Pebble-bed reactor

From Wikipedia, the free encyclopedia

The pebble-bed reactor (PBR) is a design for a graphite-moderated, gas-cooled nuclear reactor. It is a type of very-high-temperature reactor (VHTR), one of the six classes of nuclear reactors in the Generation IV initiative.

Sketch of a pebble-bed reactor.

 

Graphite pebble for reactor

The basic design of pebble-bed reactors features spherical fuel elements called pebbles. These tennis ball-sized pebbles (approx. 6.7 cm or 2.6 in in diameter) are made of pyrolytic graphite (which acts as the moderator), and they contain thousands of micro-fuel particles called tristructural-isotropic (TRISO) particles. These TRISO fuel particles consist of a fissile material (such as ²³⁵U) surrounded by a ceramic layer coating of silicon carbide for structural integrity and fission product containment. In the PBR, thousands of pebbles are amassed to create a reactor core, and are cooled by a gas, such as helium, nitrogen or carbon dioxide, that does not react chemically with the fuel elements. Other coolants such as FLiBe (molten fluoride, lithium, beryllium salt)) have also been suggested for implementation with pebble fuelled reactors. Some examples of this type of reactor are claimed to be passively safe.

Because the reactor is designed to handle high temperatures, it can cool by natural circulation and still survive in accident scenarios, which may raise the temperature of the reactor to 1,600 °C (2,910 °F). Because of its design, its high temperatures allow higher thermal efficiencies than possible in traditional nuclear power plants (up to 50%) and has the additional feature that the gases do not dissolve contaminants or absorb neutrons as water does, so the core has less in the way of radioactive fluids.

The concept was first suggested by Farrington Daniels in the 1940s, said to have been inspired by the innovative design of the Benghazi burner by British desert troops in WWII, but commercial development did not take place until the 1960s in the German AVR reactor by Rudolf Schulten. This system was plagued with problems and political and economic decisions were made to abandon the technology. The AVR design was licensed to South Africa as the PBMR and China as the HTR-10, the latter currently has the only such design in operation. In various forms, other designs are under development by MIT, University of California at Berkeley, General Atomics (U.S.), the Dutch company Romawa B.V., Adams Atomic Engines, Idaho National Laboratory, X-energy and Kairos Power.

Pebble-bed design

A pebble-bed power plant combines a gas-cooled core and a novel packaging of the fuel that dramatically reduces complexity while improving safety.

The uranium, thorium or plutonium nuclear fuels are in the form of a ceramic (usually oxides or carbides) contained within spherical pebbles a little smaller than the size of a tennis ball and made of pyrolytic graphite, which acts as the primary neutron moderator. The pebble design is relatively simple, with each sphere consisting of the nuclear fuel, fission product barrier, and moderator (which in a traditional water reactor would all be different parts). Simply piling enough pebbles together in a critical geometry will allow for criticality.

The pebbles are held in a vessel, and an inert gas (such as helium, nitrogen or carbon dioxide) circulates through the spaces between the fuel pebbles to carry heat away from the reactor. Pebble-bed reactors need fire-prevention features to keep the graphite of the pebbles from burning in the presence of air if the reactor wall is breached, although the flammability of the pebbles is disputed. Ideally, the heated gas is run directly through a turbine. However, if the gas from the primary coolant can be made radioactive by the neutrons in the reactor, or a fuel defect could still contaminate the power production equipment, it may be brought instead to a heat exchanger where it heats another gas or produces steam. The exhaust of the turbine is quite warm and may be used to warm buildings or chemical plants, or even run another heat engine.

Much of the cost of a conventional, water-cooled nuclear power plant is due to cooling system complexity. These systems are part of the safety of the overall design, and thus require extensive safety systems and redundant backups. A water-cooled reactor is generally dwarfed by the cooling systems attached to it. Additional issues are that the core irradiates the water with neutrons causing the water and impurities dissolved in it to become radioactive and that the high-pressure piping in the primary side becomes embrittled and requires continual inspection and eventual replacement.

In contrast, a pebble-bed reactor is gas-cooled, sometimes at low pressures. The spaces between the pebbles act as the "piping" in the core. Since there is no actual piping in the core and the coolant contains no hydrogen, embrittlement is not a failure concern. The preferred gas, helium, does not easily absorb neutrons or impurities. Therefore, compared to water, it is both more efficient and less likely to become radioactive.

Safety features

Pebble-bed reactors have an advantage over conventional light-water reactors in operating at higher temperatures. A technical advantage is that some designs are throttled by temperature, not by control rods. The reactor can be simpler because it does not need to operate well at the varying neutron profiles caused by partially withdrawn control rods.

Pebble-bed reactors are also capable of using fuel pebbles made from different fuels in the same basic design of reactor (though perhaps not at the same time). Proponents claim that some kinds of pebble-bed reactors should be able to use thorium, plutonium and natural unenriched uranium, as well as the customary enriched uranium. There is a project in progress to develop pebbles and reactors that use MOX fuel, that mixes uranium with plutonium from either reprocessed fuel rods or decommissioned nuclear weapons.

In most stationary pebble-bed reactor designs, fuel replacement is continuous. Instead of shutting down for weeks to replace fuel rods, pebbles are placed in a bin-shaped reactor. A pebble is recycled from the bottom to the top about ten times over a few years, and tested each time it is removed. When it is expended, it is removed to the nuclear-waste area, and a new pebble inserted.

When the nuclear fuel increases in temperature, the rapid motion of the atoms in the fuel causes an effect known as Doppler broadening. The fuel then sees a wider range of relative neutron speeds. Uranium-238, which forms the bulk of the uranium in the reactor, is much more likely to absorb fast or epithermal neutrons at higher temperatures. This reduces the number of neutrons available to cause fission, and reduces the power of the reactor. Doppler broadening therefore creates a negative feedback: as fuel temperature increases, reactor power decreases. All reactors have reactivity feedback mechanisms, but the pebble-bed reactor is designed so that this effect is very strong. Also, it is inherent to the design, and does not depend on any kind of machinery or moving parts. If the rate of fission increases, temperature will increase and Doppler broadening will occur, decreasing the rate of fission. This negative feedback creates passive control of the reaction process.

Because of this, and because the pebble-bed reactor is designed for higher temperatures, the reactor will passively reduce to a safe power-level in an accident scenario. This is the main passive safety feature of the pebble-bed reactor, and it distinguishes the pebble-bed design (as well as most other very-high-temperature reactors) from conventional light-water reactors, which require active safety controls.

The reactor is cooled by an inert, fireproof gas, so it cannot have a steam explosion as a light-water reactor can. The coolant has no phase transitions—it starts as a gas and remains a gas. Similarly, the moderator is solid carbon; it does not act as a coolant, move, or have phase transitions (i.e., between liquid and gas) as the light water in conventional reactors does. Convection of the gas driven by the heat of the pebbles ensures that the pebbles are passively cooled.

A pebble-bed reactor thus can have all of its supporting machinery fail, and the reactor will not crack, melt, explode or spew hazardous wastes. It simply goes up to a designed "idle" temperature, and stays there. In that state, the reactor vessel radiates heat, but the vessel and fuel spheres remain intact and undamaged. The machinery can be repaired or the fuel can be removed. These safety features were tested (and filmed) with the German AVR reactor. All the control rods were removed, and the coolant flow was halted. Afterward, the fuel balls were sampled and examined for damage - there was none.

