Various dates - No INES level - France - overexposure of scientists
Marie Curie (1867–1934) was a Polish-French physicist and chemist. She was a pioneer in the early field of radioactivity, later becoming the first two-time Nobel laureate and the only person with Nobel Prizes in physics and chemistry. Her death, at age 67, in 1934 was from aplastic anemia due to massive exposure to radiation in her work, much of which was carried out in a shed with no proper safety measures being taken, as the damaging effects of hard radiation were not generally understood at that time. She was known to carry test tubes full of radioactive isotopes in her pocket, and to store them in her desk drawer, resulting in massive exposure to radiation. She was known to remark on the pretty blue-green light the metals gave off in the dark. Because of their levels of radioactivity, her papers from the 1890s are considered too dangerous to handle. Even her cookbook is highly radioactive. They are kept in lead-lined boxes, and those who wish to consult them must wear protective clothing.
Various dates - No INES level - various locations - overexposure of workers
Luminescent radium was used to paint watches and other items that glowed. The most famous incident is the Radium girls of Orange, New Jersey where a large number of workers got radiation poisoning. Other towns including Ottawa, Illinois experienced contamination of homes and other structures and became Superfund cleanup sites.
Various dates - No INES Level - Colorado, USA - contamination
Radium mining and manufacturing left a number of streets in the state's capital and largest city of Denver contaminated.
1927–1930 - No INES Level - USA - radium poisoning
An earth/clay dike of an United Nuclear Corporation's uranium mill's settling/evaporating pond failed. The broken dam released 100 million U.S. gallons (380,000 m3) of radioactive liquids and 1,100 short tons (1,000 metric tonnes) of solid wastes, which settled out up to 70 miles (100 km) down the Puerco River and also near a Navaho farming community that uses surface waters. The pond was past its planned and licensed life and had been filled two feet (60 cm) deeper than design, despite evident cracking.
September 29, 1979 - Tritium leak at American Atomics in Tucson, Arizona at the public school across the street from the plant. $300,000 worth of food was found to be contaminated; the chocolate cake had 56 nCi/L (2,100 Bq/l). By contrast, the EPA safety limit for drinking water is 20 nCi/L (740 Bq/L) based on consumption of 2 liters per day.
July 1981 – Lycoming, Nine Mile Point, New York. An overloaded wastewater tank was deliberately flushed into a building sub-basement, resulting in a pool four feet deep. This caused a number of the approximately 150 55-gallon drums stored there to overturn and spill their contents. Fifty thousand U.S. gallons (190 m3) of contaminated water was discharged into Lake Ontario.
1982 – International Nutronics of Dover, New Jersey spilled an unknown quantity of radioactive cobalt solution used to treat gems, modify chemicals, and sterilize food and medical supplies. The solution spilled into the Dover sewer system and forced shutdown of the plant. The Nuclear Regulatory Commission was only informed of the accident ten months later by a whistleblower. In 1986 International Nutronics was fined $35,000 and one of its top executives was sentenced to probation for failure to report the spill.
1982 – Radioactive steel scavenged from a nuclear reactor was recycled into rebar and used in the construction of apartment buildings in northern Taiwan, principally in Taipei, from 1982 through 1984. Over 2,000 apartment units and shops were suspected as having been built using the material. About 10,000 people are believed to have been exposed to long-term low-level irradiation as a result. In the summer of 1992, a utility worker for the Taiwanese state-run electric utility Taipower brought a Geiger counter to his apartment to learn more about the device, and discovered that his apartment was contaminated. Despite awareness of the problem, owners of some of the buildings known to be contaminated have continued to rent apartments out to tenants (in part because selling the units is illegal). Some research has shown that the radiation has had a beneficial effect upon the health of the tenants based on the death rate from cancers, Another study looking at the incidence of cancer found that although the overall risk of cancer was sharply reduced (SIR = 0.6, 95 % CI 0.5 – 0.7), the incidence of certain leukemias in men (n = 6, SIR = 3.4, 95 % CI 1.2 – 7.4) and thyroid cancer in women (n = 6, SIR = 2.6, 95 % CI 1.0 – 5.7) were more prevalent. 
