Iodine-131 is a significant radioisotope of iodine and it is also known as radioiodine. Its half-life for radioactive decay is approximately eight days. It is connected to the production of natural gas, medical diagnosis and treatment, and nuclear energy. It is one of the most feared fission products when unintentionally released into the environment and is frequently utilized in small dosages in thyroid and cancer treatments. This article will explain to you about Iodine - 131 which will be helpful in preparing the Environment Syllabus for the UPSC Civil Service exam.

Iodine-131 - Production

• Nuclear fission is used commercially to create I-131 for use in industry and medicine.
• In nuclear reactors and during the testing of new weapons, it is also a byproduct of nuclear fission operations.
• Nuclear accidents and nuclear weapon tests can both emit I-131.
• Contrary to iodine-129, whose half-life is about a billion times longer than that of I-131, I-131 has a short half-life and is therefore not found in substantial quantities in cooled spent nuclear material.

Iodine-131 - Appearance

• I-131 is a non-metallic, crystalline solid that is purplish-black in colour.
• I-131 is typically discovered as a compound rather than in its pure form since it quickly binds with other elements.
• The I-131 capsules are supposed to be taken by patients and contain tiny sodium iodide I-131 granules for medical use.
• Clear liquid I-131 sodium iodide is used to identify and treat thyroid conditions.

Iodine-131 - Ways of Input in the Human Body

• In general, the human body needs some prescribed dosage of iodine for the effective functioning of the thyroid.
• As a result, the body absorbs iodine from food and preferentially concentrates it in the thyroid.
• High quantities of I-131 from radioactive fallout in the environment will also be absorbed through contaminated food and will also build up in the thyroid.
• This is because the thyroid gland is generally unable to distinguish the difference between stable (nonradioactive) iodine and radioactive iodine.

Iodine-131 - Effects of Exposure

• External exposure to high levels of I-131 can result in burns to the eyes and skin.
• The thyroid gland may become damaged when radioactive iodine gets deposited beyond the prescribed limit.
• The main danger associated with I-131 exposure is a higher chance of developing radiation-induced cancer in later life.
• The potential for thyroiditis and non-cancerous growths are additional hazards.
• As one gets older at the time of exposure, the likelihood of developing thyroid cancer in later life seems to decline.
• The majority of risk assessments are based on research where children or teenagers were exposed to radiation.
• Additionally, radioactive iodine will get into milk if dairy animals eat grass that has been polluted with I-131.
• As a result, drinking milk or consuming dairy products manufactured from tainted milk can expose people internally.

Iodine-131 - Preventive Measures Against Exposure

• Saturation of Thyroid Gland: Saturating the thyroid with regular, stable iodine-127, as an iodide or iodate salt, is a typical treatment strategy for preventing iodine-131 exposure.
• After being saturated with non-radioactive iodide, the thyroid will absorb relatively little of the radioactive iodine-131, protecting it from radiation harm.
• Iodine Tablet: It has also been established that the usage of a certain "iodine tablet" used in portable water purification can somewhat reduce radioiodine intake.
• In research it was found that the biological uptake of radioactive iodine decreased to and stayed at a value of less than 2% of the radioiodine uptake rate seen in control subjects who were fully exposed to radioiodine without therapy.
• Goitrogen: Studies on healthy adult volunteers showed that perchlorate temporarily impairs the thyroid gland's capacity to absorb iodine from the plasma at concentrations above 0.007 milligrams per kilogram per day ("iodide uptake inhibition", thus perchlorate is a known goitrogen).

Radioactive Iodine (I -131) Therapy

• Radioactive Iodine I-131 therapy is a nuclear medicine treatment.
• It is used by doctors to treat hyperthyroidism, a disorder marked by an overactive thyroid.
• Graves' disease, in which the entire thyroid gland is overactive, or thyroid nodules inside the gland, which are locally overactive in releasing too much thyroid hormone, can both result in hyperthyroidism.
• Small quantities of radioactive material known as radiotracers are used in nuclear medicine.
• Nuclear medicine is a tool used by doctors to identify, assess, and treat a variety of disorders.
• These include diseases like cancer, heart disease, digestive, endocrine, or neurological problems, among others.
• Examinations using nuclear medicine identify molecular activity.
• They may be able to detect disease in its earliest stages as a result. They can also demonstrate the level of therapy response.

What is Goitre?

• Iodine deficiency frequently leads to the development of a goitre.
• An enlarged thyroid is indicated by the word "goitre." It alludes to the thyroid gland's irregular growth.
• It could result in either an overactive (hyperthyroidism) or underactive thyroid gland (hypothyroidism).
• Not every goitre is symptomatic. When symptoms do appear, they may include coughing and edoema.