PBRs are intentionally operated above the 250 °C annealing temperature of graphite, so that Wigner energy is not accumulated. This solves a problem discovered in an infamous accident, the Windscale fire. One of the reactors at the Windscale site in England (not a PBR) caught fire because of the release of energy stored as crystalline dislocations (Wigner energy) in the graphite. The dislocations are caused by neutron passage through the graphite. Windscale had a program of regular annealing in place to release accumulated Wigner energy, but since the effect was not anticipated during the construction of the reactor, and since the reactor was cooled by ordinary air in an open cycle, the process could not be reliably controlled, and led to a fire. The second generation of UK gas-cooled reactors, the AGRs, also operate above the annealing temperature of graphite.

Berkeley professor Richard A. Muller has called pebble-bed reactors "in every way ... safer than the present nuclear reactors".

Containment

Most pebble-bed reactor designs contain many reinforcing levels of containment to prevent contact between the radioactive materials and the biosphere:

1. Most reactor systems are enclosed in a containment building designed to resist aircraft crashes and earthquakes.
2. The reactor itself is usually in a two-meter-thick-walled room with doors that can be closed, and cooling plenums that can be filled from any water source.
3. The reactor vessel is usually sealed.
4. Each pebble, within the vessel, is a 60 millimetres (2.4 in) hollow sphere of pyrolytic graphite.
5. A wrapping of fireproof silicon carbide
6. Low density porous pyrolytic carbon, high density nonporous pyrolytic carbon
7. The fission fuel is in the form of metal oxides or carbides

Pyrolytic graphite is the main structural material in these pebbles. It sublimates at 4000 °C, more than twice the design temperature of most reactors. It slows neutrons very effectively, is strong, inexpensive, and has a long history of use in reactors and other very high temperature applications. For example, pyrolytic graphite is also used, unreinforced, to construct missile reentry nose-cones and large solid rocket nozzles. Its strength and hardness come from anisotropic crystals of carbon.

Pyrolytic carbon can burn in air when the reaction is catalyzed by a hydroxyl radical (e.g., from water). Infamous examples include the accidents at Windscale and Chernobyl—both graphite-moderated reactors. However, all pebble-bed reactors are cooled by inert gases to prevent fire. All pebble designs also have at least one layer of silicon carbide that serves as a fire break as well as a seal.

Production of fuel

All kernels are precipitated from a sol-gel, then washed, dried and calcined. U.S. kernels use uranium carbide, while German (AVR) kernels use uranium dioxide. German-produced fuel-pebbles release about three orders of magnitude (1000 times) less radioactive gas than the U.S. equivalents, due to these different construction methods.

Criticisms of the reactor design

Combustible graphite

The most common criticism of pebble-bed reactors is that encasing the fuel in combustible graphite poses a hazard. When the graphite burns, fuel material could be carried away in smoke from the fire. Since burning graphite requires oxygen, the fuel kernels are coated with a layer of silicon carbide, and the reaction vessel is purged of oxygen. While silicon carbide is strong in abrasion and compression applications, it does not have the same strength against expansion and shear forces. Some fission products such as xenon-133 have a limited absorbance in carbon, and some fuel kernels could accumulate enough gas to rupture the silicon carbide layer. Even a cracked pebble will not burn without oxygen, but the fuel pebble may not be rotated out and inspected for months, leaving a window of vulnerability.

Containment building

Some designs for pebble-bed reactors lack a containment building, potentially making such reactors more vulnerable to outside attack and allowing radioactive material to spread in the case of an explosion. However, the current emphasis on reactor safety means that any new design will likely have a strong reinforced concrete containment structure.^[12] Also, any explosion would most likely be caused by an external factor, as the design does not suffer from the steam explosion-vulnerability of some water-cooled reactors.^{[citation needed]}

Waste handling

Since the fuel is contained in graphite pebbles, the volume of radioactive waste is much greater, but contains about the same radioactivity when measured in becquerels per kilowatt-hour. The waste tends to be less hazardous and simpler to handle. Current US legislation requires all waste to be safely contained, therefore pebble-bed reactors would increase existing storage problems. Defects in the production of pebbles may also cause problems. The radioactive waste must either be safely stored for many human generations, typically in a deep geological repository, reprocessed, transmuted in a different type of reactor, or disposed of by some other alternative method yet to be devised. The graphite pebbles are more difficult to reprocess due to their construction, which is not true of the fuel from other types of reactors.

1986 accident

In West Germany, in 1986, an accident involved a jammed pebble that was damaged by the reactor operators when they were attempting to dislodge it from a feeder tube (see THTR-300 section). This accident released radiation into the surrounding area, and probably was one reason for the shutdown of the research program by the West German government.

2008 report

In 2008, a report about safety aspects of the AVR reactor in Germany and some general features of pebble-bed reactors have drawn attention. The claims are under contention. Main points of discussion are

• No possibility to place standard measurement equipment in the pebble-bed core, i.e. pebble bed = black box
• Contamination of the cooling circuit with metallic fission products (⁹⁰
  Sr
  , ¹³⁷
  Cs
  ) due to the insufficient retention capabilities of fuel pebbles for metallic fission products. Even modern fuel elements do not sufficiently retain strontium and caesium.
• improper temperatures in the core (more than 200 °C (360 °F) above calculated values)
• necessity of a pressure retaining containment
• unresolved problems with dust formation by pebble friction (dust acts as a mobile fission product carrier, if fission products escape the fuel particles)

Rainer Moormann, author of the report, requests for safety reasons a limitation of average hot helium temperatures to 800 °C (1,470 °F) minus the uncertainty of the core temperatures (which is at present at about 200 °C (360 °F)).

The pebble-bed reactor has an advantage over traditional reactors in that the gases do not dissolve contaminants or absorb neutrons as water does, so the core has less in the way of radioactive fluids. However, as mentioned above, the pebbles generate graphite particulates that can blow through the coolant loop carrying fission products, if fission products escape the TRISO particles.

History

The first suggestion for this type of reactor came in 1947 from Prof. Dr. Farrington Daniels at Oak Ridge, who also created the name "pebble-bed reactor". The concept of a very simple, very safe reactor, with a commoditized nuclear fuel was developed by Professor Dr. Rudolf Schulten in the 1950s. The crucial breakthrough was the idea of combining fuel, structure, containment, and neutron moderator in a small, strong sphere. The concept was enabled by the realization that engineered forms of silicon carbide and pyrolytic carbon were quite strong, even at temperatures as high as 2,000 °C (3,630 °F). The natural geometry of close-packed spheres then provides the ducting (the spaces between the spheres) and spacing for the reactor core. To make the safety simple, the core has a low power density, about 1/30 the power density of a light water reactor.

Germany

AVR

Main article: AVR reactor

 

AVR in Germany.

A 15 MW_e demonstration reactor, Arbeitsgemeinschaft Versuchsreaktor (AVR translates to experimental reactor consortium), was built at the Jülich Research Centre in Jülich, West Germany. The goal was to gain operational experience with a high-temperature gas-cooled reactor. The unit's first criticality was on August 26, 1966. The facility ran successfully for 21 years, and was decommissioned on December 1, 1988, in the wake of the Chernobyl disaster and operational problems. During removal of the fuel elements it became apparent that the neutron reflector under the pebble-bed core had cracked during operation. Some hundred fuel elements remained stuck in the crack. During this examination it became also obvious that the AVR is the most heavily beta-contaminated (strontium-90) nuclear installation worldwide and that this contamination is present in the worst form, as dust.