December 6, 1983 – Ciudad Juárez, Mexico. A local resident salvaged materials from a discarded radiation therapy machine containing 6,000 pellets of cobalt-60. The transport of the material led to severe contamination of his truck. When the truck was scrapped, it in turn contaminated another 5,000 metric tonnes of steel to an estimated 300 Ci (11 TBq) of activity. This steel was used to manufacture kitchen and restaurant table legs and rebar, some of which was shipped to the U.S. and Canada. The incident was discovered months later when a truck delivered contaminated building materials to the Los Alamos National Laboratory drove through a radiation monitoring station. Contamination was later measured on roads used to transport the original damaged radiation source. Some pellets were actually found embedded in the roadway. In the state of Sinaloa, 109 houses were condemned due to use of contaminated building material. This incident prompted the Nuclear Regulatory Commission and Customs Service to install radiation detection equipment at all major border crossings.
1985 to 1987 – The Therac-25 was a radiation therapy machine produced by Atomic Energy of Canada Limited. It was involved in at least six known accidents between 1985 and 1987, in which patients were given massive overdoses of radiation, which were in some cases on the order of hundreds of grays. At least five patients died of the overdoses. These accidents highlighted the dangers of inadequate software control of safety-critical systems.
September 13, 1987 – In the Goiânia accident, scavengers broke open a radiation-therapy machine in an abandoned clinic in Goiânia, Brazil. They sold the kilocurie (40 TBq) caesium-137 source as a glowing curiosity. Two hundred and fifty persons were contaminated; four died.
June 6, 1988 – Radiation Sterilizers in Decatur, Georgia reported a leak of caesium-137 at their facility. Seventy thousand medical supply containers and milk cartons were recalled. Ten employees were exposed, and three "had enough on them that they contaminated other surfaces," including their homes and cars.
5 February 1989 – Three workers were exposed to gamma rays from the cobalt-60 source in a medical products irradiation plant in San Salvador, El Salvador. The most exposed person died, another lost a limb. A number of safety systems at the plant had been disabled and workers were unaware of the danger posed by the radioactive source.
In 1989, a small capsule containing highly radioactive caesium-137 was found inside the concrete wall in an apartment building in Kramatorsk, Ukraine. It is believed that the capsule, originally contained in a measurement device, was lost sometime during the late 1970s and ended up mixed in with gravel used to construct that building in 1980. By the time the capsule was discovered, six residents of the building had died from leukemia and 17 more received varying doses of radiation. See Kramatorsk nuclear poisoning incident.
June 24, 1990 – Soreq, Israel – An operator at a commercial irradiation facility bypassed the safety systems on the JS6500 sterilizer to clear a jam in the product conveyor area. The one to two minute exposure resulted in a whole body dose estimated at 10 Gy (1,000 rad) or more. He died 36 days later despite extensive medical care.
October 26, 1991 – Nesvizh, Belarus – An operator at an atomic sterilization facility bypassed the safety systems to clear a jammed conveyor. Upon entering the irradiation chamber he was exposed to an estimated whole body dose of 11 Gy, with some portions of the body receiving upwards of 20 Gy. Despite prompt intensive medical care, he died 113 days after the accident.
November 16, 1992 – Indiana Regional Cancer Center – After treating a patient with HDR brachytherapy, personnel ignored alarms indicating high radiation levels and an available radiation survey meter was not used to confirm or rule out the area alarm's signal. The patient was transported back to a nursing home where the source later fell out. The patient received a thousand times the intended dose and died several days later.
November 19, 1992 – A 10 Ci (370 GBq) Co-60 source was taken home by a worker from an industrial irradiation facility in Jilin, Xinzhou (China). This resulted in three deaths. A woman was exposed to radiation while nursing her sick husband, her dose was estimated to be 2.3 Gy by means of a blood test 41 days after the accident, 16 years after the accident the woman has been subject to premature aging which may be a result of her radiation exposure. Her unborn child (induced at 37 weeks, birth weight 2 kilograms) got a dose of almost 2 Gy in utero, at the age of 16 the child had an IQ of 50.
August 31, 1994 – Commerce Township, Michigan – David Hahn's experimental reactor was discovered in his mother's back yard. The unshielded reactor exposed his neighborhood to 1,000 times the normal levels of background radiation.
December 1998 - Istanbul, Turkey - two cobalt-60 teletherapy sources planned for export in 1993 were instead stored in a warehouse in Ankara, then moved to Istanbul, where a new owner sold them off as scrap metal. The buyers dismantled the containers, exposing themselves and others to ionizing radiation. Eighteen persons, including seven children, developed acute radiation syndrome. The exposed source was retrieved, but the other was still unaccounted for one year later.
1999 – A road near Mrima Hill, Kenya was rebuilt using local materials later found to be radioactive. Some workers were exposed to excessive radiation, and many residents of the area were tested for exposure. 2,975 tons[vague] of roadway material were to be dug up to eliminate the hazard.
