iodine has precipitated out of the solution, then the drinking water has less available iodine in the solution. Also the amount of iodine in one tablet is not sufficient to block uptake. Tetraglycine hydroperiodide maintains its effectiveness indefinitely before the container is opened; although some manufacturers suggest not using the tablets more than three months after the container has initially been opened, the shelf life is in fact very long provided that the container is resealed immediately after each time it is opened.