In 1978, the AVR suffered from a water/steam ingress accident of 30 metric tons (30 long tons; 33 short tons), which led to contamination of soil and groundwater by strontium-90 and by tritium. The leak in the steam generator, leading to this accident, was probably caused by too high core temperatures (see criticism section). A re-examination of this accident was announced by the local government in July, 2010.

The AVR was originally designed to breed uranium-233 from thorium-232. Thorium-232 is over 100 times as abundant in the Earth's crust as uranium-235 (making up about 0.72% of natural uranium), and an effective thorium breeder reactor is therefore considered valuable technology. However, the fuel design of the AVR contained the fuel so well that the transmuted fuels were uneconomic to extract—it was cheaper to simply use natural uranium isotopes.

The AVR used helium coolant. Helium has a low neutron cross-section. Since few neutrons are absorbed, the coolant remains less radioactive. In fact, it is practical to route the primary coolant directly to power generation turbines. Even though the power generation used primary coolant, it is reported that the AVR exposed its personnel to less than 1/5 as much radiation as a typical light water reactor.

The localized fuel temperature instabilities mentioned above in the criticism section resulted in a heavy contamination of the whole vessel by Cs-137 and Sr-90. Thus the reactor vessel was filled with light concrete in order to fix the radioactive dust and in 2012 the reactor vessel of 2,100 metric tons (2,100 long tons; 2,300 short tons) will be moved to an intermediate storage. There exists currently no dismantling method for the AVR vessel, but it is planned to develop some procedure during the next 60 years and to start with vessel dismantling at the end of the century. In the meantime, after transport of the AVR vessel into the intermediate storage, the reactor buildings will be dismantled and soil and groundwater will be decontaminated. AVR dismantling costs will exceed its construction costs by far. In August 2010, the German government published a new cost estimate for AVR dismantling, however without consideration of the vessel dismantling: An amount of 600 million € ( $750 million) is now expected (200 million € more than in an estimate of 2006), which corresponds to 0.4 € ($0.55) per kWh of electricity generated by the AVR. Consideration of the unresolved problem of vessel dismantling is supposed to increase the total dismantling costs to more than 1 bn €. Construction costs of AVR were 115 million Deutschmark (1966), corresponding to a 2010 value of 180 million €. A separate containment was erected for dismantling purposes, as seen in the AVR-picture.

Thorium high-temperature reactor

Main article: THTR-300

Following the experience with AVR, a full scale power station (the thorium high-temperature reactor or THTR-300 rated at 300 MW) was constructed, dedicated to using thorium as the fuel. THTR-300 suffered a number of technical difficulties, and owing to these and political events in Germany, was closed after only four years of operation. One cause for the closing was an accident on 4 May 1986, only a few days after the Chernobyl disaster, with a limited release of the radioactive inventory into the environment. Although the radiological impact of this accident remained small, it is of major relevance for PBR history. The release of radioactive dust was caused by a human error during a blockage of pebbles in a pipe. Trying to restart the pebbles' movement by increasing gas flow led to stirring up of dust, always present in PBRs, which was then released, radioactive and unfiltered, into the environment due to an erroneously open valve.

In spite of the limited amount of radioactivity released (0.1 GBq ⁶⁰Co, ¹³⁷Cs, ²³³Pa), a commission of inquiry was appointed. The radioactivity in the vicinity of the THTR-300 was finally found to result 25% from Chernobyl and 75% from THTR-300. The handling of this minor accident severely damaged the credibility of the German pebble-bed community, which lost significant support in Germany.

The overly complex design of the reactor, which is contrary to the general concept of self moderated thorium reactors designed in the U.S., also suffered from the unplanned high destruction rate of pebbles during the test series at the start up, and the resulting higher contamination of the containment structure. Pebble debris and graphite dust blocked some of the coolant channels in the bottom reflector, as was discovered during fuel removal some years after final shut-down. A failure of insulation required frequent reactor shut-downs for inspection, because the insulation could not be repaired. Further metallic components in the hot gas duct failed in September 1988, probably due to thermal fatigue induced by unexpected hot gas currents. This failure led to a long-term shut-down for inspections. In August, 1989, the THTR company almost went bankrupt, but was financially rescued by the government. Because of the unexpected high costs of THTR operation, and this accident, there was no longer any interest in THTR reactors. The government decided to terminate the THTR operation at the end of September, 1989. This particular reactor was built despite strong criticism at the design phase. Most of those design critiques by German physicists, and by American physicists at the National Laboratory level, went ignored until it was shut down. Nearly every problem encountered by the THTR 300 reactor was predicted by the physicists that criticized it as "overly complex."

Different designs

China

2004: China has licensed the German technology and has developed a pebble-bed reactor for power generation. The 10 megawatt prototype is called the HTR-10. It is a conventional helium-cooled, helium-turbine design. The Chinese have built the successor 211 MW_e gross unit HTR-PM, which has two 250 MW_t reactors, and started it in 2021. As of 2021 Four sites are being considered for a 6 reactor successor, the HTR-PM600.

South Africa

Main article: Pebble bed modular reactor

In June 2004, it was announced that a new PBMR would be built at Koeberg, South Africa by Eskom, the government-owned electrical utility. There is opposition to the PBMR from groups such as Koeberg Alert and Earthlife Africa, the latter of which has sued Eskom to stop development of the project. In September 2009 the demonstration power plant was postponed indefinitely. In February 2010 the South African government stopped funding of the PBMR because of a lack of customers and investors. PBMR Ltd started retrenchment procedures and stated the company intends to reduce staff by 75%.

On the September 17, 2010 the South African Minister of Public Enterprises announced the closure of the PBMR. The PBMR testing facility will likely be decommissioned and placed in a "care and maintenance mode" to protect the IP and the assets.

Adams Atomic Engines

Adams Atomic Engines (AAE) went out of business in December 2010. Their basic design was self-contained so it could be adapted to extreme environments such as space, polar and underwater environments. Their design was for a nitrogen coolant passing directly though a conventional low-pressure gas turbine, and due to the rapid ability of the turbine to change speeds, it can be used in applications where instead of the turbine's output being converted to electricity, the turbine itself could directly drive a mechanical device, for instance, a propeller aboard a ship.

Like all high temperature designs, the AAE engine would have been inherently safe, as the engine naturally shuts down due to Doppler broadening, stopping heat generation if the fuel in the engine gets too hot in the event of a loss of coolant or a loss of coolant flow.

X-Energy

In January 2016 X-energy was awarded a five-year $53M U.S. Department of Energy Advanced Reactor Concept Cooperative Agreement award to advance elements of their reactor development. The Xe-100 reactor will generate 200 MWt and approximately 76 MWe. The standard Xe-100 "four-pack" plant generates approximately 300 MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.

Hazardous waste

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Hazardous_waste

North Seattle household hazardous waste collection facility.

Hazardous waste is waste that has substantial or potential threats to public health or the environment. Hazardous waste is a type of dangerous goods. They usually have one or more of the following hazardous traits:ignitability, reactivity, corrosivity, toxicity. Listed hazardous wastes are materials specifically listed by regulatory authorities as hazardous wastes which are from non-specific sources, specific sources, or discarded chemical products. Hazardous wastes may be found in different physical states such as gaseous, liquids, or solids. A hazardous waste is a special type of waste because it cannot be disposed of by common means like other by-products of our everyday lives. Depending on the physical state of the waste, treatment and solidification processes might be required.

The Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal was signed by 199 countries and went into force in 1992. Plastic was added to the convention in 2019.

Amount

Worldwide, the United Nations Environment Programme (UNEP) estimated that more than 400 million tons of hazardous wastes are produced universally each year, mostly by industrialized countries (Schmit, 1999). About 1 percent of this is shipped across international boundaries, with the majority of the transfers occurring between countries in the Organization for the Economic Cooperation and Development (OECD) (Krueger, 1999). One of the reasons for industrialized countries to ship the hazardous waste to industrializing countries for disposal is the rising cost of disposing of hazardous waste in the home country.

The Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal was signed by 199 countries and went into force in 1992. Plastic was added to the convention in 2019.

Types

Universal wastes

Universal wastes are a special category of hazardous wastes that (in the U.S.) generally pose a lower threat relative to other hazardous wastes, are ubiquitous and produced in very large quantities by a large number of generators. Some of the most common "universal wastes" are: fluorescent light bulbs, some specialty batteries (e.g. lithium or lead containing batteries), cathode ray tubes, and mercury-containing devices.

Universal wastes are subject to somewhat less stringent regulatory requirements. Small quantity generators of universal wastes may be classified as "conditionally exempt small quantity generators" (CESQGs) which release them from some of the regulatory requirements for the handling and storage hazardous wastes. Universal wastes must still be disposed of properly.

Household hazardous waste

Household Hazardous Waste separated for proper disposal

 

Large debris pile near to EPA’s ‘Household Hazardous Waste’ collection PAD

 

Main article: Household Hazardous Waste

See also: Hazardous waste in the United States

Household Hazardous Waste (HHW), also referred to as domestic hazardous waste or home generated special materials, is a waste that is generated from residential households. HHW only applies to waste coming from the use of materials that are labeled for and sold for "home use". Waste generated by a company or at an industrial setting is not HHW.

The following list includes categories often applied to HHW. It is important to note that many of these categories overlap and that many household wastes can fall into multiple categories:

• Paints and solvents
• Automotive wastes (used motor oil, antifreeze, etc.)
• Pesticides (insecticides, herbicides, fungicides, etc.)
• Mercury-containing wastes (thermometers, switches, fluorescent lighting, etc.)
• Electronics (computers, televisions, cell phones)
• Aerosols / Propane cylinders
• Caustics / Cleaning agents
• Refrigerant-containing appliances
• Some specialty batteries (e.g. lithium, nickel cadmium, or button cell batteries)
• Ammunition
• Asbestos
• Car batteries
• Radioactive wastes (some home smoke detectors are classified as radioactive waste because they contain very small amounts of radioactive isotope americium - see: Disposing of Smoke Detectors).
• Smoke from chimneys

Disposal

Historically, some hazardous wastes were disposed of in regular landfills. This resulted in unfavorable amounts of hazardous materials seeping into the ground. These chemicals eventually entered to natural hydrologic systems. Many landfills now require countermeasures against groundwater contamination. For example, a barrier has to be installed along the foundation of the landfill to contain the hazardous substances that may remain in the disposed waste. Currently, hazardous wastes must often be stabilized and solidified in order to enter a landfill and must undergo different treatments in order to stabilize and dispose of them. Most flammable materials can be recycled into industrial fuel. Some materials with hazardous constituents can be recycled, such as lead acid batteries.

Recycling

Some hazardous wastes can be recycled into new products. Examples may include lead–acid batteries or electronic circuit boards. When heavy metals in these types of ashes go through the proper treatment, they could bind to other pollutants and convert them into easier-to-dispose solids, or they could be used as pavement filling. Such treatments reduce the level of threat of harmful chemicals, like fly and bottom ash, while also recycling the safe product. There is a recycling center facility in Oxnard, CA. The city does not charge for any hazardous materials being disposed of, but there is a limit to how much you can bring per month. Other than hazardous waste, the city also allows you to dispose of electronic waste, light-bulbs, and batteries.

Incineration, destruction and waste-to-energy

Hazardous waste may be "destroyed". For example, by incinerating them at a high temperature, flammable wastes can sometimes be burned as energy sources. For example, many cement kilns burn hazardous wastes like used oils or solvents. Today, incineration treatments not only reduce the amount of hazardous waste, but also generate energy from the gases released in the process. It is known that this particular waste treatment releases toxic gases produced by the combustion of byproduct or other materials which can affect the environment. However, current technology has developed more efficient incinerator units that control these emissions to a point where this treatment is considered a more beneficial option. There are different types of incinerators which vary depending on the characteristics of the waste. Starved air incineration is another method used to treat hazardous wastes. Just like in common incineration, burning occurs, however controlling the amount of oxygen allowed proves to be significant to reduce the amount of harmful byproducts produced. Starved air incineration is an improvement of the traditional incinerators in terms of air pollution. Using this technology, it is possible to control the combustion rate of the waste and therefore reduce the air pollutants produced in the process.

Hazardous waste landfill

Hazardous waste may be sequestered in a hazardous waste landfill or permanent disposal facility. "In terms of hazardous waste, a landfill is defined as a disposal facility or part of a facility where hazardous waste is placed or on land and which is not a pile, a land treatment facility, a surface impoundment, an underground injection well, a salt dome formation, a salt bed formation, an underground mine, a cave, or a corrective action management unit (40 CFR 260.10)."

Pyrolysis

Some hazardous waste types may be eliminated using pyrolysis in a high temperature not necessarily through electrical arc but starved of oxygen to avoid combustion. However, when electrical arc is used to generate the required ultra heat (in excess of 3000 degree C temperature) all materials (waste) introduced into the process will melt into a molten slag and this technology is termed Plasma not pyrolysis. Plasma technology produces inert materials and when cooled solidifies into rock like material. These treatment methods are very expensive but may be preferable to high temperature incineration in some circumstances such as in the destruction of concentrated organic waste types, including PCBs, pesticides and other persistent organic pollutants.

Management and Health Effects

Hazardous waste management and disposal comes with consequences if not done properly. If disposed of improperly, hazardous gaseous substances can be released into the air resulting in higher morbidity and mortality. These gaseous substances can include hydrogen chloride, carbon monoxide, nitrogen oxides, sulfur dioxide, and some may also include heavy metals. With the prospect of gaseous material being released into the atmosphere, several organizations (RCRA, TSCA, HSWA, CERCLA) developed an identification scale in which hazardous materials and wastes are categorized in order to be able to quickly identify and mitigate potential leaks. F-List materials were identified as non-specific industrial practices waste, K-List materials were wastes generated from specific industrial processes - pesticides, petroleum, explosive industries, and the P & U list were commercially used generated waste and shelf stable pesticides. Not only can mismanagement of hazardous wastes cause adverse direct health consequences through air pollution, mismanaged waste can also contaminate groundwater and soil. In an Austrian study, people who live near industrial sites are "more often unemployed, have lower education levels, and are twice as likely to be immigrants." This creates disproportionately larger issues for those who depend heavily on the land for harvests and streams for drinking water - this includes Native American populations. Though all lower-class and/or social minorities are at a higher risk for being exposed to toxic exposure, Native Americans are at a multiplied risk due to the facts stated above (Brook, 1998). Improper disposal of hazardous waste has resulted in many extreme health complications within certain tribes. Members of the Mohawk Nation at Akwesasne have suffered elevated levels of PCB [Polychlorinated Biphenyls] in their bloodstreams leading to higher rates of cancer.