February 1, 2000 – Samut Prakan radiation accident: The radiation source of an expired teletherapy unit was purchased and transferred without registration, and stored in an unguarded parking lot without warning signs. It was then stolen from a parking lot in Samut Prakarn, Thailand and dismantled in a junkyard for scrap metal. Workers completely removed the cobalt-60 source from the lead shielding, and became ill shortly thereafter. The radioactive nature of the metal and the resulting contamination was not discovered until 18 days later. Seven injuries and three deaths were a result of this incident.
August 2000 -March 2001; at the Instituto Oncologico Nacional of Panama, 28 patients receiving treatment for prostate cancer and cancer of the cervix receive lethal doses of radiations due to a modification in the protocol of measurement of radiation used without a verification test. The negligence, unique in its scope, was investigated by the IAT on date of 26 May-1 June 2001.
February 2001 – A medical accelerator at the Bialystok Oncology Center in Poland malfunctioned, resulting in five female patients receiving excessive doses of radiation while undergoing breast cancer treatment. The incident was revealed when one of the patients complained of a painful radiation burn. In response, a local technician was called in to repair the device, but was unable to do so, and in fact caused further damage. Subsequently, competent authorities were notified, but as the apparatus had been tampered with, they were unable to ascertain the exact doses of radiation received by the patients (localized doses may have been in excess of 60 Gy). No deaths were reported as a result of this incident, although all affected patients had to receive skin grafts. The attending doctor was charged with criminal negligence, but in 2003 a district court ruled that she was not responsible for the incident. The hospital technician was fined.
December 2001 – Three woodcutters in the nation of Georgia found two warm canisters near their camp and spent the night beside them. The canisters were discarded and unshielded heat sources from Soviet radioisotope thermoelectric generators, containing 30 kCi (1.1 PBq) of strontium-90 each. The woodcutters started showing symptoms of radiation sickness within hours, and were subsequently hospitalized with severe radiation burns. The disposal team consisted of 25 men who were restricted to 40 seconds' worth of exposure each while transferring the canisters to lead-lined drums.
March 11, 2002 - INES Level 2 – A 2.5 tonne 60Co gamma source was transported from Cookridge Hospital, Leeds, UK, to Sellafield with defective shielding. As the radiation escaped from the package downwards into the ground, it is not thought that this event caused any injury or disease in either a human or an animal. This event was treated in a serious manner because the defense in depth type of protection for the source had been eroded. If the container had been tipped over in a road crash then a strong beam of gamma rays (83.5 Gy·h−1) would have been aligned in a direction in which it would've been likely to irradiate humans. The company responsible for the transport of the source, AEA Technology plc, was fined £250,000 by a Britishcourt.
2003 – Cape of Navarin, Chukotka Autonomous Okrug, Russia. A radioisotope thermoelectric generator (RTG) located on the Arctic shore was discovered in a highly degraded state. The exposition dose rate at the generator surface was as high as 15 R/h; in July 2004 a second inspection of the same RTG showed that gamma radiation emission had risen to 87 R/h and that strontium-90 had begun to leak into the environment. In November 2003, a completely dismantled RTG located on the Island of Yuzhny Goryachinsky in the Kola Bay was found. The generator's radioactive heat source was found on the ground near the shoreline in the northern part of the island.
September 10, 2004 – Yakutia, Russia. Two radioisotope thermoelectric generators were dropped 50 meters onto the tundra at Zemlya Bunge island during an airlift when the helicopter flew into heavy weather. According to the nuclear regulators, the impact compromised the RTGs' external radiation shielding. At a height of 10 meters above the impact site, the intensity of gamma radiation was measured at 4 mSv/h.
2005 – Dounreay, UK. In September, the site's cementation plant was closed when 266 liters of radioactive reprocessing residues were spilled inside containment. In October, another of the site's reprocessing laboratories was closed down after nose-blow tests of eight workers tested positive for trace radioactivity.
March 11, 2006 – at Fleurus, Belgium, an operator working for the company Sterigenics, at a medical equipment sterilization site, entered the irradiation room and remained there for 20 seconds. The room contained a source of cobalt-60 which was not in the pool of water. Three weeks later, the worker suffered of symptoms typical of an irradiation (vomiting, loss of hair, fatigue). One estimate that he was exposed to a dose of between 4.4 and 4.8 Gy due to a malfunction of the control-command hydraulic system maintaining the radioactive source in the pool. The operator spent over one month in a specialized hospital before going back home. To protect workers, the federal nuclear control agency AFCN and private auditors from AVN recommended Sterigenics to install a redundant system of security. It is an accident of level 4 on the INES scale.