Conclusion

The I-131 isotope is utilized to radioactively label several radiopharmaceuticals that are employed in the diagnosis and treatment of pheochromocytoma and neuroblastoma. Stable iodine-127 is the only isotope of iodine that exists naturally.

FAQs

MCQs

1. What is the primary source of Iodine-131 in the environment?

A) Medical treatments
B) Nuclear reactors
C) Cosmic radiation
D) Solar activity

2. What health risks are associated with Iodine-131 exposure?

A) Liver cancer
B) Lung disease
C) Thyroid disorders
D) Skin burns

3. How does Iodine-131 affect the environment?

A) It has no impact on the environment
B) It contaminates water and soil
C) It increases plant growth
D) It causes global warming

4. What is a major use of Iodine-131 in medicine?

A) Cancer treatment
B) Diagnostic imaging
C) Blood transfusions
D) Antibiotic treatment

5. What safety precautions should be taken when handling Iodine-131?

A) No special precautions are needed
B) Wear protective clothing and use shielding
C) Only trained professionals can handle it
D) Store in a normal lab environment

GS Mains Questions and Model Answers

Q1: Discuss the potential environmental impacts of Iodine-131 and the measures that can be taken to mitigate its risks.

Answer: Iodine-131, being a radioactive isotope, poses significant risks to the environment, including contamination of soil, water, and the food chain. Its release, particularly during nuclear accidents or improper disposal, can lead to long-term ecological damage. To mitigate these risks, stringent safety protocols in nuclear reactors, proper disposal techniques for radioactive waste, and regular environmental monitoring are crucial. Furthermore, the development and use of less harmful alternatives to Iodine-131 in medical and industrial applications can reduce its environmental impact. Research into safer disposal and containment technologies is also important to prevent widespread contamination.

Q2: Analyze the health effects of exposure to Iodine-131, and discuss the measures taken in medical practice to limit these risks.

Answer: Iodine-131 exposure can lead to thyroid dysfunction, including both hypothyroidism and hyperthyroidism, and in some cases, thyroid cancer. The health risks are particularly pronounced when the isotope is inhaled, ingested, or comes into prolonged contact with the body. In medical practice, Iodine-131 is used in controlled doses for treating thyroid disorders, ensuring patient safety through careful dosage management and monitoring. For occupational exposure, guidelines are set to limit radiation exposure, such as using shielding and protective gear. Patients receiving Iodine-131 treatment are also isolated to prevent radiation exposure to others, particularly children and pregnant women.

Q3: What role does Iodine-131 play in nuclear energy production, and what are the risks associated with its use in reactors?

Answer: Iodine-131 is a byproduct of uranium fission in nuclear reactors. While its primary use is in medical treatments, its presence in nuclear reactor waste poses environmental and health risks. During a nuclear accident, the release of Iodine-131 into the atmosphere can lead to radioactive contamination. The primary risk is thyroid cancer, as the isotope can accumulate in the thyroid gland. To mitigate these risks, strict safety regulations are enforced in nuclear power plants to contain radioactive releases, including the use of containment vessels and filtration systems to trap radioactive particles. Additionally, iodine tablets are often distributed in the event of a nuclear emergency to prevent iodine-131 from accumulating in the thyroid gland.

Previous Year Questions on Iodine-131 Toxicology

1. UPSC CSE Mains 2018 (GS Paper 2):

Question: "Examine the impact of nuclear accidents on human health and the environment, with special reference to isotopes like Iodine-131."

Answer: Nuclear accidents, such as those at Chernobyl and Fukushima, release radioactive isotopes, including Iodine-131, into the environment. These isotopes can contaminate the air, water, and food supply, posing serious health risks. Iodine-131 is particularly dangerous as it accumulates in the thyroid gland, increasing the risk of cancer. Mitigation measures include immediate evacuation, distribution of iodine tablets to block thyroid absorption, and environmental decontamination.

2. UPSC CSE Mains 2020 (GS Paper 3):

Question: "Discuss the risks and benefits of using Iodine-131 in medical treatments and its management in radiation therapy."

Answer: Iodine-131 is used effectively in the treatment of thyroid cancer and hyperthyroidism by targeting and destroying cancerous thyroid tissue. However, its radioactive nature poses health risks, including thyroid damage and radiation exposure to surrounding tissues. These risks are managed through controlled doses, careful monitoring of patients, and the use of shielding to protect healthcare providers and the public. Despite these risks, the benefits of targeted treatment outweigh the potential dangers when administered correctly.