Society and culture

Global goals

The international community has defined the responsible management of hazardous waste and chemicals as an important part of sustainable development by including it in Sustainable Development Goal 12. Target 12.4 of this goal is to "achieve the environmentally sound management of chemicals and all wastes throughout their life cycle". One of the indicators for this target is: "hazardous waste generated per capita; and proportion of hazardous waste treated, by type of treatment".

Regulatory history

In the United States

Resource Conservation and Recovery Act (RCRA)

Hazardous wastes are wastes with properties that make them dangerous or potentially harmful to human health or the environment. Hazardous wastes can be liquids, solids, contained gases, or sludges. They can be by-products of manufacturing processes or simply discarded commercial products, like cleaning fluids or pesticides. In regulatory terms, RCRA hazardous wastes are wastes that appear on one of the four hazardous wastes lists (F-list, K-list, P-list, or U-list), or exhibit at least one of the following four characteristics; ignitability, corrosivity, reactivity, or toxicity. in the US, Hazardous wastes are regulated under the Resource Conservation and Recovery Act (RCRA), Subtitle C.

By definition, EPA determined that some specific wastes are hazardous. These wastes are incorporated into lists published by the Agency. These lists are organized into three categories: F-list (non-specific source wastes) found in the regulations at 40 CFR 261.31, K-list (source-specific wastes) found in the regulations at 40 CFR 261.32, and P-list and the U-list (discarded commercial chemical products) found in the regulations at 40 CFR 261.33.

RCRA's record keeping system helps to track the life cycle of hazardous waste and reduces the amount of hazardous waste illegally disposed.

Comprehensive Environmental Response, Compensation, and Liability Act

The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) was enacted in 1980. The primary contribution of CERCLA was to create a "Superfund" and provide for the clean-up and remediation of closed and abandoned hazardous waste sites. CERCLA addresses historic releases of hazardous materials, but does not specifically manage hazardous wastes.

The Valley of the Drums, a toxic waste dump in northern Bullitt County, Kentucky

Country examples

United States

Main article: Hazardous waste in the United States

In the United States, the treatment, storage, and disposal of hazardous waste are regulated under the Resource Conservation and Recovery Act (RCRA). Hazardous wastes are defined under RCRA in 40 CFR 261 where they are divided into two major categories: characteristic wastes and listed wastes.

The requirements of the RCRA apply to all the companies that generate hazardous waste as well as those companies that store or dispose hazardous waste in the United States. Many types of businesses generate hazardous waste. Dry cleaners, automobile repair shops, hospitals, exterminators, and photo processing centers may all generate hazardous waste. Some hazardous waste generators are larger companies such as chemical manufacturers, electroplating companies, and oil refineries.

A U.S. facility that treats, stores, or disposes of hazardous waste must obtain a permit for doing so under the RCRA. Generators and transporters of hazardous waste must meet specific requirements for handling, managing, and tracking waste. Through the RCRA, Congress directed the United States Environmental Protection Agency (EPA) to create regulations to manage hazardous waste. Under this mandate, the EPA developed strict requirements for all aspects of hazardous waste management including the treatment, storage, and disposal of hazardous waste. In addition to these federal requirements, states may develop more stringent requirements that are broader in scope than the federal regulations. Furthermore, RCRA allows states to develop regulatory programs that are at least as stringent as RCRA and, after review by EPA, the states may take over responsibility for the implementation of the requirements under RCRA. Most states take advantage of this authority, implementing their own hazardous waste programs that are at least as stringent, and in some cases are more stringent than the federal program.

The U.S. government provides several tools for mapping hazardous wastes to particular locations. These tools also allow the user to view additional information.

• TOXMAP was a Geographic Information System (GIS) service from the Division of Specialized Information Services Archived 2019-03-21 at the Wayback Machine of the United States National Library of Medicine (NLM) that used maps of the United States to help users visually explore data from the United States Environmental Protection Agency's (EPA) Toxics Release Inventory and Superfund Basic Research Program. This resource was funded by the US Federal Government. TOXMAP's chemical and environmental health information was taken from NLM's Toxicology Data Network (TOXNET), PubMed, and other authoritative sources.
• The US Environmental Protection Agency (EPA) "Where You Live" allows users to select a region from a map to find information about Superfund sites in that region.

Graves' disease

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Graves%27_disease 

 

Graves' disease
The classic finding of exophthalmos and lid retraction in Graves' disease
Specialty	Endocrinology
Symptoms	Enlarged thyroid, irritability, muscle weakness, sleeping problems, fast heartbeat, weight loss, poor tolerance of heat, anxiety, tremor of hands or fingers, warm and moist skin, increased perspiration, goiter, changes in menstrual cycle, easy bruising, erectile dysfunction, reduced libido, frequent bowel movements, bulging eyes (Graves' ophthalmopathy), thick red skin on shins or the top of foot (pretibial myxedema)
Complications	Graves' ophthalmopathy
Causes	Unknown
Risk factors	Family history, other autoimmune diseases
Diagnostic method	Blood tests, radioiodine uptake
Treatment	Radioiodine therapy, medications, thyroid surgery
Frequency	0.5% (males), 3% (females)

Graves' disease (German: Morbus Basedow), also known as toxic diffuse goiter, is an autoimmune disease that affects the thyroid. It frequently results in and is the most common cause of hyperthyroidism. It also often results in an enlarged thyroid. Signs and symptoms of hyperthyroidism may include irritability, muscle weakness, sleeping problems, a fast heartbeat, poor tolerance of heat, diarrhea and unintentional weight loss. Other symptoms may include thickening of the skin on the shins, known as pretibial myxedema, and eye bulging, a condition caused by Graves' ophthalmopathy. About 25 to 30% of people with the condition develop eye problems.

The exact cause of the disease is unclear, but it is believed to involve a combination of genetic and environmental factors. Persons are more likely to be affected if they have a family member with the disease. If one twin is affected, a 30% chance exists that the other twin will also have the disease. The onset of disease may be triggered by physical or emotional stress, infection, or giving birth. Those with other autoimmune diseases, such as type 1 diabetes and rheumatoid arthritis, are more likely to be affected. Smoking increases the risk of disease and may worsen eye problems. The disorder results from an antibody, called thyroid-stimulating immunoglobulin (TSI), that has a similar effect to thyroid stimulating hormone (TSH). These TSI antibodies cause the thyroid gland to produce excess thyroid hormones. The diagnosis may be suspected based on symptoms and confirmed with blood tests and radioiodine uptake. Typically, blood tests show a raised T₃ and T₄, low TSH, increased radioiodine uptake in all areas of the thyroid, and TSI antibodies.

The three treatment options are radioiodine therapy, medications, and thyroid surgery. Radioiodine therapy involves taking iodine-131 by mouth, which is then concentrated in the thyroid and destroys it over weeks to months. The resulting hypothyroidism is treated with synthetic thyroid hormones. Medications such as beta blockers may control some of the symptoms, and antithyroid medications such as methimazole may temporarily help people, while other treatments are having effect. Surgery to remove the thyroid is another option. Eye problems may require additional treatments.