May 5, 2006 – An accidental release of iodine-131 gas at the Prairie Island Nuclear Power Plant in Minnesota exposed approximately one hundred plant workers to low-level radiation. Most workers received 10 to 20 millirads (0.1-0.2 mGy), about the same as a dental X-ray. The workers were wearing protective gear at the time, and no radiation leaked outside the plant to the surrounding area.
Lisa Norris died in 2006 after having been given an overdose of radiation as a result of human error during treatment for a brain tumor at Beatson Oncology Centre in Glasgow (Scotland). The Scottish Government have published an independent investigation of this case. The intended treatment for Lisa Norris was 35 Gy to be delivered by a LINAC machine to the whole of the central nervous system to be delivered in twenty equal fractions of 1.75 Gy, which was to be followed by 19.8 Gy to be delivered to the tumor only (in eleven fractions of 1.8 Gy). In the first phase of the treatment a 58% overdose occurred, and the CNS of Lisa Norris suffered a dose of 55.5 Gy. The second phase of the treatment was abandoned on medical advice, after having lived for some time after the overdose Lisa Norris passed away.
August 23–24, 2008 — INES Level 3 - Fleurus, Belgium - Nuclear material leak
A gaseous leak of a radioisotope of iodine, iodine-131, was detected at a large medical radioisotope laboratory, Institut national des Radio-Eléments. Belgian authorities implemented restrictions on use of local farming produce within 5 km of the leak, when higher-than-expected levels of contamination was detected in local grass. The particular isotope of iodine has a half-life of 8 days. The European Commission sent out a warning over their ECURIE-alert system on the 29th of August. The quantity of radioactivity released into the environment was estimated at 45 GBq I-131, which corresponds to a dose of 160 microsievert (effective dose) for a hypothetical person remaining permanently at the site's enclosure.
January 23, 2008- A licensed Radiologic Technologist, Raven Knickerbocker, at Mad River Community Hospital in Arcata, California performed 151 CT scan slices on a single 3 mm level on the head of a 23 month-old child over a 65-minute period. The child suffered radiation burns (skin erythema) to a small strip of his face and head. In one report, an independent investigation of the child's blood was said to have found "substantial chromosomal damage" but subsequent reports reported no lasting harm. The technologist was fired, and her license was permanently revoked on March 16, 2011 by the state of California, citing "gross negligence". The hospital's radiology manager, Bruce Fleck, testified that Knickerbocker's conduct was "a rogue act of insanity".
April 2010 - INES level 4 - A 35-year old man was hospitalized in New Delhi after handling radioactive scrap metal. Investigation led to the discovery of an amount of scrap metal containing cobalt-60 in the New Delhi industrial district of Mayapuri. The 35-year old man later died from his injuries, while six others remained hospitalized.
July 2010 - During a routine inspection at the Port of Genoa, on Italy's northwest coast, a cargo container from Saudi Arabia containing nearly 23 000 kg of scrap copper was detected to be emitting gamma radiation at a rate of around 500 mSv/h. After spending over a year in quarantine on Port grounds, Italian officials dissected the container using robots and discovered a rod of cobalt-6023 cm long and one-third of an inch in diameter intermingled with the scrap. Officials suspected its provenance to be inappropriately disposed of medical or food-processing equipment. The rod was sent to Germany for further analysis, after which it was likely to be recycled.
May 2013 - J-PARC radioactive isotope leakage accident, In 23 May 2013, high-intensity proton accelerator facility, J-PARC is the accidental leakage of radioactive isotopes that occur in the hadron experimental facility, which is one of the facilities, Tokai-mura, Ibaraki Prefecture. In addition to by which the diffusion of radioactive isotopes due to the malfunction of equipment, response after the accident was incorrect, 33 people out of 55 researchers and workers who were on site at the time have been exposed, to outside the controlled area radioactive isotope small amount of leaked as well. Was evaluated as an event that corresponds to the International Nuclear Event Scale Level 1 (departure) tentatively book cases Japanese Nuclear Regulatory Commission.
Also in May 2013 a batch of metal-studded belts sold by online retailer ASOS.com were confiscated and held in a US radioactive storage facility after testing positive for cobalt-60.
December 2013 - A Mexican truck carrying cobalt-60 intended to be used for hospital radiation therapy was robbed in the early hours of December 4th. This triggered an nation wide search by Mexican authorities. The radioactive containers were found a day later opened on the outskirts of Hueypoxtla. It is assumed that the assailants received a lethal dose of radiation.