Graves' disease develops in about 0.5% of males and 3.0% of females. It occurs about 7.5 times more often in women than in men. Often, it starts between the ages of 40 and 60, but can begin at any age. It is the most common cause of hyperthyroidism in the United States (about 50 to 80% of cases). The condition is named after Irish surgeon Robert Graves, who described it in 1835. A number of prior descriptions also exist.

Signs and symptoms

Main article: Signs and symptoms of Graves' disease

 

Graves' disease symptoms

The signs and symptoms of Graves' disease virtually all result from the direct and indirect effects of hyperthyroidism, with main exceptions being Graves' ophthalmopathy, goiter, and pretibial myxedema (which are caused by the autoimmune processes of the disease). Symptoms of the resultant hyperthyroidism are mainly insomnia, hand tremor, hyperactivity, hair loss, excessive sweating, oligomenorrhea, itching, heat intolerance, weight loss despite increased appetite, diarrhea, frequent defecation, palpitations, periodic partial muscle weakness or paralysis in those especially of Asian descent, and skin warmth and moistness. Further signs that may be seen on physical examination are most commonly a diffusely enlarged (usually symmetric), nontender thyroid, lid lag, excessive lacrimation due to Graves' ophthalmopathy, arrhythmias of the heart, such as sinus tachycardia, atrial fibrillation, and premature ventricular contractions, and hypertension.

Cause

The exact cause is unclear, but it is believed to involve a combination of genetic and environmental factors. While a theoretical mechanism occurs by which exposure to severe stressors and high levels of subsequent distress such as post-traumatic stress disorder could increase the risk of immune disease and cause an aggravation of the autoimmune response that leads to Graves' disease, more robust clinical data are needed for a firm conclusion.

Genetics

A genetic predisposition for Graves' disease is seen, with some people more prone to develop TSH receptor-activating antibodies due to a genetic cause. Human leukocyte antigen DR (especially DR3) appears to play a role. To date, no clear genetic defect has been found to point to a single-gene cause.

Genes believed to be involved include those for thyroglobulin, thyrotropin receptor, protein tyrosine phosphatase nonreceptor type 22 (PTPN22), and cytotoxic T-lymphocyte–associated antigen 4, among others.

Infectious trigger

Since Graves' disease is an autoimmune disease that appears suddenly, often later in life, a viral or bacterial infection may trigger antibodies, which cross-react with the human TSH receptor, a phenomenon known as antigenic mimicry.

The bacterium Yersinia enterocolitica bears structural similarity with the human thyrotropin receptor and was hypothesized to contribute to the development of thyroid autoimmunity arising for other reasons in genetically susceptible individuals. In the 1990s, Y. enterocolitica was suggested to be possibly associated with Graves' disease. More recently, the role for Y. enterocolitica has been disputed.

Epstein–Barr virus is another potential trigger.

Mechanism

Thyroid-stimulating immunoglobulins recognize and bind to the (TSH receptor, which stimulates the secretion of thyroxine (T4) and triiodothyronine (T3). Thyroxine receptors in the pituitary gland are activated by the surplus hormone, suppressing additional release of TSH in a negative feedback loop. The result is very high levels of circulating thyroid hormones and a low TSH level.

Pathophysiology

Histopathological image of diffuse hyperplasia of the thyroid gland (clinically presenting as hyperthyroidism)

Graves' disease is an autoimmune disorder, in which the body produces antibodies that are specific to a self-protein - the receptor for thyroid-stimulating hormone. (Antibodies to thyroglobulin and to the thyroid hormones T3 and T4 may also be produced.)

These antibodies cause hyperthyroidism because they bind to the TSHr and chronically stimulate it. The TSHr is expressed on the thyroid follicular cells of the thyroid gland (the cells that produce thyroid hormone), and the result of chronic stimulation is an abnormally high production of T3 and T4. This, in turn, causes the clinical symptoms of hyperthyroidism, and the enlargement of the thyroid gland visible as goiter.

The infiltrative exophthalmos frequently encountered has been explained by postulating that the thyroid gland and the extraocular muscles share a common antigen, which is recognized by the antibodies. Antibodies binding to the extraocular muscles would cause swelling behind the eyeball.

The "orange peel" skin has been explained by the infiltration of antibodies under the skin, causing an inflammatory reaction and subsequent fibrous plaques.

The three types of autoantibodies to the TSH receptor currently recognized are:

1. Thyroid stimulating immunoglobulins: these antibodies (mainly IgG) act as long-acting thyroid stimulants, activating the cells through a slower and more drawn out process compared to TSH, leading to an elevated production of thyroid hormone.
2. Thyroid growth immunoglobulins: these antibodies bind directly to the TSH receptor and have been implicated in the growth of thyroid follicles.
3. Thyrotrophin binding-inhibiting immunoglobulins: these antibodies inhibit the normal union of TSH with its receptor.
   • Some actually act as if TSH itself is binding to its receptor, thus inducing thyroid function.
   • Other types may not stimulate the thyroid gland, but prevent TSI and TSH from binding to and stimulating the receptor.

Another effect of hyperthyroidism is bone loss from osteoporosis, caused by an increased excretion of calcium and phosphorus in the urine and stool. The effects can be minimized if the hyperthyroidism is treated early. Thyrotoxicosis can also augment calcium levels in the blood by as much as 25%. This can cause stomach upset, excessive urination, and impaired kidney function.

Diagnosis

Graves' disease may present clinically with one or more of these characteristic signs:

• Rapid heartbeat (80%)
• Diffuse palpable goiter with audible bruit (70%)
• Tremor (40%)
• Exophthalmos (protuberance of one or both eyes), periorbital edema (25%)
• Fatigue (70%), weight loss (60%) with increased appetite in young people and poor appetite in the elderly, and other symptoms of hyperthyroidism/thyrotoxicosis
• Heat intolerance (55%)
• Tremulousness (55%)
• Palpitations (50%)

Two signs are truly diagnostic of Graves' disease (i.e., not seen in other hyperthyroid conditions): exophthalmos and nonpitting edema (pretibial myxedema). Goiter is an enlarged thyroid gland and is of the diffuse type (i.e., spread throughout the gland). Diffuse goiter may be seen with other causes of hyperthyroidism, although Graves' disease is the most common cause of diffuse goiter. A large goiter will be visible to the naked eye, but a small one (mild enlargement of the gland) may be detectable only by physical examination. Occasionally, goiter is not clinically detectable, but may be seen only with computed tomography or ultrasound examination of the thyroid. Another sign of Graves' disease is hyperthyroidism, that is, overproduction of the thyroid hormones T3 and T4. Normal thyroid levels are also seen, and occasionally also hypothyroidism, which may assist in causing goiter (though it is not the cause of the Graves' disease). Hyperthyroidism in Graves' disease is confirmed, as with any other cause of hyperthyroidism, by measuring elevated blood levels of free (unbound) T3 and T4.

Other useful laboratory measurements in Graves' disease include thyroid-stimulating hormone (TSH, usually undetectable in Graves' disease due to negative feedback from the elevated T3 and T4), and protein-bound iodine (elevated). Serologically detected thyroid-stimulating antibodies, radioactive iodine uptake, or thyroid ultrasound with Doppler all can independently confirm a diagnosis of Graves' disease.

Biopsy to obtain histiological testing is not normally required, but may be obtained if thyroidectomy is performed.

The goiter in Graves' disease is often not nodular, but thyroid nodules are also common. Differentiating common forms of hyperthyroidism such as Graves' disease, single thyroid adenoma, and toxic multinodular goiter is important to determine proper treatment. The differentiation among these entities has advanced, as imaging and biochemical tests have improved. Measuring TSH-receptor antibodies with the h-TBII assay has been proven efficient and was the most practical approach found in one study.

Eye disease

Further information: Graves' ophthalmopathy

Thyroid-associated ophthalmopathy (TAO), or thyroid eye disease (TED), is the most common extrathyroidal manifestation of Graves' disease. It is a form of idiopathic lymphocytic orbital inflammation, and although its pathogenesis is not completely understood, autoimmune activation of orbital fibroblasts, which in TAO express the TSH receptor, is thought to play a central role.

Hypertrophy of the extraocular muscles, adipogenesis, and deposition of nonsulfated glycosaminoglycans and hyaluronate, causes expansion of the orbital fat and muscle compartments, which within the confines of the bony orbit may lead to dysthyroid optic neuropathy, increased intraocular pressures, proptosis, venous congestion leading to chemosis and periorbital edema, and progressive remodeling of the orbital walls. Other distinctive features of TAO include lid retraction, restrictive myopathy, superior limbic keratoconjunctivitis, and exposure keratopathy.

Severity of eye disease may be classified by the mnemonic: "NO SPECS":

• Class 0: No signs or symptoms
• Class 1: Only signs (limited to upper lid retraction and stare, with or without lid lag)
• Class 2: Soft tissue involvement (oedema of conjunctivae and lids, conjunctival injection, etc.)
• Class 3: Proptosis
• Class 4: Extraocular muscle involvement (usually with diplopia)
• Class 5: Corneal involvement (primarily due to lagophthalmos)
• Class 6: Sight loss (due to optic nerve involvement)

Typically, the natural history of TAO follows Rundle's curve, which describes a rapid worsening during an initial phase, up to a peak of maximum severity, and then improvement to a static plateau without, however, resolving back to a normal condition.

Management

Treatment of Graves' disease includes antithyroid drugs that reduce the production of thyroid hormone, radioiodine (radioactive iodine I-131) and thyroidectomy (surgical excision of the gland). As operating on a hyperthyroid patient is dangerous, prior to thyroidectomy, preoperative treatment with antithyroid drugs is given to render the patient euthyroid. Each of these treatments has advantages and disadvantages, and no single treatment approach is considered the best for everyone.

Treatment with antithyroid medications must be administered for six months to two years to be effective. Even then, upon cessation of the drugs, the hyperthyroid state may recur. The risk of recurrence is about 40–50%, and lifelong treatment with antithyroid drugs carries some side effects such as agranulocytosis and liver disease. Side effects of the antithyroid medications include a potentially fatal reduction in the level of white blood cells. Therapy with radioiodine is the most common treatment in the United States, while antithyroid drugs and/or thyroidectomy are used more often in Europe, Japan, and most of the rest of the world.

β-Blockers (such as propranolol) may be used to inhibit the sympathetic nervous system symptoms of tachycardia and nausea until antithyroid treatments start to take effect. Pure β-blockers do not inhibit lid retraction in the eyes, which is mediated by alpha adrenergic receptors.

Antithyroid drugs

The main antithyroid drugs are carbimazole (in the UK), methimazole (in the US), and propylthiouracil/PTU. These drugs block the binding of iodine and coupling of iodotyrosines. The most dangerous side effect is agranulocytosis (1/250, more in PTU). Others include granulocytopenia (dose-dependent, which improves on cessation of the drug) and aplastic anemia. Patients on these medications should see a doctor if they develop sore throat or fever. The most common side effects are rash and peripheral neuritis. These drugs also cross the placenta and are secreted in breast milk. Lugol's iodine may be used to block hormone synthesis before surgery.

A randomized control trial testing single-dose treatment for Graves' found methimazole achieved euthyroid state more effectively after 12 weeks than did propylthyouracil (77.1% on methimazole 15 mg vs 19.4% in the propylthiouracil 150 mg groups).

No difference in outcome was shown for adding thyroxine to antithyroid medication and continuing thyroxine versus placebo after antithyroid medication withdrawal. However, two markers were found that can help predict the risk of recurrence. These two markers are a positive TSHr antibody (TSHR-Ab) and smoking. A positive TSHR-Ab at the end of antithyroid drug treatment increases the risk of recurrence to 90% (sensitivity 39%, specificity 98%), and a negative TSHR-Ab at the end of antithyroid drug treatment is associated with a 78% chance of remaining in remission. Smoking was shown to have an impact independent to a positive TSHR-Ab.

Radioiodine

Scan of affected thyroid before (top) and after (bottom) radioiodine therapy

Radioiodine (radioactive iodine-131) was developed in the early 1940s at the Mallinckrodt General Clinical Research Center. This modality is suitable for most patients, although some prefer to use it mainly for older patients. Indications for radioiodine are failed medical therapy or surgery and where medical or surgical therapy are contraindicated. Hypothyroidism may be a complication of this therapy, but may be treated with thyroid hormones if it appears. The rationale for radioactive iodine is that it accumulates in the thyroid and irradiates the gland with its beta and gamma radiations, about 90% of the total radiation being emitted by the beta (electron) particles. The most common method of iodine-131 treatment is to administer a specified amount in microcuries per gram of thyroid gland based on palpation or radiodiagnostic imaging of the gland over 24 hours. Patients who receive the therapy must be monitored regularly with thyroid blood tests to ensure they are treated with thyroid hormone before they become symptomatically hypothyroid.

Contraindications to RAI are pregnancy (absolute), ophthalmopathy (relative; it can aggravate thyroid eye disease), or solitary nodules.

Disadvantages of this treatment are a high incidence of hypothyroidism (up to 80%) requiring eventual thyroid hormone supplementation in the form of a daily pill(s). The radioiodine treatment acts slowly (over months to years) to destroy the thyroid gland, and Graves' disease–associated hyperthyroidism is not cured in all persons by radioiodine, but has a relapse rate that depends on the dose of radioiodine which is administered. In rare cases, radiation induced thyroiditis has been linked to this treatment.

Surgery

Further information: Thyroidectomy

This modality is suitable for young and pregnant people. Indications for thyroidectomy can be separated into absolute indications or relative indications. These indications aid in deciding which people would benefit most from surgery. The absolute indications are a large goiter (especially when compressing the trachea), suspicious nodules or suspected cancer (to pathologically examine the thyroid), and people with ophthalmopathy and additionally if it is the person's preferred method of treatment or if refusing to undergo radioactive iodine treatment. Pregnancy is advised to be delayed for 6 months after radioactive iodine treatment.

Both bilateral subtotal thyroidectomy and the Hartley-Dunhill procedure (hemithyroidectomy on one side and partial lobectomy on other side) are possible.

Advantages are immediate cure and potential removal of carcinoma. Its risks are injury of the recurrent laryngeal nerve, hypoparathyroidism (due to removal of the parathyroid glands), hematoma (which can be life-threatening if it compresses the trachea), relapse following medical treatment, infections (less common), and scarring. The increase in the risk of nerve injury can be due to the increased vascularity of the thyroid parenchyma and the development of links between the thyroid capsule and the surrounding tissues. Reportedly, a 1% incidence exists of permanent recurrent laryngeal nerve paralysis after complete thyroidectomy. Risks related to anesthesia are many, thus coordination with the anesthesiologist and patient optimization for surgery preoperatively are essential. Removal of the gland enables complete biopsy to be performed to have definite evidence of cancer anywhere in the thyroid. (Needle biopsies are not so accurate at predicting a benign state of the thyroid). No further treatment of the thyroid is required, unless cancer is detected. Radioiodine uptake study may be done after surgery, to ensure all remaining (potentially cancerous) thyroid cells (i.e., near the nerves to the vocal cords) are destroyed. Besides this, the only remaining treatment will be levothyroxine, or thyroid replacement pills to be taken for the rest of the patient's life.

A 2013 review article concludes that surgery appears to be the most successful in the management of Graves' disease, with total thyroidectomy being the preferred surgical option.

Eyes

Mild cases are treated with lubricant eye drops or nonsteroidal anti-inflammatory drops. Severe cases threatening vision (corneal exposure or optic nerve compression) are treated with steroids or orbital decompression. In all cases, cessation of smoking is essential. Double vision can be corrected with prism glasses and surgery (the latter only when the process has been stable for a while).

Difficulty closing eyes can be treated with lubricant gel at night, or with tape on the eyes to enable full, deep sleep.

Orbital decompression can be performed to enable bulging eyes to retreat back into the head. Bone is removed from the skull behind the eyes, and space is made for the muscles and fatty tissue to fall back into the skull. 

Eyelid surgery can be performed on upper and/or lower eyelids to reverse the effects of Graves' disease on the eyelids. Eyelid muscles can become tight with Graves' disease, making it impossible to close the eyes all the way. Eyelid surgery involves an incision along the natural crease of the eyelid, and a scraping away of the muscle that holds the eyelid open. This makes the muscle weaker, which allows the eyelid to extend over the eyeball more effectively. Eyelid surgery helps reduce or eliminate dry eye symptoms.

For management of clinically active Graves' disease, orbitopathy (clinical activity score >2) with at least mild to moderate severity, intravenous glucocorticoids are the treatment of choice, usually administered in the form of pulse intravenous methylprednisolone. Studies have consistently shown that pulse intravenous methylprednisolone is superior to oral glucocorticoids both in terms of efficacy and decreased side effects for managing Graves' orbitopathy.

Prognosis

If left untreated, more serious complications could result, including birth defects in pregnancy, increased risk of a miscarriage, bone mineral loss and, in extreme cases, death. Graves' disease is often accompanied by an increase in heart rate, which may lead to further heart complications, including loss of the normal heart rhythm (atrial fibrillation), which may lead to stroke. If the eyes are proptotic (bulging) enough that the lids do not close completely at night, dryness will occur – with the risk of a secondary corneal infection, which could lead to blindness. Pressure on the optic nerve behind the globe can lead to visual field defects and vision loss, as well. Prolonged untreated hyperthyroidism can lead to bone loss, which may resolve when treated.

Epidemiology

Most common causes of hyperthyroidism by age

Graves' disease occurs in about 0.5% of people. Graves' disease data has shown that the lifetime risk for women is around 3% and 0.5% for men. It occurs about 7.5 times more often in women than in men and often starts between the ages of 40 and 60. It is the most common cause of hyperthyroidism in the United States (about 50 to 80% of cases).

History

Graves' disease owes its name to the Irish doctor Robert James Graves, who described a case of goiter with exophthalmos in 1835. (Medical eponyms are often styled nonpossessively; thus Graves' disease and Graves disease are variant stylings of the same term.)

The German Karl Adolph von Basedow independently reported the same constellation of symptoms in 1840. As a result, on the European continent, the terms "Basedow syndrome", "Basedow disease", or "Morbus Basedow" are more common than "Graves' disease".

Graves' disease has also been called exophthalmic goiter.

Less commonly, it has been known as Parry disease, Begbie disease, Flajan disease, Flajani–Basedow syndrome, and Marsh disease. These names for the disease were derived from Caleb Hillier Parry, James Begbie, Giuseppe Flajani, and Henry Marsh. Early reports, not widely circulated, of cases of goiter with exophthalmos were published by the Italians Giuseppe Flajani and Antonio Giuseppe Testa, in 1802 and 1810, respectively. Prior to these, Caleb Hillier Parry, a notable provincial physician in England of the late-18th century (and a friend of Edward Miller-Gallus), described a case in 1786. This case was not published until 1825 - ten years ahead of Graves.

However, fair credit for the first description of Graves' disease goes to the 12th century Persian physician Sayyid Ismail al-Jurjani, who noted the association of goiter and exophthalmos in his Thesaurus of the Shah of Khwarazm, the major medical dictionary of its time.

Society and culture

Notable cases

Marty Feldman used his bulging eyes, caused by Graves' disease, for comedic effect.

• Ayaka, Japanese singer, was diagnosed with Graves' disease in 2007. After going public with her diagnosis in 2009, she took a two-year hiatus from music to focus on treatment.
• Susan Elizabeth Blow, American educator and founder of the first publicly funded kindergarten in the United States, was forced to retire and seek treatment for Graves' disease in 1884.
• George H. W. Bush, former U.S. president, developed new atrial fibrillation and was diagnosed in 1991 with hyperthyroidism due to the disease and treated with radioactive iodine. The president's wife, Barbara Bush, also developed the disease around the same time, which, in her case, produced severe infiltrative exophthalmos.
• Rodney Dangerfield, American comedian and actor
• Gail Devers, American sprinter: A doctor considered amputating her feet after she developed blistering and swelling following radiation treatment for Graves' disease, but she went on to recover and win Olympic medals.
• Missy Elliott, American hip-hop artist
• Marty Feldman, British comedy writer, comedian and actor
• Sia, Australian singer and songwriter
• Sammy Gravano, Italian-American former underboss of the Gambino crime family.
• Jim Hamilton, Scottish rugby player, discovered he had Graves' disease shortly after retiring from the sport in 2017.
• Heino, German folk singer, whose dark sunglasses (worn to hide his symptoms) became part of his trademark look
• Herbert Howells, British composer; the first person to be treated with radium injections
• Yayoi Kusama, Japanese artist.
• Nadezhda Krupskaya, Russian Communist and wife of Vladimir Lenin
• Umm Kulthum was an Egyptian singer, songwriter, and film actress active from the 1920s to the 1970s.
• Barbara Leigh, an American former actress and fashion model, now spokeswoman for the National Graves' Disease Foundation
• Keiko Masuda, Japanese singer and one-half of the duo Pink Lady.
• Yūko Miyamura, Japanese voice actress
• Lord Monckton, former UKIP and Conservative politician.
• Sophia Parnok, Russian poet
• Sir Cecil Spring Rice, British ambassador to the United States during World War I, died suddenly of the disease in 1918.
• Christina Rossetti, English Victorian-era poet
• Dame Maggie Smith, British actress
• Mary Webb, British novelist and poet
• Wendy Williams, American TV show host
• Act Yasukawa, Japanese Professional wrestler.

Literature

• In Italo Svevo's novel Zeno's Conscience, character Ada develops the disease.
• Ern Malley was an acclaimed Australian poet whose work was not published until after his death from Graves' disease in 1943. However, Malley's existence and entire biography was actually later revealed to be a literary hoax.